mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-26 07:29:55 +00:00
I am really sorry for the noise, but the current state where some parts of the code use TD (from the old name: TargetData) and other parts use DL makes it hard to write a patch that changes where those variables come from and how they are passed along. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201827 91177308-0d34-0410-b5e6-96231b3b80d8
3389 lines
140 KiB
C++
3389 lines
140 KiB
C++
//===- InstCombineCompares.cpp --------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the visitICmp and visitFCmp functions.
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//
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//===----------------------------------------------------------------------===//
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#include "InstCombine.h"
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#include "llvm/Analysis/ConstantFolding.h"
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#include "llvm/Analysis/InstructionSimplify.h"
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#include "llvm/Analysis/MemoryBuiltins.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/IntrinsicInst.h"
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#include "llvm/Support/ConstantRange.h"
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#include "llvm/Support/GetElementPtrTypeIterator.h"
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#include "llvm/Support/PatternMatch.h"
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#include "llvm/Target/TargetLibraryInfo.h"
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using namespace llvm;
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using namespace PatternMatch;
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static ConstantInt *getOne(Constant *C) {
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return ConstantInt::get(cast<IntegerType>(C->getType()), 1);
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}
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static ConstantInt *ExtractElement(Constant *V, Constant *Idx) {
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return cast<ConstantInt>(ConstantExpr::getExtractElement(V, Idx));
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}
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static bool HasAddOverflow(ConstantInt *Result,
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ConstantInt *In1, ConstantInt *In2,
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bool IsSigned) {
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if (!IsSigned)
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return Result->getValue().ult(In1->getValue());
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if (In2->isNegative())
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return Result->getValue().sgt(In1->getValue());
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return Result->getValue().slt(In1->getValue());
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}
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/// AddWithOverflow - Compute Result = In1+In2, returning true if the result
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/// overflowed for this type.
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static bool AddWithOverflow(Constant *&Result, Constant *In1,
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Constant *In2, bool IsSigned = false) {
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Result = ConstantExpr::getAdd(In1, In2);
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if (VectorType *VTy = dyn_cast<VectorType>(In1->getType())) {
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for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
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Constant *Idx = ConstantInt::get(Type::getInt32Ty(In1->getContext()), i);
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if (HasAddOverflow(ExtractElement(Result, Idx),
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ExtractElement(In1, Idx),
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ExtractElement(In2, Idx),
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IsSigned))
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return true;
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}
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return false;
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}
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return HasAddOverflow(cast<ConstantInt>(Result),
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cast<ConstantInt>(In1), cast<ConstantInt>(In2),
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IsSigned);
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}
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static bool HasSubOverflow(ConstantInt *Result,
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ConstantInt *In1, ConstantInt *In2,
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bool IsSigned) {
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if (!IsSigned)
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return Result->getValue().ugt(In1->getValue());
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if (In2->isNegative())
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return Result->getValue().slt(In1->getValue());
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return Result->getValue().sgt(In1->getValue());
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}
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/// SubWithOverflow - Compute Result = In1-In2, returning true if the result
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/// overflowed for this type.
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static bool SubWithOverflow(Constant *&Result, Constant *In1,
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Constant *In2, bool IsSigned = false) {
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Result = ConstantExpr::getSub(In1, In2);
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if (VectorType *VTy = dyn_cast<VectorType>(In1->getType())) {
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for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
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Constant *Idx = ConstantInt::get(Type::getInt32Ty(In1->getContext()), i);
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if (HasSubOverflow(ExtractElement(Result, Idx),
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ExtractElement(In1, Idx),
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ExtractElement(In2, Idx),
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IsSigned))
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return true;
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}
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return false;
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}
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return HasSubOverflow(cast<ConstantInt>(Result),
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cast<ConstantInt>(In1), cast<ConstantInt>(In2),
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IsSigned);
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}
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/// isSignBitCheck - Given an exploded icmp instruction, return true if the
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/// comparison only checks the sign bit. If it only checks the sign bit, set
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/// TrueIfSigned if the result of the comparison is true when the input value is
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/// signed.
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static bool isSignBitCheck(ICmpInst::Predicate pred, ConstantInt *RHS,
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bool &TrueIfSigned) {
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switch (pred) {
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case ICmpInst::ICMP_SLT: // True if LHS s< 0
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TrueIfSigned = true;
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return RHS->isZero();
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case ICmpInst::ICMP_SLE: // True if LHS s<= RHS and RHS == -1
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TrueIfSigned = true;
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return RHS->isAllOnesValue();
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case ICmpInst::ICMP_SGT: // True if LHS s> -1
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TrueIfSigned = false;
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return RHS->isAllOnesValue();
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case ICmpInst::ICMP_UGT:
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// True if LHS u> RHS and RHS == high-bit-mask - 1
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TrueIfSigned = true;
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return RHS->isMaxValue(true);
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case ICmpInst::ICMP_UGE:
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// True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc)
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TrueIfSigned = true;
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return RHS->getValue().isSignBit();
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default:
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return false;
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}
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}
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/// Returns true if the exploded icmp can be expressed as a signed comparison
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/// to zero and updates the predicate accordingly.
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/// The signedness of the comparison is preserved.
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static bool isSignTest(ICmpInst::Predicate &pred, const ConstantInt *RHS) {
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if (!ICmpInst::isSigned(pred))
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return false;
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if (RHS->isZero())
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return ICmpInst::isRelational(pred);
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if (RHS->isOne()) {
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if (pred == ICmpInst::ICMP_SLT) {
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pred = ICmpInst::ICMP_SLE;
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return true;
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}
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} else if (RHS->isAllOnesValue()) {
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if (pred == ICmpInst::ICMP_SGT) {
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pred = ICmpInst::ICMP_SGE;
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return true;
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}
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}
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return false;
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}
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// isHighOnes - Return true if the constant is of the form 1+0+.
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// This is the same as lowones(~X).
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static bool isHighOnes(const ConstantInt *CI) {
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return (~CI->getValue() + 1).isPowerOf2();
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}
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/// ComputeSignedMinMaxValuesFromKnownBits - Given a signed integer type and a
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/// set of known zero and one bits, compute the maximum and minimum values that
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/// could have the specified known zero and known one bits, returning them in
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/// min/max.
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static void ComputeSignedMinMaxValuesFromKnownBits(const APInt& KnownZero,
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const APInt& KnownOne,
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APInt& Min, APInt& Max) {
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assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() &&
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KnownZero.getBitWidth() == Min.getBitWidth() &&
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KnownZero.getBitWidth() == Max.getBitWidth() &&
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"KnownZero, KnownOne and Min, Max must have equal bitwidth.");
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APInt UnknownBits = ~(KnownZero|KnownOne);
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// The minimum value is when all unknown bits are zeros, EXCEPT for the sign
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// bit if it is unknown.
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Min = KnownOne;
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Max = KnownOne|UnknownBits;
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if (UnknownBits.isNegative()) { // Sign bit is unknown
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Min.setBit(Min.getBitWidth()-1);
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Max.clearBit(Max.getBitWidth()-1);
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}
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}
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// ComputeUnsignedMinMaxValuesFromKnownBits - Given an unsigned integer type and
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// a set of known zero and one bits, compute the maximum and minimum values that
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// could have the specified known zero and known one bits, returning them in
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// min/max.
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static void ComputeUnsignedMinMaxValuesFromKnownBits(const APInt &KnownZero,
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const APInt &KnownOne,
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APInt &Min, APInt &Max) {
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assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() &&
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KnownZero.getBitWidth() == Min.getBitWidth() &&
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KnownZero.getBitWidth() == Max.getBitWidth() &&
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"Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth.");
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APInt UnknownBits = ~(KnownZero|KnownOne);
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// The minimum value is when the unknown bits are all zeros.
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Min = KnownOne;
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// The maximum value is when the unknown bits are all ones.
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Max = KnownOne|UnknownBits;
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}
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/// FoldCmpLoadFromIndexedGlobal - Called we see this pattern:
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/// cmp pred (load (gep GV, ...)), cmpcst
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/// where GV is a global variable with a constant initializer. Try to simplify
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/// this into some simple computation that does not need the load. For example
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/// we can optimize "icmp eq (load (gep "foo", 0, i)), 0" into "icmp eq i, 3".
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///
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/// If AndCst is non-null, then the loaded value is masked with that constant
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/// before doing the comparison. This handles cases like "A[i]&4 == 0".
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Instruction *InstCombiner::
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FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, GlobalVariable *GV,
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CmpInst &ICI, ConstantInt *AndCst) {
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// We need TD information to know the pointer size unless this is inbounds.
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if (!GEP->isInBounds() && DL == 0)
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return 0;
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Constant *Init = GV->getInitializer();
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if (!isa<ConstantArray>(Init) && !isa<ConstantDataArray>(Init))
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return 0;
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uint64_t ArrayElementCount = Init->getType()->getArrayNumElements();
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if (ArrayElementCount > 1024) return 0; // Don't blow up on huge arrays.
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// There are many forms of this optimization we can handle, for now, just do
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// the simple index into a single-dimensional array.
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//
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// Require: GEP GV, 0, i {{, constant indices}}
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if (GEP->getNumOperands() < 3 ||
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!isa<ConstantInt>(GEP->getOperand(1)) ||
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!cast<ConstantInt>(GEP->getOperand(1))->isZero() ||
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isa<Constant>(GEP->getOperand(2)))
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return 0;
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// Check that indices after the variable are constants and in-range for the
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// type they index. Collect the indices. This is typically for arrays of
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// structs.
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SmallVector<unsigned, 4> LaterIndices;
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Type *EltTy = Init->getType()->getArrayElementType();
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for (unsigned i = 3, e = GEP->getNumOperands(); i != e; ++i) {
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ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(i));
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if (Idx == 0) return 0; // Variable index.
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uint64_t IdxVal = Idx->getZExtValue();
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if ((unsigned)IdxVal != IdxVal) return 0; // Too large array index.
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if (StructType *STy = dyn_cast<StructType>(EltTy))
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EltTy = STy->getElementType(IdxVal);
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else if (ArrayType *ATy = dyn_cast<ArrayType>(EltTy)) {
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if (IdxVal >= ATy->getNumElements()) return 0;
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EltTy = ATy->getElementType();
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} else {
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return 0; // Unknown type.
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}
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LaterIndices.push_back(IdxVal);
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}
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enum { Overdefined = -3, Undefined = -2 };
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// Variables for our state machines.
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// FirstTrueElement/SecondTrueElement - Used to emit a comparison of the form
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// "i == 47 | i == 87", where 47 is the first index the condition is true for,
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// and 87 is the second (and last) index. FirstTrueElement is -2 when
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// undefined, otherwise set to the first true element. SecondTrueElement is
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// -2 when undefined, -3 when overdefined and >= 0 when that index is true.
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int FirstTrueElement = Undefined, SecondTrueElement = Undefined;
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// FirstFalseElement/SecondFalseElement - Used to emit a comparison of the
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// form "i != 47 & i != 87". Same state transitions as for true elements.
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int FirstFalseElement = Undefined, SecondFalseElement = Undefined;
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/// TrueRangeEnd/FalseRangeEnd - In conjunction with First*Element, these
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/// define a state machine that triggers for ranges of values that the index
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/// is true or false for. This triggers on things like "abbbbc"[i] == 'b'.
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/// This is -2 when undefined, -3 when overdefined, and otherwise the last
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/// index in the range (inclusive). We use -2 for undefined here because we
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/// use relative comparisons and don't want 0-1 to match -1.
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int TrueRangeEnd = Undefined, FalseRangeEnd = Undefined;
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// MagicBitvector - This is a magic bitvector where we set a bit if the
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// comparison is true for element 'i'. If there are 64 elements or less in
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// the array, this will fully represent all the comparison results.
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uint64_t MagicBitvector = 0;
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// Scan the array and see if one of our patterns matches.
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Constant *CompareRHS = cast<Constant>(ICI.getOperand(1));
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for (unsigned i = 0, e = ArrayElementCount; i != e; ++i) {
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Constant *Elt = Init->getAggregateElement(i);
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if (Elt == 0) return 0;
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// If this is indexing an array of structures, get the structure element.
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if (!LaterIndices.empty())
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Elt = ConstantExpr::getExtractValue(Elt, LaterIndices);
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// If the element is masked, handle it.
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if (AndCst) Elt = ConstantExpr::getAnd(Elt, AndCst);
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// Find out if the comparison would be true or false for the i'th element.
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Constant *C = ConstantFoldCompareInstOperands(ICI.getPredicate(), Elt,
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CompareRHS, DL, TLI);
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// If the result is undef for this element, ignore it.
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if (isa<UndefValue>(C)) {
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// Extend range state machines to cover this element in case there is an
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// undef in the middle of the range.
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if (TrueRangeEnd == (int)i-1)
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TrueRangeEnd = i;
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if (FalseRangeEnd == (int)i-1)
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FalseRangeEnd = i;
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continue;
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}
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// If we can't compute the result for any of the elements, we have to give
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// up evaluating the entire conditional.
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if (!isa<ConstantInt>(C)) return 0;
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// Otherwise, we know if the comparison is true or false for this element,
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// update our state machines.
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bool IsTrueForElt = !cast<ConstantInt>(C)->isZero();
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// State machine for single/double/range index comparison.
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if (IsTrueForElt) {
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// Update the TrueElement state machine.
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if (FirstTrueElement == Undefined)
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FirstTrueElement = TrueRangeEnd = i; // First true element.
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else {
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// Update double-compare state machine.
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if (SecondTrueElement == Undefined)
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SecondTrueElement = i;
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else
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SecondTrueElement = Overdefined;
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// Update range state machine.
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if (TrueRangeEnd == (int)i-1)
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TrueRangeEnd = i;
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else
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TrueRangeEnd = Overdefined;
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}
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} else {
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// Update the FalseElement state machine.
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if (FirstFalseElement == Undefined)
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FirstFalseElement = FalseRangeEnd = i; // First false element.
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else {
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// Update double-compare state machine.
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if (SecondFalseElement == Undefined)
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SecondFalseElement = i;
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else
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SecondFalseElement = Overdefined;
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// Update range state machine.
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if (FalseRangeEnd == (int)i-1)
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FalseRangeEnd = i;
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else
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FalseRangeEnd = Overdefined;
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}
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}
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// If this element is in range, update our magic bitvector.
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if (i < 64 && IsTrueForElt)
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MagicBitvector |= 1ULL << i;
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// If all of our states become overdefined, bail out early. Since the
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// predicate is expensive, only check it every 8 elements. This is only
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// really useful for really huge arrays.
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if ((i & 8) == 0 && i >= 64 && SecondTrueElement == Overdefined &&
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SecondFalseElement == Overdefined && TrueRangeEnd == Overdefined &&
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FalseRangeEnd == Overdefined)
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return 0;
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}
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// Now that we've scanned the entire array, emit our new comparison(s). We
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// order the state machines in complexity of the generated code.
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Value *Idx = GEP->getOperand(2);
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// If the index is larger than the pointer size of the target, truncate the
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// index down like the GEP would do implicitly. We don't have to do this for
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// an inbounds GEP because the index can't be out of range.
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if (!GEP->isInBounds()) {
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Type *IntPtrTy = DL->getIntPtrType(GEP->getType());
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unsigned PtrSize = IntPtrTy->getIntegerBitWidth();
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if (Idx->getType()->getPrimitiveSizeInBits() > PtrSize)
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Idx = Builder->CreateTrunc(Idx, IntPtrTy);
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}
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// If the comparison is only true for one or two elements, emit direct
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// comparisons.
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if (SecondTrueElement != Overdefined) {
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// None true -> false.
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if (FirstTrueElement == Undefined)
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return ReplaceInstUsesWith(ICI, Builder->getFalse());
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Value *FirstTrueIdx = ConstantInt::get(Idx->getType(), FirstTrueElement);
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// True for one element -> 'i == 47'.
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if (SecondTrueElement == Undefined)
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return new ICmpInst(ICmpInst::ICMP_EQ, Idx, FirstTrueIdx);
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// True for two elements -> 'i == 47 | i == 72'.
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Value *C1 = Builder->CreateICmpEQ(Idx, FirstTrueIdx);
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Value *SecondTrueIdx = ConstantInt::get(Idx->getType(), SecondTrueElement);
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Value *C2 = Builder->CreateICmpEQ(Idx, SecondTrueIdx);
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return BinaryOperator::CreateOr(C1, C2);
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}
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// If the comparison is only false for one or two elements, emit direct
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// comparisons.
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if (SecondFalseElement != Overdefined) {
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// None false -> true.
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if (FirstFalseElement == Undefined)
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return ReplaceInstUsesWith(ICI, Builder->getTrue());
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Value *FirstFalseIdx = ConstantInt::get(Idx->getType(), FirstFalseElement);
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// False for one element -> 'i != 47'.
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if (SecondFalseElement == Undefined)
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return new ICmpInst(ICmpInst::ICMP_NE, Idx, FirstFalseIdx);
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// False for two elements -> 'i != 47 & i != 72'.
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Value *C1 = Builder->CreateICmpNE(Idx, FirstFalseIdx);
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Value *SecondFalseIdx = ConstantInt::get(Idx->getType(),SecondFalseElement);
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Value *C2 = Builder->CreateICmpNE(Idx, SecondFalseIdx);
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return BinaryOperator::CreateAnd(C1, C2);
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}
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// If the comparison can be replaced with a range comparison for the elements
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// where it is true, emit the range check.
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if (TrueRangeEnd != Overdefined) {
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assert(TrueRangeEnd != FirstTrueElement && "Should emit single compare");
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// Generate (i-FirstTrue) <u (TrueRangeEnd-FirstTrue+1).
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if (FirstTrueElement) {
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Value *Offs = ConstantInt::get(Idx->getType(), -FirstTrueElement);
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Idx = Builder->CreateAdd(Idx, Offs);
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}
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Value *End = ConstantInt::get(Idx->getType(),
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TrueRangeEnd-FirstTrueElement+1);
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return new ICmpInst(ICmpInst::ICMP_ULT, Idx, End);
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}
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// False range check.
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if (FalseRangeEnd != Overdefined) {
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assert(FalseRangeEnd != FirstFalseElement && "Should emit single compare");
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// Generate (i-FirstFalse) >u (FalseRangeEnd-FirstFalse).
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if (FirstFalseElement) {
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Value *Offs = ConstantInt::get(Idx->getType(), -FirstFalseElement);
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Idx = Builder->CreateAdd(Idx, Offs);
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}
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Value *End = ConstantInt::get(Idx->getType(),
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FalseRangeEnd-FirstFalseElement);
|
|
return new ICmpInst(ICmpInst::ICMP_UGT, Idx, End);
|
|
}
|
|
|
|
|
|
// If a magic bitvector captures the entire comparison state
|
|
// of this load, replace it with computation that does:
|
|
// ((magic_cst >> i) & 1) != 0
|
|
{
|
|
Type *Ty = 0;
|
|
|
|
// Look for an appropriate type:
|
|
// - The type of Idx if the magic fits
|
|
// - The smallest fitting legal type if we have a DataLayout
|
|
// - Default to i32
|
|
if (ArrayElementCount <= Idx->getType()->getIntegerBitWidth())
|
|
Ty = Idx->getType();
|
|
else if (DL)
|
|
Ty = DL->getSmallestLegalIntType(Init->getContext(), ArrayElementCount);
|
|
else if (ArrayElementCount <= 32)
|
|
Ty = Type::getInt32Ty(Init->getContext());
|
|
|
|
if (Ty != 0) {
|
|
Value *V = Builder->CreateIntCast(Idx, Ty, false);
|
|
V = Builder->CreateLShr(ConstantInt::get(Ty, MagicBitvector), V);
|
|
V = Builder->CreateAnd(ConstantInt::get(Ty, 1), V);
|
|
return new ICmpInst(ICmpInst::ICMP_NE, V, ConstantInt::get(Ty, 0));
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
/// EvaluateGEPOffsetExpression - Return a value that can be used to compare
|
|
/// the *offset* implied by a GEP to zero. For example, if we have &A[i], we
|
|
/// want to return 'i' for "icmp ne i, 0". Note that, in general, indices can
|
|
/// be complex, and scales are involved. The above expression would also be
|
|
/// legal to codegen as "icmp ne (i*4), 0" (assuming A is a pointer to i32).
|
|
/// This later form is less amenable to optimization though, and we are allowed
|
|
/// to generate the first by knowing that pointer arithmetic doesn't overflow.
|
|
///
|
|
/// If we can't emit an optimized form for this expression, this returns null.
|
|
///
|
|
static Value *EvaluateGEPOffsetExpression(User *GEP, InstCombiner &IC) {
|
|
DataLayout &DL = *IC.getDataLayout();
|
|
gep_type_iterator GTI = gep_type_begin(GEP);
|
|
|
|
// Check to see if this gep only has a single variable index. If so, and if
|
|
// any constant indices are a multiple of its scale, then we can compute this
|
|
// in terms of the scale of the variable index. For example, if the GEP
|
|
// implies an offset of "12 + i*4", then we can codegen this as "3 + i",
|
|
// because the expression will cross zero at the same point.
|
|
unsigned i, e = GEP->getNumOperands();
|
|
int64_t Offset = 0;
|
|
for (i = 1; i != e; ++i, ++GTI) {
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) {
|
|
// Compute the aggregate offset of constant indices.
|
|
if (CI->isZero()) continue;
|
|
|
|
// Handle a struct index, which adds its field offset to the pointer.
|
|
if (StructType *STy = dyn_cast<StructType>(*GTI)) {
|
|
Offset += DL.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
|
|
} else {
|
|
uint64_t Size = DL.getTypeAllocSize(GTI.getIndexedType());
|
|
Offset += Size*CI->getSExtValue();
|
|
}
|
|
} else {
|
|
// Found our variable index.
|
|
break;
|
|
}
|
|
}
|
|
|
|
// If there are no variable indices, we must have a constant offset, just
|
|
// evaluate it the general way.
|
|
if (i == e) return 0;
|
|
|
|
Value *VariableIdx = GEP->getOperand(i);
|
|
// Determine the scale factor of the variable element. For example, this is
|
|
// 4 if the variable index is into an array of i32.
|
|
uint64_t VariableScale = DL.getTypeAllocSize(GTI.getIndexedType());
|
|
|
|
// Verify that there are no other variable indices. If so, emit the hard way.
|
|
for (++i, ++GTI; i != e; ++i, ++GTI) {
|
|
ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i));
|
|
if (!CI) return 0;
|
|
|
|
// Compute the aggregate offset of constant indices.
|
|
if (CI->isZero()) continue;
|
|
|
|
// Handle a struct index, which adds its field offset to the pointer.
|
|
if (StructType *STy = dyn_cast<StructType>(*GTI)) {
|
|
Offset += DL.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
|
|
} else {
|
|
uint64_t Size = DL.getTypeAllocSize(GTI.getIndexedType());
|
|
Offset += Size*CI->getSExtValue();
|
|
}
|
|
}
|
|
|
|
|
|
|
|
// Okay, we know we have a single variable index, which must be a
|
|
// pointer/array/vector index. If there is no offset, life is simple, return
|
|
// the index.
|
|
Type *IntPtrTy = DL.getIntPtrType(GEP->getOperand(0)->getType());
|
|
unsigned IntPtrWidth = IntPtrTy->getIntegerBitWidth();
|
|
if (Offset == 0) {
|
|
// Cast to intptrty in case a truncation occurs. If an extension is needed,
|
|
// we don't need to bother extending: the extension won't affect where the
|
|
// computation crosses zero.
|
|
if (VariableIdx->getType()->getPrimitiveSizeInBits() > IntPtrWidth) {
|
|
VariableIdx = IC.Builder->CreateTrunc(VariableIdx, IntPtrTy);
|
|
}
|
|
return VariableIdx;
|
|
}
|
|
|
|
// Otherwise, there is an index. The computation we will do will be modulo
|
|
// the pointer size, so get it.
|
|
uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
|
|
|
|
Offset &= PtrSizeMask;
|
|
VariableScale &= PtrSizeMask;
|
|
|
|
// To do this transformation, any constant index must be a multiple of the
|
|
// variable scale factor. For example, we can evaluate "12 + 4*i" as "3 + i",
|
|
// but we can't evaluate "10 + 3*i" in terms of i. Check that the offset is a
|
|
// multiple of the variable scale.
|
|
int64_t NewOffs = Offset / (int64_t)VariableScale;
|
|
if (Offset != NewOffs*(int64_t)VariableScale)
|
|
return 0;
|
|
|
|
// Okay, we can do this evaluation. Start by converting the index to intptr.
|
|
if (VariableIdx->getType() != IntPtrTy)
|
|
VariableIdx = IC.Builder->CreateIntCast(VariableIdx, IntPtrTy,
|
|
true /*Signed*/);
|
|
Constant *OffsetVal = ConstantInt::get(IntPtrTy, NewOffs);
|
|
return IC.Builder->CreateAdd(VariableIdx, OffsetVal, "offset");
|
|
}
|
|
|
|
/// FoldGEPICmp - Fold comparisons between a GEP instruction and something
|
|
/// else. At this point we know that the GEP is on the LHS of the comparison.
|
|
Instruction *InstCombiner::FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
|
|
ICmpInst::Predicate Cond,
|
|
Instruction &I) {
|
|
// Don't transform signed compares of GEPs into index compares. Even if the
|
|
// GEP is inbounds, the final add of the base pointer can have signed overflow
|
|
// and would change the result of the icmp.
|
|
// e.g. "&foo[0] <s &foo[1]" can't be folded to "true" because "foo" could be
|
|
// the maximum signed value for the pointer type.
|
|
if (ICmpInst::isSigned(Cond))
|
|
return 0;
|
|
|
|
// Look through bitcasts.
|
|
if (BitCastInst *BCI = dyn_cast<BitCastInst>(RHS))
|
|
RHS = BCI->getOperand(0);
|
|
|
|
Value *PtrBase = GEPLHS->getOperand(0);
|
|
if (DL && PtrBase == RHS && GEPLHS->isInBounds()) {
|
|
// ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
|
|
// This transformation (ignoring the base and scales) is valid because we
|
|
// know pointers can't overflow since the gep is inbounds. See if we can
|
|
// output an optimized form.
|
|
Value *Offset = EvaluateGEPOffsetExpression(GEPLHS, *this);
|
|
|
|
// If not, synthesize the offset the hard way.
|
|
if (Offset == 0)
|
|
Offset = EmitGEPOffset(GEPLHS);
|
|
return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset,
|
|
Constant::getNullValue(Offset->getType()));
|
|
} else if (GEPOperator *GEPRHS = dyn_cast<GEPOperator>(RHS)) {
|
|
// If the base pointers are different, but the indices are the same, just
|
|
// compare the base pointer.
|
|
if (PtrBase != GEPRHS->getOperand(0)) {
|
|
bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
|
|
IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
|
|
GEPRHS->getOperand(0)->getType();
|
|
if (IndicesTheSame)
|
|
for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
|
|
if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
|
|
IndicesTheSame = false;
|
|
break;
|
|
}
|
|
|
|
// If all indices are the same, just compare the base pointers.
|
|
if (IndicesTheSame)
|
|
return new ICmpInst(Cond, GEPLHS->getOperand(0), GEPRHS->getOperand(0));
|
|
|
|
// If we're comparing GEPs with two base pointers that only differ in type
|
|
// and both GEPs have only constant indices or just one use, then fold
|
|
// the compare with the adjusted indices.
|
|
if (DL && GEPLHS->isInBounds() && GEPRHS->isInBounds() &&
|
|
(GEPLHS->hasAllConstantIndices() || GEPLHS->hasOneUse()) &&
|
|
(GEPRHS->hasAllConstantIndices() || GEPRHS->hasOneUse()) &&
|
|
PtrBase->stripPointerCasts() ==
|
|
GEPRHS->getOperand(0)->stripPointerCasts()) {
|
|
Value *Cmp = Builder->CreateICmp(ICmpInst::getSignedPredicate(Cond),
|
|
EmitGEPOffset(GEPLHS),
|
|
EmitGEPOffset(GEPRHS));
|
|
return ReplaceInstUsesWith(I, Cmp);
|
|
}
|
|
|
|
// Otherwise, the base pointers are different and the indices are
|
|
// different, bail out.
|
|
return 0;
|
|
}
|
|
|
|
// If one of the GEPs has all zero indices, recurse.
|
|
bool AllZeros = true;
|
|
for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
|
|
if (!isa<Constant>(GEPLHS->getOperand(i)) ||
|
|
!cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) {
|
|
AllZeros = false;
|
|
break;
|
|
}
|
|
if (AllZeros)
|
|
return FoldGEPICmp(GEPRHS, GEPLHS->getOperand(0),
|
|
ICmpInst::getSwappedPredicate(Cond), I);
|
|
|
|
// If the other GEP has all zero indices, recurse.
|
|
AllZeros = true;
|
|
for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
|
|
if (!isa<Constant>(GEPRHS->getOperand(i)) ||
|
|
!cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) {
|
|
AllZeros = false;
|
|
break;
|
|
}
|
|
if (AllZeros)
|
|
return FoldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I);
|
|
|
|
bool GEPsInBounds = GEPLHS->isInBounds() && GEPRHS->isInBounds();
|
|
if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
|
|
// If the GEPs only differ by one index, compare it.
|
|
unsigned NumDifferences = 0; // Keep track of # differences.
|
|
unsigned DiffOperand = 0; // The operand that differs.
|
|
for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
|
|
if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
|
|
if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
|
|
GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
|
|
// Irreconcilable differences.
|
|
NumDifferences = 2;
|
|
break;
|
|
} else {
|
|
if (NumDifferences++) break;
|
|
DiffOperand = i;
|
|
}
|
|
}
|
|
|
|
if (NumDifferences == 0) // SAME GEP?
|
|
return ReplaceInstUsesWith(I, // No comparison is needed here.
|
|
Builder->getInt1(ICmpInst::isTrueWhenEqual(Cond)));
|
|
|
|
else if (NumDifferences == 1 && GEPsInBounds) {
|
|
Value *LHSV = GEPLHS->getOperand(DiffOperand);
|
|
Value *RHSV = GEPRHS->getOperand(DiffOperand);
|
|
// Make sure we do a signed comparison here.
|
|
return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV);
|
|
}
|
|
}
|
|
|
|
// Only lower this if the icmp is the only user of the GEP or if we expect
|
|
// the result to fold to a constant!
|
|
if (DL &&
|
|
GEPsInBounds &&
|
|
(isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
|
|
(isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
|
|
// ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
|
|
Value *L = EmitGEPOffset(GEPLHS);
|
|
Value *R = EmitGEPOffset(GEPRHS);
|
|
return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R);
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/// FoldICmpAddOpCst - Fold "icmp pred (X+CI), X".
|
|
Instruction *InstCombiner::FoldICmpAddOpCst(Instruction &ICI,
|
|
Value *X, ConstantInt *CI,
|
|
ICmpInst::Predicate Pred) {
|
|
// If we have X+0, exit early (simplifying logic below) and let it get folded
|
|
// elsewhere. icmp X+0, X -> icmp X, X
|
|
if (CI->isZero()) {
|
|
bool isTrue = ICmpInst::isTrueWhenEqual(Pred);
|
|
return ReplaceInstUsesWith(ICI, ConstantInt::get(ICI.getType(), isTrue));
|
|
}
|
|
|
|
// (X+4) == X -> false.
|
|
if (Pred == ICmpInst::ICMP_EQ)
|
|
return ReplaceInstUsesWith(ICI, Builder->getFalse());
|
|
|
|
// (X+4) != X -> true.
|
|
if (Pred == ICmpInst::ICMP_NE)
|
|
return ReplaceInstUsesWith(ICI, Builder->getTrue());
|
|
|
|
// From this point on, we know that (X+C <= X) --> (X+C < X) because C != 0,
|
|
// so the values can never be equal. Similarly for all other "or equals"
|
|
// operators.
|
|
|
|
// (X+1) <u X --> X >u (MAXUINT-1) --> X == 255
|
|
// (X+2) <u X --> X >u (MAXUINT-2) --> X > 253
|
|
// (X+MAXUINT) <u X --> X >u (MAXUINT-MAXUINT) --> X != 0
|
|
if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) {
|
|
Value *R =
|
|
ConstantExpr::getSub(ConstantInt::getAllOnesValue(CI->getType()), CI);
|
|
return new ICmpInst(ICmpInst::ICMP_UGT, X, R);
|
|
}
|
|
|
|
// (X+1) >u X --> X <u (0-1) --> X != 255
|
|
// (X+2) >u X --> X <u (0-2) --> X <u 254
|
|
// (X+MAXUINT) >u X --> X <u (0-MAXUINT) --> X <u 1 --> X == 0
|
|
if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE)
|
|
return new ICmpInst(ICmpInst::ICMP_ULT, X, ConstantExpr::getNeg(CI));
|
|
|
|
unsigned BitWidth = CI->getType()->getPrimitiveSizeInBits();
|
|
ConstantInt *SMax = ConstantInt::get(X->getContext(),
|
|
APInt::getSignedMaxValue(BitWidth));
|
|
|
|
// (X+ 1) <s X --> X >s (MAXSINT-1) --> X == 127
|
|
// (X+ 2) <s X --> X >s (MAXSINT-2) --> X >s 125
|
|
// (X+MAXSINT) <s X --> X >s (MAXSINT-MAXSINT) --> X >s 0
|
|
// (X+MINSINT) <s X --> X >s (MAXSINT-MINSINT) --> X >s -1
|
|
// (X+ -2) <s X --> X >s (MAXSINT- -2) --> X >s 126
|
|
// (X+ -1) <s X --> X >s (MAXSINT- -1) --> X != 127
|
|
if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE)
|
|
return new ICmpInst(ICmpInst::ICMP_SGT, X, ConstantExpr::getSub(SMax, CI));
|
|
|
|
// (X+ 1) >s X --> X <s (MAXSINT-(1-1)) --> X != 127
|
|
// (X+ 2) >s X --> X <s (MAXSINT-(2-1)) --> X <s 126
|
|
// (X+MAXSINT) >s X --> X <s (MAXSINT-(MAXSINT-1)) --> X <s 1
|
|
// (X+MINSINT) >s X --> X <s (MAXSINT-(MINSINT-1)) --> X <s -2
|
|
// (X+ -2) >s X --> X <s (MAXSINT-(-2-1)) --> X <s -126
|
|
// (X+ -1) >s X --> X <s (MAXSINT-(-1-1)) --> X == -128
|
|
|
|
assert(Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE);
|
|
Constant *C = Builder->getInt(CI->getValue()-1);
|
|
return new ICmpInst(ICmpInst::ICMP_SLT, X, ConstantExpr::getSub(SMax, C));
|
|
}
|
|
|
|
/// FoldICmpDivCst - Fold "icmp pred, ([su]div X, DivRHS), CmpRHS" where DivRHS
|
|
/// and CmpRHS are both known to be integer constants.
|
|
Instruction *InstCombiner::FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
|
|
ConstantInt *DivRHS) {
|
|
ConstantInt *CmpRHS = cast<ConstantInt>(ICI.getOperand(1));
|
|
const APInt &CmpRHSV = CmpRHS->getValue();
|
|
|
|
// FIXME: If the operand types don't match the type of the divide
|
|
// then don't attempt this transform. The code below doesn't have the
|
|
// logic to deal with a signed divide and an unsigned compare (and
|
|
// vice versa). This is because (x /s C1) <s C2 produces different
|
|
// results than (x /s C1) <u C2 or (x /u C1) <s C2 or even
|
|
// (x /u C1) <u C2. Simply casting the operands and result won't
|
|
// work. :( The if statement below tests that condition and bails
|
|
// if it finds it.
|
|
bool DivIsSigned = DivI->getOpcode() == Instruction::SDiv;
|
|
if (!ICI.isEquality() && DivIsSigned != ICI.isSigned())
|
|
return 0;
|
|
if (DivRHS->isZero())
|
|
return 0; // The ProdOV computation fails on divide by zero.
|
|
if (DivIsSigned && DivRHS->isAllOnesValue())
|
|
return 0; // The overflow computation also screws up here
|
|
if (DivRHS->isOne()) {
|
|
// This eliminates some funny cases with INT_MIN.
|
|
ICI.setOperand(0, DivI->getOperand(0)); // X/1 == X.
|
|
return &ICI;
|
|
}
|
|
|
|
// Compute Prod = CI * DivRHS. We are essentially solving an equation
|
|
// of form X/C1=C2. We solve for X by multiplying C1 (DivRHS) and
|
|
// C2 (CI). By solving for X we can turn this into a range check
|
|
// instead of computing a divide.
|
|
Constant *Prod = ConstantExpr::getMul(CmpRHS, DivRHS);
|
|
|
|
// Determine if the product overflows by seeing if the product is
|
|
// not equal to the divide. Make sure we do the same kind of divide
|
|
// as in the LHS instruction that we're folding.
|
|
bool ProdOV = (DivIsSigned ? ConstantExpr::getSDiv(Prod, DivRHS) :
|
|
ConstantExpr::getUDiv(Prod, DivRHS)) != CmpRHS;
|
|
|
|
// Get the ICmp opcode
|
|
ICmpInst::Predicate Pred = ICI.getPredicate();
|
|
|
|
/// If the division is known to be exact, then there is no remainder from the
|
|
/// divide, so the covered range size is unit, otherwise it is the divisor.
|
|
ConstantInt *RangeSize = DivI->isExact() ? getOne(Prod) : DivRHS;
|
|
|
|
// Figure out the interval that is being checked. For example, a comparison
|
|
// like "X /u 5 == 0" is really checking that X is in the interval [0, 5).
|
|
// Compute this interval based on the constants involved and the signedness of
|
|
// the compare/divide. This computes a half-open interval, keeping track of
|
|
// whether either value in the interval overflows. After analysis each
|
|
// overflow variable is set to 0 if it's corresponding bound variable is valid
|
|
// -1 if overflowed off the bottom end, or +1 if overflowed off the top end.
|
|
int LoOverflow = 0, HiOverflow = 0;
|
|
Constant *LoBound = 0, *HiBound = 0;
|
|
|
|
if (!DivIsSigned) { // udiv
|
|
// e.g. X/5 op 3 --> [15, 20)
|
|
LoBound = Prod;
|
|
HiOverflow = LoOverflow = ProdOV;
|
|
if (!HiOverflow) {
|
|
// If this is not an exact divide, then many values in the range collapse
|
|
// to the same result value.
|
|
HiOverflow = AddWithOverflow(HiBound, LoBound, RangeSize, false);
|
|
}
|
|
|
|
} else if (DivRHS->getValue().isStrictlyPositive()) { // Divisor is > 0.
|
|
if (CmpRHSV == 0) { // (X / pos) op 0
|
|
// Can't overflow. e.g. X/2 op 0 --> [-1, 2)
|
|
LoBound = ConstantExpr::getNeg(SubOne(RangeSize));
|
|
HiBound = RangeSize;
|
|
} else if (CmpRHSV.isStrictlyPositive()) { // (X / pos) op pos
|
|
LoBound = Prod; // e.g. X/5 op 3 --> [15, 20)
|
|
HiOverflow = LoOverflow = ProdOV;
|
|
if (!HiOverflow)
|
|
HiOverflow = AddWithOverflow(HiBound, Prod, RangeSize, true);
|
|
} else { // (X / pos) op neg
|
|
// e.g. X/5 op -3 --> [-15-4, -15+1) --> [-19, -14)
|
|
HiBound = AddOne(Prod);
|
|
LoOverflow = HiOverflow = ProdOV ? -1 : 0;
|
|
if (!LoOverflow) {
|
|
ConstantInt *DivNeg =cast<ConstantInt>(ConstantExpr::getNeg(RangeSize));
|
|
LoOverflow = AddWithOverflow(LoBound, HiBound, DivNeg, true) ? -1 : 0;
|
|
}
|
|
}
|
|
} else if (DivRHS->isNegative()) { // Divisor is < 0.
|
|
if (DivI->isExact())
|
|
RangeSize = cast<ConstantInt>(ConstantExpr::getNeg(RangeSize));
|
|
if (CmpRHSV == 0) { // (X / neg) op 0
|
|
// e.g. X/-5 op 0 --> [-4, 5)
|
|
LoBound = AddOne(RangeSize);
|
|
HiBound = cast<ConstantInt>(ConstantExpr::getNeg(RangeSize));
|
|
if (HiBound == DivRHS) { // -INTMIN = INTMIN
|
|
HiOverflow = 1; // [INTMIN+1, overflow)
|
|
HiBound = 0; // e.g. X/INTMIN = 0 --> X > INTMIN
|
|
}
|
|
} else if (CmpRHSV.isStrictlyPositive()) { // (X / neg) op pos
|
|
// e.g. X/-5 op 3 --> [-19, -14)
|
|
HiBound = AddOne(Prod);
|
|
HiOverflow = LoOverflow = ProdOV ? -1 : 0;
|
|
if (!LoOverflow)
|
|
LoOverflow = AddWithOverflow(LoBound, HiBound, RangeSize, true) ? -1:0;
|
|
} else { // (X / neg) op neg
|
|
LoBound = Prod; // e.g. X/-5 op -3 --> [15, 20)
|
|
LoOverflow = HiOverflow = ProdOV;
|
|
if (!HiOverflow)
|
|
HiOverflow = SubWithOverflow(HiBound, Prod, RangeSize, true);
|
|
}
|
|
|
|
// Dividing by a negative swaps the condition. LT <-> GT
|
|
Pred = ICmpInst::getSwappedPredicate(Pred);
|
|
}
|
|
|
|
Value *X = DivI->getOperand(0);
|
|
switch (Pred) {
|
|
default: llvm_unreachable("Unhandled icmp opcode!");
|
|
case ICmpInst::ICMP_EQ:
|
|
if (LoOverflow && HiOverflow)
|
|
return ReplaceInstUsesWith(ICI, Builder->getFalse());
|
|
if (HiOverflow)
|
|
return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
|
|
ICmpInst::ICMP_UGE, X, LoBound);
|
|
if (LoOverflow)
|
|
return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
|
|
ICmpInst::ICMP_ULT, X, HiBound);
|
|
return ReplaceInstUsesWith(ICI, InsertRangeTest(X, LoBound, HiBound,
|
|
DivIsSigned, true));
|
|
case ICmpInst::ICMP_NE:
|
|
if (LoOverflow && HiOverflow)
|
|
return ReplaceInstUsesWith(ICI, Builder->getTrue());
|
|
if (HiOverflow)
|
|
return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
|
|
ICmpInst::ICMP_ULT, X, LoBound);
|
|
if (LoOverflow)
|
|
return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
|
|
ICmpInst::ICMP_UGE, X, HiBound);
|
|
return ReplaceInstUsesWith(ICI, InsertRangeTest(X, LoBound, HiBound,
|
|
DivIsSigned, false));
|
|
case ICmpInst::ICMP_ULT:
|
|
case ICmpInst::ICMP_SLT:
|
|
if (LoOverflow == +1) // Low bound is greater than input range.
|
|
return ReplaceInstUsesWith(ICI, Builder->getTrue());
|
|
if (LoOverflow == -1) // Low bound is less than input range.
|
|
return ReplaceInstUsesWith(ICI, Builder->getFalse());
|
|
return new ICmpInst(Pred, X, LoBound);
|
|
case ICmpInst::ICMP_UGT:
|
|
case ICmpInst::ICMP_SGT:
|
|
if (HiOverflow == +1) // High bound greater than input range.
|
|
return ReplaceInstUsesWith(ICI, Builder->getFalse());
|
|
if (HiOverflow == -1) // High bound less than input range.
|
|
return ReplaceInstUsesWith(ICI, Builder->getTrue());
|
|
if (Pred == ICmpInst::ICMP_UGT)
|
|
return new ICmpInst(ICmpInst::ICMP_UGE, X, HiBound);
|
|
return new ICmpInst(ICmpInst::ICMP_SGE, X, HiBound);
|
|
}
|
|
}
|
|
|
|
/// FoldICmpShrCst - Handle "icmp(([al]shr X, cst1), cst2)".
|
|
Instruction *InstCombiner::FoldICmpShrCst(ICmpInst &ICI, BinaryOperator *Shr,
|
|
ConstantInt *ShAmt) {
|
|
const APInt &CmpRHSV = cast<ConstantInt>(ICI.getOperand(1))->getValue();
|
|
|
|
// Check that the shift amount is in range. If not, don't perform
|
|
// undefined shifts. When the shift is visited it will be
|
|
// simplified.
|
|
uint32_t TypeBits = CmpRHSV.getBitWidth();
|
|
uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
|
|
if (ShAmtVal >= TypeBits || ShAmtVal == 0)
|
|
return 0;
|
|
|
|
if (!ICI.isEquality()) {
|
|
// If we have an unsigned comparison and an ashr, we can't simplify this.
|
|
// Similarly for signed comparisons with lshr.
|
|
if (ICI.isSigned() != (Shr->getOpcode() == Instruction::AShr))
|
|
return 0;
|
|
|
|
// Otherwise, all lshr and most exact ashr's are equivalent to a udiv/sdiv
|
|
// by a power of 2. Since we already have logic to simplify these,
|
|
// transform to div and then simplify the resultant comparison.
|
|
if (Shr->getOpcode() == Instruction::AShr &&
|
|
(!Shr->isExact() || ShAmtVal == TypeBits - 1))
|
|
return 0;
|
|
|
|
// Revisit the shift (to delete it).
|
|
Worklist.Add(Shr);
|
|
|
|
Constant *DivCst =
|
|
ConstantInt::get(Shr->getType(), APInt::getOneBitSet(TypeBits, ShAmtVal));
|
|
|
|
Value *Tmp =
|
|
Shr->getOpcode() == Instruction::AShr ?
|
|
Builder->CreateSDiv(Shr->getOperand(0), DivCst, "", Shr->isExact()) :
|
|
Builder->CreateUDiv(Shr->getOperand(0), DivCst, "", Shr->isExact());
|
|
|
|
ICI.setOperand(0, Tmp);
|
|
|
|
// If the builder folded the binop, just return it.
|
|
BinaryOperator *TheDiv = dyn_cast<BinaryOperator>(Tmp);
|
|
if (TheDiv == 0)
|
|
return &ICI;
|
|
|
|
// Otherwise, fold this div/compare.
|
|
assert(TheDiv->getOpcode() == Instruction::SDiv ||
|
|
TheDiv->getOpcode() == Instruction::UDiv);
|
|
|
|
Instruction *Res = FoldICmpDivCst(ICI, TheDiv, cast<ConstantInt>(DivCst));
|
|
assert(Res && "This div/cst should have folded!");
|
|
return Res;
|
|
}
|
|
|
|
|
|
// If we are comparing against bits always shifted out, the
|
|
// comparison cannot succeed.
|
|
APInt Comp = CmpRHSV << ShAmtVal;
|
|
ConstantInt *ShiftedCmpRHS = Builder->getInt(Comp);
|
|
if (Shr->getOpcode() == Instruction::LShr)
|
|
Comp = Comp.lshr(ShAmtVal);
|
|
else
|
|
Comp = Comp.ashr(ShAmtVal);
|
|
|
|
if (Comp != CmpRHSV) { // Comparing against a bit that we know is zero.
|
|
bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
|
|
Constant *Cst = Builder->getInt1(IsICMP_NE);
|
|
return ReplaceInstUsesWith(ICI, Cst);
|
|
}
|
|
|
|
// Otherwise, check to see if the bits shifted out are known to be zero.
|
|
// If so, we can compare against the unshifted value:
|
|
// (X & 4) >> 1 == 2 --> (X & 4) == 4.
|
|
if (Shr->hasOneUse() && Shr->isExact())
|
|
return new ICmpInst(ICI.getPredicate(), Shr->getOperand(0), ShiftedCmpRHS);
|
|
|
|
if (Shr->hasOneUse()) {
|
|
// Otherwise strength reduce the shift into an and.
|
|
APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal));
|
|
Constant *Mask = Builder->getInt(Val);
|
|
|
|
Value *And = Builder->CreateAnd(Shr->getOperand(0),
|
|
Mask, Shr->getName()+".mask");
|
|
return new ICmpInst(ICI.getPredicate(), And, ShiftedCmpRHS);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
|
|
/// visitICmpInstWithInstAndIntCst - Handle "icmp (instr, intcst)".
|
|
///
|
|
Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
|
|
Instruction *LHSI,
|
|
ConstantInt *RHS) {
|
|
const APInt &RHSV = RHS->getValue();
|
|
|
|
switch (LHSI->getOpcode()) {
|
|
case Instruction::Trunc:
|
|
if (ICI.isEquality() && LHSI->hasOneUse()) {
|
|
// Simplify icmp eq (trunc x to i8), 42 -> icmp eq x, 42|highbits if all
|
|
// of the high bits truncated out of x are known.
|
|
unsigned DstBits = LHSI->getType()->getPrimitiveSizeInBits(),
|
|
SrcBits = LHSI->getOperand(0)->getType()->getPrimitiveSizeInBits();
|
|
APInt KnownZero(SrcBits, 0), KnownOne(SrcBits, 0);
|
|
ComputeMaskedBits(LHSI->getOperand(0), KnownZero, KnownOne);
|
|
|
|
// If all the high bits are known, we can do this xform.
|
|
if ((KnownZero|KnownOne).countLeadingOnes() >= SrcBits-DstBits) {
|
|
// Pull in the high bits from known-ones set.
|
|
APInt NewRHS = RHS->getValue().zext(SrcBits);
|
|
NewRHS |= KnownOne & APInt::getHighBitsSet(SrcBits, SrcBits-DstBits);
|
|
return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
|
|
Builder->getInt(NewRHS));
|
|
}
|
|
}
|
|
break;
|
|
|
|
case Instruction::Xor: // (icmp pred (xor X, XorCst), CI)
|
|
if (ConstantInt *XorCst = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
|
|
// If this is a comparison that tests the signbit (X < 0) or (x > -1),
|
|
// fold the xor.
|
|
if ((ICI.getPredicate() == ICmpInst::ICMP_SLT && RHSV == 0) ||
|
|
(ICI.getPredicate() == ICmpInst::ICMP_SGT && RHSV.isAllOnesValue())) {
|
|
Value *CompareVal = LHSI->getOperand(0);
|
|
|
|
// If the sign bit of the XorCst is not set, there is no change to
|
|
// the operation, just stop using the Xor.
|
|
if (!XorCst->isNegative()) {
|
|
ICI.setOperand(0, CompareVal);
|
|
Worklist.Add(LHSI);
|
|
return &ICI;
|
|
}
|
|
|
|
// Was the old condition true if the operand is positive?
|
|
bool isTrueIfPositive = ICI.getPredicate() == ICmpInst::ICMP_SGT;
|
|
|
|
// If so, the new one isn't.
|
|
isTrueIfPositive ^= true;
|
|
|
|
if (isTrueIfPositive)
|
|
return new ICmpInst(ICmpInst::ICMP_SGT, CompareVal,
|
|
SubOne(RHS));
|
|
else
|
|
return new ICmpInst(ICmpInst::ICMP_SLT, CompareVal,
|
|
AddOne(RHS));
|
|
}
|
|
|
|
if (LHSI->hasOneUse()) {
|
|
// (icmp u/s (xor A SignBit), C) -> (icmp s/u A, (xor C SignBit))
|
|
if (!ICI.isEquality() && XorCst->getValue().isSignBit()) {
|
|
const APInt &SignBit = XorCst->getValue();
|
|
ICmpInst::Predicate Pred = ICI.isSigned()
|
|
? ICI.getUnsignedPredicate()
|
|
: ICI.getSignedPredicate();
|
|
return new ICmpInst(Pred, LHSI->getOperand(0),
|
|
Builder->getInt(RHSV ^ SignBit));
|
|
}
|
|
|
|
// (icmp u/s (xor A ~SignBit), C) -> (icmp s/u (xor C ~SignBit), A)
|
|
if (!ICI.isEquality() && XorCst->isMaxValue(true)) {
|
|
const APInt &NotSignBit = XorCst->getValue();
|
|
ICmpInst::Predicate Pred = ICI.isSigned()
|
|
? ICI.getUnsignedPredicate()
|
|
: ICI.getSignedPredicate();
|
|
Pred = ICI.getSwappedPredicate(Pred);
|
|
return new ICmpInst(Pred, LHSI->getOperand(0),
|
|
Builder->getInt(RHSV ^ NotSignBit));
|
|
}
|
|
}
|
|
|
|
// (icmp ugt (xor X, C), ~C) -> (icmp ult X, C)
|
|
// iff -C is a power of 2
|
|
if (ICI.getPredicate() == ICmpInst::ICMP_UGT &&
|
|
XorCst->getValue() == ~RHSV && (RHSV + 1).isPowerOf2())
|
|
return new ICmpInst(ICmpInst::ICMP_ULT, LHSI->getOperand(0), XorCst);
|
|
|
|
// (icmp ult (xor X, C), -C) -> (icmp uge X, C)
|
|
// iff -C is a power of 2
|
|
if (ICI.getPredicate() == ICmpInst::ICMP_ULT &&
|
|
XorCst->getValue() == -RHSV && RHSV.isPowerOf2())
|
|
return new ICmpInst(ICmpInst::ICMP_UGE, LHSI->getOperand(0), XorCst);
|
|
}
|
|
break;
|
|
case Instruction::And: // (icmp pred (and X, AndCst), RHS)
|
|
if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
|
|
LHSI->getOperand(0)->hasOneUse()) {
|
|
ConstantInt *AndCst = cast<ConstantInt>(LHSI->getOperand(1));
|
|
|
|
// If the LHS is an AND of a truncating cast, we can widen the
|
|
// and/compare to be the input width without changing the value
|
|
// produced, eliminating a cast.
|
|
if (TruncInst *Cast = dyn_cast<TruncInst>(LHSI->getOperand(0))) {
|
|
// We can do this transformation if either the AND constant does not
|
|
// have its sign bit set or if it is an equality comparison.
|
|
// Extending a relational comparison when we're checking the sign
|
|
// bit would not work.
|
|
if (ICI.isEquality() ||
|
|
(!AndCst->isNegative() && RHSV.isNonNegative())) {
|
|
Value *NewAnd =
|
|
Builder->CreateAnd(Cast->getOperand(0),
|
|
ConstantExpr::getZExt(AndCst, Cast->getSrcTy()));
|
|
NewAnd->takeName(LHSI);
|
|
return new ICmpInst(ICI.getPredicate(), NewAnd,
|
|
ConstantExpr::getZExt(RHS, Cast->getSrcTy()));
|
|
}
|
|
}
|
|
|
|
// If the LHS is an AND of a zext, and we have an equality compare, we can
|
|
// shrink the and/compare to the smaller type, eliminating the cast.
|
|
if (ZExtInst *Cast = dyn_cast<ZExtInst>(LHSI->getOperand(0))) {
|
|
IntegerType *Ty = cast<IntegerType>(Cast->getSrcTy());
|
|
// Make sure we don't compare the upper bits, SimplifyDemandedBits
|
|
// should fold the icmp to true/false in that case.
|
|
if (ICI.isEquality() && RHSV.getActiveBits() <= Ty->getBitWidth()) {
|
|
Value *NewAnd =
|
|
Builder->CreateAnd(Cast->getOperand(0),
|
|
ConstantExpr::getTrunc(AndCst, Ty));
|
|
NewAnd->takeName(LHSI);
|
|
return new ICmpInst(ICI.getPredicate(), NewAnd,
|
|
ConstantExpr::getTrunc(RHS, Ty));
|
|
}
|
|
}
|
|
|
|
// If this is: (X >> C1) & C2 != C3 (where any shift and any compare
|
|
// could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
|
|
// happens a LOT in code produced by the C front-end, for bitfield
|
|
// access.
|
|
BinaryOperator *Shift = dyn_cast<BinaryOperator>(LHSI->getOperand(0));
|
|
if (Shift && !Shift->isShift())
|
|
Shift = 0;
|
|
|
|
ConstantInt *ShAmt;
|
|
ShAmt = Shift ? dyn_cast<ConstantInt>(Shift->getOperand(1)) : 0;
|
|
|
|
// This seemingly simple opportunity to fold away a shift turns out to
|
|
// be rather complicated. See PR17827
|
|
// ( http://llvm.org/bugs/show_bug.cgi?id=17827 ) for details.
|
|
if (ShAmt) {
|
|
bool CanFold = false;
|
|
unsigned ShiftOpcode = Shift->getOpcode();
|
|
if (ShiftOpcode == Instruction::AShr) {
|
|
// There may be some constraints that make this possible,
|
|
// but nothing simple has been discovered yet.
|
|
CanFold = false;
|
|
} else if (ShiftOpcode == Instruction::Shl) {
|
|
// For a left shift, we can fold if the comparison is not signed.
|
|
// We can also fold a signed comparison if the mask value and
|
|
// comparison value are not negative. These constraints may not be
|
|
// obvious, but we can prove that they are correct using an SMT
|
|
// solver.
|
|
if (!ICI.isSigned() || (!AndCst->isNegative() && !RHS->isNegative()))
|
|
CanFold = true;
|
|
} else if (ShiftOpcode == Instruction::LShr) {
|
|
// For a logical right shift, we can fold if the comparison is not
|
|
// signed. We can also fold a signed comparison if the shifted mask
|
|
// value and the shifted comparison value are not negative.
|
|
// These constraints may not be obvious, but we can prove that they
|
|
// are correct using an SMT solver.
|
|
if (!ICI.isSigned())
|
|
CanFold = true;
|
|
else {
|
|
ConstantInt *ShiftedAndCst =
|
|
cast<ConstantInt>(ConstantExpr::getShl(AndCst, ShAmt));
|
|
ConstantInt *ShiftedRHSCst =
|
|
cast<ConstantInt>(ConstantExpr::getShl(RHS, ShAmt));
|
|
|
|
if (!ShiftedAndCst->isNegative() && !ShiftedRHSCst->isNegative())
|
|
CanFold = true;
|
|
}
|
|
}
|
|
|
|
if (CanFold) {
|
|
Constant *NewCst;
|
|
if (ShiftOpcode == Instruction::Shl)
|
|
NewCst = ConstantExpr::getLShr(RHS, ShAmt);
|
|
else
|
|
NewCst = ConstantExpr::getShl(RHS, ShAmt);
|
|
|
|
// Check to see if we are shifting out any of the bits being
|
|
// compared.
|
|
if (ConstantExpr::get(ShiftOpcode, NewCst, ShAmt) != RHS) {
|
|
// If we shifted bits out, the fold is not going to work out.
|
|
// As a special case, check to see if this means that the
|
|
// result is always true or false now.
|
|
if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
|
|
return ReplaceInstUsesWith(ICI, Builder->getFalse());
|
|
if (ICI.getPredicate() == ICmpInst::ICMP_NE)
|
|
return ReplaceInstUsesWith(ICI, Builder->getTrue());
|
|
} else {
|
|
ICI.setOperand(1, NewCst);
|
|
Constant *NewAndCst;
|
|
if (ShiftOpcode == Instruction::Shl)
|
|
NewAndCst = ConstantExpr::getLShr(AndCst, ShAmt);
|
|
else
|
|
NewAndCst = ConstantExpr::getShl(AndCst, ShAmt);
|
|
LHSI->setOperand(1, NewAndCst);
|
|
LHSI->setOperand(0, Shift->getOperand(0));
|
|
Worklist.Add(Shift); // Shift is dead.
|
|
return &ICI;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Turn ((X >> Y) & C) == 0 into (X & (C << Y)) == 0. The later is
|
|
// preferable because it allows the C<<Y expression to be hoisted out
|
|
// of a loop if Y is invariant and X is not.
|
|
if (Shift && Shift->hasOneUse() && RHSV == 0 &&
|
|
ICI.isEquality() && !Shift->isArithmeticShift() &&
|
|
!isa<Constant>(Shift->getOperand(0))) {
|
|
// Compute C << Y.
|
|
Value *NS;
|
|
if (Shift->getOpcode() == Instruction::LShr) {
|
|
NS = Builder->CreateShl(AndCst, Shift->getOperand(1));
|
|
} else {
|
|
// Insert a logical shift.
|
|
NS = Builder->CreateLShr(AndCst, Shift->getOperand(1));
|
|
}
|
|
|
|
// Compute X & (C << Y).
|
|
Value *NewAnd =
|
|
Builder->CreateAnd(Shift->getOperand(0), NS, LHSI->getName());
|
|
|
|
ICI.setOperand(0, NewAnd);
|
|
return &ICI;
|
|
}
|
|
|
|
// Replace ((X & AndCst) > RHSV) with ((X & AndCst) != 0), if any
|
|
// bit set in (X & AndCst) will produce a result greater than RHSV.
|
|
if (ICI.getPredicate() == ICmpInst::ICMP_UGT) {
|
|
unsigned NTZ = AndCst->getValue().countTrailingZeros();
|
|
if ((NTZ < AndCst->getBitWidth()) &&
|
|
APInt::getOneBitSet(AndCst->getBitWidth(), NTZ).ugt(RHSV))
|
|
return new ICmpInst(ICmpInst::ICMP_NE, LHSI,
|
|
Constant::getNullValue(RHS->getType()));
|
|
}
|
|
}
|
|
|
|
// Try to optimize things like "A[i]&42 == 0" to index computations.
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(LHSI->getOperand(0))) {
|
|
if (GetElementPtrInst *GEP =
|
|
dyn_cast<GetElementPtrInst>(LI->getOperand(0)))
|
|
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
|
|
if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
|
|
!LI->isVolatile() && isa<ConstantInt>(LHSI->getOperand(1))) {
|
|
ConstantInt *C = cast<ConstantInt>(LHSI->getOperand(1));
|
|
if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV,ICI, C))
|
|
return Res;
|
|
}
|
|
}
|
|
|
|
// X & -C == -C -> X > u ~C
|
|
// X & -C != -C -> X <= u ~C
|
|
// iff C is a power of 2
|
|
if (ICI.isEquality() && RHS == LHSI->getOperand(1) && (-RHSV).isPowerOf2())
|
|
return new ICmpInst(
|
|
ICI.getPredicate() == ICmpInst::ICMP_EQ ? ICmpInst::ICMP_UGT
|
|
: ICmpInst::ICMP_ULE,
|
|
LHSI->getOperand(0), SubOne(RHS));
|
|
break;
|
|
|
|
case Instruction::Or: {
|
|
if (!ICI.isEquality() || !RHS->isNullValue() || !LHSI->hasOneUse())
|
|
break;
|
|
Value *P, *Q;
|
|
if (match(LHSI, m_Or(m_PtrToInt(m_Value(P)), m_PtrToInt(m_Value(Q))))) {
|
|
// Simplify icmp eq (or (ptrtoint P), (ptrtoint Q)), 0
|
|
// -> and (icmp eq P, null), (icmp eq Q, null).
|
|
Value *ICIP = Builder->CreateICmp(ICI.getPredicate(), P,
|
|
Constant::getNullValue(P->getType()));
|
|
Value *ICIQ = Builder->CreateICmp(ICI.getPredicate(), Q,
|
|
Constant::getNullValue(Q->getType()));
|
|
Instruction *Op;
|
|
if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
|
|
Op = BinaryOperator::CreateAnd(ICIP, ICIQ);
|
|
else
|
|
Op = BinaryOperator::CreateOr(ICIP, ICIQ);
|
|
return Op;
|
|
}
|
|
break;
|
|
}
|
|
|
|
case Instruction::Mul: { // (icmp pred (mul X, Val), CI)
|
|
ConstantInt *Val = dyn_cast<ConstantInt>(LHSI->getOperand(1));
|
|
if (!Val) break;
|
|
|
|
// If this is a signed comparison to 0 and the mul is sign preserving,
|
|
// use the mul LHS operand instead.
|
|
ICmpInst::Predicate pred = ICI.getPredicate();
|
|
if (isSignTest(pred, RHS) && !Val->isZero() &&
|
|
cast<BinaryOperator>(LHSI)->hasNoSignedWrap())
|
|
return new ICmpInst(Val->isNegative() ?
|
|
ICmpInst::getSwappedPredicate(pred) : pred,
|
|
LHSI->getOperand(0),
|
|
Constant::getNullValue(RHS->getType()));
|
|
|
|
break;
|
|
}
|
|
|
|
case Instruction::Shl: { // (icmp pred (shl X, ShAmt), CI)
|
|
uint32_t TypeBits = RHSV.getBitWidth();
|
|
ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
|
|
if (!ShAmt) {
|
|
Value *X;
|
|
// (1 << X) pred P2 -> X pred Log2(P2)
|
|
if (match(LHSI, m_Shl(m_One(), m_Value(X)))) {
|
|
bool RHSVIsPowerOf2 = RHSV.isPowerOf2();
|
|
ICmpInst::Predicate Pred = ICI.getPredicate();
|
|
if (ICI.isUnsigned()) {
|
|
if (!RHSVIsPowerOf2) {
|
|
// (1 << X) < 30 -> X <= 4
|
|
// (1 << X) <= 30 -> X <= 4
|
|
// (1 << X) >= 30 -> X > 4
|
|
// (1 << X) > 30 -> X > 4
|
|
if (Pred == ICmpInst::ICMP_ULT)
|
|
Pred = ICmpInst::ICMP_ULE;
|
|
else if (Pred == ICmpInst::ICMP_UGE)
|
|
Pred = ICmpInst::ICMP_UGT;
|
|
}
|
|
unsigned RHSLog2 = RHSV.logBase2();
|
|
|
|
// (1 << X) >= 2147483648 -> X >= 31 -> X == 31
|
|
// (1 << X) > 2147483648 -> X > 31 -> false
|
|
// (1 << X) <= 2147483648 -> X <= 31 -> true
|
|
// (1 << X) < 2147483648 -> X < 31 -> X != 31
|
|
if (RHSLog2 == TypeBits-1) {
|
|
if (Pred == ICmpInst::ICMP_UGE)
|
|
Pred = ICmpInst::ICMP_EQ;
|
|
else if (Pred == ICmpInst::ICMP_UGT)
|
|
return ReplaceInstUsesWith(ICI, Builder->getFalse());
|
|
else if (Pred == ICmpInst::ICMP_ULE)
|
|
return ReplaceInstUsesWith(ICI, Builder->getTrue());
|
|
else if (Pred == ICmpInst::ICMP_ULT)
|
|
Pred = ICmpInst::ICMP_NE;
|
|
}
|
|
|
|
return new ICmpInst(Pred, X,
|
|
ConstantInt::get(RHS->getType(), RHSLog2));
|
|
} else if (ICI.isSigned()) {
|
|
if (RHSV.isAllOnesValue()) {
|
|
// (1 << X) <= -1 -> X == 31
|
|
if (Pred == ICmpInst::ICMP_SLE)
|
|
return new ICmpInst(ICmpInst::ICMP_EQ, X,
|
|
ConstantInt::get(RHS->getType(), TypeBits-1));
|
|
|
|
// (1 << X) > -1 -> X != 31
|
|
if (Pred == ICmpInst::ICMP_SGT)
|
|
return new ICmpInst(ICmpInst::ICMP_NE, X,
|
|
ConstantInt::get(RHS->getType(), TypeBits-1));
|
|
} else if (!RHSV) {
|
|
// (1 << X) < 0 -> X == 31
|
|
// (1 << X) <= 0 -> X == 31
|
|
if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE)
|
|
return new ICmpInst(ICmpInst::ICMP_EQ, X,
|
|
ConstantInt::get(RHS->getType(), TypeBits-1));
|
|
|
|
// (1 << X) >= 0 -> X != 31
|
|
// (1 << X) > 0 -> X != 31
|
|
if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE)
|
|
return new ICmpInst(ICmpInst::ICMP_NE, X,
|
|
ConstantInt::get(RHS->getType(), TypeBits-1));
|
|
}
|
|
} else if (ICI.isEquality()) {
|
|
if (RHSVIsPowerOf2)
|
|
return new ICmpInst(
|
|
Pred, X, ConstantInt::get(RHS->getType(), RHSV.logBase2()));
|
|
|
|
return ReplaceInstUsesWith(
|
|
ICI, Pred == ICmpInst::ICMP_EQ ? Builder->getFalse()
|
|
: Builder->getTrue());
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
|
|
// Check that the shift amount is in range. If not, don't perform
|
|
// undefined shifts. When the shift is visited it will be
|
|
// simplified.
|
|
if (ShAmt->uge(TypeBits))
|
|
break;
|
|
|
|
if (ICI.isEquality()) {
|
|
// If we are comparing against bits always shifted out, the
|
|
// comparison cannot succeed.
|
|
Constant *Comp =
|
|
ConstantExpr::getShl(ConstantExpr::getLShr(RHS, ShAmt),
|
|
ShAmt);
|
|
if (Comp != RHS) {// Comparing against a bit that we know is zero.
|
|
bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
|
|
Constant *Cst = Builder->getInt1(IsICMP_NE);
|
|
return ReplaceInstUsesWith(ICI, Cst);
|
|
}
|
|
|
|
// If the shift is NUW, then it is just shifting out zeros, no need for an
|
|
// AND.
|
|
if (cast<BinaryOperator>(LHSI)->hasNoUnsignedWrap())
|
|
return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
|
|
ConstantExpr::getLShr(RHS, ShAmt));
|
|
|
|
// If the shift is NSW and we compare to 0, then it is just shifting out
|
|
// sign bits, no need for an AND either.
|
|
if (cast<BinaryOperator>(LHSI)->hasNoSignedWrap() && RHSV == 0)
|
|
return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
|
|
ConstantExpr::getLShr(RHS, ShAmt));
|
|
|
|
if (LHSI->hasOneUse()) {
|
|
// Otherwise strength reduce the shift into an and.
|
|
uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
|
|
Constant *Mask = Builder->getInt(APInt::getLowBitsSet(TypeBits,
|
|
TypeBits - ShAmtVal));
|
|
|
|
Value *And =
|
|
Builder->CreateAnd(LHSI->getOperand(0),Mask, LHSI->getName()+".mask");
|
|
return new ICmpInst(ICI.getPredicate(), And,
|
|
ConstantExpr::getLShr(RHS, ShAmt));
|
|
}
|
|
}
|
|
|
|
// If this is a signed comparison to 0 and the shift is sign preserving,
|
|
// use the shift LHS operand instead.
|
|
ICmpInst::Predicate pred = ICI.getPredicate();
|
|
if (isSignTest(pred, RHS) &&
|
|
cast<BinaryOperator>(LHSI)->hasNoSignedWrap())
|
|
return new ICmpInst(pred,
|
|
LHSI->getOperand(0),
|
|
Constant::getNullValue(RHS->getType()));
|
|
|
|
// Otherwise, if this is a comparison of the sign bit, simplify to and/test.
|
|
bool TrueIfSigned = false;
|
|
if (LHSI->hasOneUse() &&
|
|
isSignBitCheck(ICI.getPredicate(), RHS, TrueIfSigned)) {
|
|
// (X << 31) <s 0 --> (X&1) != 0
|
|
Constant *Mask = ConstantInt::get(LHSI->getOperand(0)->getType(),
|
|
APInt::getOneBitSet(TypeBits,
|
|
TypeBits-ShAmt->getZExtValue()-1));
|
|
Value *And =
|
|
Builder->CreateAnd(LHSI->getOperand(0), Mask, LHSI->getName()+".mask");
|
|
return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ,
|
|
And, Constant::getNullValue(And->getType()));
|
|
}
|
|
|
|
// Transform (icmp pred iM (shl iM %v, N), CI)
|
|
// -> (icmp pred i(M-N) (trunc %v iM to i(M-N)), (trunc (CI>>N))
|
|
// Transform the shl to a trunc if (trunc (CI>>N)) has no loss and M-N.
|
|
// This enables to get rid of the shift in favor of a trunc which can be
|
|
// free on the target. It has the additional benefit of comparing to a
|
|
// smaller constant, which will be target friendly.
|
|
unsigned Amt = ShAmt->getLimitedValue(TypeBits-1);
|
|
if (LHSI->hasOneUse() &&
|
|
Amt != 0 && RHSV.countTrailingZeros() >= Amt) {
|
|
Type *NTy = IntegerType::get(ICI.getContext(), TypeBits - Amt);
|
|
Constant *NCI = ConstantExpr::getTrunc(
|
|
ConstantExpr::getAShr(RHS,
|
|
ConstantInt::get(RHS->getType(), Amt)),
|
|
NTy);
|
|
return new ICmpInst(ICI.getPredicate(),
|
|
Builder->CreateTrunc(LHSI->getOperand(0), NTy),
|
|
NCI);
|
|
}
|
|
|
|
break;
|
|
}
|
|
|
|
case Instruction::LShr: // (icmp pred (shr X, ShAmt), CI)
|
|
case Instruction::AShr: {
|
|
// Handle equality comparisons of shift-by-constant.
|
|
BinaryOperator *BO = cast<BinaryOperator>(LHSI);
|
|
if (ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
|
|
if (Instruction *Res = FoldICmpShrCst(ICI, BO, ShAmt))
|
|
return Res;
|
|
}
|
|
|
|
// Handle exact shr's.
|
|
if (ICI.isEquality() && BO->isExact() && BO->hasOneUse()) {
|
|
if (RHSV.isMinValue())
|
|
return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), RHS);
|
|
}
|
|
break;
|
|
}
|
|
|
|
case Instruction::SDiv:
|
|
case Instruction::UDiv:
|
|
// Fold: icmp pred ([us]div X, C1), C2 -> range test
|
|
// Fold this div into the comparison, producing a range check.
|
|
// Determine, based on the divide type, what the range is being
|
|
// checked. If there is an overflow on the low or high side, remember
|
|
// it, otherwise compute the range [low, hi) bounding the new value.
|
|
// See: InsertRangeTest above for the kinds of replacements possible.
|
|
if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1)))
|
|
if (Instruction *R = FoldICmpDivCst(ICI, cast<BinaryOperator>(LHSI),
|
|
DivRHS))
|
|
return R;
|
|
break;
|
|
|
|
case Instruction::Sub: {
|
|
ConstantInt *LHSC = dyn_cast<ConstantInt>(LHSI->getOperand(0));
|
|
if (!LHSC) break;
|
|
const APInt &LHSV = LHSC->getValue();
|
|
|
|
// C1-X <u C2 -> (X|(C2-1)) == C1
|
|
// iff C1 & (C2-1) == C2-1
|
|
// C2 is a power of 2
|
|
if (ICI.getPredicate() == ICmpInst::ICMP_ULT && LHSI->hasOneUse() &&
|
|
RHSV.isPowerOf2() && (LHSV & (RHSV - 1)) == (RHSV - 1))
|
|
return new ICmpInst(ICmpInst::ICMP_EQ,
|
|
Builder->CreateOr(LHSI->getOperand(1), RHSV - 1),
|
|
LHSC);
|
|
|
|
// C1-X >u C2 -> (X|C2) != C1
|
|
// iff C1 & C2 == C2
|
|
// C2+1 is a power of 2
|
|
if (ICI.getPredicate() == ICmpInst::ICMP_UGT && LHSI->hasOneUse() &&
|
|
(RHSV + 1).isPowerOf2() && (LHSV & RHSV) == RHSV)
|
|
return new ICmpInst(ICmpInst::ICMP_NE,
|
|
Builder->CreateOr(LHSI->getOperand(1), RHSV), LHSC);
|
|
break;
|
|
}
|
|
|
|
case Instruction::Add:
|
|
// Fold: icmp pred (add X, C1), C2
|
|
if (!ICI.isEquality()) {
|
|
ConstantInt *LHSC = dyn_cast<ConstantInt>(LHSI->getOperand(1));
|
|
if (!LHSC) break;
|
|
const APInt &LHSV = LHSC->getValue();
|
|
|
|
ConstantRange CR = ICI.makeConstantRange(ICI.getPredicate(), RHSV)
|
|
.subtract(LHSV);
|
|
|
|
if (ICI.isSigned()) {
|
|
if (CR.getLower().isSignBit()) {
|
|
return new ICmpInst(ICmpInst::ICMP_SLT, LHSI->getOperand(0),
|
|
Builder->getInt(CR.getUpper()));
|
|
} else if (CR.getUpper().isSignBit()) {
|
|
return new ICmpInst(ICmpInst::ICMP_SGE, LHSI->getOperand(0),
|
|
Builder->getInt(CR.getLower()));
|
|
}
|
|
} else {
|
|
if (CR.getLower().isMinValue()) {
|
|
return new ICmpInst(ICmpInst::ICMP_ULT, LHSI->getOperand(0),
|
|
Builder->getInt(CR.getUpper()));
|
|
} else if (CR.getUpper().isMinValue()) {
|
|
return new ICmpInst(ICmpInst::ICMP_UGE, LHSI->getOperand(0),
|
|
Builder->getInt(CR.getLower()));
|
|
}
|
|
}
|
|
|
|
// X-C1 <u C2 -> (X & -C2) == C1
|
|
// iff C1 & (C2-1) == 0
|
|
// C2 is a power of 2
|
|
if (ICI.getPredicate() == ICmpInst::ICMP_ULT && LHSI->hasOneUse() &&
|
|
RHSV.isPowerOf2() && (LHSV & (RHSV - 1)) == 0)
|
|
return new ICmpInst(ICmpInst::ICMP_EQ,
|
|
Builder->CreateAnd(LHSI->getOperand(0), -RHSV),
|
|
ConstantExpr::getNeg(LHSC));
|
|
|
|
// X-C1 >u C2 -> (X & ~C2) != C1
|
|
// iff C1 & C2 == 0
|
|
// C2+1 is a power of 2
|
|
if (ICI.getPredicate() == ICmpInst::ICMP_UGT && LHSI->hasOneUse() &&
|
|
(RHSV + 1).isPowerOf2() && (LHSV & RHSV) == 0)
|
|
return new ICmpInst(ICmpInst::ICMP_NE,
|
|
Builder->CreateAnd(LHSI->getOperand(0), ~RHSV),
|
|
ConstantExpr::getNeg(LHSC));
|
|
}
|
|
break;
|
|
}
|
|
|
|
// Simplify icmp_eq and icmp_ne instructions with integer constant RHS.
|
|
if (ICI.isEquality()) {
|
|
bool isICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
|
|
|
|
// If the first operand is (add|sub|and|or|xor|rem) with a constant, and
|
|
// the second operand is a constant, simplify a bit.
|
|
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(LHSI)) {
|
|
switch (BO->getOpcode()) {
|
|
case Instruction::SRem:
|
|
// If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
|
|
if (RHSV == 0 && isa<ConstantInt>(BO->getOperand(1)) &&BO->hasOneUse()){
|
|
const APInt &V = cast<ConstantInt>(BO->getOperand(1))->getValue();
|
|
if (V.sgt(1) && V.isPowerOf2()) {
|
|
Value *NewRem =
|
|
Builder->CreateURem(BO->getOperand(0), BO->getOperand(1),
|
|
BO->getName());
|
|
return new ICmpInst(ICI.getPredicate(), NewRem,
|
|
Constant::getNullValue(BO->getType()));
|
|
}
|
|
}
|
|
break;
|
|
case Instruction::Add:
|
|
// Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
|
|
if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
|
|
if (BO->hasOneUse())
|
|
return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
|
|
ConstantExpr::getSub(RHS, BOp1C));
|
|
} else if (RHSV == 0) {
|
|
// Replace ((add A, B) != 0) with (A != -B) if A or B is
|
|
// efficiently invertible, or if the add has just this one use.
|
|
Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
|
|
|
|
if (Value *NegVal = dyn_castNegVal(BOp1))
|
|
return new ICmpInst(ICI.getPredicate(), BOp0, NegVal);
|
|
if (Value *NegVal = dyn_castNegVal(BOp0))
|
|
return new ICmpInst(ICI.getPredicate(), NegVal, BOp1);
|
|
if (BO->hasOneUse()) {
|
|
Value *Neg = Builder->CreateNeg(BOp1);
|
|
Neg->takeName(BO);
|
|
return new ICmpInst(ICI.getPredicate(), BOp0, Neg);
|
|
}
|
|
}
|
|
break;
|
|
case Instruction::Xor:
|
|
// For the xor case, we can xor two constants together, eliminating
|
|
// the explicit xor.
|
|
if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
|
|
return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
|
|
ConstantExpr::getXor(RHS, BOC));
|
|
} else if (RHSV == 0) {
|
|
// Replace ((xor A, B) != 0) with (A != B)
|
|
return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
|
|
BO->getOperand(1));
|
|
}
|
|
break;
|
|
case Instruction::Sub:
|
|
// Replace ((sub A, B) != C) with (B != A-C) if A & C are constants.
|
|
if (ConstantInt *BOp0C = dyn_cast<ConstantInt>(BO->getOperand(0))) {
|
|
if (BO->hasOneUse())
|
|
return new ICmpInst(ICI.getPredicate(), BO->getOperand(1),
|
|
ConstantExpr::getSub(BOp0C, RHS));
|
|
} else if (RHSV == 0) {
|
|
// Replace ((sub A, B) != 0) with (A != B)
|
|
return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
|
|
BO->getOperand(1));
|
|
}
|
|
break;
|
|
case Instruction::Or:
|
|
// If bits are being or'd in that are not present in the constant we
|
|
// are comparing against, then the comparison could never succeed!
|
|
if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
|
|
Constant *NotCI = ConstantExpr::getNot(RHS);
|
|
if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
|
|
return ReplaceInstUsesWith(ICI, Builder->getInt1(isICMP_NE));
|
|
}
|
|
break;
|
|
|
|
case Instruction::And:
|
|
if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
|
|
// If bits are being compared against that are and'd out, then the
|
|
// comparison can never succeed!
|
|
if ((RHSV & ~BOC->getValue()) != 0)
|
|
return ReplaceInstUsesWith(ICI, Builder->getInt1(isICMP_NE));
|
|
|
|
// If we have ((X & C) == C), turn it into ((X & C) != 0).
|
|
if (RHS == BOC && RHSV.isPowerOf2())
|
|
return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ :
|
|
ICmpInst::ICMP_NE, LHSI,
|
|
Constant::getNullValue(RHS->getType()));
|
|
|
|
// Don't perform the following transforms if the AND has multiple uses
|
|
if (!BO->hasOneUse())
|
|
break;
|
|
|
|
// Replace (and X, (1 << size(X)-1) != 0) with x s< 0
|
|
if (BOC->getValue().isSignBit()) {
|
|
Value *X = BO->getOperand(0);
|
|
Constant *Zero = Constant::getNullValue(X->getType());
|
|
ICmpInst::Predicate pred = isICMP_NE ?
|
|
ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE;
|
|
return new ICmpInst(pred, X, Zero);
|
|
}
|
|
|
|
// ((X & ~7) == 0) --> X < 8
|
|
if (RHSV == 0 && isHighOnes(BOC)) {
|
|
Value *X = BO->getOperand(0);
|
|
Constant *NegX = ConstantExpr::getNeg(BOC);
|
|
ICmpInst::Predicate pred = isICMP_NE ?
|
|
ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
|
|
return new ICmpInst(pred, X, NegX);
|
|
}
|
|
}
|
|
break;
|
|
case Instruction::Mul:
|
|
if (RHSV == 0 && BO->hasNoSignedWrap()) {
|
|
if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
|
|
// The trivial case (mul X, 0) is handled by InstSimplify
|
|
// General case : (mul X, C) != 0 iff X != 0
|
|
// (mul X, C) == 0 iff X == 0
|
|
if (!BOC->isZero())
|
|
return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
|
|
Constant::getNullValue(RHS->getType()));
|
|
}
|
|
}
|
|
break;
|
|
default: break;
|
|
}
|
|
} else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(LHSI)) {
|
|
// Handle icmp {eq|ne} <intrinsic>, intcst.
|
|
switch (II->getIntrinsicID()) {
|
|
case Intrinsic::bswap:
|
|
Worklist.Add(II);
|
|
ICI.setOperand(0, II->getArgOperand(0));
|
|
ICI.setOperand(1, Builder->getInt(RHSV.byteSwap()));
|
|
return &ICI;
|
|
case Intrinsic::ctlz:
|
|
case Intrinsic::cttz:
|
|
// ctz(A) == bitwidth(a) -> A == 0 and likewise for !=
|
|
if (RHSV == RHS->getType()->getBitWidth()) {
|
|
Worklist.Add(II);
|
|
ICI.setOperand(0, II->getArgOperand(0));
|
|
ICI.setOperand(1, ConstantInt::get(RHS->getType(), 0));
|
|
return &ICI;
|
|
}
|
|
break;
|
|
case Intrinsic::ctpop:
|
|
// popcount(A) == 0 -> A == 0 and likewise for !=
|
|
if (RHS->isZero()) {
|
|
Worklist.Add(II);
|
|
ICI.setOperand(0, II->getArgOperand(0));
|
|
ICI.setOperand(1, RHS);
|
|
return &ICI;
|
|
}
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/// visitICmpInstWithCastAndCast - Handle icmp (cast x to y), (cast/cst).
|
|
/// We only handle extending casts so far.
|
|
///
|
|
Instruction *InstCombiner::visitICmpInstWithCastAndCast(ICmpInst &ICI) {
|
|
const CastInst *LHSCI = cast<CastInst>(ICI.getOperand(0));
|
|
Value *LHSCIOp = LHSCI->getOperand(0);
|
|
Type *SrcTy = LHSCIOp->getType();
|
|
Type *DestTy = LHSCI->getType();
|
|
Value *RHSCIOp;
|
|
|
|
// Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the
|
|
// integer type is the same size as the pointer type.
|
|
if (DL && LHSCI->getOpcode() == Instruction::PtrToInt &&
|
|
DL->getPointerTypeSizeInBits(SrcTy) == DestTy->getIntegerBitWidth()) {
|
|
Value *RHSOp = 0;
|
|
if (Constant *RHSC = dyn_cast<Constant>(ICI.getOperand(1))) {
|
|
RHSOp = ConstantExpr::getIntToPtr(RHSC, SrcTy);
|
|
} else if (PtrToIntInst *RHSC = dyn_cast<PtrToIntInst>(ICI.getOperand(1))) {
|
|
RHSOp = RHSC->getOperand(0);
|
|
// If the pointer types don't match, insert a bitcast.
|
|
if (LHSCIOp->getType() != RHSOp->getType())
|
|
RHSOp = Builder->CreateBitCast(RHSOp, LHSCIOp->getType());
|
|
}
|
|
|
|
if (RHSOp)
|
|
return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSOp);
|
|
}
|
|
|
|
// The code below only handles extension cast instructions, so far.
|
|
// Enforce this.
|
|
if (LHSCI->getOpcode() != Instruction::ZExt &&
|
|
LHSCI->getOpcode() != Instruction::SExt)
|
|
return 0;
|
|
|
|
bool isSignedExt = LHSCI->getOpcode() == Instruction::SExt;
|
|
bool isSignedCmp = ICI.isSigned();
|
|
|
|
if (CastInst *CI = dyn_cast<CastInst>(ICI.getOperand(1))) {
|
|
// Not an extension from the same type?
|
|
RHSCIOp = CI->getOperand(0);
|
|
if (RHSCIOp->getType() != LHSCIOp->getType())
|
|
return 0;
|
|
|
|
// If the signedness of the two casts doesn't agree (i.e. one is a sext
|
|
// and the other is a zext), then we can't handle this.
|
|
if (CI->getOpcode() != LHSCI->getOpcode())
|
|
return 0;
|
|
|
|
// Deal with equality cases early.
|
|
if (ICI.isEquality())
|
|
return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
|
|
|
|
// A signed comparison of sign extended values simplifies into a
|
|
// signed comparison.
|
|
if (isSignedCmp && isSignedExt)
|
|
return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
|
|
|
|
// The other three cases all fold into an unsigned comparison.
|
|
return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, RHSCIOp);
|
|
}
|
|
|
|
// If we aren't dealing with a constant on the RHS, exit early
|
|
ConstantInt *CI = dyn_cast<ConstantInt>(ICI.getOperand(1));
|
|
if (!CI)
|
|
return 0;
|
|
|
|
// Compute the constant that would happen if we truncated to SrcTy then
|
|
// reextended to DestTy.
|
|
Constant *Res1 = ConstantExpr::getTrunc(CI, SrcTy);
|
|
Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(),
|
|
Res1, DestTy);
|
|
|
|
// If the re-extended constant didn't change...
|
|
if (Res2 == CI) {
|
|
// Deal with equality cases early.
|
|
if (ICI.isEquality())
|
|
return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1);
|
|
|
|
// A signed comparison of sign extended values simplifies into a
|
|
// signed comparison.
|
|
if (isSignedExt && isSignedCmp)
|
|
return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1);
|
|
|
|
// The other three cases all fold into an unsigned comparison.
|
|
return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, Res1);
|
|
}
|
|
|
|
// The re-extended constant changed so the constant cannot be represented
|
|
// in the shorter type. Consequently, we cannot emit a simple comparison.
|
|
// All the cases that fold to true or false will have already been handled
|
|
// by SimplifyICmpInst, so only deal with the tricky case.
|
|
|
|
if (isSignedCmp || !isSignedExt)
|
|
return 0;
|
|
|
|
// Evaluate the comparison for LT (we invert for GT below). LE and GE cases
|
|
// should have been folded away previously and not enter in here.
|
|
|
|
// We're performing an unsigned comp with a sign extended value.
|
|
// This is true if the input is >= 0. [aka >s -1]
|
|
Constant *NegOne = Constant::getAllOnesValue(SrcTy);
|
|
Value *Result = Builder->CreateICmpSGT(LHSCIOp, NegOne, ICI.getName());
|
|
|
|
// Finally, return the value computed.
|
|
if (ICI.getPredicate() == ICmpInst::ICMP_ULT)
|
|
return ReplaceInstUsesWith(ICI, Result);
|
|
|
|
assert(ICI.getPredicate() == ICmpInst::ICMP_UGT && "ICmp should be folded!");
|
|
return BinaryOperator::CreateNot(Result);
|
|
}
|
|
|
|
/// ProcessUGT_ADDCST_ADD - The caller has matched a pattern of the form:
|
|
/// I = icmp ugt (add (add A, B), CI2), CI1
|
|
/// If this is of the form:
|
|
/// sum = a + b
|
|
/// if (sum+128 >u 255)
|
|
/// Then replace it with llvm.sadd.with.overflow.i8.
|
|
///
|
|
static Instruction *ProcessUGT_ADDCST_ADD(ICmpInst &I, Value *A, Value *B,
|
|
ConstantInt *CI2, ConstantInt *CI1,
|
|
InstCombiner &IC) {
|
|
// The transformation we're trying to do here is to transform this into an
|
|
// llvm.sadd.with.overflow. To do this, we have to replace the original add
|
|
// with a narrower add, and discard the add-with-constant that is part of the
|
|
// range check (if we can't eliminate it, this isn't profitable).
|
|
|
|
// In order to eliminate the add-with-constant, the compare can be its only
|
|
// use.
|
|
Instruction *AddWithCst = cast<Instruction>(I.getOperand(0));
|
|
if (!AddWithCst->hasOneUse()) return 0;
|
|
|
|
// If CI2 is 2^7, 2^15, 2^31, then it might be an sadd.with.overflow.
|
|
if (!CI2->getValue().isPowerOf2()) return 0;
|
|
unsigned NewWidth = CI2->getValue().countTrailingZeros();
|
|
if (NewWidth != 7 && NewWidth != 15 && NewWidth != 31) return 0;
|
|
|
|
// The width of the new add formed is 1 more than the bias.
|
|
++NewWidth;
|
|
|
|
// Check to see that CI1 is an all-ones value with NewWidth bits.
|
|
if (CI1->getBitWidth() == NewWidth ||
|
|
CI1->getValue() != APInt::getLowBitsSet(CI1->getBitWidth(), NewWidth))
|
|
return 0;
|
|
|
|
// This is only really a signed overflow check if the inputs have been
|
|
// sign-extended; check for that condition. For example, if CI2 is 2^31 and
|
|
// the operands of the add are 64 bits wide, we need at least 33 sign bits.
|
|
unsigned NeededSignBits = CI1->getBitWidth() - NewWidth + 1;
|
|
if (IC.ComputeNumSignBits(A) < NeededSignBits ||
|
|
IC.ComputeNumSignBits(B) < NeededSignBits)
|
|
return 0;
|
|
|
|
// In order to replace the original add with a narrower
|
|
// llvm.sadd.with.overflow, the only uses allowed are the add-with-constant
|
|
// and truncates that discard the high bits of the add. Verify that this is
|
|
// the case.
|
|
Instruction *OrigAdd = cast<Instruction>(AddWithCst->getOperand(0));
|
|
for (Value::use_iterator UI = OrigAdd->use_begin(), E = OrigAdd->use_end();
|
|
UI != E; ++UI) {
|
|
if (*UI == AddWithCst) continue;
|
|
|
|
// Only accept truncates for now. We would really like a nice recursive
|
|
// predicate like SimplifyDemandedBits, but which goes downwards the use-def
|
|
// chain to see which bits of a value are actually demanded. If the
|
|
// original add had another add which was then immediately truncated, we
|
|
// could still do the transformation.
|
|
TruncInst *TI = dyn_cast<TruncInst>(*UI);
|
|
if (TI == 0 ||
|
|
TI->getType()->getPrimitiveSizeInBits() > NewWidth) return 0;
|
|
}
|
|
|
|
// If the pattern matches, truncate the inputs to the narrower type and
|
|
// use the sadd_with_overflow intrinsic to efficiently compute both the
|
|
// result and the overflow bit.
|
|
Module *M = I.getParent()->getParent()->getParent();
|
|
|
|
Type *NewType = IntegerType::get(OrigAdd->getContext(), NewWidth);
|
|
Value *F = Intrinsic::getDeclaration(M, Intrinsic::sadd_with_overflow,
|
|
NewType);
|
|
|
|
InstCombiner::BuilderTy *Builder = IC.Builder;
|
|
|
|
// Put the new code above the original add, in case there are any uses of the
|
|
// add between the add and the compare.
|
|
Builder->SetInsertPoint(OrigAdd);
|
|
|
|
Value *TruncA = Builder->CreateTrunc(A, NewType, A->getName()+".trunc");
|
|
Value *TruncB = Builder->CreateTrunc(B, NewType, B->getName()+".trunc");
|
|
CallInst *Call = Builder->CreateCall2(F, TruncA, TruncB, "sadd");
|
|
Value *Add = Builder->CreateExtractValue(Call, 0, "sadd.result");
|
|
Value *ZExt = Builder->CreateZExt(Add, OrigAdd->getType());
|
|
|
|
// The inner add was the result of the narrow add, zero extended to the
|
|
// wider type. Replace it with the result computed by the intrinsic.
|
|
IC.ReplaceInstUsesWith(*OrigAdd, ZExt);
|
|
|
|
// The original icmp gets replaced with the overflow value.
|
|
return ExtractValueInst::Create(Call, 1, "sadd.overflow");
|
|
}
|
|
|
|
static Instruction *ProcessUAddIdiom(Instruction &I, Value *OrigAddV,
|
|
InstCombiner &IC) {
|
|
// Don't bother doing this transformation for pointers, don't do it for
|
|
// vectors.
|
|
if (!isa<IntegerType>(OrigAddV->getType())) return 0;
|
|
|
|
// If the add is a constant expr, then we don't bother transforming it.
|
|
Instruction *OrigAdd = dyn_cast<Instruction>(OrigAddV);
|
|
if (OrigAdd == 0) return 0;
|
|
|
|
Value *LHS = OrigAdd->getOperand(0), *RHS = OrigAdd->getOperand(1);
|
|
|
|
// Put the new code above the original add, in case there are any uses of the
|
|
// add between the add and the compare.
|
|
InstCombiner::BuilderTy *Builder = IC.Builder;
|
|
Builder->SetInsertPoint(OrigAdd);
|
|
|
|
Module *M = I.getParent()->getParent()->getParent();
|
|
Type *Ty = LHS->getType();
|
|
Value *F = Intrinsic::getDeclaration(M, Intrinsic::uadd_with_overflow, Ty);
|
|
CallInst *Call = Builder->CreateCall2(F, LHS, RHS, "uadd");
|
|
Value *Add = Builder->CreateExtractValue(Call, 0);
|
|
|
|
IC.ReplaceInstUsesWith(*OrigAdd, Add);
|
|
|
|
// The original icmp gets replaced with the overflow value.
|
|
return ExtractValueInst::Create(Call, 1, "uadd.overflow");
|
|
}
|
|
|
|
// DemandedBitsLHSMask - When performing a comparison against a constant,
|
|
// it is possible that not all the bits in the LHS are demanded. This helper
|
|
// method computes the mask that IS demanded.
|
|
static APInt DemandedBitsLHSMask(ICmpInst &I,
|
|
unsigned BitWidth, bool isSignCheck) {
|
|
if (isSignCheck)
|
|
return APInt::getSignBit(BitWidth);
|
|
|
|
ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand(1));
|
|
if (!CI) return APInt::getAllOnesValue(BitWidth);
|
|
const APInt &RHS = CI->getValue();
|
|
|
|
switch (I.getPredicate()) {
|
|
// For a UGT comparison, we don't care about any bits that
|
|
// correspond to the trailing ones of the comparand. The value of these
|
|
// bits doesn't impact the outcome of the comparison, because any value
|
|
// greater than the RHS must differ in a bit higher than these due to carry.
|
|
case ICmpInst::ICMP_UGT: {
|
|
unsigned trailingOnes = RHS.countTrailingOnes();
|
|
APInt lowBitsSet = APInt::getLowBitsSet(BitWidth, trailingOnes);
|
|
return ~lowBitsSet;
|
|
}
|
|
|
|
// Similarly, for a ULT comparison, we don't care about the trailing zeros.
|
|
// Any value less than the RHS must differ in a higher bit because of carries.
|
|
case ICmpInst::ICMP_ULT: {
|
|
unsigned trailingZeros = RHS.countTrailingZeros();
|
|
APInt lowBitsSet = APInt::getLowBitsSet(BitWidth, trailingZeros);
|
|
return ~lowBitsSet;
|
|
}
|
|
|
|
default:
|
|
return APInt::getAllOnesValue(BitWidth);
|
|
}
|
|
|
|
}
|
|
|
|
/// \brief Check if the order of \p Op0 and \p Op1 as operand in an ICmpInst
|
|
/// should be swapped.
|
|
/// The decision is based on how many times these two operands are reused
|
|
/// as subtract operands and their positions in those instructions.
|
|
/// The rational is that several architectures use the same instruction for
|
|
/// both subtract and cmp, thus it is better if the order of those operands
|
|
/// match.
|
|
/// \return true if Op0 and Op1 should be swapped.
|
|
static bool swapMayExposeCSEOpportunities(const Value * Op0,
|
|
const Value * Op1) {
|
|
// Filter out pointer value as those cannot appears directly in subtract.
|
|
// FIXME: we may want to go through inttoptrs or bitcasts.
|
|
if (Op0->getType()->isPointerTy())
|
|
return false;
|
|
// Count every uses of both Op0 and Op1 in a subtract.
|
|
// Each time Op0 is the first operand, count -1: swapping is bad, the
|
|
// subtract has already the same layout as the compare.
|
|
// Each time Op0 is the second operand, count +1: swapping is good, the
|
|
// subtract has a different layout as the compare.
|
|
// At the end, if the benefit is greater than 0, Op0 should come second to
|
|
// expose more CSE opportunities.
|
|
int GlobalSwapBenefits = 0;
|
|
for (Value::const_use_iterator UI = Op0->use_begin(), UIEnd = Op0->use_end(); UI != UIEnd; ++UI) {
|
|
const BinaryOperator *BinOp = dyn_cast<BinaryOperator>(*UI);
|
|
if (!BinOp || BinOp->getOpcode() != Instruction::Sub)
|
|
continue;
|
|
// If Op0 is the first argument, this is not beneficial to swap the
|
|
// arguments.
|
|
int LocalSwapBenefits = -1;
|
|
unsigned Op1Idx = 1;
|
|
if (BinOp->getOperand(Op1Idx) == Op0) {
|
|
Op1Idx = 0;
|
|
LocalSwapBenefits = 1;
|
|
}
|
|
if (BinOp->getOperand(Op1Idx) != Op1)
|
|
continue;
|
|
GlobalSwapBenefits += LocalSwapBenefits;
|
|
}
|
|
return GlobalSwapBenefits > 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
|
|
bool Changed = false;
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
unsigned Op0Cplxity = getComplexity(Op0);
|
|
unsigned Op1Cplxity = getComplexity(Op1);
|
|
|
|
/// Orders the operands of the compare so that they are listed from most
|
|
/// complex to least complex. This puts constants before unary operators,
|
|
/// before binary operators.
|
|
if (Op0Cplxity < Op1Cplxity ||
|
|
(Op0Cplxity == Op1Cplxity &&
|
|
swapMayExposeCSEOpportunities(Op0, Op1))) {
|
|
I.swapOperands();
|
|
std::swap(Op0, Op1);
|
|
Changed = true;
|
|
}
|
|
|
|
if (Value *V = SimplifyICmpInst(I.getPredicate(), Op0, Op1, DL))
|
|
return ReplaceInstUsesWith(I, V);
|
|
|
|
// comparing -val or val with non-zero is the same as just comparing val
|
|
// ie, abs(val) != 0 -> val != 0
|
|
if (I.getPredicate() == ICmpInst::ICMP_NE && match(Op1, m_Zero()))
|
|
{
|
|
Value *Cond, *SelectTrue, *SelectFalse;
|
|
if (match(Op0, m_Select(m_Value(Cond), m_Value(SelectTrue),
|
|
m_Value(SelectFalse)))) {
|
|
if (Value *V = dyn_castNegVal(SelectTrue)) {
|
|
if (V == SelectFalse)
|
|
return CmpInst::Create(Instruction::ICmp, I.getPredicate(), V, Op1);
|
|
}
|
|
else if (Value *V = dyn_castNegVal(SelectFalse)) {
|
|
if (V == SelectTrue)
|
|
return CmpInst::Create(Instruction::ICmp, I.getPredicate(), V, Op1);
|
|
}
|
|
}
|
|
}
|
|
|
|
Type *Ty = Op0->getType();
|
|
|
|
// icmp's with boolean values can always be turned into bitwise operations
|
|
if (Ty->isIntegerTy(1)) {
|
|
switch (I.getPredicate()) {
|
|
default: llvm_unreachable("Invalid icmp instruction!");
|
|
case ICmpInst::ICMP_EQ: { // icmp eq i1 A, B -> ~(A^B)
|
|
Value *Xor = Builder->CreateXor(Op0, Op1, I.getName()+"tmp");
|
|
return BinaryOperator::CreateNot(Xor);
|
|
}
|
|
case ICmpInst::ICMP_NE: // icmp eq i1 A, B -> A^B
|
|
return BinaryOperator::CreateXor(Op0, Op1);
|
|
|
|
case ICmpInst::ICMP_UGT:
|
|
std::swap(Op0, Op1); // Change icmp ugt -> icmp ult
|
|
// FALL THROUGH
|
|
case ICmpInst::ICMP_ULT:{ // icmp ult i1 A, B -> ~A & B
|
|
Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp");
|
|
return BinaryOperator::CreateAnd(Not, Op1);
|
|
}
|
|
case ICmpInst::ICMP_SGT:
|
|
std::swap(Op0, Op1); // Change icmp sgt -> icmp slt
|
|
// FALL THROUGH
|
|
case ICmpInst::ICMP_SLT: { // icmp slt i1 A, B -> A & ~B
|
|
Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp");
|
|
return BinaryOperator::CreateAnd(Not, Op0);
|
|
}
|
|
case ICmpInst::ICMP_UGE:
|
|
std::swap(Op0, Op1); // Change icmp uge -> icmp ule
|
|
// FALL THROUGH
|
|
case ICmpInst::ICMP_ULE: { // icmp ule i1 A, B -> ~A | B
|
|
Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp");
|
|
return BinaryOperator::CreateOr(Not, Op1);
|
|
}
|
|
case ICmpInst::ICMP_SGE:
|
|
std::swap(Op0, Op1); // Change icmp sge -> icmp sle
|
|
// FALL THROUGH
|
|
case ICmpInst::ICMP_SLE: { // icmp sle i1 A, B -> A | ~B
|
|
Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp");
|
|
return BinaryOperator::CreateOr(Not, Op0);
|
|
}
|
|
}
|
|
}
|
|
|
|
unsigned BitWidth = 0;
|
|
if (Ty->isIntOrIntVectorTy())
|
|
BitWidth = Ty->getScalarSizeInBits();
|
|
else if (DL) // Pointers require DL info to get their size.
|
|
BitWidth = DL->getTypeSizeInBits(Ty->getScalarType());
|
|
|
|
bool isSignBit = false;
|
|
|
|
// See if we are doing a comparison with a constant.
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
|
|
Value *A = 0, *B = 0;
|
|
|
|
// Match the following pattern, which is a common idiom when writing
|
|
// overflow-safe integer arithmetic function. The source performs an
|
|
// addition in wider type, and explicitly checks for overflow using
|
|
// comparisons against INT_MIN and INT_MAX. Simplify this by using the
|
|
// sadd_with_overflow intrinsic.
|
|
//
|
|
// TODO: This could probably be generalized to handle other overflow-safe
|
|
// operations if we worked out the formulas to compute the appropriate
|
|
// magic constants.
|
|
//
|
|
// sum = a + b
|
|
// if (sum+128 >u 255) ... -> llvm.sadd.with.overflow.i8
|
|
{
|
|
ConstantInt *CI2; // I = icmp ugt (add (add A, B), CI2), CI
|
|
if (I.getPredicate() == ICmpInst::ICMP_UGT &&
|
|
match(Op0, m_Add(m_Add(m_Value(A), m_Value(B)), m_ConstantInt(CI2))))
|
|
if (Instruction *Res = ProcessUGT_ADDCST_ADD(I, A, B, CI2, CI, *this))
|
|
return Res;
|
|
}
|
|
|
|
// (icmp ne/eq (sub A B) 0) -> (icmp ne/eq A, B)
|
|
if (I.isEquality() && CI->isZero() &&
|
|
match(Op0, m_Sub(m_Value(A), m_Value(B)))) {
|
|
// (icmp cond A B) if cond is equality
|
|
return new ICmpInst(I.getPredicate(), A, B);
|
|
}
|
|
|
|
// If we have an icmp le or icmp ge instruction, turn it into the
|
|
// appropriate icmp lt or icmp gt instruction. This allows us to rely on
|
|
// them being folded in the code below. The SimplifyICmpInst code has
|
|
// already handled the edge cases for us, so we just assert on them.
|
|
switch (I.getPredicate()) {
|
|
default: break;
|
|
case ICmpInst::ICMP_ULE:
|
|
assert(!CI->isMaxValue(false)); // A <=u MAX -> TRUE
|
|
return new ICmpInst(ICmpInst::ICMP_ULT, Op0,
|
|
Builder->getInt(CI->getValue()+1));
|
|
case ICmpInst::ICMP_SLE:
|
|
assert(!CI->isMaxValue(true)); // A <=s MAX -> TRUE
|
|
return new ICmpInst(ICmpInst::ICMP_SLT, Op0,
|
|
Builder->getInt(CI->getValue()+1));
|
|
case ICmpInst::ICMP_UGE:
|
|
assert(!CI->isMinValue(false)); // A >=u MIN -> TRUE
|
|
return new ICmpInst(ICmpInst::ICMP_UGT, Op0,
|
|
Builder->getInt(CI->getValue()-1));
|
|
case ICmpInst::ICMP_SGE:
|
|
assert(!CI->isMinValue(true)); // A >=s MIN -> TRUE
|
|
return new ICmpInst(ICmpInst::ICMP_SGT, Op0,
|
|
Builder->getInt(CI->getValue()-1));
|
|
}
|
|
|
|
// If this comparison is a normal comparison, it demands all
|
|
// bits, if it is a sign bit comparison, it only demands the sign bit.
|
|
bool UnusedBit;
|
|
isSignBit = isSignBitCheck(I.getPredicate(), CI, UnusedBit);
|
|
}
|
|
|
|
// See if we can fold the comparison based on range information we can get
|
|
// by checking whether bits are known to be zero or one in the input.
|
|
if (BitWidth != 0) {
|
|
APInt Op0KnownZero(BitWidth, 0), Op0KnownOne(BitWidth, 0);
|
|
APInt Op1KnownZero(BitWidth, 0), Op1KnownOne(BitWidth, 0);
|
|
|
|
if (SimplifyDemandedBits(I.getOperandUse(0),
|
|
DemandedBitsLHSMask(I, BitWidth, isSignBit),
|
|
Op0KnownZero, Op0KnownOne, 0))
|
|
return &I;
|
|
if (SimplifyDemandedBits(I.getOperandUse(1),
|
|
APInt::getAllOnesValue(BitWidth),
|
|
Op1KnownZero, Op1KnownOne, 0))
|
|
return &I;
|
|
|
|
// Given the known and unknown bits, compute a range that the LHS could be
|
|
// in. Compute the Min, Max and RHS values based on the known bits. For the
|
|
// EQ and NE we use unsigned values.
|
|
APInt Op0Min(BitWidth, 0), Op0Max(BitWidth, 0);
|
|
APInt Op1Min(BitWidth, 0), Op1Max(BitWidth, 0);
|
|
if (I.isSigned()) {
|
|
ComputeSignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne,
|
|
Op0Min, Op0Max);
|
|
ComputeSignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne,
|
|
Op1Min, Op1Max);
|
|
} else {
|
|
ComputeUnsignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne,
|
|
Op0Min, Op0Max);
|
|
ComputeUnsignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne,
|
|
Op1Min, Op1Max);
|
|
}
|
|
|
|
// If Min and Max are known to be the same, then SimplifyDemandedBits
|
|
// figured out that the LHS is a constant. Just constant fold this now so
|
|
// that code below can assume that Min != Max.
|
|
if (!isa<Constant>(Op0) && Op0Min == Op0Max)
|
|
return new ICmpInst(I.getPredicate(),
|
|
ConstantInt::get(Op0->getType(), Op0Min), Op1);
|
|
if (!isa<Constant>(Op1) && Op1Min == Op1Max)
|
|
return new ICmpInst(I.getPredicate(), Op0,
|
|
ConstantInt::get(Op1->getType(), Op1Min));
|
|
|
|
// Based on the range information we know about the LHS, see if we can
|
|
// simplify this comparison. For example, (x&4) < 8 is always true.
|
|
switch (I.getPredicate()) {
|
|
default: llvm_unreachable("Unknown icmp opcode!");
|
|
case ICmpInst::ICMP_EQ: {
|
|
if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max))
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
|
|
|
|
// If all bits are known zero except for one, then we know at most one
|
|
// bit is set. If the comparison is against zero, then this is a check
|
|
// to see if *that* bit is set.
|
|
APInt Op0KnownZeroInverted = ~Op0KnownZero;
|
|
if (~Op1KnownZero == 0 && Op0KnownZeroInverted.isPowerOf2()) {
|
|
// If the LHS is an AND with the same constant, look through it.
|
|
Value *LHS = 0;
|
|
ConstantInt *LHSC = 0;
|
|
if (!match(Op0, m_And(m_Value(LHS), m_ConstantInt(LHSC))) ||
|
|
LHSC->getValue() != Op0KnownZeroInverted)
|
|
LHS = Op0;
|
|
|
|
// If the LHS is 1 << x, and we know the result is a power of 2 like 8,
|
|
// then turn "((1 << x)&8) == 0" into "x != 3".
|
|
Value *X = 0;
|
|
if (match(LHS, m_Shl(m_One(), m_Value(X)))) {
|
|
unsigned CmpVal = Op0KnownZeroInverted.countTrailingZeros();
|
|
return new ICmpInst(ICmpInst::ICMP_NE, X,
|
|
ConstantInt::get(X->getType(), CmpVal));
|
|
}
|
|
|
|
// If the LHS is 8 >>u x, and we know the result is a power of 2 like 1,
|
|
// then turn "((8 >>u x)&1) == 0" into "x != 3".
|
|
const APInt *CI;
|
|
if (Op0KnownZeroInverted == 1 &&
|
|
match(LHS, m_LShr(m_Power2(CI), m_Value(X))))
|
|
return new ICmpInst(ICmpInst::ICMP_NE, X,
|
|
ConstantInt::get(X->getType(),
|
|
CI->countTrailingZeros()));
|
|
}
|
|
|
|
break;
|
|
}
|
|
case ICmpInst::ICMP_NE: {
|
|
if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max))
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
|
|
|
|
// If all bits are known zero except for one, then we know at most one
|
|
// bit is set. If the comparison is against zero, then this is a check
|
|
// to see if *that* bit is set.
|
|
APInt Op0KnownZeroInverted = ~Op0KnownZero;
|
|
if (~Op1KnownZero == 0 && Op0KnownZeroInverted.isPowerOf2()) {
|
|
// If the LHS is an AND with the same constant, look through it.
|
|
Value *LHS = 0;
|
|
ConstantInt *LHSC = 0;
|
|
if (!match(Op0, m_And(m_Value(LHS), m_ConstantInt(LHSC))) ||
|
|
LHSC->getValue() != Op0KnownZeroInverted)
|
|
LHS = Op0;
|
|
|
|
// If the LHS is 1 << x, and we know the result is a power of 2 like 8,
|
|
// then turn "((1 << x)&8) != 0" into "x == 3".
|
|
Value *X = 0;
|
|
if (match(LHS, m_Shl(m_One(), m_Value(X)))) {
|
|
unsigned CmpVal = Op0KnownZeroInverted.countTrailingZeros();
|
|
return new ICmpInst(ICmpInst::ICMP_EQ, X,
|
|
ConstantInt::get(X->getType(), CmpVal));
|
|
}
|
|
|
|
// If the LHS is 8 >>u x, and we know the result is a power of 2 like 1,
|
|
// then turn "((8 >>u x)&1) != 0" into "x == 3".
|
|
const APInt *CI;
|
|
if (Op0KnownZeroInverted == 1 &&
|
|
match(LHS, m_LShr(m_Power2(CI), m_Value(X))))
|
|
return new ICmpInst(ICmpInst::ICMP_EQ, X,
|
|
ConstantInt::get(X->getType(),
|
|
CI->countTrailingZeros()));
|
|
}
|
|
|
|
break;
|
|
}
|
|
case ICmpInst::ICMP_ULT:
|
|
if (Op0Max.ult(Op1Min)) // A <u B -> true if max(A) < min(B)
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
|
|
if (Op0Min.uge(Op1Max)) // A <u B -> false if min(A) >= max(B)
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
|
|
if (Op1Min == Op0Max) // A <u B -> A != B if max(A) == min(B)
|
|
return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
|
|
if (Op1Max == Op0Min+1) // A <u C -> A == C-1 if min(A)+1 == C
|
|
return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
|
|
Builder->getInt(CI->getValue()-1));
|
|
|
|
// (x <u 2147483648) -> (x >s -1) -> true if sign bit clear
|
|
if (CI->isMinValue(true))
|
|
return new ICmpInst(ICmpInst::ICMP_SGT, Op0,
|
|
Constant::getAllOnesValue(Op0->getType()));
|
|
}
|
|
break;
|
|
case ICmpInst::ICMP_UGT:
|
|
if (Op0Min.ugt(Op1Max)) // A >u B -> true if min(A) > max(B)
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
|
|
if (Op0Max.ule(Op1Min)) // A >u B -> false if max(A) <= max(B)
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
|
|
|
|
if (Op1Max == Op0Min) // A >u B -> A != B if min(A) == max(B)
|
|
return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
|
|
if (Op1Min == Op0Max-1) // A >u C -> A == C+1 if max(a)-1 == C
|
|
return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
|
|
Builder->getInt(CI->getValue()+1));
|
|
|
|
// (x >u 2147483647) -> (x <s 0) -> true if sign bit set
|
|
if (CI->isMaxValue(true))
|
|
return new ICmpInst(ICmpInst::ICMP_SLT, Op0,
|
|
Constant::getNullValue(Op0->getType()));
|
|
}
|
|
break;
|
|
case ICmpInst::ICMP_SLT:
|
|
if (Op0Max.slt(Op1Min)) // A <s B -> true if max(A) < min(C)
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
|
|
if (Op0Min.sge(Op1Max)) // A <s B -> false if min(A) >= max(C)
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
|
|
if (Op1Min == Op0Max) // A <s B -> A != B if max(A) == min(B)
|
|
return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
|
|
if (Op1Max == Op0Min+1) // A <s C -> A == C-1 if min(A)+1 == C
|
|
return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
|
|
Builder->getInt(CI->getValue()-1));
|
|
}
|
|
break;
|
|
case ICmpInst::ICMP_SGT:
|
|
if (Op0Min.sgt(Op1Max)) // A >s B -> true if min(A) > max(B)
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
|
|
if (Op0Max.sle(Op1Min)) // A >s B -> false if max(A) <= min(B)
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
|
|
|
|
if (Op1Max == Op0Min) // A >s B -> A != B if min(A) == max(B)
|
|
return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
|
|
if (Op1Min == Op0Max-1) // A >s C -> A == C+1 if max(A)-1 == C
|
|
return new ICmpInst(ICmpInst::ICMP_EQ, Op0,
|
|
Builder->getInt(CI->getValue()+1));
|
|
}
|
|
break;
|
|
case ICmpInst::ICMP_SGE:
|
|
assert(!isa<ConstantInt>(Op1) && "ICMP_SGE with ConstantInt not folded!");
|
|
if (Op0Min.sge(Op1Max)) // A >=s B -> true if min(A) >= max(B)
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
|
|
if (Op0Max.slt(Op1Min)) // A >=s B -> false if max(A) < min(B)
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
|
|
break;
|
|
case ICmpInst::ICMP_SLE:
|
|
assert(!isa<ConstantInt>(Op1) && "ICMP_SLE with ConstantInt not folded!");
|
|
if (Op0Max.sle(Op1Min)) // A <=s B -> true if max(A) <= min(B)
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
|
|
if (Op0Min.sgt(Op1Max)) // A <=s B -> false if min(A) > max(B)
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
|
|
break;
|
|
case ICmpInst::ICMP_UGE:
|
|
assert(!isa<ConstantInt>(Op1) && "ICMP_UGE with ConstantInt not folded!");
|
|
if (Op0Min.uge(Op1Max)) // A >=u B -> true if min(A) >= max(B)
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
|
|
if (Op0Max.ult(Op1Min)) // A >=u B -> false if max(A) < min(B)
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
|
|
break;
|
|
case ICmpInst::ICMP_ULE:
|
|
assert(!isa<ConstantInt>(Op1) && "ICMP_ULE with ConstantInt not folded!");
|
|
if (Op0Max.ule(Op1Min)) // A <=u B -> true if max(A) <= min(B)
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
|
|
if (Op0Min.ugt(Op1Max)) // A <=u B -> false if min(A) > max(B)
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
|
|
break;
|
|
}
|
|
|
|
// Turn a signed comparison into an unsigned one if both operands
|
|
// are known to have the same sign.
|
|
if (I.isSigned() &&
|
|
((Op0KnownZero.isNegative() && Op1KnownZero.isNegative()) ||
|
|
(Op0KnownOne.isNegative() && Op1KnownOne.isNegative())))
|
|
return new ICmpInst(I.getUnsignedPredicate(), Op0, Op1);
|
|
}
|
|
|
|
// Test if the ICmpInst instruction is used exclusively by a select as
|
|
// part of a minimum or maximum operation. If so, refrain from doing
|
|
// any other folding. This helps out other analyses which understand
|
|
// non-obfuscated minimum and maximum idioms, such as ScalarEvolution
|
|
// and CodeGen. And in this case, at least one of the comparison
|
|
// operands has at least one user besides the compare (the select),
|
|
// which would often largely negate the benefit of folding anyway.
|
|
if (I.hasOneUse())
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(*I.use_begin()))
|
|
if ((SI->getOperand(1) == Op0 && SI->getOperand(2) == Op1) ||
|
|
(SI->getOperand(2) == Op0 && SI->getOperand(1) == Op1))
|
|
return 0;
|
|
|
|
// See if we are doing a comparison between a constant and an instruction that
|
|
// can be folded into the comparison.
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
|
|
// Since the RHS is a ConstantInt (CI), if the left hand side is an
|
|
// instruction, see if that instruction also has constants so that the
|
|
// instruction can be folded into the icmp
|
|
if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
|
|
if (Instruction *Res = visitICmpInstWithInstAndIntCst(I, LHSI, CI))
|
|
return Res;
|
|
}
|
|
|
|
// Handle icmp with constant (but not simple integer constant) RHS
|
|
if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
|
|
if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
|
|
switch (LHSI->getOpcode()) {
|
|
case Instruction::GetElementPtr:
|
|
// icmp pred GEP (P, int 0, int 0, int 0), null -> icmp pred P, null
|
|
if (RHSC->isNullValue() &&
|
|
cast<GetElementPtrInst>(LHSI)->hasAllZeroIndices())
|
|
return new ICmpInst(I.getPredicate(), LHSI->getOperand(0),
|
|
Constant::getNullValue(LHSI->getOperand(0)->getType()));
|
|
break;
|
|
case Instruction::PHI:
|
|
// Only fold icmp into the PHI if the phi and icmp are in the same
|
|
// block. If in the same block, we're encouraging jump threading. If
|
|
// not, we are just pessimizing the code by making an i1 phi.
|
|
if (LHSI->getParent() == I.getParent())
|
|
if (Instruction *NV = FoldOpIntoPhi(I))
|
|
return NV;
|
|
break;
|
|
case Instruction::Select: {
|
|
// If either operand of the select is a constant, we can fold the
|
|
// comparison into the select arms, which will cause one to be
|
|
// constant folded and the select turned into a bitwise or.
|
|
Value *Op1 = 0, *Op2 = 0;
|
|
if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1)))
|
|
Op1 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
|
|
if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2)))
|
|
Op2 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
|
|
|
|
// We only want to perform this transformation if it will not lead to
|
|
// additional code. This is true if either both sides of the select
|
|
// fold to a constant (in which case the icmp is replaced with a select
|
|
// which will usually simplify) or this is the only user of the
|
|
// select (in which case we are trading a select+icmp for a simpler
|
|
// select+icmp).
|
|
if ((Op1 && Op2) || (LHSI->hasOneUse() && (Op1 || Op2))) {
|
|
if (!Op1)
|
|
Op1 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(1),
|
|
RHSC, I.getName());
|
|
if (!Op2)
|
|
Op2 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(2),
|
|
RHSC, I.getName());
|
|
return SelectInst::Create(LHSI->getOperand(0), Op1, Op2);
|
|
}
|
|
break;
|
|
}
|
|
case Instruction::IntToPtr:
|
|
// icmp pred inttoptr(X), null -> icmp pred X, 0
|
|
if (RHSC->isNullValue() && DL &&
|
|
DL->getIntPtrType(RHSC->getType()) ==
|
|
LHSI->getOperand(0)->getType())
|
|
return new ICmpInst(I.getPredicate(), LHSI->getOperand(0),
|
|
Constant::getNullValue(LHSI->getOperand(0)->getType()));
|
|
break;
|
|
|
|
case Instruction::Load:
|
|
// Try to optimize things like "A[i] > 4" to index computations.
|
|
if (GetElementPtrInst *GEP =
|
|
dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) {
|
|
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
|
|
if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
|
|
!cast<LoadInst>(LHSI)->isVolatile())
|
|
if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I))
|
|
return Res;
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
|
|
// If we can optimize a 'icmp GEP, P' or 'icmp P, GEP', do so now.
|
|
if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op0))
|
|
if (Instruction *NI = FoldGEPICmp(GEP, Op1, I.getPredicate(), I))
|
|
return NI;
|
|
if (GEPOperator *GEP = dyn_cast<GEPOperator>(Op1))
|
|
if (Instruction *NI = FoldGEPICmp(GEP, Op0,
|
|
ICmpInst::getSwappedPredicate(I.getPredicate()), I))
|
|
return NI;
|
|
|
|
// Test to see if the operands of the icmp are casted versions of other
|
|
// values. If the ptr->ptr cast can be stripped off both arguments, we do so
|
|
// now.
|
|
if (BitCastInst *CI = dyn_cast<BitCastInst>(Op0)) {
|
|
if (Op0->getType()->isPointerTy() &&
|
|
(isa<Constant>(Op1) || isa<BitCastInst>(Op1))) {
|
|
// We keep moving the cast from the left operand over to the right
|
|
// operand, where it can often be eliminated completely.
|
|
Op0 = CI->getOperand(0);
|
|
|
|
// If operand #1 is a bitcast instruction, it must also be a ptr->ptr cast
|
|
// so eliminate it as well.
|
|
if (BitCastInst *CI2 = dyn_cast<BitCastInst>(Op1))
|
|
Op1 = CI2->getOperand(0);
|
|
|
|
// If Op1 is a constant, we can fold the cast into the constant.
|
|
if (Op0->getType() != Op1->getType()) {
|
|
if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
|
|
Op1 = ConstantExpr::getBitCast(Op1C, Op0->getType());
|
|
} else {
|
|
// Otherwise, cast the RHS right before the icmp
|
|
Op1 = Builder->CreateBitCast(Op1, Op0->getType());
|
|
}
|
|
}
|
|
return new ICmpInst(I.getPredicate(), Op0, Op1);
|
|
}
|
|
}
|
|
|
|
if (isa<CastInst>(Op0)) {
|
|
// Handle the special case of: icmp (cast bool to X), <cst>
|
|
// This comes up when you have code like
|
|
// int X = A < B;
|
|
// if (X) ...
|
|
// For generality, we handle any zero-extension of any operand comparison
|
|
// with a constant or another cast from the same type.
|
|
if (isa<Constant>(Op1) || isa<CastInst>(Op1))
|
|
if (Instruction *R = visitICmpInstWithCastAndCast(I))
|
|
return R;
|
|
}
|
|
|
|
// Special logic for binary operators.
|
|
BinaryOperator *BO0 = dyn_cast<BinaryOperator>(Op0);
|
|
BinaryOperator *BO1 = dyn_cast<BinaryOperator>(Op1);
|
|
if (BO0 || BO1) {
|
|
CmpInst::Predicate Pred = I.getPredicate();
|
|
bool NoOp0WrapProblem = false, NoOp1WrapProblem = false;
|
|
if (BO0 && isa<OverflowingBinaryOperator>(BO0))
|
|
NoOp0WrapProblem = ICmpInst::isEquality(Pred) ||
|
|
(CmpInst::isUnsigned(Pred) && BO0->hasNoUnsignedWrap()) ||
|
|
(CmpInst::isSigned(Pred) && BO0->hasNoSignedWrap());
|
|
if (BO1 && isa<OverflowingBinaryOperator>(BO1))
|
|
NoOp1WrapProblem = ICmpInst::isEquality(Pred) ||
|
|
(CmpInst::isUnsigned(Pred) && BO1->hasNoUnsignedWrap()) ||
|
|
(CmpInst::isSigned(Pred) && BO1->hasNoSignedWrap());
|
|
|
|
// Analyze the case when either Op0 or Op1 is an add instruction.
|
|
// Op0 = A + B (or A and B are null); Op1 = C + D (or C and D are null).
|
|
Value *A = 0, *B = 0, *C = 0, *D = 0;
|
|
if (BO0 && BO0->getOpcode() == Instruction::Add)
|
|
A = BO0->getOperand(0), B = BO0->getOperand(1);
|
|
if (BO1 && BO1->getOpcode() == Instruction::Add)
|
|
C = BO1->getOperand(0), D = BO1->getOperand(1);
|
|
|
|
// icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
|
|
if ((A == Op1 || B == Op1) && NoOp0WrapProblem)
|
|
return new ICmpInst(Pred, A == Op1 ? B : A,
|
|
Constant::getNullValue(Op1->getType()));
|
|
|
|
// icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
|
|
if ((C == Op0 || D == Op0) && NoOp1WrapProblem)
|
|
return new ICmpInst(Pred, Constant::getNullValue(Op0->getType()),
|
|
C == Op0 ? D : C);
|
|
|
|
// icmp (X+Y), (X+Z) -> icmp Y, Z for equalities or if there is no overflow.
|
|
if (A && C && (A == C || A == D || B == C || B == D) &&
|
|
NoOp0WrapProblem && NoOp1WrapProblem &&
|
|
// Try not to increase register pressure.
|
|
BO0->hasOneUse() && BO1->hasOneUse()) {
|
|
// Determine Y and Z in the form icmp (X+Y), (X+Z).
|
|
Value *Y, *Z;
|
|
if (A == C) {
|
|
// C + B == C + D -> B == D
|
|
Y = B;
|
|
Z = D;
|
|
} else if (A == D) {
|
|
// D + B == C + D -> B == C
|
|
Y = B;
|
|
Z = C;
|
|
} else if (B == C) {
|
|
// A + C == C + D -> A == D
|
|
Y = A;
|
|
Z = D;
|
|
} else {
|
|
assert(B == D);
|
|
// A + D == C + D -> A == C
|
|
Y = A;
|
|
Z = C;
|
|
}
|
|
return new ICmpInst(Pred, Y, Z);
|
|
}
|
|
|
|
// icmp slt (X + -1), Y -> icmp sle X, Y
|
|
if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SLT &&
|
|
match(B, m_AllOnes()))
|
|
return new ICmpInst(CmpInst::ICMP_SLE, A, Op1);
|
|
|
|
// icmp sge (X + -1), Y -> icmp sgt X, Y
|
|
if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SGE &&
|
|
match(B, m_AllOnes()))
|
|
return new ICmpInst(CmpInst::ICMP_SGT, A, Op1);
|
|
|
|
// icmp sle (X + 1), Y -> icmp slt X, Y
|
|
if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SLE &&
|
|
match(B, m_One()))
|
|
return new ICmpInst(CmpInst::ICMP_SLT, A, Op1);
|
|
|
|
// icmp sgt (X + 1), Y -> icmp sge X, Y
|
|
if (A && NoOp0WrapProblem && Pred == CmpInst::ICMP_SGT &&
|
|
match(B, m_One()))
|
|
return new ICmpInst(CmpInst::ICMP_SGE, A, Op1);
|
|
|
|
// if C1 has greater magnitude than C2:
|
|
// icmp (X + C1), (Y + C2) -> icmp (X + C3), Y
|
|
// s.t. C3 = C1 - C2
|
|
//
|
|
// if C2 has greater magnitude than C1:
|
|
// icmp (X + C1), (Y + C2) -> icmp X, (Y + C3)
|
|
// s.t. C3 = C2 - C1
|
|
if (A && C && NoOp0WrapProblem && NoOp1WrapProblem &&
|
|
(BO0->hasOneUse() || BO1->hasOneUse()) && !I.isUnsigned())
|
|
if (ConstantInt *C1 = dyn_cast<ConstantInt>(B))
|
|
if (ConstantInt *C2 = dyn_cast<ConstantInt>(D)) {
|
|
const APInt &AP1 = C1->getValue();
|
|
const APInt &AP2 = C2->getValue();
|
|
if (AP1.isNegative() == AP2.isNegative()) {
|
|
APInt AP1Abs = C1->getValue().abs();
|
|
APInt AP2Abs = C2->getValue().abs();
|
|
if (AP1Abs.uge(AP2Abs)) {
|
|
ConstantInt *C3 = Builder->getInt(AP1 - AP2);
|
|
Value *NewAdd = Builder->CreateNSWAdd(A, C3);
|
|
return new ICmpInst(Pred, NewAdd, C);
|
|
} else {
|
|
ConstantInt *C3 = Builder->getInt(AP2 - AP1);
|
|
Value *NewAdd = Builder->CreateNSWAdd(C, C3);
|
|
return new ICmpInst(Pred, A, NewAdd);
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
// Analyze the case when either Op0 or Op1 is a sub instruction.
|
|
// Op0 = A - B (or A and B are null); Op1 = C - D (or C and D are null).
|
|
A = 0; B = 0; C = 0; D = 0;
|
|
if (BO0 && BO0->getOpcode() == Instruction::Sub)
|
|
A = BO0->getOperand(0), B = BO0->getOperand(1);
|
|
if (BO1 && BO1->getOpcode() == Instruction::Sub)
|
|
C = BO1->getOperand(0), D = BO1->getOperand(1);
|
|
|
|
// icmp (X-Y), X -> icmp 0, Y for equalities or if there is no overflow.
|
|
if (A == Op1 && NoOp0WrapProblem)
|
|
return new ICmpInst(Pred, Constant::getNullValue(Op1->getType()), B);
|
|
|
|
// icmp X, (X-Y) -> icmp Y, 0 for equalities or if there is no overflow.
|
|
if (C == Op0 && NoOp1WrapProblem)
|
|
return new ICmpInst(Pred, D, Constant::getNullValue(Op0->getType()));
|
|
|
|
// icmp (Y-X), (Z-X) -> icmp Y, Z for equalities or if there is no overflow.
|
|
if (B && D && B == D && NoOp0WrapProblem && NoOp1WrapProblem &&
|
|
// Try not to increase register pressure.
|
|
BO0->hasOneUse() && BO1->hasOneUse())
|
|
return new ICmpInst(Pred, A, C);
|
|
|
|
// icmp (X-Y), (X-Z) -> icmp Z, Y for equalities or if there is no overflow.
|
|
if (A && C && A == C && NoOp0WrapProblem && NoOp1WrapProblem &&
|
|
// Try not to increase register pressure.
|
|
BO0->hasOneUse() && BO1->hasOneUse())
|
|
return new ICmpInst(Pred, D, B);
|
|
|
|
BinaryOperator *SRem = NULL;
|
|
// icmp (srem X, Y), Y
|
|
if (BO0 && BO0->getOpcode() == Instruction::SRem &&
|
|
Op1 == BO0->getOperand(1))
|
|
SRem = BO0;
|
|
// icmp Y, (srem X, Y)
|
|
else if (BO1 && BO1->getOpcode() == Instruction::SRem &&
|
|
Op0 == BO1->getOperand(1))
|
|
SRem = BO1;
|
|
if (SRem) {
|
|
// We don't check hasOneUse to avoid increasing register pressure because
|
|
// the value we use is the same value this instruction was already using.
|
|
switch (SRem == BO0 ? ICmpInst::getSwappedPredicate(Pred) : Pred) {
|
|
default: break;
|
|
case ICmpInst::ICMP_EQ:
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getType()));
|
|
case ICmpInst::ICMP_NE:
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getType()));
|
|
case ICmpInst::ICMP_SGT:
|
|
case ICmpInst::ICMP_SGE:
|
|
return new ICmpInst(ICmpInst::ICMP_SGT, SRem->getOperand(1),
|
|
Constant::getAllOnesValue(SRem->getType()));
|
|
case ICmpInst::ICMP_SLT:
|
|
case ICmpInst::ICMP_SLE:
|
|
return new ICmpInst(ICmpInst::ICMP_SLT, SRem->getOperand(1),
|
|
Constant::getNullValue(SRem->getType()));
|
|
}
|
|
}
|
|
|
|
if (BO0 && BO1 && BO0->getOpcode() == BO1->getOpcode() &&
|
|
BO0->hasOneUse() && BO1->hasOneUse() &&
|
|
BO0->getOperand(1) == BO1->getOperand(1)) {
|
|
switch (BO0->getOpcode()) {
|
|
default: break;
|
|
case Instruction::Add:
|
|
case Instruction::Sub:
|
|
case Instruction::Xor:
|
|
if (I.isEquality()) // a+x icmp eq/ne b+x --> a icmp b
|
|
return new ICmpInst(I.getPredicate(), BO0->getOperand(0),
|
|
BO1->getOperand(0));
|
|
// icmp u/s (a ^ signbit), (b ^ signbit) --> icmp s/u a, b
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(BO0->getOperand(1))) {
|
|
if (CI->getValue().isSignBit()) {
|
|
ICmpInst::Predicate Pred = I.isSigned()
|
|
? I.getUnsignedPredicate()
|
|
: I.getSignedPredicate();
|
|
return new ICmpInst(Pred, BO0->getOperand(0),
|
|
BO1->getOperand(0));
|
|
}
|
|
|
|
if (CI->isMaxValue(true)) {
|
|
ICmpInst::Predicate Pred = I.isSigned()
|
|
? I.getUnsignedPredicate()
|
|
: I.getSignedPredicate();
|
|
Pred = I.getSwappedPredicate(Pred);
|
|
return new ICmpInst(Pred, BO0->getOperand(0),
|
|
BO1->getOperand(0));
|
|
}
|
|
}
|
|
break;
|
|
case Instruction::Mul:
|
|
if (!I.isEquality())
|
|
break;
|
|
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(BO0->getOperand(1))) {
|
|
// a * Cst icmp eq/ne b * Cst --> a & Mask icmp b & Mask
|
|
// Mask = -1 >> count-trailing-zeros(Cst).
|
|
if (!CI->isZero() && !CI->isOne()) {
|
|
const APInt &AP = CI->getValue();
|
|
ConstantInt *Mask = ConstantInt::get(I.getContext(),
|
|
APInt::getLowBitsSet(AP.getBitWidth(),
|
|
AP.getBitWidth() -
|
|
AP.countTrailingZeros()));
|
|
Value *And1 = Builder->CreateAnd(BO0->getOperand(0), Mask);
|
|
Value *And2 = Builder->CreateAnd(BO1->getOperand(0), Mask);
|
|
return new ICmpInst(I.getPredicate(), And1, And2);
|
|
}
|
|
}
|
|
break;
|
|
case Instruction::UDiv:
|
|
case Instruction::LShr:
|
|
if (I.isSigned())
|
|
break;
|
|
// fall-through
|
|
case Instruction::SDiv:
|
|
case Instruction::AShr:
|
|
if (!BO0->isExact() || !BO1->isExact())
|
|
break;
|
|
return new ICmpInst(I.getPredicate(), BO0->getOperand(0),
|
|
BO1->getOperand(0));
|
|
case Instruction::Shl: {
|
|
bool NUW = BO0->hasNoUnsignedWrap() && BO1->hasNoUnsignedWrap();
|
|
bool NSW = BO0->hasNoSignedWrap() && BO1->hasNoSignedWrap();
|
|
if (!NUW && !NSW)
|
|
break;
|
|
if (!NSW && I.isSigned())
|
|
break;
|
|
return new ICmpInst(I.getPredicate(), BO0->getOperand(0),
|
|
BO1->getOperand(0));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
{ Value *A, *B;
|
|
// Transform (A & ~B) == 0 --> (A & B) != 0
|
|
// and (A & ~B) != 0 --> (A & B) == 0
|
|
// if A is a power of 2.
|
|
if (match(Op0, m_And(m_Value(A), m_Not(m_Value(B)))) &&
|
|
match(Op1, m_Zero()) && isKnownToBeAPowerOfTwo(A) && I.isEquality())
|
|
return new ICmpInst(I.getInversePredicate(),
|
|
Builder->CreateAnd(A, B),
|
|
Op1);
|
|
|
|
// ~x < ~y --> y < x
|
|
// ~x < cst --> ~cst < x
|
|
if (match(Op0, m_Not(m_Value(A)))) {
|
|
if (match(Op1, m_Not(m_Value(B))))
|
|
return new ICmpInst(I.getPredicate(), B, A);
|
|
if (ConstantInt *RHSC = dyn_cast<ConstantInt>(Op1))
|
|
return new ICmpInst(I.getPredicate(), ConstantExpr::getNot(RHSC), A);
|
|
}
|
|
|
|
// (a+b) <u a --> llvm.uadd.with.overflow.
|
|
// (a+b) <u b --> llvm.uadd.with.overflow.
|
|
if (I.getPredicate() == ICmpInst::ICMP_ULT &&
|
|
match(Op0, m_Add(m_Value(A), m_Value(B))) &&
|
|
(Op1 == A || Op1 == B))
|
|
if (Instruction *R = ProcessUAddIdiom(I, Op0, *this))
|
|
return R;
|
|
|
|
// a >u (a+b) --> llvm.uadd.with.overflow.
|
|
// b >u (a+b) --> llvm.uadd.with.overflow.
|
|
if (I.getPredicate() == ICmpInst::ICMP_UGT &&
|
|
match(Op1, m_Add(m_Value(A), m_Value(B))) &&
|
|
(Op0 == A || Op0 == B))
|
|
if (Instruction *R = ProcessUAddIdiom(I, Op1, *this))
|
|
return R;
|
|
}
|
|
|
|
if (I.isEquality()) {
|
|
Value *A, *B, *C, *D;
|
|
|
|
if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
|
|
if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0
|
|
Value *OtherVal = A == Op1 ? B : A;
|
|
return new ICmpInst(I.getPredicate(), OtherVal,
|
|
Constant::getNullValue(A->getType()));
|
|
}
|
|
|
|
if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) {
|
|
// A^c1 == C^c2 --> A == C^(c1^c2)
|
|
ConstantInt *C1, *C2;
|
|
if (match(B, m_ConstantInt(C1)) &&
|
|
match(D, m_ConstantInt(C2)) && Op1->hasOneUse()) {
|
|
Constant *NC = Builder->getInt(C1->getValue() ^ C2->getValue());
|
|
Value *Xor = Builder->CreateXor(C, NC);
|
|
return new ICmpInst(I.getPredicate(), A, Xor);
|
|
}
|
|
|
|
// A^B == A^D -> B == D
|
|
if (A == C) return new ICmpInst(I.getPredicate(), B, D);
|
|
if (A == D) return new ICmpInst(I.getPredicate(), B, C);
|
|
if (B == C) return new ICmpInst(I.getPredicate(), A, D);
|
|
if (B == D) return new ICmpInst(I.getPredicate(), A, C);
|
|
}
|
|
}
|
|
|
|
if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
|
|
(A == Op0 || B == Op0)) {
|
|
// A == (A^B) -> B == 0
|
|
Value *OtherVal = A == Op0 ? B : A;
|
|
return new ICmpInst(I.getPredicate(), OtherVal,
|
|
Constant::getNullValue(A->getType()));
|
|
}
|
|
|
|
// (X&Z) == (Y&Z) -> (X^Y) & Z == 0
|
|
if (match(Op0, m_OneUse(m_And(m_Value(A), m_Value(B)))) &&
|
|
match(Op1, m_OneUse(m_And(m_Value(C), m_Value(D))))) {
|
|
Value *X = 0, *Y = 0, *Z = 0;
|
|
|
|
if (A == C) {
|
|
X = B; Y = D; Z = A;
|
|
} else if (A == D) {
|
|
X = B; Y = C; Z = A;
|
|
} else if (B == C) {
|
|
X = A; Y = D; Z = B;
|
|
} else if (B == D) {
|
|
X = A; Y = C; Z = B;
|
|
}
|
|
|
|
if (X) { // Build (X^Y) & Z
|
|
Op1 = Builder->CreateXor(X, Y);
|
|
Op1 = Builder->CreateAnd(Op1, Z);
|
|
I.setOperand(0, Op1);
|
|
I.setOperand(1, Constant::getNullValue(Op1->getType()));
|
|
return &I;
|
|
}
|
|
}
|
|
|
|
// Transform (zext A) == (B & (1<<X)-1) --> A == (trunc B)
|
|
// and (B & (1<<X)-1) == (zext A) --> A == (trunc B)
|
|
ConstantInt *Cst1;
|
|
if ((Op0->hasOneUse() &&
|
|
match(Op0, m_ZExt(m_Value(A))) &&
|
|
match(Op1, m_And(m_Value(B), m_ConstantInt(Cst1)))) ||
|
|
(Op1->hasOneUse() &&
|
|
match(Op0, m_And(m_Value(B), m_ConstantInt(Cst1))) &&
|
|
match(Op1, m_ZExt(m_Value(A))))) {
|
|
APInt Pow2 = Cst1->getValue() + 1;
|
|
if (Pow2.isPowerOf2() && isa<IntegerType>(A->getType()) &&
|
|
Pow2.logBase2() == cast<IntegerType>(A->getType())->getBitWidth())
|
|
return new ICmpInst(I.getPredicate(), A,
|
|
Builder->CreateTrunc(B, A->getType()));
|
|
}
|
|
|
|
// (A >> C) == (B >> C) --> (A^B) u< (1 << C)
|
|
// For lshr and ashr pairs.
|
|
if ((match(Op0, m_OneUse(m_LShr(m_Value(A), m_ConstantInt(Cst1)))) &&
|
|
match(Op1, m_OneUse(m_LShr(m_Value(B), m_Specific(Cst1))))) ||
|
|
(match(Op0, m_OneUse(m_AShr(m_Value(A), m_ConstantInt(Cst1)))) &&
|
|
match(Op1, m_OneUse(m_AShr(m_Value(B), m_Specific(Cst1)))))) {
|
|
unsigned TypeBits = Cst1->getBitWidth();
|
|
unsigned ShAmt = (unsigned)Cst1->getLimitedValue(TypeBits);
|
|
if (ShAmt < TypeBits && ShAmt != 0) {
|
|
ICmpInst::Predicate Pred = I.getPredicate() == ICmpInst::ICMP_NE
|
|
? ICmpInst::ICMP_UGE
|
|
: ICmpInst::ICMP_ULT;
|
|
Value *Xor = Builder->CreateXor(A, B, I.getName() + ".unshifted");
|
|
APInt CmpVal = APInt::getOneBitSet(TypeBits, ShAmt);
|
|
return new ICmpInst(Pred, Xor, Builder->getInt(CmpVal));
|
|
}
|
|
}
|
|
|
|
// Transform "icmp eq (trunc (lshr(X, cst1)), cst" to
|
|
// "icmp (and X, mask), cst"
|
|
uint64_t ShAmt = 0;
|
|
if (Op0->hasOneUse() &&
|
|
match(Op0, m_Trunc(m_OneUse(m_LShr(m_Value(A),
|
|
m_ConstantInt(ShAmt))))) &&
|
|
match(Op1, m_ConstantInt(Cst1)) &&
|
|
// Only do this when A has multiple uses. This is most important to do
|
|
// when it exposes other optimizations.
|
|
!A->hasOneUse()) {
|
|
unsigned ASize =cast<IntegerType>(A->getType())->getPrimitiveSizeInBits();
|
|
|
|
if (ShAmt < ASize) {
|
|
APInt MaskV =
|
|
APInt::getLowBitsSet(ASize, Op0->getType()->getPrimitiveSizeInBits());
|
|
MaskV <<= ShAmt;
|
|
|
|
APInt CmpV = Cst1->getValue().zext(ASize);
|
|
CmpV <<= ShAmt;
|
|
|
|
Value *Mask = Builder->CreateAnd(A, Builder->getInt(MaskV));
|
|
return new ICmpInst(I.getPredicate(), Mask, Builder->getInt(CmpV));
|
|
}
|
|
}
|
|
}
|
|
|
|
{
|
|
Value *X; ConstantInt *Cst;
|
|
// icmp X+Cst, X
|
|
if (match(Op0, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op1 == X)
|
|
return FoldICmpAddOpCst(I, X, Cst, I.getPredicate());
|
|
|
|
// icmp X, X+Cst
|
|
if (match(Op1, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op0 == X)
|
|
return FoldICmpAddOpCst(I, X, Cst, I.getSwappedPredicate());
|
|
}
|
|
return Changed ? &I : 0;
|
|
}
|
|
|
|
/// FoldFCmp_IntToFP_Cst - Fold fcmp ([us]itofp x, cst) if possible.
|
|
///
|
|
Instruction *InstCombiner::FoldFCmp_IntToFP_Cst(FCmpInst &I,
|
|
Instruction *LHSI,
|
|
Constant *RHSC) {
|
|
if (!isa<ConstantFP>(RHSC)) return 0;
|
|
const APFloat &RHS = cast<ConstantFP>(RHSC)->getValueAPF();
|
|
|
|
// Get the width of the mantissa. We don't want to hack on conversions that
|
|
// might lose information from the integer, e.g. "i64 -> float"
|
|
int MantissaWidth = LHSI->getType()->getFPMantissaWidth();
|
|
if (MantissaWidth == -1) return 0; // Unknown.
|
|
|
|
// Check to see that the input is converted from an integer type that is small
|
|
// enough that preserves all bits. TODO: check here for "known" sign bits.
|
|
// This would allow us to handle (fptosi (x >>s 62) to float) if x is i64 f.e.
|
|
unsigned InputSize = LHSI->getOperand(0)->getType()->getScalarSizeInBits();
|
|
|
|
// If this is a uitofp instruction, we need an extra bit to hold the sign.
|
|
bool LHSUnsigned = isa<UIToFPInst>(LHSI);
|
|
if (LHSUnsigned)
|
|
++InputSize;
|
|
|
|
// If the conversion would lose info, don't hack on this.
|
|
if ((int)InputSize > MantissaWidth)
|
|
return 0;
|
|
|
|
// Otherwise, we can potentially simplify the comparison. We know that it
|
|
// will always come through as an integer value and we know the constant is
|
|
// not a NAN (it would have been previously simplified).
|
|
assert(!RHS.isNaN() && "NaN comparison not already folded!");
|
|
|
|
ICmpInst::Predicate Pred;
|
|
switch (I.getPredicate()) {
|
|
default: llvm_unreachable("Unexpected predicate!");
|
|
case FCmpInst::FCMP_UEQ:
|
|
case FCmpInst::FCMP_OEQ:
|
|
Pred = ICmpInst::ICMP_EQ;
|
|
break;
|
|
case FCmpInst::FCMP_UGT:
|
|
case FCmpInst::FCMP_OGT:
|
|
Pred = LHSUnsigned ? ICmpInst::ICMP_UGT : ICmpInst::ICMP_SGT;
|
|
break;
|
|
case FCmpInst::FCMP_UGE:
|
|
case FCmpInst::FCMP_OGE:
|
|
Pred = LHSUnsigned ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_SGE;
|
|
break;
|
|
case FCmpInst::FCMP_ULT:
|
|
case FCmpInst::FCMP_OLT:
|
|
Pred = LHSUnsigned ? ICmpInst::ICMP_ULT : ICmpInst::ICMP_SLT;
|
|
break;
|
|
case FCmpInst::FCMP_ULE:
|
|
case FCmpInst::FCMP_OLE:
|
|
Pred = LHSUnsigned ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_SLE;
|
|
break;
|
|
case FCmpInst::FCMP_UNE:
|
|
case FCmpInst::FCMP_ONE:
|
|
Pred = ICmpInst::ICMP_NE;
|
|
break;
|
|
case FCmpInst::FCMP_ORD:
|
|
return ReplaceInstUsesWith(I, Builder->getTrue());
|
|
case FCmpInst::FCMP_UNO:
|
|
return ReplaceInstUsesWith(I, Builder->getFalse());
|
|
}
|
|
|
|
IntegerType *IntTy = cast<IntegerType>(LHSI->getOperand(0)->getType());
|
|
|
|
// Now we know that the APFloat is a normal number, zero or inf.
|
|
|
|
// See if the FP constant is too large for the integer. For example,
|
|
// comparing an i8 to 300.0.
|
|
unsigned IntWidth = IntTy->getScalarSizeInBits();
|
|
|
|
if (!LHSUnsigned) {
|
|
// If the RHS value is > SignedMax, fold the comparison. This handles +INF
|
|
// and large values.
|
|
APFloat SMax(RHS.getSemantics());
|
|
SMax.convertFromAPInt(APInt::getSignedMaxValue(IntWidth), true,
|
|
APFloat::rmNearestTiesToEven);
|
|
if (SMax.compare(RHS) == APFloat::cmpLessThan) { // smax < 13123.0
|
|
if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SLT ||
|
|
Pred == ICmpInst::ICMP_SLE)
|
|
return ReplaceInstUsesWith(I, Builder->getTrue());
|
|
return ReplaceInstUsesWith(I, Builder->getFalse());
|
|
}
|
|
} else {
|
|
// If the RHS value is > UnsignedMax, fold the comparison. This handles
|
|
// +INF and large values.
|
|
APFloat UMax(RHS.getSemantics());
|
|
UMax.convertFromAPInt(APInt::getMaxValue(IntWidth), false,
|
|
APFloat::rmNearestTiesToEven);
|
|
if (UMax.compare(RHS) == APFloat::cmpLessThan) { // umax < 13123.0
|
|
if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_ULT ||
|
|
Pred == ICmpInst::ICMP_ULE)
|
|
return ReplaceInstUsesWith(I, Builder->getTrue());
|
|
return ReplaceInstUsesWith(I, Builder->getFalse());
|
|
}
|
|
}
|
|
|
|
if (!LHSUnsigned) {
|
|
// See if the RHS value is < SignedMin.
|
|
APFloat SMin(RHS.getSemantics());
|
|
SMin.convertFromAPInt(APInt::getSignedMinValue(IntWidth), true,
|
|
APFloat::rmNearestTiesToEven);
|
|
if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // smin > 12312.0
|
|
if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SGT ||
|
|
Pred == ICmpInst::ICMP_SGE)
|
|
return ReplaceInstUsesWith(I, Builder->getTrue());
|
|
return ReplaceInstUsesWith(I, Builder->getFalse());
|
|
}
|
|
} else {
|
|
// See if the RHS value is < UnsignedMin.
|
|
APFloat SMin(RHS.getSemantics());
|
|
SMin.convertFromAPInt(APInt::getMinValue(IntWidth), true,
|
|
APFloat::rmNearestTiesToEven);
|
|
if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // umin > 12312.0
|
|
if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_UGT ||
|
|
Pred == ICmpInst::ICMP_UGE)
|
|
return ReplaceInstUsesWith(I, Builder->getTrue());
|
|
return ReplaceInstUsesWith(I, Builder->getFalse());
|
|
}
|
|
}
|
|
|
|
// Okay, now we know that the FP constant fits in the range [SMIN, SMAX] or
|
|
// [0, UMAX], but it may still be fractional. See if it is fractional by
|
|
// casting the FP value to the integer value and back, checking for equality.
|
|
// Don't do this for zero, because -0.0 is not fractional.
|
|
Constant *RHSInt = LHSUnsigned
|
|
? ConstantExpr::getFPToUI(RHSC, IntTy)
|
|
: ConstantExpr::getFPToSI(RHSC, IntTy);
|
|
if (!RHS.isZero()) {
|
|
bool Equal = LHSUnsigned
|
|
? ConstantExpr::getUIToFP(RHSInt, RHSC->getType()) == RHSC
|
|
: ConstantExpr::getSIToFP(RHSInt, RHSC->getType()) == RHSC;
|
|
if (!Equal) {
|
|
// If we had a comparison against a fractional value, we have to adjust
|
|
// the compare predicate and sometimes the value. RHSC is rounded towards
|
|
// zero at this point.
|
|
switch (Pred) {
|
|
default: llvm_unreachable("Unexpected integer comparison!");
|
|
case ICmpInst::ICMP_NE: // (float)int != 4.4 --> true
|
|
return ReplaceInstUsesWith(I, Builder->getTrue());
|
|
case ICmpInst::ICMP_EQ: // (float)int == 4.4 --> false
|
|
return ReplaceInstUsesWith(I, Builder->getFalse());
|
|
case ICmpInst::ICMP_ULE:
|
|
// (float)int <= 4.4 --> int <= 4
|
|
// (float)int <= -4.4 --> false
|
|
if (RHS.isNegative())
|
|
return ReplaceInstUsesWith(I, Builder->getFalse());
|
|
break;
|
|
case ICmpInst::ICMP_SLE:
|
|
// (float)int <= 4.4 --> int <= 4
|
|
// (float)int <= -4.4 --> int < -4
|
|
if (RHS.isNegative())
|
|
Pred = ICmpInst::ICMP_SLT;
|
|
break;
|
|
case ICmpInst::ICMP_ULT:
|
|
// (float)int < -4.4 --> false
|
|
// (float)int < 4.4 --> int <= 4
|
|
if (RHS.isNegative())
|
|
return ReplaceInstUsesWith(I, Builder->getFalse());
|
|
Pred = ICmpInst::ICMP_ULE;
|
|
break;
|
|
case ICmpInst::ICMP_SLT:
|
|
// (float)int < -4.4 --> int < -4
|
|
// (float)int < 4.4 --> int <= 4
|
|
if (!RHS.isNegative())
|
|
Pred = ICmpInst::ICMP_SLE;
|
|
break;
|
|
case ICmpInst::ICMP_UGT:
|
|
// (float)int > 4.4 --> int > 4
|
|
// (float)int > -4.4 --> true
|
|
if (RHS.isNegative())
|
|
return ReplaceInstUsesWith(I, Builder->getTrue());
|
|
break;
|
|
case ICmpInst::ICMP_SGT:
|
|
// (float)int > 4.4 --> int > 4
|
|
// (float)int > -4.4 --> int >= -4
|
|
if (RHS.isNegative())
|
|
Pred = ICmpInst::ICMP_SGE;
|
|
break;
|
|
case ICmpInst::ICMP_UGE:
|
|
// (float)int >= -4.4 --> true
|
|
// (float)int >= 4.4 --> int > 4
|
|
if (RHS.isNegative())
|
|
return ReplaceInstUsesWith(I, Builder->getTrue());
|
|
Pred = ICmpInst::ICMP_UGT;
|
|
break;
|
|
case ICmpInst::ICMP_SGE:
|
|
// (float)int >= -4.4 --> int >= -4
|
|
// (float)int >= 4.4 --> int > 4
|
|
if (!RHS.isNegative())
|
|
Pred = ICmpInst::ICMP_SGT;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Lower this FP comparison into an appropriate integer version of the
|
|
// comparison.
|
|
return new ICmpInst(Pred, LHSI->getOperand(0), RHSInt);
|
|
}
|
|
|
|
Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) {
|
|
bool Changed = false;
|
|
|
|
/// Orders the operands of the compare so that they are listed from most
|
|
/// complex to least complex. This puts constants before unary operators,
|
|
/// before binary operators.
|
|
if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1))) {
|
|
I.swapOperands();
|
|
Changed = true;
|
|
}
|
|
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
if (Value *V = SimplifyFCmpInst(I.getPredicate(), Op0, Op1, DL))
|
|
return ReplaceInstUsesWith(I, V);
|
|
|
|
// Simplify 'fcmp pred X, X'
|
|
if (Op0 == Op1) {
|
|
switch (I.getPredicate()) {
|
|
default: llvm_unreachable("Unknown predicate!");
|
|
case FCmpInst::FCMP_UNO: // True if unordered: isnan(X) | isnan(Y)
|
|
case FCmpInst::FCMP_ULT: // True if unordered or less than
|
|
case FCmpInst::FCMP_UGT: // True if unordered or greater than
|
|
case FCmpInst::FCMP_UNE: // True if unordered or not equal
|
|
// Canonicalize these to be 'fcmp uno %X, 0.0'.
|
|
I.setPredicate(FCmpInst::FCMP_UNO);
|
|
I.setOperand(1, Constant::getNullValue(Op0->getType()));
|
|
return &I;
|
|
|
|
case FCmpInst::FCMP_ORD: // True if ordered (no nans)
|
|
case FCmpInst::FCMP_OEQ: // True if ordered and equal
|
|
case FCmpInst::FCMP_OGE: // True if ordered and greater than or equal
|
|
case FCmpInst::FCMP_OLE: // True if ordered and less than or equal
|
|
// Canonicalize these to be 'fcmp ord %X, 0.0'.
|
|
I.setPredicate(FCmpInst::FCMP_ORD);
|
|
I.setOperand(1, Constant::getNullValue(Op0->getType()));
|
|
return &I;
|
|
}
|
|
}
|
|
|
|
// Handle fcmp with constant RHS
|
|
if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
|
|
if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
|
|
switch (LHSI->getOpcode()) {
|
|
case Instruction::FPExt: {
|
|
// fcmp (fpext x), C -> fcmp x, (fptrunc C) if fptrunc is lossless
|
|
FPExtInst *LHSExt = cast<FPExtInst>(LHSI);
|
|
ConstantFP *RHSF = dyn_cast<ConstantFP>(RHSC);
|
|
if (!RHSF)
|
|
break;
|
|
|
|
const fltSemantics *Sem;
|
|
// FIXME: This shouldn't be here.
|
|
if (LHSExt->getSrcTy()->isHalfTy())
|
|
Sem = &APFloat::IEEEhalf;
|
|
else if (LHSExt->getSrcTy()->isFloatTy())
|
|
Sem = &APFloat::IEEEsingle;
|
|
else if (LHSExt->getSrcTy()->isDoubleTy())
|
|
Sem = &APFloat::IEEEdouble;
|
|
else if (LHSExt->getSrcTy()->isFP128Ty())
|
|
Sem = &APFloat::IEEEquad;
|
|
else if (LHSExt->getSrcTy()->isX86_FP80Ty())
|
|
Sem = &APFloat::x87DoubleExtended;
|
|
else if (LHSExt->getSrcTy()->isPPC_FP128Ty())
|
|
Sem = &APFloat::PPCDoubleDouble;
|
|
else
|
|
break;
|
|
|
|
bool Lossy;
|
|
APFloat F = RHSF->getValueAPF();
|
|
F.convert(*Sem, APFloat::rmNearestTiesToEven, &Lossy);
|
|
|
|
// Avoid lossy conversions and denormals. Zero is a special case
|
|
// that's OK to convert.
|
|
APFloat Fabs = F;
|
|
Fabs.clearSign();
|
|
if (!Lossy &&
|
|
((Fabs.compare(APFloat::getSmallestNormalized(*Sem)) !=
|
|
APFloat::cmpLessThan) || Fabs.isZero()))
|
|
|
|
return new FCmpInst(I.getPredicate(), LHSExt->getOperand(0),
|
|
ConstantFP::get(RHSC->getContext(), F));
|
|
break;
|
|
}
|
|
case Instruction::PHI:
|
|
// Only fold fcmp into the PHI if the phi and fcmp are in the same
|
|
// block. If in the same block, we're encouraging jump threading. If
|
|
// not, we are just pessimizing the code by making an i1 phi.
|
|
if (LHSI->getParent() == I.getParent())
|
|
if (Instruction *NV = FoldOpIntoPhi(I))
|
|
return NV;
|
|
break;
|
|
case Instruction::SIToFP:
|
|
case Instruction::UIToFP:
|
|
if (Instruction *NV = FoldFCmp_IntToFP_Cst(I, LHSI, RHSC))
|
|
return NV;
|
|
break;
|
|
case Instruction::FSub: {
|
|
// fcmp pred (fneg x), C -> fcmp swap(pred) x, -C
|
|
Value *Op;
|
|
if (match(LHSI, m_FNeg(m_Value(Op))))
|
|
return new FCmpInst(I.getSwappedPredicate(), Op,
|
|
ConstantExpr::getFNeg(RHSC));
|
|
break;
|
|
}
|
|
case Instruction::Load:
|
|
if (GetElementPtrInst *GEP =
|
|
dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) {
|
|
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0)))
|
|
if (GV->isConstant() && GV->hasDefinitiveInitializer() &&
|
|
!cast<LoadInst>(LHSI)->isVolatile())
|
|
if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I))
|
|
return Res;
|
|
}
|
|
break;
|
|
case Instruction::Call: {
|
|
CallInst *CI = cast<CallInst>(LHSI);
|
|
LibFunc::Func Func;
|
|
// Various optimization for fabs compared with zero.
|
|
if (RHSC->isNullValue() && CI->getCalledFunction() &&
|
|
TLI->getLibFunc(CI->getCalledFunction()->getName(), Func) &&
|
|
TLI->has(Func)) {
|
|
if (Func == LibFunc::fabs || Func == LibFunc::fabsf ||
|
|
Func == LibFunc::fabsl) {
|
|
switch (I.getPredicate()) {
|
|
default: break;
|
|
// fabs(x) < 0 --> false
|
|
case FCmpInst::FCMP_OLT:
|
|
return ReplaceInstUsesWith(I, Builder->getFalse());
|
|
// fabs(x) > 0 --> x != 0
|
|
case FCmpInst::FCMP_OGT:
|
|
return new FCmpInst(FCmpInst::FCMP_ONE, CI->getArgOperand(0),
|
|
RHSC);
|
|
// fabs(x) <= 0 --> x == 0
|
|
case FCmpInst::FCMP_OLE:
|
|
return new FCmpInst(FCmpInst::FCMP_OEQ, CI->getArgOperand(0),
|
|
RHSC);
|
|
// fabs(x) >= 0 --> !isnan(x)
|
|
case FCmpInst::FCMP_OGE:
|
|
return new FCmpInst(FCmpInst::FCMP_ORD, CI->getArgOperand(0),
|
|
RHSC);
|
|
// fabs(x) == 0 --> x == 0
|
|
// fabs(x) != 0 --> x != 0
|
|
case FCmpInst::FCMP_OEQ:
|
|
case FCmpInst::FCMP_UEQ:
|
|
case FCmpInst::FCMP_ONE:
|
|
case FCmpInst::FCMP_UNE:
|
|
return new FCmpInst(I.getPredicate(), CI->getArgOperand(0),
|
|
RHSC);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// fcmp pred (fneg x), (fneg y) -> fcmp swap(pred) x, y
|
|
Value *X, *Y;
|
|
if (match(Op0, m_FNeg(m_Value(X))) && match(Op1, m_FNeg(m_Value(Y))))
|
|
return new FCmpInst(I.getSwappedPredicate(), X, Y);
|
|
|
|
// fcmp (fpext x), (fpext y) -> fcmp x, y
|
|
if (FPExtInst *LHSExt = dyn_cast<FPExtInst>(Op0))
|
|
if (FPExtInst *RHSExt = dyn_cast<FPExtInst>(Op1))
|
|
if (LHSExt->getSrcTy() == RHSExt->getSrcTy())
|
|
return new FCmpInst(I.getPredicate(), LHSExt->getOperand(0),
|
|
RHSExt->getOperand(0));
|
|
|
|
return Changed ? &I : 0;
|
|
}
|