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50ca4d37f7
llvm-6502/lib/Analysis/InstructionSimplify.cpp
Duncan Sands 50ca4d37f7 Improve threading of comparisons over select instructions (spotted by my 
auto-simplifier).  This has a big impact on Ada code, but not much else.
Unfortunately the impact is mostly negative!  This is due to PR9004 (aka
SCCP failing to resolve conditional branch conditions in the destination
blocks of the branch), in which simple correlated expressions are not
resolved but complicated ones are, so simplifying has a bad effect!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124788 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-03 09:37:39 +00:00

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//===- InstructionSimplify.cpp - Fold instruction operands ----------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements routines for folding instructions into simpler forms
// that do not require creating new instructions. This does constant folding
// ("add i32 1, 1" -> "2") but can also handle non-constant operands, either
// returning a constant ("and i32 %x, 0" -> "0") or an already existing value
// ("and i32 %x, %x" -> "%x"). All operands are assumed to have already been
// simplified: This is usually true and assuming it simplifies the logic (if
// they have not been simplified then results are correct but maybe suboptimal).
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "instsimplify"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Support/PatternMatch.h"
#include "llvm/Support/ValueHandle.h"
#include "llvm/Target/TargetData.h"
using namespace llvm;
using namespace llvm::PatternMatch;
#define RecursionLimit 3
STATISTIC(NumExpand, "Number of expansions");
STATISTIC(NumFactor , "Number of factorizations");
STATISTIC(NumReassoc, "Number of reassociations");
static Value *SimplifyAndInst(Value *, Value *, const TargetData *,
const DominatorTree *, unsigned);
static Value *SimplifyBinOp(unsigned, Value *, Value *, const TargetData *,
const DominatorTree *, unsigned);
static Value *SimplifyCmpInst(unsigned, Value *, Value *, const TargetData *,
const DominatorTree *, unsigned);
static Value *SimplifyOrInst(Value *, Value *, const TargetData *,
const DominatorTree *, unsigned);
static Value *SimplifyXorInst(Value *, Value *, const TargetData *,
const DominatorTree *, unsigned);
/// ValueDominatesPHI - Does the given value dominate the specified phi node?
static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) {
Instruction *I = dyn_cast<Instruction>(V);
if (!I)
// Arguments and constants dominate all instructions.
return true;
// If we have a DominatorTree then do a precise test.
if (DT)
return DT->dominates(I, P);
// Otherwise, if the instruction is in the entry block, and is not an invoke,
// then it obviously dominates all phi nodes.
if (I->getParent() == &I->getParent()->getParent()->getEntryBlock() &&
!isa<InvokeInst>(I))
return true;
return false;
}
/// ExpandBinOp - Simplify "A op (B op' C)" by distributing op over op', turning
/// it into "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is
/// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS.
/// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)".
/// Returns the simplified value, or null if no simplification was performed.
static Value *ExpandBinOp(unsigned Opcode, Value *LHS, Value *RHS,
unsigned OpcToExpand, const TargetData *TD,
const DominatorTree *DT, unsigned MaxRecurse) {
Instruction::BinaryOps OpcodeToExpand = (Instruction::BinaryOps)OpcToExpand;
// Recursion is always used, so bail out at once if we already hit the limit.
if (!MaxRecurse--)
return 0;
// Check whether the expression has the form "(A op' B) op C".
if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
if (Op0->getOpcode() == OpcodeToExpand) {
// It does! Try turning it into "(A op C) op' (B op C)".
Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
// Do "A op C" and "B op C" both simplify?
if (Value *L = SimplifyBinOp(Opcode, A, C, TD, DT, MaxRecurse))
if (Value *R = SimplifyBinOp(Opcode, B, C, TD, DT, MaxRecurse)) {
// They do! Return "L op' R" if it simplifies or is already available.
// If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand)
&& L == B && R == A)) {
++NumExpand;
return LHS;
}
// Otherwise return "L op' R" if it simplifies.
if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, TD, DT,
MaxRecurse)) {
++NumExpand;
return V;
}
}
}
// Check whether the expression has the form "A op (B op' C)".
if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
if (Op1->getOpcode() == OpcodeToExpand) {
// It does! Try turning it into "(A op B) op' (A op C)".
Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
// Do "A op B" and "A op C" both simplify?
if (Value *L = SimplifyBinOp(Opcode, A, B, TD, DT, MaxRecurse))
if (Value *R = SimplifyBinOp(Opcode, A, C, TD, DT, MaxRecurse)) {
// They do! Return "L op' R" if it simplifies or is already available.
// If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand)
&& L == C && R == B)) {
++NumExpand;
return RHS;
}
// Otherwise return "L op' R" if it simplifies.
if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, TD, DT,
MaxRecurse)) {
++NumExpand;
return V;
}
}
}
return 0;
}
/// FactorizeBinOp - Simplify "LHS Opcode RHS" by factorizing out a common term
/// using the operation OpCodeToExtract. For example, when Opcode is Add and
/// OpCodeToExtract is Mul then this tries to turn "(A*B)+(A*C)" into "A*(B+C)".
/// Returns the simplified value, or null if no simplification was performed.
static Value *FactorizeBinOp(unsigned Opcode, Value *LHS, Value *RHS,
unsigned OpcToExtract, const TargetData *TD,
const DominatorTree *DT, unsigned MaxRecurse) {
Instruction::BinaryOps OpcodeToExtract = (Instruction::BinaryOps)OpcToExtract;
// Recursion is always used, so bail out at once if we already hit the limit.
if (!MaxRecurse--)
return 0;
BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
if (!Op0 || Op0->getOpcode() != OpcodeToExtract ||
!Op1 || Op1->getOpcode() != OpcodeToExtract)
return 0;
// The expression has the form "(A op' B) op (C op' D)".
Value *A = Op0->getOperand(0), *B = Op0->getOperand(1);
Value *C = Op1->getOperand(0), *D = Op1->getOperand(1);
// Use left distributivity, i.e. "X op' (Y op Z) = (X op' Y) op (X op' Z)".
// Does the instruction have the form "(A op' B) op (A op' D)" or, in the
// commutative case, "(A op' B) op (C op' A)"?
if (A == C || (Instruction::isCommutative(OpcodeToExtract) && A == D)) {
Value *DD = A == C ? D : C;
// Form "A op' (B op DD)" if it simplifies completely.
// Does "B op DD" simplify?
if (Value *V = SimplifyBinOp(Opcode, B, DD, TD, DT, MaxRecurse)) {
// It does! Return "A op' V" if it simplifies or is already available.
// If V equals B then "A op' V" is just the LHS. If V equals DD then
// "A op' V" is just the RHS.
if (V == B || V == DD) {
++NumFactor;
return V == B ? LHS : RHS;
}
// Otherwise return "A op' V" if it simplifies.
if (Value *W = SimplifyBinOp(OpcodeToExtract, A, V, TD, DT, MaxRecurse)) {
++NumFactor;
return W;
}
}
}
// Use right distributivity, i.e. "(X op Y) op' Z = (X op' Z) op (Y op' Z)".
// Does the instruction have the form "(A op' B) op (C op' B)" or, in the
// commutative case, "(A op' B) op (B op' D)"?
if (B == D || (Instruction::isCommutative(OpcodeToExtract) && B == C)) {
Value *CC = B == D ? C : D;
// Form "(A op CC) op' B" if it simplifies completely..
// Does "A op CC" simplify?
if (Value *V = SimplifyBinOp(Opcode, A, CC, TD, DT, MaxRecurse)) {
// It does! Return "V op' B" if it simplifies or is already available.
// If V equals A then "V op' B" is just the LHS. If V equals CC then
// "V op' B" is just the RHS.
if (V == A || V == CC) {
++NumFactor;
return V == A ? LHS : RHS;
}
// Otherwise return "V op' B" if it simplifies.
if (Value *W = SimplifyBinOp(OpcodeToExtract, V, B, TD, DT, MaxRecurse)) {
++NumFactor;
return W;
}
}
}
return 0;
}
/// SimplifyAssociativeBinOp - Generic simplifications for associative binary
/// operations. Returns the simpler value, or null if none was found.
static Value *SimplifyAssociativeBinOp(unsigned Opc, Value *LHS, Value *RHS,
const TargetData *TD,
const DominatorTree *DT,
unsigned MaxRecurse) {
Instruction::BinaryOps Opcode = (Instruction::BinaryOps)Opc;
assert(Instruction::isAssociative(Opcode) && "Not an associative operation!");
// Recursion is always used, so bail out at once if we already hit the limit.
if (!MaxRecurse--)
return 0;
BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
// Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely.
if (Op0 && Op0->getOpcode() == Opcode) {
Value *A = Op0->getOperand(0);
Value *B = Op0->getOperand(1);
Value *C = RHS;
// Does "B op C" simplify?
if (Value *V = SimplifyBinOp(Opcode, B, C, TD, DT, MaxRecurse)) {
// It does! Return "A op V" if it simplifies or is already available.
// If V equals B then "A op V" is just the LHS.
if (V == B) return LHS;
// Otherwise return "A op V" if it simplifies.
if (Value *W = SimplifyBinOp(Opcode, A, V, TD, DT, MaxRecurse)) {
++NumReassoc;
return W;
}
}
}
// Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely.
if (Op1 && Op1->getOpcode() == Opcode) {
Value *A = LHS;
Value *B = Op1->getOperand(0);
Value *C = Op1->getOperand(1);
// Does "A op B" simplify?
if (Value *V = SimplifyBinOp(Opcode, A, B, TD, DT, MaxRecurse)) {
// It does! Return "V op C" if it simplifies or is already available.
// If V equals B then "V op C" is just the RHS.
if (V == B) return RHS;
// Otherwise return "V op C" if it simplifies.
if (Value *W = SimplifyBinOp(Opcode, V, C, TD, DT, MaxRecurse)) {
++NumReassoc;
return W;
}
}
}
// The remaining transforms require commutativity as well as associativity.
if (!Instruction::isCommutative(Opcode))
return 0;
// Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely.
if (Op0 && Op0->getOpcode() == Opcode) {
Value *A = Op0->getOperand(0);
Value *B = Op0->getOperand(1);
Value *C = RHS;
// Does "C op A" simplify?
if (Value *V = SimplifyBinOp(Opcode, C, A, TD, DT, MaxRecurse)) {
// It does! Return "V op B" if it simplifies or is already available.
// If V equals A then "V op B" is just the LHS.
if (V == A) return LHS;
// Otherwise return "V op B" if it simplifies.
if (Value *W = SimplifyBinOp(Opcode, V, B, TD, DT, MaxRecurse)) {
++NumReassoc;
return W;
}
}
}
// Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely.
if (Op1 && Op1->getOpcode() == Opcode) {
Value *A = LHS;
Value *B = Op1->getOperand(0);
Value *C = Op1->getOperand(1);
// Does "C op A" simplify?
if (Value *V = SimplifyBinOp(Opcode, C, A, TD, DT, MaxRecurse)) {
// It does! Return "B op V" if it simplifies or is already available.
// If V equals C then "B op V" is just the RHS.
if (V == C) return RHS;
// Otherwise return "B op V" if it simplifies.
if (Value *W = SimplifyBinOp(Opcode, B, V, TD, DT, MaxRecurse)) {
++NumReassoc;
return W;
}
}
}
return 0;
}
/// ThreadBinOpOverSelect - In the case of a binary operation with a select
/// instruction as an operand, try to simplify the binop by seeing whether
/// evaluating it on both branches of the select results in the same value.
/// Returns the common value if so, otherwise returns null.
static Value *ThreadBinOpOverSelect(unsigned Opcode, Value *LHS, Value *RHS,
const TargetData *TD,
const DominatorTree *DT,
unsigned MaxRecurse) {
// Recursion is always used, so bail out at once if we already hit the limit.
if (!MaxRecurse--)
return 0;
SelectInst *SI;
if (isa<SelectInst>(LHS)) {
SI = cast<SelectInst>(LHS);
} else {
assert(isa<SelectInst>(RHS) && "No select instruction operand!");
SI = cast<SelectInst>(RHS);
}
// Evaluate the BinOp on the true and false branches of the select.
Value *TV;
Value *FV;
if (SI == LHS) {
TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, TD, DT, MaxRecurse);
FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, TD, DT, MaxRecurse);
} else {
TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), TD, DT, MaxRecurse);
FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), TD, DT, MaxRecurse);
}
// If they simplified to the same value, then return the common value.
// If they both failed to simplify then return null.
if (TV == FV)
return TV;
// If one branch simplified to undef, return the other one.
if (TV && isa<UndefValue>(TV))
return FV;
if (FV && isa<UndefValue>(FV))
return TV;
// If applying the operation did not change the true and false select values,
// then the result of the binop is the select itself.
if (TV == SI->getTrueValue() && FV == SI->getFalseValue())
return SI;
// If one branch simplified and the other did not, and the simplified
// value is equal to the unsimplified one, return the simplified value.
// For example, select (cond, X, X & Z) & Z -> X & Z.
if ((FV && !TV) || (TV && !FV)) {
// Check that the simplified value has the form "X op Y" where "op" is the
// same as the original operation.
Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV);
if (Simplified && Simplified->getOpcode() == Opcode) {
// The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS".
// We already know that "op" is the same as for the simplified value. See
// if the operands match too. If so, return the simplified value.
Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue();
Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS;
Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch;
if (Simplified->getOperand(0) == UnsimplifiedLHS &&
Simplified->getOperand(1) == UnsimplifiedRHS)
return Simplified;
if (Simplified->isCommutative() &&
Simplified->getOperand(1) == UnsimplifiedLHS &&
Simplified->getOperand(0) == UnsimplifiedRHS)
return Simplified;
}
}
return 0;
}
/// ThreadCmpOverSelect - In the case of a comparison with a select instruction,
/// try to simplify the comparison by seeing whether both branches of the select
/// result in the same value. Returns the common value if so, otherwise returns
/// null.
static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS,
Value *RHS, const TargetData *TD,
const DominatorTree *DT,
unsigned MaxRecurse) {
// Recursion is always used, so bail out at once if we already hit the limit.
if (!MaxRecurse--)
return 0;
// Make sure the select is on the LHS.
if (!isa<SelectInst>(LHS)) {
std::swap(LHS, RHS);
Pred = CmpInst::getSwappedPredicate(Pred);
}
assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
SelectInst *SI = cast<SelectInst>(LHS);
// Now that we have "cmp select(Cond, TV, FV), RHS", analyse it.
// Does "cmp TV, RHS" simplify?
if (Value *TCmp = SimplifyCmpInst(Pred, SI->getTrueValue(), RHS, TD, DT,
MaxRecurse)) {
// It does! Does "cmp FV, RHS" simplify?
if (Value *FCmp = SimplifyCmpInst(Pred, SI->getFalseValue(), RHS, TD, DT,
MaxRecurse)) {
// It does! If they simplified to the same value, then use it as the
// result of the original comparison.
if (TCmp == FCmp)
return TCmp;
Value *Cond = SI->getCondition();
// If the false value simplified to false, then the result of the compare
// is equal to "Cond && TCmp". This also catches the case when the false
// value simplified to false and the true value to true, returning "Cond".
if (match(FCmp, m_Zero()))
if (Value *V = SimplifyAndInst(Cond, TCmp, TD, DT, MaxRecurse))
return V;
// If the true value simplified to true, then the result of the compare
// is equal to "Cond || FCmp".
if (match(TCmp, m_One()))
if (Value *V = SimplifyOrInst(Cond, FCmp, TD, DT, MaxRecurse))
return V;
// Finally, if the false value simplified to true and the true value to
// false, then the result of the compare is equal to "!Cond".
if (match(FCmp, m_One()) && match(TCmp, m_Zero()))
if (Value *V =
SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()),
TD, DT, MaxRecurse))
return V;
}
}
return 0;
}
/// ThreadBinOpOverPHI - In the case of a binary operation with an operand that
/// is a PHI instruction, try to simplify the binop by seeing whether evaluating
/// it on the incoming phi values yields the same result for every value. If so
/// returns the common value, otherwise returns null.
static Value *ThreadBinOpOverPHI(unsigned Opcode, Value *LHS, Value *RHS,
const TargetData *TD, const DominatorTree *DT,
unsigned MaxRecurse) {
// Recursion is always used, so bail out at once if we already hit the limit.
if (!MaxRecurse--)
return 0;
PHINode *PI;
if (isa<PHINode>(LHS)) {
PI = cast<PHINode>(LHS);
// Bail out if RHS and the phi may be mutually interdependent due to a loop.
if (!ValueDominatesPHI(RHS, PI, DT))
return 0;
} else {
assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
PI = cast<PHINode>(RHS);
// Bail out if LHS and the phi may be mutually interdependent due to a loop.
if (!ValueDominatesPHI(LHS, PI, DT))
return 0;
}
// Evaluate the BinOp on the incoming phi values.
Value *CommonValue = 0;
for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
Value *Incoming = PI->getIncomingValue(i);
// If the incoming value is the phi node itself, it can safely be skipped.
if (Incoming == PI) continue;
Value *V = PI == LHS ?
SimplifyBinOp(Opcode, Incoming, RHS, TD, DT, MaxRecurse) :
SimplifyBinOp(Opcode, LHS, Incoming, TD, DT, MaxRecurse);
// If the operation failed to simplify, or simplified to a different value
// to previously, then give up.
if (!V || (CommonValue && V != CommonValue))
return 0;
CommonValue = V;
}
return CommonValue;
}
/// ThreadCmpOverPHI - In the case of a comparison with a PHI instruction, try
/// try to simplify the comparison by seeing whether comparing with all of the
/// incoming phi values yields the same result every time. If so returns the
/// common result, otherwise returns null.
static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS,
const TargetData *TD, const DominatorTree *DT,
unsigned MaxRecurse) {
// Recursion is always used, so bail out at once if we already hit the limit.
if (!MaxRecurse--)
return 0;
// Make sure the phi is on the LHS.
if (!isa<PHINode>(LHS)) {
std::swap(LHS, RHS);
Pred = CmpInst::getSwappedPredicate(Pred);
}
assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
PHINode *PI = cast<PHINode>(LHS);
// Bail out if RHS and the phi may be mutually interdependent due to a loop.
if (!ValueDominatesPHI(RHS, PI, DT))
return 0;
// Evaluate the BinOp on the incoming phi values.
Value *CommonValue = 0;
for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
Value *Incoming = PI->getIncomingValue(i);
// If the incoming value is the phi node itself, it can safely be skipped.
if (Incoming == PI) continue;
Value *V = SimplifyCmpInst(Pred, Incoming, RHS, TD, DT, MaxRecurse);
// If the operation failed to simplify, or simplified to a different value
// to previously, then give up.
if (!V || (CommonValue && V != CommonValue))
return 0;
CommonValue = V;
}
return CommonValue;
}
/// SimplifyAddInst - Given operands for an Add, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
const TargetData *TD, const DominatorTree *DT,
unsigned MaxRecurse) {
if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
Constant *Ops[] = { CLHS, CRHS };
return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(),
Ops, 2, TD);
}
// Canonicalize the constant to the RHS.
std::swap(Op0, Op1);
}
// X + undef -> undef
if (match(Op1, m_Undef()))
return Op1;
// X + 0 -> X
if (match(Op1, m_Zero()))
return Op0;
// X + (Y - X) -> Y
// (Y - X) + X -> Y
// Eg: X + -X -> 0
Value *Y = 0;
if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
return Y;
// X + ~X -> -1 since ~X = -X-1
if (match(Op0, m_Not(m_Specific(Op1))) ||
match(Op1, m_Not(m_Specific(Op0))))
return Constant::getAllOnesValue(Op0->getType());
/// i1 add -> xor.
if (MaxRecurse && Op0->getType()->isIntegerTy(1))
if (Value *V = SimplifyXorInst(Op0, Op1, TD, DT, MaxRecurse-1))
return V;
// Try some generic simplifications for associative operations.
if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, TD, DT,
MaxRecurse))
return V;
// Mul distributes over Add. Try some generic simplifications based on this.
if (Value *V = FactorizeBinOp(Instruction::Add, Op0, Op1, Instruction::Mul,
TD, DT, MaxRecurse))
return V;
// Threading Add over selects and phi nodes is pointless, so don't bother.
// Threading over the select in "A + select(cond, B, C)" means evaluating
// "A+B" and "A+C" and seeing if they are equal; but they are equal if and
// only if B and C are equal. If B and C are equal then (since we assume
// that operands have already been simplified) "select(cond, B, C)" should
// have been simplified to the common value of B and C already. Analysing
// "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly
// for threading over phi nodes.
return 0;
}
Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
const TargetData *TD, const DominatorTree *DT) {
return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, TD, DT, RecursionLimit);
}
/// SimplifySubInst - Given operands for a Sub, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
const TargetData *TD, const DominatorTree *DT,
unsigned MaxRecurse) {
if (Constant *CLHS = dyn_cast<Constant>(Op0))
if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
Constant *Ops[] = { CLHS, CRHS };
return ConstantFoldInstOperands(Instruction::Sub, CLHS->getType(),
Ops, 2, TD);
}
// X - undef -> undef
// undef - X -> undef
if (match(Op0, m_Undef()) || match(Op1, m_Undef()))
return UndefValue::get(Op0->getType());
// X - 0 -> X
if (match(Op1, m_Zero()))
return Op0;
// X - X -> 0
if (Op0 == Op1)
return Constant::getNullValue(Op0->getType());
// (X*2) - X -> X
// (X<<1) - X -> X
Value *X = 0;
if (match(Op0, m_Mul(m_Specific(Op1), m_ConstantInt<2>())) ||
match(Op0, m_Shl(m_Specific(Op1), m_One())))
return Op1;
// (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies.
// For example, (X + Y) - Y -> X; (Y + X) - Y -> X
Value *Y = 0, *Z = Op1;
if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z
// See if "V === Y - Z" simplifies.
if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, TD, DT, MaxRecurse-1))
// It does! Now see if "X + V" simplifies.
if (Value *W = SimplifyBinOp(Instruction::Add, X, V, TD, DT,
MaxRecurse-1)) {
// It does, we successfully reassociated!
++NumReassoc;
return W;
}
// See if "V === X - Z" simplifies.
if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, TD, DT, MaxRecurse-1))
// It does! Now see if "Y + V" simplifies.
if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, TD, DT,
MaxRecurse-1)) {
// It does, we successfully reassociated!
++NumReassoc;
return W;
}
}
// X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies.
// For example, X - (X + 1) -> -1
X = Op0;
if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z)
// See if "V === X - Y" simplifies.
if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, TD, DT, MaxRecurse-1))
// It does! Now see if "V - Z" simplifies.
if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, TD, DT,
MaxRecurse-1)) {
// It does, we successfully reassociated!
++NumReassoc;
return W;
}
// See if "V === X - Z" simplifies.
if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, TD, DT, MaxRecurse-1))
// It does! Now see if "V - Y" simplifies.
if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, TD, DT,
MaxRecurse-1)) {
// It does, we successfully reassociated!
++NumReassoc;
return W;
}
}
// Z - (X - Y) -> (Z - X) + Y if everything simplifies.
// For example, X - (X - Y) -> Y.
Z = Op0;
if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y)
// See if "V === Z - X" simplifies.
if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, TD, DT, MaxRecurse-1))
// It does! Now see if "V + Y" simplifies.
if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, TD, DT,
MaxRecurse-1)) {
// It does, we successfully reassociated!
++NumReassoc;
return W;
}
// Mul distributes over Sub. Try some generic simplifications based on this.
if (Value *V = FactorizeBinOp(Instruction::Sub, Op0, Op1, Instruction::Mul,
TD, DT, MaxRecurse))
return V;
// i1 sub -> xor.
if (MaxRecurse && Op0->getType()->isIntegerTy(1))
if (Value *V = SimplifyXorInst(Op0, Op1, TD, DT, MaxRecurse-1))
return V;
// Threading Sub over selects and phi nodes is pointless, so don't bother.
// Threading over the select in "A - select(cond, B, C)" means evaluating
// "A-B" and "A-C" and seeing if they are equal; but they are equal if and
// only if B and C are equal. If B and C are equal then (since we assume
// that operands have already been simplified) "select(cond, B, C)" should
// have been simplified to the common value of B and C already. Analysing
// "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly
// for threading over phi nodes.
return 0;
}
Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
const TargetData *TD, const DominatorTree *DT) {
return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, TD, DT, RecursionLimit);
}
/// SimplifyMulInst - Given operands for a Mul, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
const DominatorTree *DT, unsigned MaxRecurse) {
if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
Constant *Ops[] = { CLHS, CRHS };
return ConstantFoldInstOperands(Instruction::Mul, CLHS->getType(),
Ops, 2, TD);
}
// Canonicalize the constant to the RHS.
std::swap(Op0, Op1);
}
// X * undef -> 0
if (match(Op1, m_Undef()))
return Constant::getNullValue(Op0->getType());
// X * 0 -> 0
if (match(Op1, m_Zero()))
return Op1;
// X * 1 -> X
if (match(Op1, m_One()))
return Op0;
// (X / Y) * Y -> X if the division is exact.
Value *X = 0, *Y = 0;
if ((match(Op0, m_SDiv(m_Value(X), m_Value(Y))) && Y == Op1) || // (X / Y) * Y
(match(Op1, m_SDiv(m_Value(X), m_Value(Y))) && Y == Op0)) { // Y * (X / Y)
BinaryOperator *SDiv = cast<BinaryOperator>(Y == Op1 ? Op0 : Op1);
if (SDiv->isExact())
return X;
}
// i1 mul -> and.
if (MaxRecurse && Op0->getType()->isIntegerTy(1))
if (Value *V = SimplifyAndInst(Op0, Op1, TD, DT, MaxRecurse-1))
return V;
// Try some generic simplifications for associative operations.
if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, TD, DT,
MaxRecurse))
return V;
// Mul distributes over Add. Try some generic simplifications based on this.
if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
TD, DT, MaxRecurse))
return V;
// If the operation is with the result of a select instruction, check whether
// operating on either branch of the select always yields the same value.
if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, TD, DT,
MaxRecurse))
return V;
// If the operation is with the result of a phi instruction, check whether
// operating on all incoming values of the phi always yields the same value.
if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, TD, DT,
MaxRecurse))
return V;
return 0;
}
Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
const DominatorTree *DT) {
return ::SimplifyMulInst(Op0, Op1, TD, DT, RecursionLimit);
}
/// SimplifyDiv - Given operands for an SDiv or UDiv, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyDiv(unsigned Opcode, Value *Op0, Value *Op1,
const TargetData *TD, const DominatorTree *DT,
unsigned MaxRecurse) {
if (Constant *C0 = dyn_cast<Constant>(Op0)) {
if (Constant *C1 = dyn_cast<Constant>(Op1)) {
Constant *Ops[] = { C0, C1 };
return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, 2, TD);
}
}
bool isSigned = Opcode == Instruction::SDiv;
// X / undef -> undef
if (match(Op1, m_Undef()))
return Op1;
// undef / X -> 0
if (match(Op0, m_Undef()))
return Constant::getNullValue(Op0->getType());
// 0 / X -> 0, we don't need to preserve faults!
if (match(Op0, m_Zero()))
return Op0;
// X / 1 -> X
if (match(Op1, m_One()))
return Op0;
if (Op0->getType()->isIntegerTy(1))
// It can't be division by zero, hence it must be division by one.
return Op0;
// X / X -> 1
if (Op0 == Op1)
return ConstantInt::get(Op0->getType(), 1);
// (X * Y) / Y -> X if the multiplication does not overflow.
Value *X = 0, *Y = 0;
if (match(Op0, m_Mul(m_Value(X), m_Value(Y))) && (X == Op1 || Y == Op1)) {
if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1
BinaryOperator *Mul = cast<BinaryOperator>(Op0);
// If the Mul knows it does not overflow, then we are good to go.
if ((isSigned && Mul->hasNoSignedWrap()) ||
(!isSigned && Mul->hasNoUnsignedWrap()))
return X;
// If X has the form X = A / Y then X * Y cannot overflow.
if (BinaryOperator *Div = dyn_cast<BinaryOperator>(X))
if (Div->getOpcode() == Opcode && Div->getOperand(1) == Y)
return X;
}
// (X rem Y) / Y -> 0
if ((isSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
(!isSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
return Constant::getNullValue(Op0->getType());
// If the operation is with the result of a select instruction, check whether
// operating on either branch of the select always yields the same value.
if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, TD, DT, MaxRecurse))
return V;
// If the operation is with the result of a phi instruction, check whether
// operating on all incoming values of the phi always yields the same value.
if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, TD, DT, MaxRecurse))
return V;
return 0;
}
/// SimplifySDivInst - Given operands for an SDiv, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifySDivInst(Value *Op0, Value *Op1, const TargetData *TD,
const DominatorTree *DT, unsigned MaxRecurse) {
if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, TD, DT, MaxRecurse))
return V;
return 0;
}
Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const TargetData *TD,
const DominatorTree *DT) {
return ::SimplifySDivInst(Op0, Op1, TD, DT, RecursionLimit);
}
/// SimplifyUDivInst - Given operands for a UDiv, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const TargetData *TD,
const DominatorTree *DT, unsigned MaxRecurse) {
if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, TD, DT, MaxRecurse))
return V;
return 0;
}
Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const TargetData *TD,
const DominatorTree *DT) {
return ::SimplifyUDivInst(Op0, Op1, TD, DT, RecursionLimit);
}
static Value *SimplifyFDivInst(Value *Op0, Value *Op1, const TargetData *,
const DominatorTree *, unsigned) {
// undef / X -> undef (the undef could be a snan).
if (match(Op0, m_Undef()))
return Op0;
// X / undef -> undef
if (match(Op1, m_Undef()))
return Op1;
return 0;
}
Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, const TargetData *TD,
const DominatorTree *DT) {
return ::SimplifyFDivInst(Op0, Op1, TD, DT, RecursionLimit);
}
/// SimplifyShift - Given operands for an Shl, LShr or AShr, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyShift(unsigned Opcode, Value *Op0, Value *Op1,
const TargetData *TD, const DominatorTree *DT,
unsigned MaxRecurse) {
if (Constant *C0 = dyn_cast<Constant>(Op0)) {
if (Constant *C1 = dyn_cast<Constant>(Op1)) {
Constant *Ops[] = { C0, C1 };
return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, 2, TD);
}
}
// 0 shift by X -> 0
if (match(Op0, m_Zero()))
return Op0;
// X shift by 0 -> X
if (match(Op1, m_Zero()))
return Op0;
// X shift by undef -> undef because it may shift by the bitwidth.
if (match(Op1, m_Undef()))
return Op1;
// Shifting by the bitwidth or more is undefined.
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1))
if (CI->getValue().getLimitedValue() >=
Op0->getType()->getScalarSizeInBits())
return UndefValue::get(Op0->getType());
// If the operation is with the result of a select instruction, check whether
// operating on either branch of the select always yields the same value.
if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, TD, DT, MaxRecurse))
return V;
// If the operation is with the result of a phi instruction, check whether
// operating on all incoming values of the phi always yields the same value.
if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, TD, DT, MaxRecurse))
return V;
return 0;
}
/// SimplifyShlInst - Given operands for an Shl, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyShlInst(Value *Op0, Value *Op1, const TargetData *TD,
const DominatorTree *DT, unsigned MaxRecurse) {
if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, TD, DT, MaxRecurse))
return V;
// undef << X -> 0
if (match(Op0, m_Undef()))
return Constant::getNullValue(Op0->getType());
return 0;
}
Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, const TargetData *TD,
const DominatorTree *DT) {
return ::SimplifyShlInst(Op0, Op1, TD, DT, RecursionLimit);
}
/// SimplifyLShrInst - Given operands for an LShr, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyLShrInst(Value *Op0, Value *Op1, const TargetData *TD,
const DominatorTree *DT, unsigned MaxRecurse) {
if (Value *V = SimplifyShift(Instruction::LShr, Op0, Op1, TD, DT, MaxRecurse))
return V;
// undef >>l X -> 0
if (match(Op0, m_Undef()))
return Constant::getNullValue(Op0->getType());
return 0;
}
Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, const TargetData *TD,
const DominatorTree *DT) {
return ::SimplifyLShrInst(Op0, Op1, TD, DT, RecursionLimit);
}
/// SimplifyAShrInst - Given operands for an AShr, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyAShrInst(Value *Op0, Value *Op1, const TargetData *TD,
const DominatorTree *DT, unsigned MaxRecurse) {
if (Value *V = SimplifyShift(Instruction::AShr, Op0, Op1, TD, DT, MaxRecurse))
return V;
// all ones >>a X -> all ones
if (match(Op0, m_AllOnes()))
return Op0;
// undef >>a X -> all ones
if (match(Op0, m_Undef()))
return Constant::getAllOnesValue(Op0->getType());
return 0;
}
Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, const TargetData *TD,
const DominatorTree *DT) {
return ::SimplifyAShrInst(Op0, Op1, TD, DT, RecursionLimit);
}
/// SimplifyAndInst - Given operands for an And, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
const DominatorTree *DT, unsigned MaxRecurse) {
if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
Constant *Ops[] = { CLHS, CRHS };
return ConstantFoldInstOperands(Instruction::And, CLHS->getType(),
Ops, 2, TD);
}
// Canonicalize the constant to the RHS.
std::swap(Op0, Op1);
}
// X & undef -> 0
if (match(Op1, m_Undef()))
return Constant::getNullValue(Op0->getType());
// X & X = X
if (Op0 == Op1)
return Op0;
// X & 0 = 0
if (match(Op1, m_Zero()))
return Op1;
// X & -1 = X
if (match(Op1, m_AllOnes()))
return Op0;
// A & ~A = ~A & A = 0
Value *A = 0, *B = 0;
if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
(match(Op1, m_Not(m_Value(A))) && A == Op0))
return Constant::getNullValue(Op0->getType());
// (A | ?) & A = A
if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
(A == Op1 || B == Op1))
return Op1;
// A & (A | ?) = A
if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
(A == Op0 || B == Op0))
return Op0;
// Try some generic simplifications for associative operations.
if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, TD, DT,
MaxRecurse))
return V;
// And distributes over Or. Try some generic simplifications based on this.
if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
TD, DT, MaxRecurse))
return V;
// And distributes over Xor. Try some generic simplifications based on this.
if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
TD, DT, MaxRecurse))
return V;
// Or distributes over And. Try some generic simplifications based on this.
if (Value *V = FactorizeBinOp(Instruction::And, Op0, Op1, Instruction::Or,
TD, DT, MaxRecurse))
return V;
// If the operation is with the result of a select instruction, check whether
// operating on either branch of the select always yields the same value.
if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, TD, DT,
MaxRecurse))
return V;
// If the operation is with the result of a phi instruction, check whether
// operating on all incoming values of the phi always yields the same value.
if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, TD, DT,
MaxRecurse))
return V;
return 0;
}
Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
const DominatorTree *DT) {
return ::SimplifyAndInst(Op0, Op1, TD, DT, RecursionLimit);
}
/// SimplifyOrInst - Given operands for an Or, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
const DominatorTree *DT, unsigned MaxRecurse) {
if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
Constant *Ops[] = { CLHS, CRHS };
return ConstantFoldInstOperands(Instruction::Or, CLHS->getType(),
Ops, 2, TD);
}
// Canonicalize the constant to the RHS.
std::swap(Op0, Op1);
}
// X | undef -> -1
if (match(Op1, m_Undef()))
return Constant::getAllOnesValue(Op0->getType());
// X | X = X
if (Op0 == Op1)
return Op0;
// X | 0 = X
if (match(Op1, m_Zero()))
return Op0;
// X | -1 = -1
if (match(Op1, m_AllOnes()))
return Op1;
// A | ~A = ~A | A = -1
Value *A = 0, *B = 0;
if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
(match(Op1, m_Not(m_Value(A))) && A == Op0))
return Constant::getAllOnesValue(Op0->getType());
// (A & ?) | A = A
if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
(A == Op1 || B == Op1))
return Op1;
// A | (A & ?) = A
if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
(A == Op0 || B == Op0))
return Op0;
// Try some generic simplifications for associative operations.
if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, TD, DT,
MaxRecurse))
return V;
// Or distributes over And. Try some generic simplifications based on this.
if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And,
TD, DT, MaxRecurse))
return V;
// And distributes over Or. Try some generic simplifications based on this.
if (Value *V = FactorizeBinOp(Instruction::Or, Op0, Op1, Instruction::And,
TD, DT, MaxRecurse))
return V;
// If the operation is with the result of a select instruction, check whether
// operating on either branch of the select always yields the same value.
if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, TD, DT,
MaxRecurse))
return V;
// If the operation is with the result of a phi instruction, check whether
// operating on all incoming values of the phi always yields the same value.
if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, TD, DT,
MaxRecurse))
return V;
return 0;
}
Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD,
const DominatorTree *DT) {
return ::SimplifyOrInst(Op0, Op1, TD, DT, RecursionLimit);
}
/// SimplifyXorInst - Given operands for a Xor, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
const DominatorTree *DT, unsigned MaxRecurse) {
if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
Constant *Ops[] = { CLHS, CRHS };
return ConstantFoldInstOperands(Instruction::Xor, CLHS->getType(),
Ops, 2, TD);
}
// Canonicalize the constant to the RHS.
std::swap(Op0, Op1);
}
// A ^ undef -> undef
if (match(Op1, m_Undef()))
return Op1;
// A ^ 0 = A
if (match(Op1, m_Zero()))
return Op0;
// A ^ A = 0
if (Op0 == Op1)
return Constant::getNullValue(Op0->getType());
// A ^ ~A = ~A ^ A = -1
Value *A = 0;
if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
(match(Op1, m_Not(m_Value(A))) && A == Op0))
return Constant::getAllOnesValue(Op0->getType());
// Try some generic simplifications for associative operations.
if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, TD, DT,
MaxRecurse))
return V;
// And distributes over Xor. Try some generic simplifications based on this.
if (Value *V = FactorizeBinOp(Instruction::Xor, Op0, Op1, Instruction::And,
TD, DT, MaxRecurse))
return V;
// Threading Xor over selects and phi nodes is pointless, so don't bother.
// Threading over the select in "A ^ select(cond, B, C)" means evaluating
// "A^B" and "A^C" and seeing if they are equal; but they are equal if and
// only if B and C are equal. If B and C are equal then (since we assume
// that operands have already been simplified) "select(cond, B, C)" should
// have been simplified to the common value of B and C already. Analysing
// "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly
// for threading over phi nodes.
return 0;
}
Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
const DominatorTree *DT) {
return ::SimplifyXorInst(Op0, Op1, TD, DT, RecursionLimit);
}
static const Type *GetCompareTy(Value *Op) {
return CmpInst::makeCmpResultType(Op->getType());
}
/// SimplifyICmpInst - Given operands for an ICmpInst, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
const TargetData *TD, const DominatorTree *DT,
unsigned MaxRecurse) {
CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
if (Constant *CRHS = dyn_cast<Constant>(RHS))
return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD);
// If we have a constant, make sure it is on the RHS.
std::swap(LHS, RHS);
Pred = CmpInst::getSwappedPredicate(Pred);
}
const Type *ITy = GetCompareTy(LHS); // The return type.
const Type *OpTy = LHS->getType(); // The operand type.
// icmp X, X -> true/false
// X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
// because X could be 0.
if (LHS == RHS || isa<UndefValue>(RHS))
return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
// Special case logic when the operands have i1 type.
if (OpTy->isIntegerTy(1) || (OpTy->isVectorTy() &&
cast<VectorType>(OpTy)->getElementType()->isIntegerTy(1))) {
switch (Pred) {
default: break;
case ICmpInst::ICMP_EQ:
// X == 1 -> X
if (match(RHS, m_One()))
return LHS;
break;
case ICmpInst::ICMP_NE:
// X != 0 -> X
if (match(RHS, m_Zero()))
return LHS;
break;
case ICmpInst::ICMP_UGT:
// X >u 0 -> X
if (match(RHS, m_Zero()))
return LHS;
break;
case ICmpInst::ICMP_UGE:
// X >=u 1 -> X
if (match(RHS, m_One()))
return LHS;
break;
case ICmpInst::ICMP_SLT:
// X <s 0 -> X
if (match(RHS, m_Zero()))
return LHS;
break;
case ICmpInst::ICMP_SLE:
// X <=s -1 -> X
if (match(RHS, m_One()))
return LHS;
break;
}
}
// icmp <alloca*>, <global/alloca*/null> - Different stack variables have
// different addresses, and what's more the address of a stack variable is
// never null or equal to the address of a global. Note that generalizing
// to the case where LHS is a global variable address or null is pointless,
// since if both LHS and RHS are constants then we already constant folded
// the compare, and if only one of them is then we moved it to RHS already.
if (isa<AllocaInst>(LHS) && (isa<GlobalValue>(RHS) || isa<AllocaInst>(RHS) ||
isa<ConstantPointerNull>(RHS)))
// We already know that LHS != LHS.
return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred));
// If we are comparing with zero then try hard since this is a common case.
if (match(RHS, m_Zero())) {
bool LHSKnownNonNegative, LHSKnownNegative;
switch (Pred) {
default:
assert(false && "Unknown ICmp predicate!");
case ICmpInst::ICMP_ULT:
return ConstantInt::getFalse(LHS->getContext());
case ICmpInst::ICMP_UGE:
return ConstantInt::getTrue(LHS->getContext());
case ICmpInst::ICMP_EQ:
case ICmpInst::ICMP_ULE:
if (isKnownNonZero(LHS, TD))
return ConstantInt::getFalse(LHS->getContext());
break;
case ICmpInst::ICMP_NE:
case ICmpInst::ICMP_UGT:
if (isKnownNonZero(LHS, TD))
return ConstantInt::getTrue(LHS->getContext());
break;
case ICmpInst::ICMP_SLT:
ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
if (LHSKnownNegative)
return ConstantInt::getTrue(LHS->getContext());
if (LHSKnownNonNegative)
return ConstantInt::getFalse(LHS->getContext());
break;
case ICmpInst::ICMP_SLE:
ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
if (LHSKnownNegative)
return ConstantInt::getTrue(LHS->getContext());
if (LHSKnownNonNegative && isKnownNonZero(LHS, TD))
return ConstantInt::getFalse(LHS->getContext());
break;
case ICmpInst::ICMP_SGE:
ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
if (LHSKnownNegative)
return ConstantInt::getFalse(LHS->getContext());
if (LHSKnownNonNegative)
return ConstantInt::getTrue(LHS->getContext());
break;
case ICmpInst::ICMP_SGT:
ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
if (LHSKnownNegative)
return ConstantInt::getFalse(LHS->getContext());
if (LHSKnownNonNegative && isKnownNonZero(LHS, TD))
return ConstantInt::getTrue(LHS->getContext());
break;
}
}
// See if we are doing a comparison with a constant integer.
if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
switch (Pred) {
default: break;
case ICmpInst::ICMP_UGT:
if (CI->isMaxValue(false)) // A >u MAX -> FALSE
return ConstantInt::getFalse(CI->getContext());
break;
case ICmpInst::ICMP_UGE:
if (CI->isMinValue(false)) // A >=u MIN -> TRUE
return ConstantInt::getTrue(CI->getContext());
break;
case ICmpInst::ICMP_ULT:
if (CI->isMinValue(false)) // A <u MIN -> FALSE
return ConstantInt::getFalse(CI->getContext());
break;
case ICmpInst::ICMP_ULE:
if (CI->isMaxValue(false)) // A <=u MAX -> TRUE
return ConstantInt::getTrue(CI->getContext());
break;
case ICmpInst::ICMP_SGT:
if (CI->isMaxValue(true)) // A >s MAX -> FALSE
return ConstantInt::getFalse(CI->getContext());
break;
case ICmpInst::ICMP_SGE:
if (CI->isMinValue(true)) // A >=s MIN -> TRUE
return ConstantInt::getTrue(CI->getContext());
break;
case ICmpInst::ICMP_SLT:
if (CI->isMinValue(true)) // A <s MIN -> FALSE
return ConstantInt::getFalse(CI->getContext());
break;
case ICmpInst::ICMP_SLE:
if (CI->isMaxValue(true)) // A <=s MAX -> TRUE
return ConstantInt::getTrue(CI->getContext());
break;
}
}
// Compare of cast, for example (zext X) != 0 -> X != 0
if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) {
Instruction *LI = cast<CastInst>(LHS);
Value *SrcOp = LI->getOperand(0);
const Type *SrcTy = SrcOp->getType();
const Type *DstTy = LI->getType();
// Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input
// if the integer type is the same size as the pointer type.
if (MaxRecurse && TD && isa<PtrToIntInst>(LI) &&
TD->getPointerSizeInBits() == DstTy->getPrimitiveSizeInBits()) {
if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
// Transfer the cast to the constant.
if (Value *V = SimplifyICmpInst(Pred, SrcOp,
ConstantExpr::getIntToPtr(RHSC, SrcTy),
TD, DT, MaxRecurse-1))
return V;
} else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) {
if (RI->getOperand(0)->getType() == SrcTy)
// Compare without the cast.
if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
TD, DT, MaxRecurse-1))
return V;
}
}
if (isa<ZExtInst>(LHS)) {
// Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the
// same type.
if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
// Compare X and Y. Note that signed predicates become unsigned.
if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
SrcOp, RI->getOperand(0), TD, DT,
MaxRecurse-1))
return V;
}
// Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
// too. If not, then try to deduce the result of the comparison.
else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
// Compute the constant that would happen if we truncated to SrcTy then
// reextended to DstTy.
Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy);
// If the re-extended constant didn't change then this is effectively
// also a case of comparing two zero-extended values.
if (RExt == CI && MaxRecurse)
if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
SrcOp, Trunc, TD, DT, MaxRecurse-1))
return V;
// Otherwise the upper bits of LHS are zero while RHS has a non-zero bit
// there. Use this to work out the result of the comparison.
if (RExt != CI) {
switch (Pred) {
default:
assert(false && "Unknown ICmp predicate!");
// LHS <u RHS.
case ICmpInst::ICMP_EQ:
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_UGE:
return ConstantInt::getFalse(CI->getContext());
case ICmpInst::ICMP_NE:
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_ULE:
return ConstantInt::getTrue(CI->getContext());
// LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS
// is non-negative then LHS <s RHS.
case ICmpInst::ICMP_SGT:
case ICmpInst::ICMP_SGE:
return CI->getValue().isNegative() ?
ConstantInt::getTrue(CI->getContext()) :
ConstantInt::getFalse(CI->getContext());
case ICmpInst::ICMP_SLT:
case ICmpInst::ICMP_SLE:
return CI->getValue().isNegative() ?
ConstantInt::getFalse(CI->getContext()) :
ConstantInt::getTrue(CI->getContext());
}
}
}
}
if (isa<SExtInst>(LHS)) {
// Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the
// same type.
if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
// Compare X and Y. Note that the predicate does not change.
if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
TD, DT, MaxRecurse-1))
return V;
}
// Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended
// too. If not, then try to deduce the result of the comparison.
else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
// Compute the constant that would happen if we truncated to SrcTy then
// reextended to DstTy.
Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy);
// If the re-extended constant didn't change then this is effectively
// also a case of comparing two sign-extended values.
if (RExt == CI && MaxRecurse)
if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, TD, DT,
MaxRecurse-1))
return V;
// Otherwise the upper bits of LHS are all equal, while RHS has varying
// bits there. Use this to work out the result of the comparison.
if (RExt != CI) {
switch (Pred) {
default:
assert(false && "Unknown ICmp predicate!");
case ICmpInst::ICMP_EQ:
return ConstantInt::getFalse(CI->getContext());
case ICmpInst::ICMP_NE:
return ConstantInt::getTrue(CI->getContext());
// If RHS is non-negative then LHS <s RHS. If RHS is negative then
// LHS >s RHS.
case ICmpInst::ICMP_SGT:
case ICmpInst::ICMP_SGE:
return CI->getValue().isNegative() ?
ConstantInt::getTrue(CI->getContext()) :
ConstantInt::getFalse(CI->getContext());
case ICmpInst::ICMP_SLT:
case ICmpInst::ICMP_SLE:
return CI->getValue().isNegative() ?
ConstantInt::getFalse(CI->getContext()) :
ConstantInt::getTrue(CI->getContext());
// If LHS is non-negative then LHS <u RHS. If LHS is negative then
// LHS >u RHS.
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_UGE:
// Comparison is true iff the LHS <s 0.
if (MaxRecurse)
if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp,
Constant::getNullValue(SrcTy),
TD, DT, MaxRecurse-1))
return V;
break;
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_ULE:
// Comparison is true iff the LHS >=s 0.
if (MaxRecurse)
if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp,
Constant::getNullValue(SrcTy),
TD, DT, MaxRecurse-1))
return V;
break;
}
}
}
}
}
// If the comparison is with the result of a select instruction, check whether
// comparing with either branch of the select always yields the same value.
if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, DT, MaxRecurse))
return V;
// If the comparison is with the result of a phi instruction, check whether
// doing the compare with each incoming phi value yields a common result.
if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, DT, MaxRecurse))
return V;
return 0;
}
Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
const TargetData *TD, const DominatorTree *DT) {
return ::SimplifyICmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
}
/// SimplifyFCmpInst - Given operands for an FCmpInst, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
const TargetData *TD, const DominatorTree *DT,
unsigned MaxRecurse) {
CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
if (Constant *CRHS = dyn_cast<Constant>(RHS))
return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, TD);
// If we have a constant, make sure it is on the RHS.
std::swap(LHS, RHS);
Pred = CmpInst::getSwappedPredicate(Pred);
}
// Fold trivial predicates.
if (Pred == FCmpInst::FCMP_FALSE)
return ConstantInt::get(GetCompareTy(LHS), 0);
if (Pred == FCmpInst::FCMP_TRUE)
return ConstantInt::get(GetCompareTy(LHS), 1);
if (isa<UndefValue>(RHS)) // fcmp pred X, undef -> undef
return UndefValue::get(GetCompareTy(LHS));
// fcmp x,x -> true/false. Not all compares are foldable.
if (LHS == RHS) {
if (CmpInst::isTrueWhenEqual(Pred))
return ConstantInt::get(GetCompareTy(LHS), 1);
if (CmpInst::isFalseWhenEqual(Pred))
return ConstantInt::get(GetCompareTy(LHS), 0);
}
// Handle fcmp with constant RHS
if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
// If the constant is a nan, see if we can fold the comparison based on it.
if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
if (CFP->getValueAPF().isNaN()) {
if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo"
return ConstantInt::getFalse(CFP->getContext());
assert(FCmpInst::isUnordered(Pred) &&
"Comparison must be either ordered or unordered!");
// True if unordered.
return ConstantInt::getTrue(CFP->getContext());
}
// Check whether the constant is an infinity.
if (CFP->getValueAPF().isInfinity()) {
if (CFP->getValueAPF().isNegative()) {
switch (Pred) {
case FCmpInst::FCMP_OLT:
// No value is ordered and less than negative infinity.
return ConstantInt::getFalse(CFP->getContext());
case FCmpInst::FCMP_UGE:
// All values are unordered with or at least negative infinity.
return ConstantInt::getTrue(CFP->getContext());
default:
break;
}
} else {
switch (Pred) {
case FCmpInst::FCMP_OGT:
// No value is ordered and greater than infinity.
return ConstantInt::getFalse(CFP->getContext());
case FCmpInst::FCMP_ULE:
// All values are unordered with and at most infinity.
return ConstantInt::getTrue(CFP->getContext());
default:
break;
}
}
}
}
}
// If the comparison is with the result of a select instruction, check whether
// comparing with either branch of the select always yields the same value.
if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, DT, MaxRecurse))
return V;
// If the comparison is with the result of a phi instruction, check whether
// doing the compare with each incoming phi value yields a common result.
if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, DT, MaxRecurse))
return V;
return 0;
}
Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
const TargetData *TD, const DominatorTree *DT) {
return ::SimplifyFCmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
}
/// SimplifySelectInst - Given operands for a SelectInst, see if we can fold
/// the result. If not, this returns null.
Value *llvm::SimplifySelectInst(Value *CondVal, Value *TrueVal, Value *FalseVal,
const TargetData *TD, const DominatorTree *) {
// select true, X, Y -> X
// select false, X, Y -> Y
if (ConstantInt *CB = dyn_cast<ConstantInt>(CondVal))
return CB->getZExtValue() ? TrueVal : FalseVal;
// select C, X, X -> X
if (TrueVal == FalseVal)
return TrueVal;
if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
return FalseVal;
if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
return TrueVal;
if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
if (isa<Constant>(TrueVal))
return TrueVal;
return FalseVal;
}
return 0;
}
/// SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can
/// fold the result. If not, this returns null.
Value *llvm::SimplifyGEPInst(Value *const *Ops, unsigned NumOps,
const TargetData *TD, const DominatorTree *) {
// The type of the GEP pointer operand.
const PointerType *PtrTy = cast<PointerType>(Ops[0]->getType());
// getelementptr P -> P.
if (NumOps == 1)
return Ops[0];
if (isa<UndefValue>(Ops[0])) {
// Compute the (pointer) type returned by the GEP instruction.
const Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, &Ops[1],
NumOps-1);
const Type *GEPTy = PointerType::get(LastType, PtrTy->getAddressSpace());
return UndefValue::get(GEPTy);
}
if (NumOps == 2) {
// getelementptr P, 0 -> P.
if (ConstantInt *C = dyn_cast<ConstantInt>(Ops[1]))
if (C->isZero())
return Ops[0];
// getelementptr P, N -> P if P points to a type of zero size.
if (TD) {
const Type *Ty = PtrTy->getElementType();
if (Ty->isSized() && TD->getTypeAllocSize(Ty) == 0)
return Ops[0];
}
}
// Check to see if this is constant foldable.
for (unsigned i = 0; i != NumOps; ++i)
if (!isa<Constant>(Ops[i]))
return 0;
return ConstantExpr::getGetElementPtr(cast<Constant>(Ops[0]),
(Constant *const*)Ops+1, NumOps-1);
}
/// SimplifyPHINode - See if we can fold the given phi. If not, returns null.
static Value *SimplifyPHINode(PHINode *PN, const DominatorTree *DT) {
// If all of the PHI's incoming values are the same then replace the PHI node
// with the common value.
Value *CommonValue = 0;
bool HasUndefInput = false;
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
Value *Incoming = PN->getIncomingValue(i);
// If the incoming value is the phi node itself, it can safely be skipped.
if (Incoming == PN) continue;
if (isa<UndefValue>(Incoming)) {
// Remember that we saw an undef value, but otherwise ignore them.
HasUndefInput = true;
continue;
}
if (CommonValue && Incoming != CommonValue)
return 0; // Not the same, bail out.
CommonValue = Incoming;
}
// If CommonValue is null then all of the incoming values were either undef or
// equal to the phi node itself.
if (!CommonValue)
return UndefValue::get(PN->getType());
// If we have a PHI node like phi(X, undef, X), where X is defined by some
// instruction, we cannot return X as the result of the PHI node unless it
// dominates the PHI block.
if (HasUndefInput)
return ValueDominatesPHI(CommonValue, PN, DT) ? CommonValue : 0;
return CommonValue;
}
//=== Helper functions for higher up the class hierarchy.
/// SimplifyBinOp - Given operands for a BinaryOperator, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
const TargetData *TD, const DominatorTree *DT,
unsigned MaxRecurse) {
switch (Opcode) {
case Instruction::Add: return SimplifyAddInst(LHS, RHS, /* isNSW */ false,
/* isNUW */ false, TD, DT,
MaxRecurse);
case Instruction::Sub: return SimplifySubInst(LHS, RHS, /* isNSW */ false,
/* isNUW */ false, TD, DT,
MaxRecurse);
case Instruction::Mul: return SimplifyMulInst(LHS, RHS, TD, DT, MaxRecurse);
case Instruction::SDiv: return SimplifySDivInst(LHS, RHS, TD, DT, MaxRecurse);
case Instruction::UDiv: return SimplifyUDivInst(LHS, RHS, TD, DT, MaxRecurse);
case Instruction::FDiv: return SimplifyFDivInst(LHS, RHS, TD, DT, MaxRecurse);
case Instruction::Shl: return SimplifyShlInst(LHS, RHS, TD, DT, MaxRecurse);
case Instruction::LShr: return SimplifyLShrInst(LHS, RHS, TD, DT, MaxRecurse);
case Instruction::AShr: return SimplifyAShrInst(LHS, RHS, TD, DT, MaxRecurse);
case Instruction::And: return SimplifyAndInst(LHS, RHS, TD, DT, MaxRecurse);
case Instruction::Or: return SimplifyOrInst(LHS, RHS, TD, DT, MaxRecurse);
case Instruction::Xor: return SimplifyXorInst(LHS, RHS, TD, DT, MaxRecurse);
default:
if (Constant *CLHS = dyn_cast<Constant>(LHS))
if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
Constant *COps[] = {CLHS, CRHS};
return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, 2, TD);
}
// If the operation is associative, try some generic simplifications.
if (Instruction::isAssociative(Opcode))
if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, TD, DT,
MaxRecurse))
return V;
// If the operation is with the result of a select instruction, check whether
// operating on either branch of the select always yields the same value.
if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, TD, DT,
MaxRecurse))
return V;
// If the operation is with the result of a phi instruction, check whether
// operating on all incoming values of the phi always yields the same value.
if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, TD, DT, MaxRecurse))
return V;
return 0;
}
}
Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
const TargetData *TD, const DominatorTree *DT) {
return ::SimplifyBinOp(Opcode, LHS, RHS, TD, DT, RecursionLimit);
}
/// SimplifyCmpInst - Given operands for a CmpInst, see if we can
/// fold the result.
static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
const TargetData *TD, const DominatorTree *DT,
unsigned MaxRecurse) {
if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate))
return SimplifyICmpInst(Predicate, LHS, RHS, TD, DT, MaxRecurse);
return SimplifyFCmpInst(Predicate, LHS, RHS, TD, DT, MaxRecurse);
}
Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
const TargetData *TD, const DominatorTree *DT) {
return ::SimplifyCmpInst(Predicate, LHS, RHS, TD, DT, RecursionLimit);
}
/// SimplifyInstruction - See if we can compute a simplified version of this
/// instruction. If not, this returns null.
Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD,
const DominatorTree *DT) {
Value *Result;
switch (I->getOpcode()) {
default:
Result = ConstantFoldInstruction(I, TD);
break;
case Instruction::Add:
Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
cast<BinaryOperator>(I)->hasNoSignedWrap(),
cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
TD, DT);
break;
case Instruction::Sub:
Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
cast<BinaryOperator>(I)->hasNoSignedWrap(),
cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
TD, DT);
break;
case Instruction::Mul:
Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), TD, DT);
break;
case Instruction::SDiv:
Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), TD, DT);
break;
case Instruction::UDiv:
Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), TD, DT);
break;
case Instruction::FDiv:
Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1), TD, DT);
break;
case Instruction::Shl:
Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1), TD, DT);
break;
case Instruction::LShr:
Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1), TD, DT);
break;
case Instruction::AShr:
Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1), TD, DT);
break;
case Instruction::And:
Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, DT);
break;
case Instruction::Or:
Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, DT);
break;
case Instruction::Xor:
Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), TD, DT);
break;
case Instruction::ICmp:
Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
I->getOperand(0), I->getOperand(1), TD, DT);
break;
case Instruction::FCmp:
Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
I->getOperand(0), I->getOperand(1), TD, DT);
break;
case Instruction::Select:
Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
I->getOperand(2), TD, DT);
break;
case Instruction::GetElementPtr: {
SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
Result = SimplifyGEPInst(&Ops[0], Ops.size(), TD, DT);
break;
}
case Instruction::PHI:
Result = SimplifyPHINode(cast<PHINode>(I), DT);
break;
}
/// If called on unreachable code, the above logic may report that the
/// instruction simplified to itself. Make life easier for users by
/// detecting that case here, returning a safe value instead.
return Result == I ? UndefValue::get(I->getType()) : Result;
}
/// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then
/// delete the From instruction. In addition to a basic RAUW, this does a
/// recursive simplification of the newly formed instructions. This catches
/// things where one simplification exposes other opportunities. This only
/// simplifies and deletes scalar operations, it does not change the CFG.
///
void llvm::ReplaceAndSimplifyAllUses(Instruction *From, Value *To,
const TargetData *TD,
const DominatorTree *DT) {
assert(From != To && "ReplaceAndSimplifyAllUses(X,X) is not valid!");
// FromHandle/ToHandle - This keeps a WeakVH on the from/to values so that
// we can know if it gets deleted out from under us or replaced in a
// recursive simplification.
WeakVH FromHandle(From);
WeakVH ToHandle(To);
while (!From->use_empty()) {
// Update the instruction to use the new value.
Use &TheUse = From->use_begin().getUse();
Instruction *User = cast<Instruction>(TheUse.getUser());
TheUse = To;
// Check to see if the instruction can be folded due to the operand
// replacement. For example changing (or X, Y) into (or X, -1) can replace
// the 'or' with -1.
Value *SimplifiedVal;
{
// Sanity check to make sure 'User' doesn't dangle across
// SimplifyInstruction.
AssertingVH<> UserHandle(User);
SimplifiedVal = SimplifyInstruction(User, TD, DT);
if (SimplifiedVal == 0) continue;
}
// Recursively simplify this user to the new value.
ReplaceAndSimplifyAllUses(User, SimplifiedVal, TD, DT);
From = dyn_cast_or_null<Instruction>((Value*)FromHandle);
To = ToHandle;
assert(ToHandle && "To value deleted by recursive simplification?");
// If the recursive simplification ended up revisiting and deleting
// 'From' then we're done.
if (From == 0)
return;
}
// If 'From' has value handles referring to it, do a real RAUW to update them.
From->replaceAllUsesWith(To);
From->eraseFromParent();
}
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