mirror of
https://github.com/c64scene-ar/llvm-6502.git
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This seems to cause a miscompile when building clang, which causes a bootstrapped clang to fail or crash in several of its tests. See: http://lab.llvm.org:8013/builders/clang-x86_64-darwin11-RA/builds/1184 http://bb.pgr.jp/builders/clang-3stage-x86_64-linux/builds/7813 This reverts commit r219282. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219317 91177308-0d34-0410-b5e6-96231b3b80d8
2974 lines
115 KiB
C++
2974 lines
115 KiB
C++
//===- InstructionCombining.cpp - Combine multiple instructions -----------===//
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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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// InstructionCombining - Combine instructions to form fewer, simple
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// instructions. This pass does not modify the CFG. This pass is where
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// algebraic simplification happens.
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//
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// This pass combines things like:
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// %Y = add i32 %X, 1
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// %Z = add i32 %Y, 1
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// into:
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// %Z = add i32 %X, 2
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//
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// This is a simple worklist driven algorithm.
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//
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// This pass guarantees that the following canonicalizations are performed on
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// the program:
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// 1. If a binary operator has a constant operand, it is moved to the RHS
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// 2. Bitwise operators with constant operands are always grouped so that
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// shifts are performed first, then or's, then and's, then xor's.
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// 3. Compare instructions are converted from <,>,<=,>= to ==,!= if possible
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// 4. All cmp instructions on boolean values are replaced with logical ops
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// 5. add X, X is represented as (X*2) => (X << 1)
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// 6. Multiplies with a power-of-two constant argument are transformed into
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// shifts.
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// ... etc.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Scalar.h"
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#include "InstCombine.h"
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#include "llvm-c/Initialization.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/ADT/StringSwitch.h"
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#include "llvm/Analysis/AssumptionTracker.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/Analysis/ValueTracking.h"
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#include "llvm/IR/CFG.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/Dominators.h"
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#include "llvm/IR/GetElementPtrTypeIterator.h"
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#include "llvm/IR/IntrinsicInst.h"
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#include "llvm/IR/PatternMatch.h"
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#include "llvm/IR/ValueHandle.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Target/TargetLibraryInfo.h"
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#include "llvm/Transforms/Utils/Local.h"
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#include <algorithm>
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#include <climits>
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using namespace llvm;
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using namespace llvm::PatternMatch;
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#define DEBUG_TYPE "instcombine"
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STATISTIC(NumCombined , "Number of insts combined");
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STATISTIC(NumConstProp, "Number of constant folds");
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STATISTIC(NumDeadInst , "Number of dead inst eliminated");
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STATISTIC(NumSunkInst , "Number of instructions sunk");
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STATISTIC(NumExpand, "Number of expansions");
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STATISTIC(NumFactor , "Number of factorizations");
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STATISTIC(NumReassoc , "Number of reassociations");
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static cl::opt<bool>
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EnableUnsafeFPShrink("enable-double-float-shrink", cl::Hidden,
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cl::init(false),
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cl::desc("Enable unsafe double to float "
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"shrinking for math lib calls"));
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// Initialization Routines
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void llvm::initializeInstCombine(PassRegistry &Registry) {
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initializeInstCombinerPass(Registry);
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}
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void LLVMInitializeInstCombine(LLVMPassRegistryRef R) {
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initializeInstCombine(*unwrap(R));
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}
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char InstCombiner::ID = 0;
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INITIALIZE_PASS_BEGIN(InstCombiner, "instcombine",
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"Combine redundant instructions", false, false)
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INITIALIZE_PASS_DEPENDENCY(AssumptionTracker)
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INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)
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INITIALIZE_PASS_END(InstCombiner, "instcombine",
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"Combine redundant instructions", false, false)
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void InstCombiner::getAnalysisUsage(AnalysisUsage &AU) const {
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AU.setPreservesCFG();
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AU.addRequired<AssumptionTracker>();
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AU.addRequired<TargetLibraryInfo>();
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}
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Value *InstCombiner::EmitGEPOffset(User *GEP) {
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return llvm::EmitGEPOffset(Builder, *getDataLayout(), GEP);
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}
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/// ShouldChangeType - Return true if it is desirable to convert a computation
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/// from 'From' to 'To'. We don't want to convert from a legal to an illegal
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/// type for example, or from a smaller to a larger illegal type.
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bool InstCombiner::ShouldChangeType(Type *From, Type *To) const {
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assert(From->isIntegerTy() && To->isIntegerTy());
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// If we don't have DL, we don't know if the source/dest are legal.
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if (!DL) return false;
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unsigned FromWidth = From->getPrimitiveSizeInBits();
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unsigned ToWidth = To->getPrimitiveSizeInBits();
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bool FromLegal = DL->isLegalInteger(FromWidth);
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bool ToLegal = DL->isLegalInteger(ToWidth);
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// If this is a legal integer from type, and the result would be an illegal
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// type, don't do the transformation.
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if (FromLegal && !ToLegal)
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return false;
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// Otherwise, if both are illegal, do not increase the size of the result. We
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// do allow things like i160 -> i64, but not i64 -> i160.
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if (!FromLegal && !ToLegal && ToWidth > FromWidth)
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return false;
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return true;
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}
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// Return true, if No Signed Wrap should be maintained for I.
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// The No Signed Wrap flag can be kept if the operation "B (I.getOpcode) C",
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// where both B and C should be ConstantInts, results in a constant that does
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// not overflow. This function only handles the Add and Sub opcodes. For
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// all other opcodes, the function conservatively returns false.
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static bool MaintainNoSignedWrap(BinaryOperator &I, Value *B, Value *C) {
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OverflowingBinaryOperator *OBO = dyn_cast<OverflowingBinaryOperator>(&I);
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if (!OBO || !OBO->hasNoSignedWrap()) {
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return false;
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}
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// We reason about Add and Sub Only.
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Instruction::BinaryOps Opcode = I.getOpcode();
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if (Opcode != Instruction::Add &&
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Opcode != Instruction::Sub) {
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return false;
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}
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ConstantInt *CB = dyn_cast<ConstantInt>(B);
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ConstantInt *CC = dyn_cast<ConstantInt>(C);
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if (!CB || !CC) {
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return false;
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}
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const APInt &BVal = CB->getValue();
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const APInt &CVal = CC->getValue();
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bool Overflow = false;
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if (Opcode == Instruction::Add) {
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BVal.sadd_ov(CVal, Overflow);
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} else {
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BVal.ssub_ov(CVal, Overflow);
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}
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return !Overflow;
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}
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/// Conservatively clears subclassOptionalData after a reassociation or
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/// commutation. We preserve fast-math flags when applicable as they can be
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/// preserved.
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static void ClearSubclassDataAfterReassociation(BinaryOperator &I) {
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FPMathOperator *FPMO = dyn_cast<FPMathOperator>(&I);
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if (!FPMO) {
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I.clearSubclassOptionalData();
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return;
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}
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FastMathFlags FMF = I.getFastMathFlags();
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I.clearSubclassOptionalData();
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I.setFastMathFlags(FMF);
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}
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/// SimplifyAssociativeOrCommutative - This performs a few simplifications for
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/// operators which are associative or commutative:
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//
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// Commutative operators:
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//
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// 1. Order operands such that they are listed from right (least complex) to
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// left (most complex). This puts constants before unary operators before
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// binary operators.
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//
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// Associative operators:
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//
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// 2. Transform: "(A op B) op C" ==> "A op (B op C)" if "B op C" simplifies.
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// 3. Transform: "A op (B op C)" ==> "(A op B) op C" if "A op B" simplifies.
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//
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// Associative and commutative operators:
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//
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// 4. Transform: "(A op B) op C" ==> "(C op A) op B" if "C op A" simplifies.
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// 5. Transform: "A op (B op C)" ==> "B op (C op A)" if "C op A" simplifies.
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// 6. Transform: "(A op C1) op (B op C2)" ==> "(A op B) op (C1 op C2)"
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// if C1 and C2 are constants.
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//
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bool InstCombiner::SimplifyAssociativeOrCommutative(BinaryOperator &I) {
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Instruction::BinaryOps Opcode = I.getOpcode();
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bool Changed = false;
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do {
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// Order operands such that they are listed from right (least complex) to
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// left (most complex). This puts constants before unary operators before
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// binary operators.
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if (I.isCommutative() && getComplexity(I.getOperand(0)) <
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getComplexity(I.getOperand(1)))
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Changed = !I.swapOperands();
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BinaryOperator *Op0 = dyn_cast<BinaryOperator>(I.getOperand(0));
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BinaryOperator *Op1 = dyn_cast<BinaryOperator>(I.getOperand(1));
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if (I.isAssociative()) {
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// Transform: "(A op B) op C" ==> "A op (B op C)" if "B op C" simplifies.
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if (Op0 && Op0->getOpcode() == Opcode) {
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Value *A = Op0->getOperand(0);
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Value *B = Op0->getOperand(1);
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Value *C = I.getOperand(1);
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// Does "B op C" simplify?
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if (Value *V = SimplifyBinOp(Opcode, B, C, DL)) {
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// It simplifies to V. Form "A op V".
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I.setOperand(0, A);
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I.setOperand(1, V);
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// Conservatively clear the optional flags, since they may not be
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// preserved by the reassociation.
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if (MaintainNoSignedWrap(I, B, C) &&
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(!Op0 || (isa<BinaryOperator>(Op0) && Op0->hasNoSignedWrap()))) {
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// Note: this is only valid because SimplifyBinOp doesn't look at
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// the operands to Op0.
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I.clearSubclassOptionalData();
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I.setHasNoSignedWrap(true);
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} else {
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ClearSubclassDataAfterReassociation(I);
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}
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Changed = true;
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++NumReassoc;
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continue;
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}
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}
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// Transform: "A op (B op C)" ==> "(A op B) op C" if "A op B" simplifies.
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if (Op1 && Op1->getOpcode() == Opcode) {
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Value *A = I.getOperand(0);
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Value *B = Op1->getOperand(0);
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Value *C = Op1->getOperand(1);
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// Does "A op B" simplify?
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if (Value *V = SimplifyBinOp(Opcode, A, B, DL)) {
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// It simplifies to V. Form "V op C".
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I.setOperand(0, V);
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I.setOperand(1, C);
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// Conservatively clear the optional flags, since they may not be
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// preserved by the reassociation.
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ClearSubclassDataAfterReassociation(I);
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Changed = true;
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++NumReassoc;
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continue;
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}
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}
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}
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if (I.isAssociative() && I.isCommutative()) {
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// Transform: "(A op B) op C" ==> "(C op A) op B" if "C op A" simplifies.
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if (Op0 && Op0->getOpcode() == Opcode) {
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Value *A = Op0->getOperand(0);
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Value *B = Op0->getOperand(1);
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Value *C = I.getOperand(1);
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// Does "C op A" simplify?
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if (Value *V = SimplifyBinOp(Opcode, C, A, DL)) {
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// It simplifies to V. Form "V op B".
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I.setOperand(0, V);
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I.setOperand(1, B);
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// Conservatively clear the optional flags, since they may not be
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// preserved by the reassociation.
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ClearSubclassDataAfterReassociation(I);
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Changed = true;
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++NumReassoc;
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continue;
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}
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}
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// Transform: "A op (B op C)" ==> "B op (C op A)" if "C op A" simplifies.
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if (Op1 && Op1->getOpcode() == Opcode) {
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Value *A = I.getOperand(0);
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Value *B = Op1->getOperand(0);
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Value *C = Op1->getOperand(1);
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// Does "C op A" simplify?
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if (Value *V = SimplifyBinOp(Opcode, C, A, DL)) {
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// It simplifies to V. Form "B op V".
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I.setOperand(0, B);
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I.setOperand(1, V);
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// Conservatively clear the optional flags, since they may not be
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// preserved by the reassociation.
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ClearSubclassDataAfterReassociation(I);
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Changed = true;
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++NumReassoc;
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continue;
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}
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}
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// Transform: "(A op C1) op (B op C2)" ==> "(A op B) op (C1 op C2)"
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// if C1 and C2 are constants.
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if (Op0 && Op1 &&
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Op0->getOpcode() == Opcode && Op1->getOpcode() == Opcode &&
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isa<Constant>(Op0->getOperand(1)) &&
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isa<Constant>(Op1->getOperand(1)) &&
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Op0->hasOneUse() && Op1->hasOneUse()) {
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Value *A = Op0->getOperand(0);
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Constant *C1 = cast<Constant>(Op0->getOperand(1));
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Value *B = Op1->getOperand(0);
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Constant *C2 = cast<Constant>(Op1->getOperand(1));
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Constant *Folded = ConstantExpr::get(Opcode, C1, C2);
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BinaryOperator *New = BinaryOperator::Create(Opcode, A, B);
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if (isa<FPMathOperator>(New)) {
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FastMathFlags Flags = I.getFastMathFlags();
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Flags &= Op0->getFastMathFlags();
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Flags &= Op1->getFastMathFlags();
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New->setFastMathFlags(Flags);
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}
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InsertNewInstWith(New, I);
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New->takeName(Op1);
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I.setOperand(0, New);
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I.setOperand(1, Folded);
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// Conservatively clear the optional flags, since they may not be
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// preserved by the reassociation.
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ClearSubclassDataAfterReassociation(I);
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Changed = true;
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continue;
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}
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}
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// No further simplifications.
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return Changed;
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} while (1);
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}
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/// LeftDistributesOverRight - Whether "X LOp (Y ROp Z)" is always equal to
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/// "(X LOp Y) ROp (X LOp Z)".
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static bool LeftDistributesOverRight(Instruction::BinaryOps LOp,
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Instruction::BinaryOps ROp) {
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switch (LOp) {
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default:
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return false;
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case Instruction::And:
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// And distributes over Or and Xor.
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switch (ROp) {
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default:
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return false;
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case Instruction::Or:
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case Instruction::Xor:
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return true;
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}
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case Instruction::Mul:
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// Multiplication distributes over addition and subtraction.
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switch (ROp) {
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default:
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return false;
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case Instruction::Add:
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case Instruction::Sub:
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return true;
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}
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case Instruction::Or:
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// Or distributes over And.
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switch (ROp) {
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default:
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return false;
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case Instruction::And:
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return true;
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}
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}
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}
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/// RightDistributesOverLeft - Whether "(X LOp Y) ROp Z" is always equal to
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/// "(X ROp Z) LOp (Y ROp Z)".
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static bool RightDistributesOverLeft(Instruction::BinaryOps LOp,
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Instruction::BinaryOps ROp) {
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if (Instruction::isCommutative(ROp))
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return LeftDistributesOverRight(ROp, LOp);
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switch (LOp) {
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default:
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return false;
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// (X >> Z) & (Y >> Z) -> (X&Y) >> Z for all shifts.
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// (X >> Z) | (Y >> Z) -> (X|Y) >> Z for all shifts.
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// (X >> Z) ^ (Y >> Z) -> (X^Y) >> Z for all shifts.
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case Instruction::And:
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case Instruction::Or:
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case Instruction::Xor:
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switch (ROp) {
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default:
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return false;
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case Instruction::Shl:
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case Instruction::LShr:
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case Instruction::AShr:
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return true;
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}
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}
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// TODO: It would be nice to handle division, aka "(X + Y)/Z = X/Z + Y/Z",
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// but this requires knowing that the addition does not overflow and other
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// such subtleties.
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return false;
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}
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/// This function returns identity value for given opcode, which can be used to
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/// factor patterns like (X * 2) + X ==> (X * 2) + (X * 1) ==> X * (2 + 1).
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static Value *getIdentityValue(Instruction::BinaryOps OpCode, Value *V) {
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if (isa<Constant>(V))
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return nullptr;
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if (OpCode == Instruction::Mul)
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return ConstantInt::get(V->getType(), 1);
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// TODO: We can handle other cases e.g. Instruction::And, Instruction::Or etc.
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return nullptr;
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}
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/// This function factors binary ops which can be combined using distributive
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/// laws. This function tries to transform 'Op' based TopLevelOpcode to enable
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/// factorization e.g for ADD(SHL(X , 2), MUL(X, 5)), When this function called
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/// with TopLevelOpcode == Instruction::Add and Op = SHL(X, 2), transforms
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/// SHL(X, 2) to MUL(X, 4) i.e. returns Instruction::Mul with LHS set to 'X' and
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/// RHS to 4.
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static Instruction::BinaryOps
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getBinOpsForFactorization(Instruction::BinaryOps TopLevelOpcode,
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BinaryOperator *Op, Value *&LHS, Value *&RHS) {
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if (!Op)
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return Instruction::BinaryOpsEnd;
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LHS = Op->getOperand(0);
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RHS = Op->getOperand(1);
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switch (TopLevelOpcode) {
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default:
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return Op->getOpcode();
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case Instruction::Add:
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case Instruction::Sub:
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if (Op->getOpcode() == Instruction::Shl) {
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if (Constant *CST = dyn_cast<Constant>(Op->getOperand(1))) {
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// The multiplier is really 1 << CST.
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RHS = ConstantExpr::getShl(ConstantInt::get(Op->getType(), 1), CST);
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return Instruction::Mul;
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}
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}
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return Op->getOpcode();
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}
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// TODO: We can add other conversions e.g. shr => div etc.
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}
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/// This tries to simplify binary operations by factorizing out common terms
|
|
/// (e. g. "(A*B)+(A*C)" -> "A*(B+C)").
|
|
static Value *tryFactorization(InstCombiner::BuilderTy *Builder,
|
|
const DataLayout *DL, BinaryOperator &I,
|
|
Instruction::BinaryOps InnerOpcode, Value *A,
|
|
Value *B, Value *C, Value *D) {
|
|
|
|
// If any of A, B, C, D are null, we can not factor I, return early.
|
|
// Checking A and C should be enough.
|
|
if (!A || !C || !B || !D)
|
|
return nullptr;
|
|
|
|
Value *SimplifiedInst = nullptr;
|
|
Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
|
|
Instruction::BinaryOps TopLevelOpcode = I.getOpcode();
|
|
|
|
// Does "X op' Y" always equal "Y op' X"?
|
|
bool InnerCommutative = Instruction::isCommutative(InnerOpcode);
|
|
|
|
// Does "X op' (Y op Z)" always equal "(X op' Y) op (X op' Z)"?
|
|
if (LeftDistributesOverRight(InnerOpcode, TopLevelOpcode))
|
|
// 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 || (InnerCommutative && A == D)) {
|
|
if (A != C)
|
|
std::swap(C, D);
|
|
// Consider forming "A op' (B op D)".
|
|
// If "B op D" simplifies then it can be formed with no cost.
|
|
Value *V = SimplifyBinOp(TopLevelOpcode, B, D, DL);
|
|
// If "B op D" doesn't simplify then only go on if both of the existing
|
|
// operations "A op' B" and "C op' D" will be zapped as no longer used.
|
|
if (!V && LHS->hasOneUse() && RHS->hasOneUse())
|
|
V = Builder->CreateBinOp(TopLevelOpcode, B, D, RHS->getName());
|
|
if (V) {
|
|
SimplifiedInst = Builder->CreateBinOp(InnerOpcode, A, V);
|
|
}
|
|
}
|
|
|
|
// Does "(X op Y) op' Z" always equal "(X op' Z) op (Y op' Z)"?
|
|
if (!SimplifiedInst && RightDistributesOverLeft(TopLevelOpcode, InnerOpcode))
|
|
// 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 || (InnerCommutative && B == C)) {
|
|
if (B != D)
|
|
std::swap(C, D);
|
|
// Consider forming "(A op C) op' B".
|
|
// If "A op C" simplifies then it can be formed with no cost.
|
|
Value *V = SimplifyBinOp(TopLevelOpcode, A, C, DL);
|
|
|
|
// If "A op C" doesn't simplify then only go on if both of the existing
|
|
// operations "A op' B" and "C op' D" will be zapped as no longer used.
|
|
if (!V && LHS->hasOneUse() && RHS->hasOneUse())
|
|
V = Builder->CreateBinOp(TopLevelOpcode, A, C, LHS->getName());
|
|
if (V) {
|
|
SimplifiedInst = Builder->CreateBinOp(InnerOpcode, V, B);
|
|
}
|
|
}
|
|
|
|
if (SimplifiedInst) {
|
|
++NumFactor;
|
|
SimplifiedInst->takeName(&I);
|
|
|
|
// Check if we can add NSW flag to SimplifiedInst. If so, set NSW flag.
|
|
// TODO: Check for NUW.
|
|
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(SimplifiedInst)) {
|
|
if (isa<OverflowingBinaryOperator>(SimplifiedInst)) {
|
|
bool HasNSW = false;
|
|
if (isa<OverflowingBinaryOperator>(&I))
|
|
HasNSW = I.hasNoSignedWrap();
|
|
|
|
if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
|
|
if (isa<OverflowingBinaryOperator>(Op0))
|
|
HasNSW &= Op0->hasNoSignedWrap();
|
|
|
|
if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
|
|
if (isa<OverflowingBinaryOperator>(Op1))
|
|
HasNSW &= Op1->hasNoSignedWrap();
|
|
BO->setHasNoSignedWrap(HasNSW);
|
|
}
|
|
}
|
|
}
|
|
return SimplifiedInst;
|
|
}
|
|
|
|
/// SimplifyUsingDistributiveLaws - This tries to simplify binary operations
|
|
/// which some other binary operation distributes over either by factorizing
|
|
/// out common terms (eg "(A*B)+(A*C)" -> "A*(B+C)") or expanding out if this
|
|
/// results in simplifications (eg: "A & (B | C) -> (A&B) | (A&C)" if this is
|
|
/// a win). Returns the simplified value, or null if it didn't simplify.
|
|
Value *InstCombiner::SimplifyUsingDistributiveLaws(BinaryOperator &I) {
|
|
Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
|
|
BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
|
|
BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
|
|
|
|
// Factorization.
|
|
Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
|
|
auto TopLevelOpcode = I.getOpcode();
|
|
auto LHSOpcode = getBinOpsForFactorization(TopLevelOpcode, Op0, A, B);
|
|
auto RHSOpcode = getBinOpsForFactorization(TopLevelOpcode, Op1, C, D);
|
|
|
|
// The instruction has the form "(A op' B) op (C op' D)". Try to factorize
|
|
// a common term.
|
|
if (LHSOpcode == RHSOpcode) {
|
|
if (Value *V = tryFactorization(Builder, DL, I, LHSOpcode, A, B, C, D))
|
|
return V;
|
|
}
|
|
|
|
// The instruction has the form "(A op' B) op (C)". Try to factorize common
|
|
// term.
|
|
if (Value *V = tryFactorization(Builder, DL, I, LHSOpcode, A, B, RHS,
|
|
getIdentityValue(LHSOpcode, RHS)))
|
|
return V;
|
|
|
|
// The instruction has the form "(B) op (C op' D)". Try to factorize common
|
|
// term.
|
|
if (Value *V = tryFactorization(Builder, DL, I, RHSOpcode, LHS,
|
|
getIdentityValue(RHSOpcode, LHS), C, D))
|
|
return V;
|
|
|
|
// Expansion.
|
|
if (Op0 && RightDistributesOverLeft(Op0->getOpcode(), TopLevelOpcode)) {
|
|
// The instruction has the form "(A op' B) op C". See if expanding it out
|
|
// to "(A op C) op' (B op C)" results in simplifications.
|
|
Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
|
|
Instruction::BinaryOps InnerOpcode = Op0->getOpcode(); // op'
|
|
|
|
// Do "A op C" and "B op C" both simplify?
|
|
if (Value *L = SimplifyBinOp(TopLevelOpcode, A, C, DL))
|
|
if (Value *R = SimplifyBinOp(TopLevelOpcode, B, C, DL)) {
|
|
// They do! Return "L op' R".
|
|
++NumExpand;
|
|
// If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
|
|
if ((L == A && R == B) ||
|
|
(Instruction::isCommutative(InnerOpcode) && L == B && R == A))
|
|
return Op0;
|
|
// Otherwise return "L op' R" if it simplifies.
|
|
if (Value *V = SimplifyBinOp(InnerOpcode, L, R, DL))
|
|
return V;
|
|
// Otherwise, create a new instruction.
|
|
C = Builder->CreateBinOp(InnerOpcode, L, R);
|
|
C->takeName(&I);
|
|
return C;
|
|
}
|
|
}
|
|
|
|
if (Op1 && LeftDistributesOverRight(TopLevelOpcode, Op1->getOpcode())) {
|
|
// The instruction has the form "A op (B op' C)". See if expanding it out
|
|
// to "(A op B) op' (A op C)" results in simplifications.
|
|
Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
|
|
Instruction::BinaryOps InnerOpcode = Op1->getOpcode(); // op'
|
|
|
|
// Do "A op B" and "A op C" both simplify?
|
|
if (Value *L = SimplifyBinOp(TopLevelOpcode, A, B, DL))
|
|
if (Value *R = SimplifyBinOp(TopLevelOpcode, A, C, DL)) {
|
|
// They do! Return "L op' R".
|
|
++NumExpand;
|
|
// If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
|
|
if ((L == B && R == C) ||
|
|
(Instruction::isCommutative(InnerOpcode) && L == C && R == B))
|
|
return Op1;
|
|
// Otherwise return "L op' R" if it simplifies.
|
|
if (Value *V = SimplifyBinOp(InnerOpcode, L, R, DL))
|
|
return V;
|
|
// Otherwise, create a new instruction.
|
|
A = Builder->CreateBinOp(InnerOpcode, L, R);
|
|
A->takeName(&I);
|
|
return A;
|
|
}
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
// dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
|
|
// if the LHS is a constant zero (which is the 'negate' form).
|
|
//
|
|
Value *InstCombiner::dyn_castNegVal(Value *V) const {
|
|
if (BinaryOperator::isNeg(V))
|
|
return BinaryOperator::getNegArgument(V);
|
|
|
|
// Constants can be considered to be negated values if they can be folded.
|
|
if (ConstantInt *C = dyn_cast<ConstantInt>(V))
|
|
return ConstantExpr::getNeg(C);
|
|
|
|
if (ConstantDataVector *C = dyn_cast<ConstantDataVector>(V))
|
|
if (C->getType()->getElementType()->isIntegerTy())
|
|
return ConstantExpr::getNeg(C);
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
// dyn_castFNegVal - Given a 'fsub' instruction, return the RHS of the
|
|
// instruction if the LHS is a constant negative zero (which is the 'negate'
|
|
// form).
|
|
//
|
|
Value *InstCombiner::dyn_castFNegVal(Value *V, bool IgnoreZeroSign) const {
|
|
if (BinaryOperator::isFNeg(V, IgnoreZeroSign))
|
|
return BinaryOperator::getFNegArgument(V);
|
|
|
|
// Constants can be considered to be negated values if they can be folded.
|
|
if (ConstantFP *C = dyn_cast<ConstantFP>(V))
|
|
return ConstantExpr::getFNeg(C);
|
|
|
|
if (ConstantDataVector *C = dyn_cast<ConstantDataVector>(V))
|
|
if (C->getType()->getElementType()->isFloatingPointTy())
|
|
return ConstantExpr::getFNeg(C);
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
|
|
InstCombiner *IC) {
|
|
if (CastInst *CI = dyn_cast<CastInst>(&I)) {
|
|
return IC->Builder->CreateCast(CI->getOpcode(), SO, I.getType());
|
|
}
|
|
|
|
// Figure out if the constant is the left or the right argument.
|
|
bool ConstIsRHS = isa<Constant>(I.getOperand(1));
|
|
Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS));
|
|
|
|
if (Constant *SOC = dyn_cast<Constant>(SO)) {
|
|
if (ConstIsRHS)
|
|
return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand);
|
|
return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC);
|
|
}
|
|
|
|
Value *Op0 = SO, *Op1 = ConstOperand;
|
|
if (!ConstIsRHS)
|
|
std::swap(Op0, Op1);
|
|
|
|
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I)) {
|
|
Value *RI = IC->Builder->CreateBinOp(BO->getOpcode(), Op0, Op1,
|
|
SO->getName()+".op");
|
|
Instruction *FPInst = dyn_cast<Instruction>(RI);
|
|
if (FPInst && isa<FPMathOperator>(FPInst))
|
|
FPInst->copyFastMathFlags(BO);
|
|
return RI;
|
|
}
|
|
if (ICmpInst *CI = dyn_cast<ICmpInst>(&I))
|
|
return IC->Builder->CreateICmp(CI->getPredicate(), Op0, Op1,
|
|
SO->getName()+".cmp");
|
|
if (FCmpInst *CI = dyn_cast<FCmpInst>(&I))
|
|
return IC->Builder->CreateICmp(CI->getPredicate(), Op0, Op1,
|
|
SO->getName()+".cmp");
|
|
llvm_unreachable("Unknown binary instruction type!");
|
|
}
|
|
|
|
// FoldOpIntoSelect - Given an instruction with a select as one operand and a
|
|
// constant as the other operand, try to fold the binary operator into the
|
|
// select arguments. This also works for Cast instructions, which obviously do
|
|
// not have a second operand.
|
|
Instruction *InstCombiner::FoldOpIntoSelect(Instruction &Op, SelectInst *SI) {
|
|
// Don't modify shared select instructions
|
|
if (!SI->hasOneUse()) return nullptr;
|
|
Value *TV = SI->getOperand(1);
|
|
Value *FV = SI->getOperand(2);
|
|
|
|
if (isa<Constant>(TV) || isa<Constant>(FV)) {
|
|
// Bool selects with constant operands can be folded to logical ops.
|
|
if (SI->getType()->isIntegerTy(1)) return nullptr;
|
|
|
|
// If it's a bitcast involving vectors, make sure it has the same number of
|
|
// elements on both sides.
|
|
if (BitCastInst *BC = dyn_cast<BitCastInst>(&Op)) {
|
|
VectorType *DestTy = dyn_cast<VectorType>(BC->getDestTy());
|
|
VectorType *SrcTy = dyn_cast<VectorType>(BC->getSrcTy());
|
|
|
|
// Verify that either both or neither are vectors.
|
|
if ((SrcTy == nullptr) != (DestTy == nullptr)) return nullptr;
|
|
// If vectors, verify that they have the same number of elements.
|
|
if (SrcTy && SrcTy->getNumElements() != DestTy->getNumElements())
|
|
return nullptr;
|
|
}
|
|
|
|
Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, this);
|
|
Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, this);
|
|
|
|
return SelectInst::Create(SI->getCondition(),
|
|
SelectTrueVal, SelectFalseVal);
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
|
|
/// FoldOpIntoPhi - Given a binary operator, cast instruction, or select which
|
|
/// has a PHI node as operand #0, see if we can fold the instruction into the
|
|
/// PHI (which is only possible if all operands to the PHI are constants).
|
|
///
|
|
Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
|
|
PHINode *PN = cast<PHINode>(I.getOperand(0));
|
|
unsigned NumPHIValues = PN->getNumIncomingValues();
|
|
if (NumPHIValues == 0)
|
|
return nullptr;
|
|
|
|
// We normally only transform phis with a single use. However, if a PHI has
|
|
// multiple uses and they are all the same operation, we can fold *all* of the
|
|
// uses into the PHI.
|
|
if (!PN->hasOneUse()) {
|
|
// Walk the use list for the instruction, comparing them to I.
|
|
for (User *U : PN->users()) {
|
|
Instruction *UI = cast<Instruction>(U);
|
|
if (UI != &I && !I.isIdenticalTo(UI))
|
|
return nullptr;
|
|
}
|
|
// Otherwise, we can replace *all* users with the new PHI we form.
|
|
}
|
|
|
|
// Check to see if all of the operands of the PHI are simple constants
|
|
// (constantint/constantfp/undef). If there is one non-constant value,
|
|
// remember the BB it is in. If there is more than one or if *it* is a PHI,
|
|
// bail out. We don't do arbitrary constant expressions here because moving
|
|
// their computation can be expensive without a cost model.
|
|
BasicBlock *NonConstBB = nullptr;
|
|
for (unsigned i = 0; i != NumPHIValues; ++i) {
|
|
Value *InVal = PN->getIncomingValue(i);
|
|
if (isa<Constant>(InVal) && !isa<ConstantExpr>(InVal))
|
|
continue;
|
|
|
|
if (isa<PHINode>(InVal)) return nullptr; // Itself a phi.
|
|
if (NonConstBB) return nullptr; // More than one non-const value.
|
|
|
|
NonConstBB = PN->getIncomingBlock(i);
|
|
|
|
// If the InVal is an invoke at the end of the pred block, then we can't
|
|
// insert a computation after it without breaking the edge.
|
|
if (InvokeInst *II = dyn_cast<InvokeInst>(InVal))
|
|
if (II->getParent() == NonConstBB)
|
|
return nullptr;
|
|
|
|
// If the incoming non-constant value is in I's block, we will remove one
|
|
// instruction, but insert another equivalent one, leading to infinite
|
|
// instcombine.
|
|
if (NonConstBB == I.getParent())
|
|
return nullptr;
|
|
}
|
|
|
|
// If there is exactly one non-constant value, we can insert a copy of the
|
|
// operation in that block. However, if this is a critical edge, we would be
|
|
// inserting the computation one some other paths (e.g. inside a loop). Only
|
|
// do this if the pred block is unconditionally branching into the phi block.
|
|
if (NonConstBB != nullptr) {
|
|
BranchInst *BI = dyn_cast<BranchInst>(NonConstBB->getTerminator());
|
|
if (!BI || !BI->isUnconditional()) return nullptr;
|
|
}
|
|
|
|
// Okay, we can do the transformation: create the new PHI node.
|
|
PHINode *NewPN = PHINode::Create(I.getType(), PN->getNumIncomingValues());
|
|
InsertNewInstBefore(NewPN, *PN);
|
|
NewPN->takeName(PN);
|
|
|
|
// If we are going to have to insert a new computation, do so right before the
|
|
// predecessors terminator.
|
|
if (NonConstBB)
|
|
Builder->SetInsertPoint(NonConstBB->getTerminator());
|
|
|
|
// Next, add all of the operands to the PHI.
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(&I)) {
|
|
// We only currently try to fold the condition of a select when it is a phi,
|
|
// not the true/false values.
|
|
Value *TrueV = SI->getTrueValue();
|
|
Value *FalseV = SI->getFalseValue();
|
|
BasicBlock *PhiTransBB = PN->getParent();
|
|
for (unsigned i = 0; i != NumPHIValues; ++i) {
|
|
BasicBlock *ThisBB = PN->getIncomingBlock(i);
|
|
Value *TrueVInPred = TrueV->DoPHITranslation(PhiTransBB, ThisBB);
|
|
Value *FalseVInPred = FalseV->DoPHITranslation(PhiTransBB, ThisBB);
|
|
Value *InV = nullptr;
|
|
// Beware of ConstantExpr: it may eventually evaluate to getNullValue,
|
|
// even if currently isNullValue gives false.
|
|
Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i));
|
|
if (InC && !isa<ConstantExpr>(InC))
|
|
InV = InC->isNullValue() ? FalseVInPred : TrueVInPred;
|
|
else
|
|
InV = Builder->CreateSelect(PN->getIncomingValue(i),
|
|
TrueVInPred, FalseVInPred, "phitmp");
|
|
NewPN->addIncoming(InV, ThisBB);
|
|
}
|
|
} else if (CmpInst *CI = dyn_cast<CmpInst>(&I)) {
|
|
Constant *C = cast<Constant>(I.getOperand(1));
|
|
for (unsigned i = 0; i != NumPHIValues; ++i) {
|
|
Value *InV = nullptr;
|
|
if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i)))
|
|
InV = ConstantExpr::getCompare(CI->getPredicate(), InC, C);
|
|
else if (isa<ICmpInst>(CI))
|
|
InV = Builder->CreateICmp(CI->getPredicate(), PN->getIncomingValue(i),
|
|
C, "phitmp");
|
|
else
|
|
InV = Builder->CreateFCmp(CI->getPredicate(), PN->getIncomingValue(i),
|
|
C, "phitmp");
|
|
NewPN->addIncoming(InV, PN->getIncomingBlock(i));
|
|
}
|
|
} else if (I.getNumOperands() == 2) {
|
|
Constant *C = cast<Constant>(I.getOperand(1));
|
|
for (unsigned i = 0; i != NumPHIValues; ++i) {
|
|
Value *InV = nullptr;
|
|
if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i)))
|
|
InV = ConstantExpr::get(I.getOpcode(), InC, C);
|
|
else
|
|
InV = Builder->CreateBinOp(cast<BinaryOperator>(I).getOpcode(),
|
|
PN->getIncomingValue(i), C, "phitmp");
|
|
NewPN->addIncoming(InV, PN->getIncomingBlock(i));
|
|
}
|
|
} else {
|
|
CastInst *CI = cast<CastInst>(&I);
|
|
Type *RetTy = CI->getType();
|
|
for (unsigned i = 0; i != NumPHIValues; ++i) {
|
|
Value *InV;
|
|
if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i)))
|
|
InV = ConstantExpr::getCast(CI->getOpcode(), InC, RetTy);
|
|
else
|
|
InV = Builder->CreateCast(CI->getOpcode(),
|
|
PN->getIncomingValue(i), I.getType(), "phitmp");
|
|
NewPN->addIncoming(InV, PN->getIncomingBlock(i));
|
|
}
|
|
}
|
|
|
|
for (auto UI = PN->user_begin(), E = PN->user_end(); UI != E;) {
|
|
Instruction *User = cast<Instruction>(*UI++);
|
|
if (User == &I) continue;
|
|
ReplaceInstUsesWith(*User, NewPN);
|
|
EraseInstFromFunction(*User);
|
|
}
|
|
return ReplaceInstUsesWith(I, NewPN);
|
|
}
|
|
|
|
/// FindElementAtOffset - Given a pointer type and a constant offset, determine
|
|
/// whether or not there is a sequence of GEP indices into the pointed type that
|
|
/// will land us at the specified offset. If so, fill them into NewIndices and
|
|
/// return the resultant element type, otherwise return null.
|
|
Type *InstCombiner::FindElementAtOffset(Type *PtrTy, int64_t Offset,
|
|
SmallVectorImpl<Value*> &NewIndices) {
|
|
assert(PtrTy->isPtrOrPtrVectorTy());
|
|
|
|
if (!DL)
|
|
return nullptr;
|
|
|
|
Type *Ty = PtrTy->getPointerElementType();
|
|
if (!Ty->isSized())
|
|
return nullptr;
|
|
|
|
// Start with the index over the outer type. Note that the type size
|
|
// might be zero (even if the offset isn't zero) if the indexed type
|
|
// is something like [0 x {int, int}]
|
|
Type *IntPtrTy = DL->getIntPtrType(PtrTy);
|
|
int64_t FirstIdx = 0;
|
|
if (int64_t TySize = DL->getTypeAllocSize(Ty)) {
|
|
FirstIdx = Offset/TySize;
|
|
Offset -= FirstIdx*TySize;
|
|
|
|
// Handle hosts where % returns negative instead of values [0..TySize).
|
|
if (Offset < 0) {
|
|
--FirstIdx;
|
|
Offset += TySize;
|
|
assert(Offset >= 0);
|
|
}
|
|
assert((uint64_t)Offset < (uint64_t)TySize && "Out of range offset");
|
|
}
|
|
|
|
NewIndices.push_back(ConstantInt::get(IntPtrTy, FirstIdx));
|
|
|
|
// Index into the types. If we fail, set OrigBase to null.
|
|
while (Offset) {
|
|
// Indexing into tail padding between struct/array elements.
|
|
if (uint64_t(Offset*8) >= DL->getTypeSizeInBits(Ty))
|
|
return nullptr;
|
|
|
|
if (StructType *STy = dyn_cast<StructType>(Ty)) {
|
|
const StructLayout *SL = DL->getStructLayout(STy);
|
|
assert(Offset < (int64_t)SL->getSizeInBytes() &&
|
|
"Offset must stay within the indexed type");
|
|
|
|
unsigned Elt = SL->getElementContainingOffset(Offset);
|
|
NewIndices.push_back(ConstantInt::get(Type::getInt32Ty(Ty->getContext()),
|
|
Elt));
|
|
|
|
Offset -= SL->getElementOffset(Elt);
|
|
Ty = STy->getElementType(Elt);
|
|
} else if (ArrayType *AT = dyn_cast<ArrayType>(Ty)) {
|
|
uint64_t EltSize = DL->getTypeAllocSize(AT->getElementType());
|
|
assert(EltSize && "Cannot index into a zero-sized array");
|
|
NewIndices.push_back(ConstantInt::get(IntPtrTy,Offset/EltSize));
|
|
Offset %= EltSize;
|
|
Ty = AT->getElementType();
|
|
} else {
|
|
// Otherwise, we can't index into the middle of this atomic type, bail.
|
|
return nullptr;
|
|
}
|
|
}
|
|
|
|
return Ty;
|
|
}
|
|
|
|
static bool shouldMergeGEPs(GEPOperator &GEP, GEPOperator &Src) {
|
|
// If this GEP has only 0 indices, it is the same pointer as
|
|
// Src. If Src is not a trivial GEP too, don't combine
|
|
// the indices.
|
|
if (GEP.hasAllZeroIndices() && !Src.hasAllZeroIndices() &&
|
|
!Src.hasOneUse())
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
/// Descale - Return a value X such that Val = X * Scale, or null if none. If
|
|
/// the multiplication is known not to overflow then NoSignedWrap is set.
|
|
Value *InstCombiner::Descale(Value *Val, APInt Scale, bool &NoSignedWrap) {
|
|
assert(isa<IntegerType>(Val->getType()) && "Can only descale integers!");
|
|
assert(cast<IntegerType>(Val->getType())->getBitWidth() ==
|
|
Scale.getBitWidth() && "Scale not compatible with value!");
|
|
|
|
// If Val is zero or Scale is one then Val = Val * Scale.
|
|
if (match(Val, m_Zero()) || Scale == 1) {
|
|
NoSignedWrap = true;
|
|
return Val;
|
|
}
|
|
|
|
// If Scale is zero then it does not divide Val.
|
|
if (Scale.isMinValue())
|
|
return nullptr;
|
|
|
|
// Look through chains of multiplications, searching for a constant that is
|
|
// divisible by Scale. For example, descaling X*(Y*(Z*4)) by a factor of 4
|
|
// will find the constant factor 4 and produce X*(Y*Z). Descaling X*(Y*8) by
|
|
// a factor of 4 will produce X*(Y*2). The principle of operation is to bore
|
|
// down from Val:
|
|
//
|
|
// Val = M1 * X || Analysis starts here and works down
|
|
// M1 = M2 * Y || Doesn't descend into terms with more
|
|
// M2 = Z * 4 \/ than one use
|
|
//
|
|
// Then to modify a term at the bottom:
|
|
//
|
|
// Val = M1 * X
|
|
// M1 = Z * Y || Replaced M2 with Z
|
|
//
|
|
// Then to work back up correcting nsw flags.
|
|
|
|
// Op - the term we are currently analyzing. Starts at Val then drills down.
|
|
// Replaced with its descaled value before exiting from the drill down loop.
|
|
Value *Op = Val;
|
|
|
|
// Parent - initially null, but after drilling down notes where Op came from.
|
|
// In the example above, Parent is (Val, 0) when Op is M1, because M1 is the
|
|
// 0'th operand of Val.
|
|
std::pair<Instruction*, unsigned> Parent;
|
|
|
|
// RequireNoSignedWrap - Set if the transform requires a descaling at deeper
|
|
// levels that doesn't overflow.
|
|
bool RequireNoSignedWrap = false;
|
|
|
|
// logScale - log base 2 of the scale. Negative if not a power of 2.
|
|
int32_t logScale = Scale.exactLogBase2();
|
|
|
|
for (;; Op = Parent.first->getOperand(Parent.second)) { // Drill down
|
|
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op)) {
|
|
// If Op is a constant divisible by Scale then descale to the quotient.
|
|
APInt Quotient(Scale), Remainder(Scale); // Init ensures right bitwidth.
|
|
APInt::sdivrem(CI->getValue(), Scale, Quotient, Remainder);
|
|
if (!Remainder.isMinValue())
|
|
// Not divisible by Scale.
|
|
return nullptr;
|
|
// Replace with the quotient in the parent.
|
|
Op = ConstantInt::get(CI->getType(), Quotient);
|
|
NoSignedWrap = true;
|
|
break;
|
|
}
|
|
|
|
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op)) {
|
|
|
|
if (BO->getOpcode() == Instruction::Mul) {
|
|
// Multiplication.
|
|
NoSignedWrap = BO->hasNoSignedWrap();
|
|
if (RequireNoSignedWrap && !NoSignedWrap)
|
|
return nullptr;
|
|
|
|
// There are three cases for multiplication: multiplication by exactly
|
|
// the scale, multiplication by a constant different to the scale, and
|
|
// multiplication by something else.
|
|
Value *LHS = BO->getOperand(0);
|
|
Value *RHS = BO->getOperand(1);
|
|
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
|
|
// Multiplication by a constant.
|
|
if (CI->getValue() == Scale) {
|
|
// Multiplication by exactly the scale, replace the multiplication
|
|
// by its left-hand side in the parent.
|
|
Op = LHS;
|
|
break;
|
|
}
|
|
|
|
// Otherwise drill down into the constant.
|
|
if (!Op->hasOneUse())
|
|
return nullptr;
|
|
|
|
Parent = std::make_pair(BO, 1);
|
|
continue;
|
|
}
|
|
|
|
// Multiplication by something else. Drill down into the left-hand side
|
|
// since that's where the reassociate pass puts the good stuff.
|
|
if (!Op->hasOneUse())
|
|
return nullptr;
|
|
|
|
Parent = std::make_pair(BO, 0);
|
|
continue;
|
|
}
|
|
|
|
if (logScale > 0 && BO->getOpcode() == Instruction::Shl &&
|
|
isa<ConstantInt>(BO->getOperand(1))) {
|
|
// Multiplication by a power of 2.
|
|
NoSignedWrap = BO->hasNoSignedWrap();
|
|
if (RequireNoSignedWrap && !NoSignedWrap)
|
|
return nullptr;
|
|
|
|
Value *LHS = BO->getOperand(0);
|
|
int32_t Amt = cast<ConstantInt>(BO->getOperand(1))->
|
|
getLimitedValue(Scale.getBitWidth());
|
|
// Op = LHS << Amt.
|
|
|
|
if (Amt == logScale) {
|
|
// Multiplication by exactly the scale, replace the multiplication
|
|
// by its left-hand side in the parent.
|
|
Op = LHS;
|
|
break;
|
|
}
|
|
if (Amt < logScale || !Op->hasOneUse())
|
|
return nullptr;
|
|
|
|
// Multiplication by more than the scale. Reduce the multiplying amount
|
|
// by the scale in the parent.
|
|
Parent = std::make_pair(BO, 1);
|
|
Op = ConstantInt::get(BO->getType(), Amt - logScale);
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (!Op->hasOneUse())
|
|
return nullptr;
|
|
|
|
if (CastInst *Cast = dyn_cast<CastInst>(Op)) {
|
|
if (Cast->getOpcode() == Instruction::SExt) {
|
|
// Op is sign-extended from a smaller type, descale in the smaller type.
|
|
unsigned SmallSize = Cast->getSrcTy()->getPrimitiveSizeInBits();
|
|
APInt SmallScale = Scale.trunc(SmallSize);
|
|
// Suppose Op = sext X, and we descale X as Y * SmallScale. We want to
|
|
// descale Op as (sext Y) * Scale. In order to have
|
|
// sext (Y * SmallScale) = (sext Y) * Scale
|
|
// some conditions need to hold however: SmallScale must sign-extend to
|
|
// Scale and the multiplication Y * SmallScale should not overflow.
|
|
if (SmallScale.sext(Scale.getBitWidth()) != Scale)
|
|
// SmallScale does not sign-extend to Scale.
|
|
return nullptr;
|
|
assert(SmallScale.exactLogBase2() == logScale);
|
|
// Require that Y * SmallScale must not overflow.
|
|
RequireNoSignedWrap = true;
|
|
|
|
// Drill down through the cast.
|
|
Parent = std::make_pair(Cast, 0);
|
|
Scale = SmallScale;
|
|
continue;
|
|
}
|
|
|
|
if (Cast->getOpcode() == Instruction::Trunc) {
|
|
// Op is truncated from a larger type, descale in the larger type.
|
|
// Suppose Op = trunc X, and we descale X as Y * sext Scale. Then
|
|
// trunc (Y * sext Scale) = (trunc Y) * Scale
|
|
// always holds. However (trunc Y) * Scale may overflow even if
|
|
// trunc (Y * sext Scale) does not, so nsw flags need to be cleared
|
|
// from this point up in the expression (see later).
|
|
if (RequireNoSignedWrap)
|
|
return nullptr;
|
|
|
|
// Drill down through the cast.
|
|
unsigned LargeSize = Cast->getSrcTy()->getPrimitiveSizeInBits();
|
|
Parent = std::make_pair(Cast, 0);
|
|
Scale = Scale.sext(LargeSize);
|
|
if (logScale + 1 == (int32_t)Cast->getType()->getPrimitiveSizeInBits())
|
|
logScale = -1;
|
|
assert(Scale.exactLogBase2() == logScale);
|
|
continue;
|
|
}
|
|
}
|
|
|
|
// Unsupported expression, bail out.
|
|
return nullptr;
|
|
}
|
|
|
|
// If Op is zero then Val = Op * Scale.
|
|
if (match(Op, m_Zero())) {
|
|
NoSignedWrap = true;
|
|
return Op;
|
|
}
|
|
|
|
// We know that we can successfully descale, so from here on we can safely
|
|
// modify the IR. Op holds the descaled version of the deepest term in the
|
|
// expression. NoSignedWrap is 'true' if multiplying Op by Scale is known
|
|
// not to overflow.
|
|
|
|
if (!Parent.first)
|
|
// The expression only had one term.
|
|
return Op;
|
|
|
|
// Rewrite the parent using the descaled version of its operand.
|
|
assert(Parent.first->hasOneUse() && "Drilled down when more than one use!");
|
|
assert(Op != Parent.first->getOperand(Parent.second) &&
|
|
"Descaling was a no-op?");
|
|
Parent.first->setOperand(Parent.second, Op);
|
|
Worklist.Add(Parent.first);
|
|
|
|
// Now work back up the expression correcting nsw flags. The logic is based
|
|
// on the following observation: if X * Y is known not to overflow as a signed
|
|
// multiplication, and Y is replaced by a value Z with smaller absolute value,
|
|
// then X * Z will not overflow as a signed multiplication either. As we work
|
|
// our way up, having NoSignedWrap 'true' means that the descaled value at the
|
|
// current level has strictly smaller absolute value than the original.
|
|
Instruction *Ancestor = Parent.first;
|
|
do {
|
|
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Ancestor)) {
|
|
// If the multiplication wasn't nsw then we can't say anything about the
|
|
// value of the descaled multiplication, and we have to clear nsw flags
|
|
// from this point on up.
|
|
bool OpNoSignedWrap = BO->hasNoSignedWrap();
|
|
NoSignedWrap &= OpNoSignedWrap;
|
|
if (NoSignedWrap != OpNoSignedWrap) {
|
|
BO->setHasNoSignedWrap(NoSignedWrap);
|
|
Worklist.Add(Ancestor);
|
|
}
|
|
} else if (Ancestor->getOpcode() == Instruction::Trunc) {
|
|
// The fact that the descaled input to the trunc has smaller absolute
|
|
// value than the original input doesn't tell us anything useful about
|
|
// the absolute values of the truncations.
|
|
NoSignedWrap = false;
|
|
}
|
|
assert((Ancestor->getOpcode() != Instruction::SExt || NoSignedWrap) &&
|
|
"Failed to keep proper track of nsw flags while drilling down?");
|
|
|
|
if (Ancestor == Val)
|
|
// Got to the top, all done!
|
|
return Val;
|
|
|
|
// Move up one level in the expression.
|
|
assert(Ancestor->hasOneUse() && "Drilled down when more than one use!");
|
|
Ancestor = Ancestor->user_back();
|
|
} while (1);
|
|
}
|
|
|
|
/// \brief Creates node of binary operation with the same attributes as the
|
|
/// specified one but with other operands.
|
|
static Value *CreateBinOpAsGiven(BinaryOperator &Inst, Value *LHS, Value *RHS,
|
|
InstCombiner::BuilderTy *B) {
|
|
Value *BORes = B->CreateBinOp(Inst.getOpcode(), LHS, RHS);
|
|
if (BinaryOperator *NewBO = dyn_cast<BinaryOperator>(BORes)) {
|
|
if (isa<OverflowingBinaryOperator>(NewBO)) {
|
|
NewBO->setHasNoSignedWrap(Inst.hasNoSignedWrap());
|
|
NewBO->setHasNoUnsignedWrap(Inst.hasNoUnsignedWrap());
|
|
}
|
|
if (isa<PossiblyExactOperator>(NewBO))
|
|
NewBO->setIsExact(Inst.isExact());
|
|
}
|
|
return BORes;
|
|
}
|
|
|
|
/// \brief Makes transformation of binary operation specific for vector types.
|
|
/// \param Inst Binary operator to transform.
|
|
/// \return Pointer to node that must replace the original binary operator, or
|
|
/// null pointer if no transformation was made.
|
|
Value *InstCombiner::SimplifyVectorOp(BinaryOperator &Inst) {
|
|
if (!Inst.getType()->isVectorTy()) return nullptr;
|
|
|
|
// It may not be safe to reorder shuffles and things like div, urem, etc.
|
|
// because we may trap when executing those ops on unknown vector elements.
|
|
// See PR20059.
|
|
if (!isSafeToSpeculativelyExecute(&Inst, DL)) return nullptr;
|
|
|
|
unsigned VWidth = cast<VectorType>(Inst.getType())->getNumElements();
|
|
Value *LHS = Inst.getOperand(0), *RHS = Inst.getOperand(1);
|
|
assert(cast<VectorType>(LHS->getType())->getNumElements() == VWidth);
|
|
assert(cast<VectorType>(RHS->getType())->getNumElements() == VWidth);
|
|
|
|
// If both arguments of binary operation are shuffles, which use the same
|
|
// mask and shuffle within a single vector, it is worthwhile to move the
|
|
// shuffle after binary operation:
|
|
// Op(shuffle(v1, m), shuffle(v2, m)) -> shuffle(Op(v1, v2), m)
|
|
if (isa<ShuffleVectorInst>(LHS) && isa<ShuffleVectorInst>(RHS)) {
|
|
ShuffleVectorInst *LShuf = cast<ShuffleVectorInst>(LHS);
|
|
ShuffleVectorInst *RShuf = cast<ShuffleVectorInst>(RHS);
|
|
if (isa<UndefValue>(LShuf->getOperand(1)) &&
|
|
isa<UndefValue>(RShuf->getOperand(1)) &&
|
|
LShuf->getOperand(0)->getType() == RShuf->getOperand(0)->getType() &&
|
|
LShuf->getMask() == RShuf->getMask()) {
|
|
Value *NewBO = CreateBinOpAsGiven(Inst, LShuf->getOperand(0),
|
|
RShuf->getOperand(0), Builder);
|
|
Value *Res = Builder->CreateShuffleVector(NewBO,
|
|
UndefValue::get(NewBO->getType()), LShuf->getMask());
|
|
return Res;
|
|
}
|
|
}
|
|
|
|
// If one argument is a shuffle within one vector, the other is a constant,
|
|
// try moving the shuffle after the binary operation.
|
|
ShuffleVectorInst *Shuffle = nullptr;
|
|
Constant *C1 = nullptr;
|
|
if (isa<ShuffleVectorInst>(LHS)) Shuffle = cast<ShuffleVectorInst>(LHS);
|
|
if (isa<ShuffleVectorInst>(RHS)) Shuffle = cast<ShuffleVectorInst>(RHS);
|
|
if (isa<Constant>(LHS)) C1 = cast<Constant>(LHS);
|
|
if (isa<Constant>(RHS)) C1 = cast<Constant>(RHS);
|
|
if (Shuffle && C1 &&
|
|
(isa<ConstantVector>(C1) || isa<ConstantDataVector>(C1)) &&
|
|
isa<UndefValue>(Shuffle->getOperand(1)) &&
|
|
Shuffle->getType() == Shuffle->getOperand(0)->getType()) {
|
|
SmallVector<int, 16> ShMask = Shuffle->getShuffleMask();
|
|
// Find constant C2 that has property:
|
|
// shuffle(C2, ShMask) = C1
|
|
// If such constant does not exist (example: ShMask=<0,0> and C1=<1,2>)
|
|
// reorder is not possible.
|
|
SmallVector<Constant*, 16> C2M(VWidth,
|
|
UndefValue::get(C1->getType()->getScalarType()));
|
|
bool MayChange = true;
|
|
for (unsigned I = 0; I < VWidth; ++I) {
|
|
if (ShMask[I] >= 0) {
|
|
assert(ShMask[I] < (int)VWidth);
|
|
if (!isa<UndefValue>(C2M[ShMask[I]])) {
|
|
MayChange = false;
|
|
break;
|
|
}
|
|
C2M[ShMask[I]] = C1->getAggregateElement(I);
|
|
}
|
|
}
|
|
if (MayChange) {
|
|
Constant *C2 = ConstantVector::get(C2M);
|
|
Value *NewLHS, *NewRHS;
|
|
if (isa<Constant>(LHS)) {
|
|
NewLHS = C2;
|
|
NewRHS = Shuffle->getOperand(0);
|
|
} else {
|
|
NewLHS = Shuffle->getOperand(0);
|
|
NewRHS = C2;
|
|
}
|
|
Value *NewBO = CreateBinOpAsGiven(Inst, NewLHS, NewRHS, Builder);
|
|
Value *Res = Builder->CreateShuffleVector(NewBO,
|
|
UndefValue::get(Inst.getType()), Shuffle->getMask());
|
|
return Res;
|
|
}
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
|
|
SmallVector<Value*, 8> Ops(GEP.op_begin(), GEP.op_end());
|
|
|
|
if (Value *V = SimplifyGEPInst(Ops, DL, TLI, DT, AT))
|
|
return ReplaceInstUsesWith(GEP, V);
|
|
|
|
Value *PtrOp = GEP.getOperand(0);
|
|
|
|
// Eliminate unneeded casts for indices, and replace indices which displace
|
|
// by multiples of a zero size type with zero.
|
|
if (DL) {
|
|
bool MadeChange = false;
|
|
Type *IntPtrTy = DL->getIntPtrType(GEP.getPointerOperandType());
|
|
|
|
gep_type_iterator GTI = gep_type_begin(GEP);
|
|
for (User::op_iterator I = GEP.op_begin() + 1, E = GEP.op_end();
|
|
I != E; ++I, ++GTI) {
|
|
// Skip indices into struct types.
|
|
SequentialType *SeqTy = dyn_cast<SequentialType>(*GTI);
|
|
if (!SeqTy) continue;
|
|
|
|
// If the element type has zero size then any index over it is equivalent
|
|
// to an index of zero, so replace it with zero if it is not zero already.
|
|
if (SeqTy->getElementType()->isSized() &&
|
|
DL->getTypeAllocSize(SeqTy->getElementType()) == 0)
|
|
if (!isa<Constant>(*I) || !cast<Constant>(*I)->isNullValue()) {
|
|
*I = Constant::getNullValue(IntPtrTy);
|
|
MadeChange = true;
|
|
}
|
|
|
|
Type *IndexTy = (*I)->getType();
|
|
if (IndexTy != IntPtrTy) {
|
|
// If we are using a wider index than needed for this platform, shrink
|
|
// it to what we need. If narrower, sign-extend it to what we need.
|
|
// This explicit cast can make subsequent optimizations more obvious.
|
|
*I = Builder->CreateIntCast(*I, IntPtrTy, true);
|
|
MadeChange = true;
|
|
}
|
|
}
|
|
if (MadeChange) return &GEP;
|
|
}
|
|
|
|
// Check to see if the inputs to the PHI node are getelementptr instructions.
|
|
if (PHINode *PN = dyn_cast<PHINode>(PtrOp)) {
|
|
GetElementPtrInst *Op1 = dyn_cast<GetElementPtrInst>(PN->getOperand(0));
|
|
if (!Op1)
|
|
return nullptr;
|
|
|
|
signed DI = -1;
|
|
|
|
for (auto I = PN->op_begin()+1, E = PN->op_end(); I !=E; ++I) {
|
|
GetElementPtrInst *Op2 = dyn_cast<GetElementPtrInst>(*I);
|
|
if (!Op2 || Op1->getNumOperands() != Op2->getNumOperands())
|
|
return nullptr;
|
|
|
|
// Keep track of the type as we walk the GEP.
|
|
Type *CurTy = Op1->getOperand(0)->getType()->getScalarType();
|
|
|
|
for (unsigned J = 0, F = Op1->getNumOperands(); J != F; ++J) {
|
|
if (Op1->getOperand(J)->getType() != Op2->getOperand(J)->getType())
|
|
return nullptr;
|
|
|
|
if (Op1->getOperand(J) != Op2->getOperand(J)) {
|
|
if (DI == -1) {
|
|
// We have not seen any differences yet in the GEPs feeding the
|
|
// PHI yet, so we record this one if it is allowed to be a
|
|
// variable.
|
|
|
|
// The first two arguments can vary for any GEP, the rest have to be
|
|
// static for struct slots
|
|
if (J > 1 && CurTy->isStructTy())
|
|
return nullptr;
|
|
|
|
DI = J;
|
|
} else {
|
|
// The GEP is different by more than one input. While this could be
|
|
// extended to support GEPs that vary by more than one variable it
|
|
// doesn't make sense since it greatly increases the complexity and
|
|
// would result in an R+R+R addressing mode which no backend
|
|
// directly supports and would need to be broken into several
|
|
// simpler instructions anyway.
|
|
return nullptr;
|
|
}
|
|
}
|
|
|
|
// Sink down a layer of the type for the next iteration.
|
|
if (J > 0) {
|
|
if (CompositeType *CT = dyn_cast<CompositeType>(CurTy)) {
|
|
CurTy = CT->getTypeAtIndex(Op1->getOperand(J));
|
|
} else {
|
|
CurTy = nullptr;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
GetElementPtrInst *NewGEP = cast<GetElementPtrInst>(Op1->clone());
|
|
|
|
if (DI == -1) {
|
|
// All the GEPs feeding the PHI are identical. Clone one down into our
|
|
// BB so that it can be merged with the current GEP.
|
|
GEP.getParent()->getInstList().insert(GEP.getParent()->getFirstNonPHI(),
|
|
NewGEP);
|
|
} else {
|
|
// All the GEPs feeding the PHI differ at a single offset. Clone a GEP
|
|
// into the current block so it can be merged, and create a new PHI to
|
|
// set that index.
|
|
Instruction *InsertPt = Builder->GetInsertPoint();
|
|
Builder->SetInsertPoint(PN);
|
|
PHINode *NewPN = Builder->CreatePHI(Op1->getOperand(DI)->getType(),
|
|
PN->getNumOperands());
|
|
Builder->SetInsertPoint(InsertPt);
|
|
|
|
for (auto &I : PN->operands())
|
|
NewPN->addIncoming(cast<GEPOperator>(I)->getOperand(DI),
|
|
PN->getIncomingBlock(I));
|
|
|
|
NewGEP->setOperand(DI, NewPN);
|
|
GEP.getParent()->getInstList().insert(GEP.getParent()->getFirstNonPHI(),
|
|
NewGEP);
|
|
NewGEP->setOperand(DI, NewPN);
|
|
}
|
|
|
|
GEP.setOperand(0, NewGEP);
|
|
PtrOp = NewGEP;
|
|
}
|
|
|
|
// Combine Indices - If the source pointer to this getelementptr instruction
|
|
// is a getelementptr instruction, combine the indices of the two
|
|
// getelementptr instructions into a single instruction.
|
|
//
|
|
if (GEPOperator *Src = dyn_cast<GEPOperator>(PtrOp)) {
|
|
if (!shouldMergeGEPs(*cast<GEPOperator>(&GEP), *Src))
|
|
return nullptr;
|
|
|
|
// Note that if our source is a gep chain itself then we wait for that
|
|
// chain to be resolved before we perform this transformation. This
|
|
// avoids us creating a TON of code in some cases.
|
|
if (GEPOperator *SrcGEP =
|
|
dyn_cast<GEPOperator>(Src->getOperand(0)))
|
|
if (SrcGEP->getNumOperands() == 2 && shouldMergeGEPs(*Src, *SrcGEP))
|
|
return nullptr; // Wait until our source is folded to completion.
|
|
|
|
SmallVector<Value*, 8> Indices;
|
|
|
|
// Find out whether the last index in the source GEP is a sequential idx.
|
|
bool EndsWithSequential = false;
|
|
for (gep_type_iterator I = gep_type_begin(*Src), E = gep_type_end(*Src);
|
|
I != E; ++I)
|
|
EndsWithSequential = !(*I)->isStructTy();
|
|
|
|
// Can we combine the two pointer arithmetics offsets?
|
|
if (EndsWithSequential) {
|
|
// Replace: gep (gep %P, long B), long A, ...
|
|
// With: T = long A+B; gep %P, T, ...
|
|
//
|
|
Value *Sum;
|
|
Value *SO1 = Src->getOperand(Src->getNumOperands()-1);
|
|
Value *GO1 = GEP.getOperand(1);
|
|
if (SO1 == Constant::getNullValue(SO1->getType())) {
|
|
Sum = GO1;
|
|
} else if (GO1 == Constant::getNullValue(GO1->getType())) {
|
|
Sum = SO1;
|
|
} else {
|
|
// If they aren't the same type, then the input hasn't been processed
|
|
// by the loop above yet (which canonicalizes sequential index types to
|
|
// intptr_t). Just avoid transforming this until the input has been
|
|
// normalized.
|
|
if (SO1->getType() != GO1->getType())
|
|
return nullptr;
|
|
Sum = Builder->CreateAdd(SO1, GO1, PtrOp->getName()+".sum");
|
|
}
|
|
|
|
// Update the GEP in place if possible.
|
|
if (Src->getNumOperands() == 2) {
|
|
GEP.setOperand(0, Src->getOperand(0));
|
|
GEP.setOperand(1, Sum);
|
|
return &GEP;
|
|
}
|
|
Indices.append(Src->op_begin()+1, Src->op_end()-1);
|
|
Indices.push_back(Sum);
|
|
Indices.append(GEP.op_begin()+2, GEP.op_end());
|
|
} else if (isa<Constant>(*GEP.idx_begin()) &&
|
|
cast<Constant>(*GEP.idx_begin())->isNullValue() &&
|
|
Src->getNumOperands() != 1) {
|
|
// Otherwise we can do the fold if the first index of the GEP is a zero
|
|
Indices.append(Src->op_begin()+1, Src->op_end());
|
|
Indices.append(GEP.idx_begin()+1, GEP.idx_end());
|
|
}
|
|
|
|
if (!Indices.empty())
|
|
return (GEP.isInBounds() && Src->isInBounds()) ?
|
|
GetElementPtrInst::CreateInBounds(Src->getOperand(0), Indices,
|
|
GEP.getName()) :
|
|
GetElementPtrInst::Create(Src->getOperand(0), Indices, GEP.getName());
|
|
}
|
|
|
|
if (DL && GEP.getNumIndices() == 1) {
|
|
unsigned AS = GEP.getPointerAddressSpace();
|
|
if (GEP.getOperand(1)->getType()->getScalarSizeInBits() ==
|
|
DL->getPointerSizeInBits(AS)) {
|
|
Type *PtrTy = GEP.getPointerOperandType();
|
|
Type *Ty = PtrTy->getPointerElementType();
|
|
uint64_t TyAllocSize = DL->getTypeAllocSize(Ty);
|
|
|
|
bool Matched = false;
|
|
uint64_t C;
|
|
Value *V = nullptr;
|
|
if (TyAllocSize == 1) {
|
|
V = GEP.getOperand(1);
|
|
Matched = true;
|
|
} else if (match(GEP.getOperand(1),
|
|
m_AShr(m_Value(V), m_ConstantInt(C)))) {
|
|
if (TyAllocSize == 1ULL << C)
|
|
Matched = true;
|
|
} else if (match(GEP.getOperand(1),
|
|
m_SDiv(m_Value(V), m_ConstantInt(C)))) {
|
|
if (TyAllocSize == C)
|
|
Matched = true;
|
|
}
|
|
|
|
if (Matched) {
|
|
// Canonicalize (gep i8* X, -(ptrtoint Y))
|
|
// to (inttoptr (sub (ptrtoint X), (ptrtoint Y)))
|
|
// The GEP pattern is emitted by the SCEV expander for certain kinds of
|
|
// pointer arithmetic.
|
|
if (match(V, m_Neg(m_PtrToInt(m_Value())))) {
|
|
Operator *Index = cast<Operator>(V);
|
|
Value *PtrToInt = Builder->CreatePtrToInt(PtrOp, Index->getType());
|
|
Value *NewSub = Builder->CreateSub(PtrToInt, Index->getOperand(1));
|
|
return CastInst::Create(Instruction::IntToPtr, NewSub, GEP.getType());
|
|
}
|
|
// Canonicalize (gep i8* X, (ptrtoint Y)-(ptrtoint X))
|
|
// to (bitcast Y)
|
|
Value *Y;
|
|
if (match(V, m_Sub(m_PtrToInt(m_Value(Y)),
|
|
m_PtrToInt(m_Specific(GEP.getOperand(0)))))) {
|
|
return CastInst::CreatePointerBitCastOrAddrSpaceCast(Y,
|
|
GEP.getType());
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Handle gep(bitcast x) and gep(gep x, 0, 0, 0).
|
|
Value *StrippedPtr = PtrOp->stripPointerCasts();
|
|
PointerType *StrippedPtrTy = dyn_cast<PointerType>(StrippedPtr->getType());
|
|
|
|
// We do not handle pointer-vector geps here.
|
|
if (!StrippedPtrTy)
|
|
return nullptr;
|
|
|
|
if (StrippedPtr != PtrOp) {
|
|
bool HasZeroPointerIndex = false;
|
|
if (ConstantInt *C = dyn_cast<ConstantInt>(GEP.getOperand(1)))
|
|
HasZeroPointerIndex = C->isZero();
|
|
|
|
// Transform: GEP (bitcast [10 x i8]* X to [0 x i8]*), i32 0, ...
|
|
// into : GEP [10 x i8]* X, i32 0, ...
|
|
//
|
|
// Likewise, transform: GEP (bitcast i8* X to [0 x i8]*), i32 0, ...
|
|
// into : GEP i8* X, ...
|
|
//
|
|
// This occurs when the program declares an array extern like "int X[];"
|
|
if (HasZeroPointerIndex) {
|
|
PointerType *CPTy = cast<PointerType>(PtrOp->getType());
|
|
if (ArrayType *CATy =
|
|
dyn_cast<ArrayType>(CPTy->getElementType())) {
|
|
// GEP (bitcast i8* X to [0 x i8]*), i32 0, ... ?
|
|
if (CATy->getElementType() == StrippedPtrTy->getElementType()) {
|
|
// -> GEP i8* X, ...
|
|
SmallVector<Value*, 8> Idx(GEP.idx_begin()+1, GEP.idx_end());
|
|
GetElementPtrInst *Res =
|
|
GetElementPtrInst::Create(StrippedPtr, Idx, GEP.getName());
|
|
Res->setIsInBounds(GEP.isInBounds());
|
|
if (StrippedPtrTy->getAddressSpace() == GEP.getAddressSpace())
|
|
return Res;
|
|
// Insert Res, and create an addrspacecast.
|
|
// e.g.,
|
|
// GEP (addrspacecast i8 addrspace(1)* X to [0 x i8]*), i32 0, ...
|
|
// ->
|
|
// %0 = GEP i8 addrspace(1)* X, ...
|
|
// addrspacecast i8 addrspace(1)* %0 to i8*
|
|
return new AddrSpaceCastInst(Builder->Insert(Res), GEP.getType());
|
|
}
|
|
|
|
if (ArrayType *XATy =
|
|
dyn_cast<ArrayType>(StrippedPtrTy->getElementType())){
|
|
// GEP (bitcast [10 x i8]* X to [0 x i8]*), i32 0, ... ?
|
|
if (CATy->getElementType() == XATy->getElementType()) {
|
|
// -> GEP [10 x i8]* X, i32 0, ...
|
|
// At this point, we know that the cast source type is a pointer
|
|
// to an array of the same type as the destination pointer
|
|
// array. Because the array type is never stepped over (there
|
|
// is a leading zero) we can fold the cast into this GEP.
|
|
if (StrippedPtrTy->getAddressSpace() == GEP.getAddressSpace()) {
|
|
GEP.setOperand(0, StrippedPtr);
|
|
return &GEP;
|
|
}
|
|
// Cannot replace the base pointer directly because StrippedPtr's
|
|
// address space is different. Instead, create a new GEP followed by
|
|
// an addrspacecast.
|
|
// e.g.,
|
|
// GEP (addrspacecast [10 x i8] addrspace(1)* X to [0 x i8]*),
|
|
// i32 0, ...
|
|
// ->
|
|
// %0 = GEP [10 x i8] addrspace(1)* X, ...
|
|
// addrspacecast i8 addrspace(1)* %0 to i8*
|
|
SmallVector<Value*, 8> Idx(GEP.idx_begin(), GEP.idx_end());
|
|
Value *NewGEP = GEP.isInBounds() ?
|
|
Builder->CreateInBoundsGEP(StrippedPtr, Idx, GEP.getName()) :
|
|
Builder->CreateGEP(StrippedPtr, Idx, GEP.getName());
|
|
return new AddrSpaceCastInst(NewGEP, GEP.getType());
|
|
}
|
|
}
|
|
}
|
|
} else if (GEP.getNumOperands() == 2) {
|
|
// Transform things like:
|
|
// %t = getelementptr i32* bitcast ([2 x i32]* %str to i32*), i32 %V
|
|
// into: %t1 = getelementptr [2 x i32]* %str, i32 0, i32 %V; bitcast
|
|
Type *SrcElTy = StrippedPtrTy->getElementType();
|
|
Type *ResElTy = PtrOp->getType()->getPointerElementType();
|
|
if (DL && SrcElTy->isArrayTy() &&
|
|
DL->getTypeAllocSize(SrcElTy->getArrayElementType()) ==
|
|
DL->getTypeAllocSize(ResElTy)) {
|
|
Type *IdxType = DL->getIntPtrType(GEP.getType());
|
|
Value *Idx[2] = { Constant::getNullValue(IdxType), GEP.getOperand(1) };
|
|
Value *NewGEP = GEP.isInBounds() ?
|
|
Builder->CreateInBoundsGEP(StrippedPtr, Idx, GEP.getName()) :
|
|
Builder->CreateGEP(StrippedPtr, Idx, GEP.getName());
|
|
|
|
// V and GEP are both pointer types --> BitCast
|
|
return CastInst::CreatePointerBitCastOrAddrSpaceCast(NewGEP,
|
|
GEP.getType());
|
|
}
|
|
|
|
// Transform things like:
|
|
// %V = mul i64 %N, 4
|
|
// %t = getelementptr i8* bitcast (i32* %arr to i8*), i32 %V
|
|
// into: %t1 = getelementptr i32* %arr, i32 %N; bitcast
|
|
if (DL && ResElTy->isSized() && SrcElTy->isSized()) {
|
|
// Check that changing the type amounts to dividing the index by a scale
|
|
// factor.
|
|
uint64_t ResSize = DL->getTypeAllocSize(ResElTy);
|
|
uint64_t SrcSize = DL->getTypeAllocSize(SrcElTy);
|
|
if (ResSize && SrcSize % ResSize == 0) {
|
|
Value *Idx = GEP.getOperand(1);
|
|
unsigned BitWidth = Idx->getType()->getPrimitiveSizeInBits();
|
|
uint64_t Scale = SrcSize / ResSize;
|
|
|
|
// Earlier transforms ensure that the index has type IntPtrType, which
|
|
// considerably simplifies the logic by eliminating implicit casts.
|
|
assert(Idx->getType() == DL->getIntPtrType(GEP.getType()) &&
|
|
"Index not cast to pointer width?");
|
|
|
|
bool NSW;
|
|
if (Value *NewIdx = Descale(Idx, APInt(BitWidth, Scale), NSW)) {
|
|
// Successfully decomposed Idx as NewIdx * Scale, form a new GEP.
|
|
// If the multiplication NewIdx * Scale may overflow then the new
|
|
// GEP may not be "inbounds".
|
|
Value *NewGEP = GEP.isInBounds() && NSW ?
|
|
Builder->CreateInBoundsGEP(StrippedPtr, NewIdx, GEP.getName()) :
|
|
Builder->CreateGEP(StrippedPtr, NewIdx, GEP.getName());
|
|
|
|
// The NewGEP must be pointer typed, so must the old one -> BitCast
|
|
return CastInst::CreatePointerBitCastOrAddrSpaceCast(NewGEP,
|
|
GEP.getType());
|
|
}
|
|
}
|
|
}
|
|
|
|
// Similarly, transform things like:
|
|
// getelementptr i8* bitcast ([100 x double]* X to i8*), i32 %tmp
|
|
// (where tmp = 8*tmp2) into:
|
|
// getelementptr [100 x double]* %arr, i32 0, i32 %tmp2; bitcast
|
|
if (DL && ResElTy->isSized() && SrcElTy->isSized() &&
|
|
SrcElTy->isArrayTy()) {
|
|
// Check that changing to the array element type amounts to dividing the
|
|
// index by a scale factor.
|
|
uint64_t ResSize = DL->getTypeAllocSize(ResElTy);
|
|
uint64_t ArrayEltSize
|
|
= DL->getTypeAllocSize(SrcElTy->getArrayElementType());
|
|
if (ResSize && ArrayEltSize % ResSize == 0) {
|
|
Value *Idx = GEP.getOperand(1);
|
|
unsigned BitWidth = Idx->getType()->getPrimitiveSizeInBits();
|
|
uint64_t Scale = ArrayEltSize / ResSize;
|
|
|
|
// Earlier transforms ensure that the index has type IntPtrType, which
|
|
// considerably simplifies the logic by eliminating implicit casts.
|
|
assert(Idx->getType() == DL->getIntPtrType(GEP.getType()) &&
|
|
"Index not cast to pointer width?");
|
|
|
|
bool NSW;
|
|
if (Value *NewIdx = Descale(Idx, APInt(BitWidth, Scale), NSW)) {
|
|
// Successfully decomposed Idx as NewIdx * Scale, form a new GEP.
|
|
// If the multiplication NewIdx * Scale may overflow then the new
|
|
// GEP may not be "inbounds".
|
|
Value *Off[2] = {
|
|
Constant::getNullValue(DL->getIntPtrType(GEP.getType())),
|
|
NewIdx
|
|
};
|
|
|
|
Value *NewGEP = GEP.isInBounds() && NSW ?
|
|
Builder->CreateInBoundsGEP(StrippedPtr, Off, GEP.getName()) :
|
|
Builder->CreateGEP(StrippedPtr, Off, GEP.getName());
|
|
// The NewGEP must be pointer typed, so must the old one -> BitCast
|
|
return CastInst::CreatePointerBitCastOrAddrSpaceCast(NewGEP,
|
|
GEP.getType());
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
if (!DL)
|
|
return nullptr;
|
|
|
|
// addrspacecast between types is canonicalized as a bitcast, then an
|
|
// addrspacecast. To take advantage of the below bitcast + struct GEP, look
|
|
// through the addrspacecast.
|
|
if (AddrSpaceCastInst *ASC = dyn_cast<AddrSpaceCastInst>(PtrOp)) {
|
|
// X = bitcast A addrspace(1)* to B addrspace(1)*
|
|
// Y = addrspacecast A addrspace(1)* to B addrspace(2)*
|
|
// Z = gep Y, <...constant indices...>
|
|
// Into an addrspacecasted GEP of the struct.
|
|
if (BitCastInst *BC = dyn_cast<BitCastInst>(ASC->getOperand(0)))
|
|
PtrOp = BC;
|
|
}
|
|
|
|
/// See if we can simplify:
|
|
/// X = bitcast A* to B*
|
|
/// Y = gep X, <...constant indices...>
|
|
/// into a gep of the original struct. This is important for SROA and alias
|
|
/// analysis of unions. If "A" is also a bitcast, wait for A/X to be merged.
|
|
if (BitCastInst *BCI = dyn_cast<BitCastInst>(PtrOp)) {
|
|
Value *Operand = BCI->getOperand(0);
|
|
PointerType *OpType = cast<PointerType>(Operand->getType());
|
|
unsigned OffsetBits = DL->getPointerTypeSizeInBits(GEP.getType());
|
|
APInt Offset(OffsetBits, 0);
|
|
if (!isa<BitCastInst>(Operand) &&
|
|
GEP.accumulateConstantOffset(*DL, Offset)) {
|
|
|
|
// If this GEP instruction doesn't move the pointer, just replace the GEP
|
|
// with a bitcast of the real input to the dest type.
|
|
if (!Offset) {
|
|
// If the bitcast is of an allocation, and the allocation will be
|
|
// converted to match the type of the cast, don't touch this.
|
|
if (isa<AllocaInst>(Operand) || isAllocationFn(Operand, TLI)) {
|
|
// See if the bitcast simplifies, if so, don't nuke this GEP yet.
|
|
if (Instruction *I = visitBitCast(*BCI)) {
|
|
if (I != BCI) {
|
|
I->takeName(BCI);
|
|
BCI->getParent()->getInstList().insert(BCI, I);
|
|
ReplaceInstUsesWith(*BCI, I);
|
|
}
|
|
return &GEP;
|
|
}
|
|
}
|
|
|
|
if (Operand->getType()->getPointerAddressSpace() != GEP.getAddressSpace())
|
|
return new AddrSpaceCastInst(Operand, GEP.getType());
|
|
return new BitCastInst(Operand, GEP.getType());
|
|
}
|
|
|
|
// Otherwise, if the offset is non-zero, we need to find out if there is a
|
|
// field at Offset in 'A's type. If so, we can pull the cast through the
|
|
// GEP.
|
|
SmallVector<Value*, 8> NewIndices;
|
|
if (FindElementAtOffset(OpType, Offset.getSExtValue(), NewIndices)) {
|
|
Value *NGEP = GEP.isInBounds() ?
|
|
Builder->CreateInBoundsGEP(Operand, NewIndices) :
|
|
Builder->CreateGEP(Operand, NewIndices);
|
|
|
|
if (NGEP->getType() == GEP.getType())
|
|
return ReplaceInstUsesWith(GEP, NGEP);
|
|
NGEP->takeName(&GEP);
|
|
|
|
if (NGEP->getType()->getPointerAddressSpace() != GEP.getAddressSpace())
|
|
return new AddrSpaceCastInst(NGEP, GEP.getType());
|
|
return new BitCastInst(NGEP, GEP.getType());
|
|
}
|
|
}
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
static bool
|
|
isAllocSiteRemovable(Instruction *AI, SmallVectorImpl<WeakVH> &Users,
|
|
const TargetLibraryInfo *TLI) {
|
|
SmallVector<Instruction*, 4> Worklist;
|
|
Worklist.push_back(AI);
|
|
|
|
do {
|
|
Instruction *PI = Worklist.pop_back_val();
|
|
for (User *U : PI->users()) {
|
|
Instruction *I = cast<Instruction>(U);
|
|
switch (I->getOpcode()) {
|
|
default:
|
|
// Give up the moment we see something we can't handle.
|
|
return false;
|
|
|
|
case Instruction::BitCast:
|
|
case Instruction::GetElementPtr:
|
|
Users.push_back(I);
|
|
Worklist.push_back(I);
|
|
continue;
|
|
|
|
case Instruction::ICmp: {
|
|
ICmpInst *ICI = cast<ICmpInst>(I);
|
|
// We can fold eq/ne comparisons with null to false/true, respectively.
|
|
if (!ICI->isEquality() || !isa<ConstantPointerNull>(ICI->getOperand(1)))
|
|
return false;
|
|
Users.push_back(I);
|
|
continue;
|
|
}
|
|
|
|
case Instruction::Call:
|
|
// Ignore no-op and store intrinsics.
|
|
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
|
|
switch (II->getIntrinsicID()) {
|
|
default:
|
|
return false;
|
|
|
|
case Intrinsic::memmove:
|
|
case Intrinsic::memcpy:
|
|
case Intrinsic::memset: {
|
|
MemIntrinsic *MI = cast<MemIntrinsic>(II);
|
|
if (MI->isVolatile() || MI->getRawDest() != PI)
|
|
return false;
|
|
}
|
|
// fall through
|
|
case Intrinsic::dbg_declare:
|
|
case Intrinsic::dbg_value:
|
|
case Intrinsic::invariant_start:
|
|
case Intrinsic::invariant_end:
|
|
case Intrinsic::lifetime_start:
|
|
case Intrinsic::lifetime_end:
|
|
case Intrinsic::objectsize:
|
|
Users.push_back(I);
|
|
continue;
|
|
}
|
|
}
|
|
|
|
if (isFreeCall(I, TLI)) {
|
|
Users.push_back(I);
|
|
continue;
|
|
}
|
|
return false;
|
|
|
|
case Instruction::Store: {
|
|
StoreInst *SI = cast<StoreInst>(I);
|
|
if (SI->isVolatile() || SI->getPointerOperand() != PI)
|
|
return false;
|
|
Users.push_back(I);
|
|
continue;
|
|
}
|
|
}
|
|
llvm_unreachable("missing a return?");
|
|
}
|
|
} while (!Worklist.empty());
|
|
return true;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitAllocSite(Instruction &MI) {
|
|
// If we have a malloc call which is only used in any amount of comparisons
|
|
// to null and free calls, delete the calls and replace the comparisons with
|
|
// true or false as appropriate.
|
|
SmallVector<WeakVH, 64> Users;
|
|
if (isAllocSiteRemovable(&MI, Users, TLI)) {
|
|
for (unsigned i = 0, e = Users.size(); i != e; ++i) {
|
|
Instruction *I = cast_or_null<Instruction>(&*Users[i]);
|
|
if (!I) continue;
|
|
|
|
if (ICmpInst *C = dyn_cast<ICmpInst>(I)) {
|
|
ReplaceInstUsesWith(*C,
|
|
ConstantInt::get(Type::getInt1Ty(C->getContext()),
|
|
C->isFalseWhenEqual()));
|
|
} else if (isa<BitCastInst>(I) || isa<GetElementPtrInst>(I)) {
|
|
ReplaceInstUsesWith(*I, UndefValue::get(I->getType()));
|
|
} else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
|
|
if (II->getIntrinsicID() == Intrinsic::objectsize) {
|
|
ConstantInt *CI = cast<ConstantInt>(II->getArgOperand(1));
|
|
uint64_t DontKnow = CI->isZero() ? -1ULL : 0;
|
|
ReplaceInstUsesWith(*I, ConstantInt::get(I->getType(), DontKnow));
|
|
}
|
|
}
|
|
EraseInstFromFunction(*I);
|
|
}
|
|
|
|
if (InvokeInst *II = dyn_cast<InvokeInst>(&MI)) {
|
|
// Replace invoke with a NOP intrinsic to maintain the original CFG
|
|
Module *M = II->getParent()->getParent()->getParent();
|
|
Function *F = Intrinsic::getDeclaration(M, Intrinsic::donothing);
|
|
InvokeInst::Create(F, II->getNormalDest(), II->getUnwindDest(),
|
|
None, "", II->getParent());
|
|
}
|
|
return EraseInstFromFunction(MI);
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
/// \brief Move the call to free before a NULL test.
|
|
///
|
|
/// Check if this free is accessed after its argument has been test
|
|
/// against NULL (property 0).
|
|
/// If yes, it is legal to move this call in its predecessor block.
|
|
///
|
|
/// The move is performed only if the block containing the call to free
|
|
/// will be removed, i.e.:
|
|
/// 1. it has only one predecessor P, and P has two successors
|
|
/// 2. it contains the call and an unconditional branch
|
|
/// 3. its successor is the same as its predecessor's successor
|
|
///
|
|
/// The profitability is out-of concern here and this function should
|
|
/// be called only if the caller knows this transformation would be
|
|
/// profitable (e.g., for code size).
|
|
static Instruction *
|
|
tryToMoveFreeBeforeNullTest(CallInst &FI) {
|
|
Value *Op = FI.getArgOperand(0);
|
|
BasicBlock *FreeInstrBB = FI.getParent();
|
|
BasicBlock *PredBB = FreeInstrBB->getSinglePredecessor();
|
|
|
|
// Validate part of constraint #1: Only one predecessor
|
|
// FIXME: We can extend the number of predecessor, but in that case, we
|
|
// would duplicate the call to free in each predecessor and it may
|
|
// not be profitable even for code size.
|
|
if (!PredBB)
|
|
return nullptr;
|
|
|
|
// Validate constraint #2: Does this block contains only the call to
|
|
// free and an unconditional branch?
|
|
// FIXME: We could check if we can speculate everything in the
|
|
// predecessor block
|
|
if (FreeInstrBB->size() != 2)
|
|
return nullptr;
|
|
BasicBlock *SuccBB;
|
|
if (!match(FreeInstrBB->getTerminator(), m_UnconditionalBr(SuccBB)))
|
|
return nullptr;
|
|
|
|
// Validate the rest of constraint #1 by matching on the pred branch.
|
|
TerminatorInst *TI = PredBB->getTerminator();
|
|
BasicBlock *TrueBB, *FalseBB;
|
|
ICmpInst::Predicate Pred;
|
|
if (!match(TI, m_Br(m_ICmp(Pred, m_Specific(Op), m_Zero()), TrueBB, FalseBB)))
|
|
return nullptr;
|
|
if (Pred != ICmpInst::ICMP_EQ && Pred != ICmpInst::ICMP_NE)
|
|
return nullptr;
|
|
|
|
// Validate constraint #3: Ensure the null case just falls through.
|
|
if (SuccBB != (Pred == ICmpInst::ICMP_EQ ? TrueBB : FalseBB))
|
|
return nullptr;
|
|
assert(FreeInstrBB == (Pred == ICmpInst::ICMP_EQ ? FalseBB : TrueBB) &&
|
|
"Broken CFG: missing edge from predecessor to successor");
|
|
|
|
FI.moveBefore(TI);
|
|
return &FI;
|
|
}
|
|
|
|
|
|
Instruction *InstCombiner::visitFree(CallInst &FI) {
|
|
Value *Op = FI.getArgOperand(0);
|
|
|
|
// free undef -> unreachable.
|
|
if (isa<UndefValue>(Op)) {
|
|
// Insert a new store to null because we cannot modify the CFG here.
|
|
Builder->CreateStore(ConstantInt::getTrue(FI.getContext()),
|
|
UndefValue::get(Type::getInt1PtrTy(FI.getContext())));
|
|
return EraseInstFromFunction(FI);
|
|
}
|
|
|
|
// If we have 'free null' delete the instruction. This can happen in stl code
|
|
// when lots of inlining happens.
|
|
if (isa<ConstantPointerNull>(Op))
|
|
return EraseInstFromFunction(FI);
|
|
|
|
// If we optimize for code size, try to move the call to free before the null
|
|
// test so that simplify cfg can remove the empty block and dead code
|
|
// elimination the branch. I.e., helps to turn something like:
|
|
// if (foo) free(foo);
|
|
// into
|
|
// free(foo);
|
|
if (MinimizeSize)
|
|
if (Instruction *I = tryToMoveFreeBeforeNullTest(FI))
|
|
return I;
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitReturnInst(ReturnInst &RI) {
|
|
if (RI.getNumOperands() == 0) // ret void
|
|
return nullptr;
|
|
|
|
Value *ResultOp = RI.getOperand(0);
|
|
Type *VTy = ResultOp->getType();
|
|
if (!VTy->isIntegerTy())
|
|
return nullptr;
|
|
|
|
// There might be assume intrinsics dominating this return that completely
|
|
// determine the value. If so, constant fold it.
|
|
unsigned BitWidth = VTy->getPrimitiveSizeInBits();
|
|
APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
|
|
computeKnownBits(ResultOp, KnownZero, KnownOne, 0, &RI);
|
|
if ((KnownZero|KnownOne).isAllOnesValue())
|
|
RI.setOperand(0, Constant::getIntegerValue(VTy, KnownOne));
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
|
|
// Change br (not X), label True, label False to: br X, label False, True
|
|
Value *X = nullptr;
|
|
BasicBlock *TrueDest;
|
|
BasicBlock *FalseDest;
|
|
if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
|
|
!isa<Constant>(X)) {
|
|
// Swap Destinations and condition...
|
|
BI.setCondition(X);
|
|
BI.swapSuccessors();
|
|
return &BI;
|
|
}
|
|
|
|
// Canonicalize fcmp_one -> fcmp_oeq
|
|
FCmpInst::Predicate FPred; Value *Y;
|
|
if (match(&BI, m_Br(m_FCmp(FPred, m_Value(X), m_Value(Y)),
|
|
TrueDest, FalseDest)) &&
|
|
BI.getCondition()->hasOneUse())
|
|
if (FPred == FCmpInst::FCMP_ONE || FPred == FCmpInst::FCMP_OLE ||
|
|
FPred == FCmpInst::FCMP_OGE) {
|
|
FCmpInst *Cond = cast<FCmpInst>(BI.getCondition());
|
|
Cond->setPredicate(FCmpInst::getInversePredicate(FPred));
|
|
|
|
// Swap Destinations and condition.
|
|
BI.swapSuccessors();
|
|
Worklist.Add(Cond);
|
|
return &BI;
|
|
}
|
|
|
|
// Canonicalize icmp_ne -> icmp_eq
|
|
ICmpInst::Predicate IPred;
|
|
if (match(&BI, m_Br(m_ICmp(IPred, m_Value(X), m_Value(Y)),
|
|
TrueDest, FalseDest)) &&
|
|
BI.getCondition()->hasOneUse())
|
|
if (IPred == ICmpInst::ICMP_NE || IPred == ICmpInst::ICMP_ULE ||
|
|
IPred == ICmpInst::ICMP_SLE || IPred == ICmpInst::ICMP_UGE ||
|
|
IPred == ICmpInst::ICMP_SGE) {
|
|
ICmpInst *Cond = cast<ICmpInst>(BI.getCondition());
|
|
Cond->setPredicate(ICmpInst::getInversePredicate(IPred));
|
|
// Swap Destinations and condition.
|
|
BI.swapSuccessors();
|
|
Worklist.Add(Cond);
|
|
return &BI;
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
|
|
Value *Cond = SI.getCondition();
|
|
if (Instruction *I = dyn_cast<Instruction>(Cond)) {
|
|
if (I->getOpcode() == Instruction::Add)
|
|
if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
|
|
// change 'switch (X+4) case 1:' into 'switch (X) case -3'
|
|
// Skip the first item since that's the default case.
|
|
for (SwitchInst::CaseIt i = SI.case_begin(), e = SI.case_end();
|
|
i != e; ++i) {
|
|
ConstantInt* CaseVal = i.getCaseValue();
|
|
Constant* NewCaseVal = ConstantExpr::getSub(cast<Constant>(CaseVal),
|
|
AddRHS);
|
|
assert(isa<ConstantInt>(NewCaseVal) &&
|
|
"Result of expression should be constant");
|
|
i.setValue(cast<ConstantInt>(NewCaseVal));
|
|
}
|
|
SI.setCondition(I->getOperand(0));
|
|
Worklist.Add(I);
|
|
return &SI;
|
|
}
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitExtractValueInst(ExtractValueInst &EV) {
|
|
Value *Agg = EV.getAggregateOperand();
|
|
|
|
if (!EV.hasIndices())
|
|
return ReplaceInstUsesWith(EV, Agg);
|
|
|
|
if (Constant *C = dyn_cast<Constant>(Agg)) {
|
|
if (Constant *C2 = C->getAggregateElement(*EV.idx_begin())) {
|
|
if (EV.getNumIndices() == 0)
|
|
return ReplaceInstUsesWith(EV, C2);
|
|
// Extract the remaining indices out of the constant indexed by the
|
|
// first index
|
|
return ExtractValueInst::Create(C2, EV.getIndices().slice(1));
|
|
}
|
|
return nullptr; // Can't handle other constants
|
|
}
|
|
|
|
if (InsertValueInst *IV = dyn_cast<InsertValueInst>(Agg)) {
|
|
// We're extracting from an insertvalue instruction, compare the indices
|
|
const unsigned *exti, *exte, *insi, *inse;
|
|
for (exti = EV.idx_begin(), insi = IV->idx_begin(),
|
|
exte = EV.idx_end(), inse = IV->idx_end();
|
|
exti != exte && insi != inse;
|
|
++exti, ++insi) {
|
|
if (*insi != *exti)
|
|
// The insert and extract both reference distinctly different elements.
|
|
// This means the extract is not influenced by the insert, and we can
|
|
// replace the aggregate operand of the extract with the aggregate
|
|
// operand of the insert. i.e., replace
|
|
// %I = insertvalue { i32, { i32 } } %A, { i32 } { i32 42 }, 1
|
|
// %E = extractvalue { i32, { i32 } } %I, 0
|
|
// with
|
|
// %E = extractvalue { i32, { i32 } } %A, 0
|
|
return ExtractValueInst::Create(IV->getAggregateOperand(),
|
|
EV.getIndices());
|
|
}
|
|
if (exti == exte && insi == inse)
|
|
// Both iterators are at the end: Index lists are identical. Replace
|
|
// %B = insertvalue { i32, { i32 } } %A, i32 42, 1, 0
|
|
// %C = extractvalue { i32, { i32 } } %B, 1, 0
|
|
// with "i32 42"
|
|
return ReplaceInstUsesWith(EV, IV->getInsertedValueOperand());
|
|
if (exti == exte) {
|
|
// The extract list is a prefix of the insert list. i.e. replace
|
|
// %I = insertvalue { i32, { i32 } } %A, i32 42, 1, 0
|
|
// %E = extractvalue { i32, { i32 } } %I, 1
|
|
// with
|
|
// %X = extractvalue { i32, { i32 } } %A, 1
|
|
// %E = insertvalue { i32 } %X, i32 42, 0
|
|
// by switching the order of the insert and extract (though the
|
|
// insertvalue should be left in, since it may have other uses).
|
|
Value *NewEV = Builder->CreateExtractValue(IV->getAggregateOperand(),
|
|
EV.getIndices());
|
|
return InsertValueInst::Create(NewEV, IV->getInsertedValueOperand(),
|
|
makeArrayRef(insi, inse));
|
|
}
|
|
if (insi == inse)
|
|
// The insert list is a prefix of the extract list
|
|
// We can simply remove the common indices from the extract and make it
|
|
// operate on the inserted value instead of the insertvalue result.
|
|
// i.e., replace
|
|
// %I = insertvalue { i32, { i32 } } %A, { i32 } { i32 42 }, 1
|
|
// %E = extractvalue { i32, { i32 } } %I, 1, 0
|
|
// with
|
|
// %E extractvalue { i32 } { i32 42 }, 0
|
|
return ExtractValueInst::Create(IV->getInsertedValueOperand(),
|
|
makeArrayRef(exti, exte));
|
|
}
|
|
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Agg)) {
|
|
// We're extracting from an intrinsic, see if we're the only user, which
|
|
// allows us to simplify multiple result intrinsics to simpler things that
|
|
// just get one value.
|
|
if (II->hasOneUse()) {
|
|
// Check if we're grabbing the overflow bit or the result of a 'with
|
|
// overflow' intrinsic. If it's the latter we can remove the intrinsic
|
|
// and replace it with a traditional binary instruction.
|
|
switch (II->getIntrinsicID()) {
|
|
case Intrinsic::uadd_with_overflow:
|
|
case Intrinsic::sadd_with_overflow:
|
|
if (*EV.idx_begin() == 0) { // Normal result.
|
|
Value *LHS = II->getArgOperand(0), *RHS = II->getArgOperand(1);
|
|
ReplaceInstUsesWith(*II, UndefValue::get(II->getType()));
|
|
EraseInstFromFunction(*II);
|
|
return BinaryOperator::CreateAdd(LHS, RHS);
|
|
}
|
|
|
|
// If the normal result of the add is dead, and the RHS is a constant,
|
|
// we can transform this into a range comparison.
|
|
// overflow = uadd a, -4 --> overflow = icmp ugt a, 3
|
|
if (II->getIntrinsicID() == Intrinsic::uadd_with_overflow)
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(II->getArgOperand(1)))
|
|
return new ICmpInst(ICmpInst::ICMP_UGT, II->getArgOperand(0),
|
|
ConstantExpr::getNot(CI));
|
|
break;
|
|
case Intrinsic::usub_with_overflow:
|
|
case Intrinsic::ssub_with_overflow:
|
|
if (*EV.idx_begin() == 0) { // Normal result.
|
|
Value *LHS = II->getArgOperand(0), *RHS = II->getArgOperand(1);
|
|
ReplaceInstUsesWith(*II, UndefValue::get(II->getType()));
|
|
EraseInstFromFunction(*II);
|
|
return BinaryOperator::CreateSub(LHS, RHS);
|
|
}
|
|
break;
|
|
case Intrinsic::umul_with_overflow:
|
|
case Intrinsic::smul_with_overflow:
|
|
if (*EV.idx_begin() == 0) { // Normal result.
|
|
Value *LHS = II->getArgOperand(0), *RHS = II->getArgOperand(1);
|
|
ReplaceInstUsesWith(*II, UndefValue::get(II->getType()));
|
|
EraseInstFromFunction(*II);
|
|
return BinaryOperator::CreateMul(LHS, RHS);
|
|
}
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
if (LoadInst *L = dyn_cast<LoadInst>(Agg))
|
|
// If the (non-volatile) load only has one use, we can rewrite this to a
|
|
// load from a GEP. This reduces the size of the load.
|
|
// FIXME: If a load is used only by extractvalue instructions then this
|
|
// could be done regardless of having multiple uses.
|
|
if (L->isSimple() && L->hasOneUse()) {
|
|
// extractvalue has integer indices, getelementptr has Value*s. Convert.
|
|
SmallVector<Value*, 4> Indices;
|
|
// Prefix an i32 0 since we need the first element.
|
|
Indices.push_back(Builder->getInt32(0));
|
|
for (ExtractValueInst::idx_iterator I = EV.idx_begin(), E = EV.idx_end();
|
|
I != E; ++I)
|
|
Indices.push_back(Builder->getInt32(*I));
|
|
|
|
// We need to insert these at the location of the old load, not at that of
|
|
// the extractvalue.
|
|
Builder->SetInsertPoint(L->getParent(), L);
|
|
Value *GEP = Builder->CreateInBoundsGEP(L->getPointerOperand(), Indices);
|
|
// Returning the load directly will cause the main loop to insert it in
|
|
// the wrong spot, so use ReplaceInstUsesWith().
|
|
return ReplaceInstUsesWith(EV, Builder->CreateLoad(GEP));
|
|
}
|
|
// We could simplify extracts from other values. Note that nested extracts may
|
|
// already be simplified implicitly by the above: extract (extract (insert) )
|
|
// will be translated into extract ( insert ( extract ) ) first and then just
|
|
// the value inserted, if appropriate. Similarly for extracts from single-use
|
|
// loads: extract (extract (load)) will be translated to extract (load (gep))
|
|
// and if again single-use then via load (gep (gep)) to load (gep).
|
|
// However, double extracts from e.g. function arguments or return values
|
|
// aren't handled yet.
|
|
return nullptr;
|
|
}
|
|
|
|
enum Personality_Type {
|
|
Unknown_Personality,
|
|
GNU_Ada_Personality,
|
|
GNU_CXX_Personality,
|
|
GNU_ObjC_Personality
|
|
};
|
|
|
|
/// RecognizePersonality - See if the given exception handling personality
|
|
/// function is one that we understand. If so, return a description of it;
|
|
/// otherwise return Unknown_Personality.
|
|
static Personality_Type RecognizePersonality(Value *Pers) {
|
|
Function *F = dyn_cast<Function>(Pers->stripPointerCasts());
|
|
if (!F)
|
|
return Unknown_Personality;
|
|
return StringSwitch<Personality_Type>(F->getName())
|
|
.Case("__gnat_eh_personality", GNU_Ada_Personality)
|
|
.Case("__gxx_personality_v0", GNU_CXX_Personality)
|
|
.Case("__objc_personality_v0", GNU_ObjC_Personality)
|
|
.Default(Unknown_Personality);
|
|
}
|
|
|
|
/// isCatchAll - Return 'true' if the given typeinfo will match anything.
|
|
static bool isCatchAll(Personality_Type Personality, Constant *TypeInfo) {
|
|
switch (Personality) {
|
|
case Unknown_Personality:
|
|
return false;
|
|
case GNU_Ada_Personality:
|
|
// While __gnat_all_others_value will match any Ada exception, it doesn't
|
|
// match foreign exceptions (or didn't, before gcc-4.7).
|
|
return false;
|
|
case GNU_CXX_Personality:
|
|
case GNU_ObjC_Personality:
|
|
return TypeInfo->isNullValue();
|
|
}
|
|
llvm_unreachable("Unknown personality!");
|
|
}
|
|
|
|
static bool shorter_filter(const Value *LHS, const Value *RHS) {
|
|
return
|
|
cast<ArrayType>(LHS->getType())->getNumElements()
|
|
<
|
|
cast<ArrayType>(RHS->getType())->getNumElements();
|
|
}
|
|
|
|
Instruction *InstCombiner::visitLandingPadInst(LandingPadInst &LI) {
|
|
// The logic here should be correct for any real-world personality function.
|
|
// However if that turns out not to be true, the offending logic can always
|
|
// be conditioned on the personality function, like the catch-all logic is.
|
|
Personality_Type Personality = RecognizePersonality(LI.getPersonalityFn());
|
|
|
|
// Simplify the list of clauses, eg by removing repeated catch clauses
|
|
// (these are often created by inlining).
|
|
bool MakeNewInstruction = false; // If true, recreate using the following:
|
|
SmallVector<Constant *, 16> NewClauses; // - Clauses for the new instruction;
|
|
bool CleanupFlag = LI.isCleanup(); // - The new instruction is a cleanup.
|
|
|
|
SmallPtrSet<Value *, 16> AlreadyCaught; // Typeinfos known caught already.
|
|
for (unsigned i = 0, e = LI.getNumClauses(); i != e; ++i) {
|
|
bool isLastClause = i + 1 == e;
|
|
if (LI.isCatch(i)) {
|
|
// A catch clause.
|
|
Constant *CatchClause = LI.getClause(i);
|
|
Constant *TypeInfo = CatchClause->stripPointerCasts();
|
|
|
|
// If we already saw this clause, there is no point in having a second
|
|
// copy of it.
|
|
if (AlreadyCaught.insert(TypeInfo)) {
|
|
// This catch clause was not already seen.
|
|
NewClauses.push_back(CatchClause);
|
|
} else {
|
|
// Repeated catch clause - drop the redundant copy.
|
|
MakeNewInstruction = true;
|
|
}
|
|
|
|
// If this is a catch-all then there is no point in keeping any following
|
|
// clauses or marking the landingpad as having a cleanup.
|
|
if (isCatchAll(Personality, TypeInfo)) {
|
|
if (!isLastClause)
|
|
MakeNewInstruction = true;
|
|
CleanupFlag = false;
|
|
break;
|
|
}
|
|
} else {
|
|
// A filter clause. If any of the filter elements were already caught
|
|
// then they can be dropped from the filter. It is tempting to try to
|
|
// exploit the filter further by saying that any typeinfo that does not
|
|
// occur in the filter can't be caught later (and thus can be dropped).
|
|
// However this would be wrong, since typeinfos can match without being
|
|
// equal (for example if one represents a C++ class, and the other some
|
|
// class derived from it).
|
|
assert(LI.isFilter(i) && "Unsupported landingpad clause!");
|
|
Constant *FilterClause = LI.getClause(i);
|
|
ArrayType *FilterType = cast<ArrayType>(FilterClause->getType());
|
|
unsigned NumTypeInfos = FilterType->getNumElements();
|
|
|
|
// An empty filter catches everything, so there is no point in keeping any
|
|
// following clauses or marking the landingpad as having a cleanup. By
|
|
// dealing with this case here the following code is made a bit simpler.
|
|
if (!NumTypeInfos) {
|
|
NewClauses.push_back(FilterClause);
|
|
if (!isLastClause)
|
|
MakeNewInstruction = true;
|
|
CleanupFlag = false;
|
|
break;
|
|
}
|
|
|
|
bool MakeNewFilter = false; // If true, make a new filter.
|
|
SmallVector<Constant *, 16> NewFilterElts; // New elements.
|
|
if (isa<ConstantAggregateZero>(FilterClause)) {
|
|
// Not an empty filter - it contains at least one null typeinfo.
|
|
assert(NumTypeInfos > 0 && "Should have handled empty filter already!");
|
|
Constant *TypeInfo =
|
|
Constant::getNullValue(FilterType->getElementType());
|
|
// If this typeinfo is a catch-all then the filter can never match.
|
|
if (isCatchAll(Personality, TypeInfo)) {
|
|
// Throw the filter away.
|
|
MakeNewInstruction = true;
|
|
continue;
|
|
}
|
|
|
|
// There is no point in having multiple copies of this typeinfo, so
|
|
// discard all but the first copy if there is more than one.
|
|
NewFilterElts.push_back(TypeInfo);
|
|
if (NumTypeInfos > 1)
|
|
MakeNewFilter = true;
|
|
} else {
|
|
ConstantArray *Filter = cast<ConstantArray>(FilterClause);
|
|
SmallPtrSet<Value *, 16> SeenInFilter; // For uniquing the elements.
|
|
NewFilterElts.reserve(NumTypeInfos);
|
|
|
|
// Remove any filter elements that were already caught or that already
|
|
// occurred in the filter. While there, see if any of the elements are
|
|
// catch-alls. If so, the filter can be discarded.
|
|
bool SawCatchAll = false;
|
|
for (unsigned j = 0; j != NumTypeInfos; ++j) {
|
|
Constant *Elt = Filter->getOperand(j);
|
|
Constant *TypeInfo = Elt->stripPointerCasts();
|
|
if (isCatchAll(Personality, TypeInfo)) {
|
|
// This element is a catch-all. Bail out, noting this fact.
|
|
SawCatchAll = true;
|
|
break;
|
|
}
|
|
if (AlreadyCaught.count(TypeInfo))
|
|
// Already caught by an earlier clause, so having it in the filter
|
|
// is pointless.
|
|
continue;
|
|
// There is no point in having multiple copies of the same typeinfo in
|
|
// a filter, so only add it if we didn't already.
|
|
if (SeenInFilter.insert(TypeInfo))
|
|
NewFilterElts.push_back(cast<Constant>(Elt));
|
|
}
|
|
// A filter containing a catch-all cannot match anything by definition.
|
|
if (SawCatchAll) {
|
|
// Throw the filter away.
|
|
MakeNewInstruction = true;
|
|
continue;
|
|
}
|
|
|
|
// If we dropped something from the filter, make a new one.
|
|
if (NewFilterElts.size() < NumTypeInfos)
|
|
MakeNewFilter = true;
|
|
}
|
|
if (MakeNewFilter) {
|
|
FilterType = ArrayType::get(FilterType->getElementType(),
|
|
NewFilterElts.size());
|
|
FilterClause = ConstantArray::get(FilterType, NewFilterElts);
|
|
MakeNewInstruction = true;
|
|
}
|
|
|
|
NewClauses.push_back(FilterClause);
|
|
|
|
// If the new filter is empty then it will catch everything so there is
|
|
// no point in keeping any following clauses or marking the landingpad
|
|
// as having a cleanup. The case of the original filter being empty was
|
|
// already handled above.
|
|
if (MakeNewFilter && !NewFilterElts.size()) {
|
|
assert(MakeNewInstruction && "New filter but not a new instruction!");
|
|
CleanupFlag = false;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
// If several filters occur in a row then reorder them so that the shortest
|
|
// filters come first (those with the smallest number of elements). This is
|
|
// advantageous because shorter filters are more likely to match, speeding up
|
|
// unwinding, but mostly because it increases the effectiveness of the other
|
|
// filter optimizations below.
|
|
for (unsigned i = 0, e = NewClauses.size(); i + 1 < e; ) {
|
|
unsigned j;
|
|
// Find the maximal 'j' s.t. the range [i, j) consists entirely of filters.
|
|
for (j = i; j != e; ++j)
|
|
if (!isa<ArrayType>(NewClauses[j]->getType()))
|
|
break;
|
|
|
|
// Check whether the filters are already sorted by length. We need to know
|
|
// if sorting them is actually going to do anything so that we only make a
|
|
// new landingpad instruction if it does.
|
|
for (unsigned k = i; k + 1 < j; ++k)
|
|
if (shorter_filter(NewClauses[k+1], NewClauses[k])) {
|
|
// Not sorted, so sort the filters now. Doing an unstable sort would be
|
|
// correct too but reordering filters pointlessly might confuse users.
|
|
std::stable_sort(NewClauses.begin() + i, NewClauses.begin() + j,
|
|
shorter_filter);
|
|
MakeNewInstruction = true;
|
|
break;
|
|
}
|
|
|
|
// Look for the next batch of filters.
|
|
i = j + 1;
|
|
}
|
|
|
|
// If typeinfos matched if and only if equal, then the elements of a filter L
|
|
// that occurs later than a filter F could be replaced by the intersection of
|
|
// the elements of F and L. In reality two typeinfos can match without being
|
|
// equal (for example if one represents a C++ class, and the other some class
|
|
// derived from it) so it would be wrong to perform this transform in general.
|
|
// However the transform is correct and useful if F is a subset of L. In that
|
|
// case L can be replaced by F, and thus removed altogether since repeating a
|
|
// filter is pointless. So here we look at all pairs of filters F and L where
|
|
// L follows F in the list of clauses, and remove L if every element of F is
|
|
// an element of L. This can occur when inlining C++ functions with exception
|
|
// specifications.
|
|
for (unsigned i = 0; i + 1 < NewClauses.size(); ++i) {
|
|
// Examine each filter in turn.
|
|
Value *Filter = NewClauses[i];
|
|
ArrayType *FTy = dyn_cast<ArrayType>(Filter->getType());
|
|
if (!FTy)
|
|
// Not a filter - skip it.
|
|
continue;
|
|
unsigned FElts = FTy->getNumElements();
|
|
// Examine each filter following this one. Doing this backwards means that
|
|
// we don't have to worry about filters disappearing under us when removed.
|
|
for (unsigned j = NewClauses.size() - 1; j != i; --j) {
|
|
Value *LFilter = NewClauses[j];
|
|
ArrayType *LTy = dyn_cast<ArrayType>(LFilter->getType());
|
|
if (!LTy)
|
|
// Not a filter - skip it.
|
|
continue;
|
|
// If Filter is a subset of LFilter, i.e. every element of Filter is also
|
|
// an element of LFilter, then discard LFilter.
|
|
SmallVectorImpl<Constant *>::iterator J = NewClauses.begin() + j;
|
|
// If Filter is empty then it is a subset of LFilter.
|
|
if (!FElts) {
|
|
// Discard LFilter.
|
|
NewClauses.erase(J);
|
|
MakeNewInstruction = true;
|
|
// Move on to the next filter.
|
|
continue;
|
|
}
|
|
unsigned LElts = LTy->getNumElements();
|
|
// If Filter is longer than LFilter then it cannot be a subset of it.
|
|
if (FElts > LElts)
|
|
// Move on to the next filter.
|
|
continue;
|
|
// At this point we know that LFilter has at least one element.
|
|
if (isa<ConstantAggregateZero>(LFilter)) { // LFilter only contains zeros.
|
|
// Filter is a subset of LFilter iff Filter contains only zeros (as we
|
|
// already know that Filter is not longer than LFilter).
|
|
if (isa<ConstantAggregateZero>(Filter)) {
|
|
assert(FElts <= LElts && "Should have handled this case earlier!");
|
|
// Discard LFilter.
|
|
NewClauses.erase(J);
|
|
MakeNewInstruction = true;
|
|
}
|
|
// Move on to the next filter.
|
|
continue;
|
|
}
|
|
ConstantArray *LArray = cast<ConstantArray>(LFilter);
|
|
if (isa<ConstantAggregateZero>(Filter)) { // Filter only contains zeros.
|
|
// Since Filter is non-empty and contains only zeros, it is a subset of
|
|
// LFilter iff LFilter contains a zero.
|
|
assert(FElts > 0 && "Should have eliminated the empty filter earlier!");
|
|
for (unsigned l = 0; l != LElts; ++l)
|
|
if (LArray->getOperand(l)->isNullValue()) {
|
|
// LFilter contains a zero - discard it.
|
|
NewClauses.erase(J);
|
|
MakeNewInstruction = true;
|
|
break;
|
|
}
|
|
// Move on to the next filter.
|
|
continue;
|
|
}
|
|
// At this point we know that both filters are ConstantArrays. Loop over
|
|
// operands to see whether every element of Filter is also an element of
|
|
// LFilter. Since filters tend to be short this is probably faster than
|
|
// using a method that scales nicely.
|
|
ConstantArray *FArray = cast<ConstantArray>(Filter);
|
|
bool AllFound = true;
|
|
for (unsigned f = 0; f != FElts; ++f) {
|
|
Value *FTypeInfo = FArray->getOperand(f)->stripPointerCasts();
|
|
AllFound = false;
|
|
for (unsigned l = 0; l != LElts; ++l) {
|
|
Value *LTypeInfo = LArray->getOperand(l)->stripPointerCasts();
|
|
if (LTypeInfo == FTypeInfo) {
|
|
AllFound = true;
|
|
break;
|
|
}
|
|
}
|
|
if (!AllFound)
|
|
break;
|
|
}
|
|
if (AllFound) {
|
|
// Discard LFilter.
|
|
NewClauses.erase(J);
|
|
MakeNewInstruction = true;
|
|
}
|
|
// Move on to the next filter.
|
|
}
|
|
}
|
|
|
|
// If we changed any of the clauses, replace the old landingpad instruction
|
|
// with a new one.
|
|
if (MakeNewInstruction) {
|
|
LandingPadInst *NLI = LandingPadInst::Create(LI.getType(),
|
|
LI.getPersonalityFn(),
|
|
NewClauses.size());
|
|
for (unsigned i = 0, e = NewClauses.size(); i != e; ++i)
|
|
NLI->addClause(NewClauses[i]);
|
|
// A landing pad with no clauses must have the cleanup flag set. It is
|
|
// theoretically possible, though highly unlikely, that we eliminated all
|
|
// clauses. If so, force the cleanup flag to true.
|
|
if (NewClauses.empty())
|
|
CleanupFlag = true;
|
|
NLI->setCleanup(CleanupFlag);
|
|
return NLI;
|
|
}
|
|
|
|
// Even if none of the clauses changed, we may nonetheless have understood
|
|
// that the cleanup flag is pointless. Clear it if so.
|
|
if (LI.isCleanup() != CleanupFlag) {
|
|
assert(!CleanupFlag && "Adding a cleanup, not removing one?!");
|
|
LI.setCleanup(CleanupFlag);
|
|
return &LI;
|
|
}
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
|
|
|
|
|
|
/// TryToSinkInstruction - Try to move the specified instruction from its
|
|
/// current block into the beginning of DestBlock, which can only happen if it's
|
|
/// safe to move the instruction past all of the instructions between it and the
|
|
/// end of its block.
|
|
static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
|
|
assert(I->hasOneUse() && "Invariants didn't hold!");
|
|
|
|
// Cannot move control-flow-involving, volatile loads, vaarg, etc.
|
|
if (isa<PHINode>(I) || isa<LandingPadInst>(I) || I->mayHaveSideEffects() ||
|
|
isa<TerminatorInst>(I))
|
|
return false;
|
|
|
|
// Do not sink alloca instructions out of the entry block.
|
|
if (isa<AllocaInst>(I) && I->getParent() ==
|
|
&DestBlock->getParent()->getEntryBlock())
|
|
return false;
|
|
|
|
// We can only sink load instructions if there is nothing between the load and
|
|
// the end of block that could change the value.
|
|
if (I->mayReadFromMemory()) {
|
|
for (BasicBlock::iterator Scan = I, E = I->getParent()->end();
|
|
Scan != E; ++Scan)
|
|
if (Scan->mayWriteToMemory())
|
|
return false;
|
|
}
|
|
|
|
BasicBlock::iterator InsertPos = DestBlock->getFirstInsertionPt();
|
|
I->moveBefore(InsertPos);
|
|
++NumSunkInst;
|
|
return true;
|
|
}
|
|
|
|
|
|
/// AddReachableCodeToWorklist - Walk the function in depth-first order, adding
|
|
/// all reachable code to the worklist.
|
|
///
|
|
/// This has a couple of tricks to make the code faster and more powerful. In
|
|
/// particular, we constant fold and DCE instructions as we go, to avoid adding
|
|
/// them to the worklist (this significantly speeds up instcombine on code where
|
|
/// many instructions are dead or constant). Additionally, if we find a branch
|
|
/// whose condition is a known constant, we only visit the reachable successors.
|
|
///
|
|
static bool AddReachableCodeToWorklist(BasicBlock *BB,
|
|
SmallPtrSetImpl<BasicBlock*> &Visited,
|
|
InstCombiner &IC,
|
|
const DataLayout *DL,
|
|
const TargetLibraryInfo *TLI) {
|
|
bool MadeIRChange = false;
|
|
SmallVector<BasicBlock*, 256> Worklist;
|
|
Worklist.push_back(BB);
|
|
|
|
SmallVector<Instruction*, 128> InstrsForInstCombineWorklist;
|
|
DenseMap<ConstantExpr*, Constant*> FoldedConstants;
|
|
|
|
do {
|
|
BB = Worklist.pop_back_val();
|
|
|
|
// We have now visited this block! If we've already been here, ignore it.
|
|
if (!Visited.insert(BB)) continue;
|
|
|
|
for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) {
|
|
Instruction *Inst = BBI++;
|
|
|
|
// DCE instruction if trivially dead.
|
|
if (isInstructionTriviallyDead(Inst, TLI)) {
|
|
++NumDeadInst;
|
|
DEBUG(dbgs() << "IC: DCE: " << *Inst << '\n');
|
|
Inst->eraseFromParent();
|
|
continue;
|
|
}
|
|
|
|
// ConstantProp instruction if trivially constant.
|
|
if (!Inst->use_empty() && isa<Constant>(Inst->getOperand(0)))
|
|
if (Constant *C = ConstantFoldInstruction(Inst, DL, TLI)) {
|
|
DEBUG(dbgs() << "IC: ConstFold to: " << *C << " from: "
|
|
<< *Inst << '\n');
|
|
Inst->replaceAllUsesWith(C);
|
|
++NumConstProp;
|
|
Inst->eraseFromParent();
|
|
continue;
|
|
}
|
|
|
|
if (DL) {
|
|
// See if we can constant fold its operands.
|
|
for (User::op_iterator i = Inst->op_begin(), e = Inst->op_end();
|
|
i != e; ++i) {
|
|
ConstantExpr *CE = dyn_cast<ConstantExpr>(i);
|
|
if (CE == nullptr) continue;
|
|
|
|
Constant*& FoldRes = FoldedConstants[CE];
|
|
if (!FoldRes)
|
|
FoldRes = ConstantFoldConstantExpression(CE, DL, TLI);
|
|
if (!FoldRes)
|
|
FoldRes = CE;
|
|
|
|
if (FoldRes != CE) {
|
|
*i = FoldRes;
|
|
MadeIRChange = true;
|
|
}
|
|
}
|
|
}
|
|
|
|
InstrsForInstCombineWorklist.push_back(Inst);
|
|
}
|
|
|
|
// Recursively visit successors. If this is a branch or switch on a
|
|
// constant, only visit the reachable successor.
|
|
TerminatorInst *TI = BB->getTerminator();
|
|
if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
|
|
if (BI->isConditional() && isa<ConstantInt>(BI->getCondition())) {
|
|
bool CondVal = cast<ConstantInt>(BI->getCondition())->getZExtValue();
|
|
BasicBlock *ReachableBB = BI->getSuccessor(!CondVal);
|
|
Worklist.push_back(ReachableBB);
|
|
continue;
|
|
}
|
|
} else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
|
|
if (ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition())) {
|
|
// See if this is an explicit destination.
|
|
for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end();
|
|
i != e; ++i)
|
|
if (i.getCaseValue() == Cond) {
|
|
BasicBlock *ReachableBB = i.getCaseSuccessor();
|
|
Worklist.push_back(ReachableBB);
|
|
continue;
|
|
}
|
|
|
|
// Otherwise it is the default destination.
|
|
Worklist.push_back(SI->getDefaultDest());
|
|
continue;
|
|
}
|
|
}
|
|
|
|
for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
|
|
Worklist.push_back(TI->getSuccessor(i));
|
|
} while (!Worklist.empty());
|
|
|
|
// Once we've found all of the instructions to add to instcombine's worklist,
|
|
// add them in reverse order. This way instcombine will visit from the top
|
|
// of the function down. This jives well with the way that it adds all uses
|
|
// of instructions to the worklist after doing a transformation, thus avoiding
|
|
// some N^2 behavior in pathological cases.
|
|
IC.Worklist.AddInitialGroup(&InstrsForInstCombineWorklist[0],
|
|
InstrsForInstCombineWorklist.size());
|
|
|
|
return MadeIRChange;
|
|
}
|
|
|
|
bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
|
|
MadeIRChange = false;
|
|
|
|
DEBUG(dbgs() << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
|
|
<< F.getName() << "\n");
|
|
|
|
{
|
|
// Do a depth-first traversal of the function, populate the worklist with
|
|
// the reachable instructions. Ignore blocks that are not reachable. Keep
|
|
// track of which blocks we visit.
|
|
SmallPtrSet<BasicBlock*, 64> Visited;
|
|
MadeIRChange |= AddReachableCodeToWorklist(F.begin(), Visited, *this, DL,
|
|
TLI);
|
|
|
|
// Do a quick scan over the function. If we find any blocks that are
|
|
// unreachable, remove any instructions inside of them. This prevents
|
|
// the instcombine code from having to deal with some bad special cases.
|
|
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
|
|
if (Visited.count(BB)) continue;
|
|
|
|
// Delete the instructions backwards, as it has a reduced likelihood of
|
|
// having to update as many def-use and use-def chains.
|
|
Instruction *EndInst = BB->getTerminator(); // Last not to be deleted.
|
|
while (EndInst != BB->begin()) {
|
|
// Delete the next to last instruction.
|
|
BasicBlock::iterator I = EndInst;
|
|
Instruction *Inst = --I;
|
|
if (!Inst->use_empty())
|
|
Inst->replaceAllUsesWith(UndefValue::get(Inst->getType()));
|
|
if (isa<LandingPadInst>(Inst)) {
|
|
EndInst = Inst;
|
|
continue;
|
|
}
|
|
if (!isa<DbgInfoIntrinsic>(Inst)) {
|
|
++NumDeadInst;
|
|
MadeIRChange = true;
|
|
}
|
|
Inst->eraseFromParent();
|
|
}
|
|
}
|
|
}
|
|
|
|
while (!Worklist.isEmpty()) {
|
|
Instruction *I = Worklist.RemoveOne();
|
|
if (I == nullptr) continue; // skip null values.
|
|
|
|
// Check to see if we can DCE the instruction.
|
|
if (isInstructionTriviallyDead(I, TLI)) {
|
|
DEBUG(dbgs() << "IC: DCE: " << *I << '\n');
|
|
EraseInstFromFunction(*I);
|
|
++NumDeadInst;
|
|
MadeIRChange = true;
|
|
continue;
|
|
}
|
|
|
|
// Instruction isn't dead, see if we can constant propagate it.
|
|
if (!I->use_empty() && isa<Constant>(I->getOperand(0)))
|
|
if (Constant *C = ConstantFoldInstruction(I, DL, TLI)) {
|
|
DEBUG(dbgs() << "IC: ConstFold to: " << *C << " from: " << *I << '\n');
|
|
|
|
// Add operands to the worklist.
|
|
ReplaceInstUsesWith(*I, C);
|
|
++NumConstProp;
|
|
EraseInstFromFunction(*I);
|
|
MadeIRChange = true;
|
|
continue;
|
|
}
|
|
|
|
// See if we can trivially sink this instruction to a successor basic block.
|
|
if (I->hasOneUse()) {
|
|
BasicBlock *BB = I->getParent();
|
|
Instruction *UserInst = cast<Instruction>(*I->user_begin());
|
|
BasicBlock *UserParent;
|
|
|
|
// Get the block the use occurs in.
|
|
if (PHINode *PN = dyn_cast<PHINode>(UserInst))
|
|
UserParent = PN->getIncomingBlock(*I->use_begin());
|
|
else
|
|
UserParent = UserInst->getParent();
|
|
|
|
if (UserParent != BB) {
|
|
bool UserIsSuccessor = false;
|
|
// See if the user is one of our successors.
|
|
for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
|
|
if (*SI == UserParent) {
|
|
UserIsSuccessor = true;
|
|
break;
|
|
}
|
|
|
|
// If the user is one of our immediate successors, and if that successor
|
|
// only has us as a predecessors (we'd have to split the critical edge
|
|
// otherwise), we can keep going.
|
|
if (UserIsSuccessor && UserParent->getSinglePredecessor()) {
|
|
// Okay, the CFG is simple enough, try to sink this instruction.
|
|
if (TryToSinkInstruction(I, UserParent)) {
|
|
MadeIRChange = true;
|
|
// We'll add uses of the sunk instruction below, but since sinking
|
|
// can expose opportunities for it's *operands* add them to the
|
|
// worklist
|
|
for (Use &U : I->operands())
|
|
if (Instruction *OpI = dyn_cast<Instruction>(U.get()))
|
|
Worklist.Add(OpI);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Now that we have an instruction, try combining it to simplify it.
|
|
Builder->SetInsertPoint(I->getParent(), I);
|
|
Builder->SetCurrentDebugLocation(I->getDebugLoc());
|
|
|
|
#ifndef NDEBUG
|
|
std::string OrigI;
|
|
#endif
|
|
DEBUG(raw_string_ostream SS(OrigI); I->print(SS); OrigI = SS.str(););
|
|
DEBUG(dbgs() << "IC: Visiting: " << OrigI << '\n');
|
|
|
|
if (Instruction *Result = visit(*I)) {
|
|
++NumCombined;
|
|
// Should we replace the old instruction with a new one?
|
|
if (Result != I) {
|
|
DEBUG(dbgs() << "IC: Old = " << *I << '\n'
|
|
<< " New = " << *Result << '\n');
|
|
|
|
if (!I->getDebugLoc().isUnknown())
|
|
Result->setDebugLoc(I->getDebugLoc());
|
|
// Everything uses the new instruction now.
|
|
I->replaceAllUsesWith(Result);
|
|
|
|
// Move the name to the new instruction first.
|
|
Result->takeName(I);
|
|
|
|
// Push the new instruction and any users onto the worklist.
|
|
Worklist.Add(Result);
|
|
Worklist.AddUsersToWorkList(*Result);
|
|
|
|
// Insert the new instruction into the basic block...
|
|
BasicBlock *InstParent = I->getParent();
|
|
BasicBlock::iterator InsertPos = I;
|
|
|
|
// If we replace a PHI with something that isn't a PHI, fix up the
|
|
// insertion point.
|
|
if (!isa<PHINode>(Result) && isa<PHINode>(InsertPos))
|
|
InsertPos = InstParent->getFirstInsertionPt();
|
|
|
|
InstParent->getInstList().insert(InsertPos, Result);
|
|
|
|
EraseInstFromFunction(*I);
|
|
} else {
|
|
#ifndef NDEBUG
|
|
DEBUG(dbgs() << "IC: Mod = " << OrigI << '\n'
|
|
<< " New = " << *I << '\n');
|
|
#endif
|
|
|
|
// If the instruction was modified, it's possible that it is now dead.
|
|
// if so, remove it.
|
|
if (isInstructionTriviallyDead(I, TLI)) {
|
|
EraseInstFromFunction(*I);
|
|
} else {
|
|
Worklist.Add(I);
|
|
Worklist.AddUsersToWorkList(*I);
|
|
}
|
|
}
|
|
MadeIRChange = true;
|
|
}
|
|
}
|
|
|
|
Worklist.Zap();
|
|
return MadeIRChange;
|
|
}
|
|
|
|
namespace {
|
|
class InstCombinerLibCallSimplifier final : public LibCallSimplifier {
|
|
InstCombiner *IC;
|
|
public:
|
|
InstCombinerLibCallSimplifier(const DataLayout *DL,
|
|
const TargetLibraryInfo *TLI,
|
|
InstCombiner *IC)
|
|
: LibCallSimplifier(DL, TLI, EnableUnsafeFPShrink) {
|
|
this->IC = IC;
|
|
}
|
|
|
|
/// replaceAllUsesWith - override so that instruction replacement
|
|
/// can be defined in terms of the instruction combiner framework.
|
|
void replaceAllUsesWith(Instruction *I, Value *With) const override {
|
|
IC->ReplaceInstUsesWith(*I, With);
|
|
}
|
|
};
|
|
}
|
|
|
|
bool InstCombiner::runOnFunction(Function &F) {
|
|
if (skipOptnoneFunction(F))
|
|
return false;
|
|
|
|
AT = &getAnalysis<AssumptionTracker>();
|
|
DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
|
|
DL = DLP ? &DLP->getDataLayout() : nullptr;
|
|
TLI = &getAnalysis<TargetLibraryInfo>();
|
|
|
|
DominatorTreeWrapperPass *DTWP =
|
|
getAnalysisIfAvailable<DominatorTreeWrapperPass>();
|
|
DT = DTWP ? &DTWP->getDomTree() : nullptr;
|
|
|
|
// Minimizing size?
|
|
MinimizeSize = F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
|
|
Attribute::MinSize);
|
|
|
|
/// Builder - This is an IRBuilder that automatically inserts new
|
|
/// instructions into the worklist when they are created.
|
|
IRBuilder<true, TargetFolder, InstCombineIRInserter>
|
|
TheBuilder(F.getContext(), TargetFolder(DL),
|
|
InstCombineIRInserter(Worklist, AT));
|
|
Builder = &TheBuilder;
|
|
|
|
InstCombinerLibCallSimplifier TheSimplifier(DL, TLI, this);
|
|
Simplifier = &TheSimplifier;
|
|
|
|
bool EverMadeChange = false;
|
|
|
|
// Lower dbg.declare intrinsics otherwise their value may be clobbered
|
|
// by instcombiner.
|
|
EverMadeChange = LowerDbgDeclare(F);
|
|
|
|
// Iterate while there is work to do.
|
|
unsigned Iteration = 0;
|
|
while (DoOneIteration(F, Iteration++))
|
|
EverMadeChange = true;
|
|
|
|
Builder = nullptr;
|
|
return EverMadeChange;
|
|
}
|
|
|
|
FunctionPass *llvm::createInstructionCombiningPass() {
|
|
return new InstCombiner();
|
|
}
|