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Pull a few more simplifications out of instcombine (there are still

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plenty left though!), in particular for multiplication.

llvm-svn: 122330
This commit is contained in:
Duncan Sands 2010-12-21 14:00:22 +00:00
parent 3ceeaf218e
commit 6b0ed93a81
3 changed files with 94 additions and 11 deletions
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5
include/llvm/Analysis/InstructionSimplify.h
View File

@ -39,6 +39,11 @@ namespace llvm {
Value *SimplifyAndInst(Value *LHS, Value *RHS, const TargetData *TD = 0,
const DominatorTree *DT = 0);
/// SimplifyMulInst - Given operands for a Mul, see if we can
/// fold the result. If not, this returns null.
Value *SimplifyMulInst(Value *LHS, Value *RHS, const TargetData *TD = 0,
const DominatorTree *DT = 0);
/// SimplifyOrInst - Given operands for an Or, see if we can
/// fold the result. If not, this returns null.
Value *SimplifyOrInst(Value *LHS, Value *RHS, const TargetData *TD = 0,

91
lib/Analysis/InstructionSimplify.cpp
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@ -28,10 +28,16 @@ using namespace llvm::PatternMatch;
#define RecursionLimit 3
static Value *SimplifyAndInst(Value *, Value *, const TargetData *,
const DominatorTree *, unsigned);
static Value *SimplifyBinOp(unsigned, Value *, Value *, const TargetData *,
const DominatorTree *, unsigned);
static Value *SimplifyCmpInst(unsigned, Value *, Value *, const TargetData *,
const DominatorTree *, unsigned);
static Value *SimplifyOrInst(Value *, Value *, const TargetData *,
const DominatorTree *, unsigned);
static Value *SimplifyXorInst(Value *, Value *, const TargetData *,
const DominatorTree *, unsigned);
/// ValueDominatesPHI - Does the given value dominate the specified phi node?
static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) {
@ -125,8 +131,8 @@ static Value *FactorizeBinOp(unsigned Opcode, Value *LHS, Value *RHS,
return 0;
// The expression has the form "(A op' B) op (C op' D)".
Value *A = Op0->getOperand(0); Value *B = Op0->getOperand(1);
Value *C = Op1->getOperand(0); Value *D = Op1->getOperand(1);
Value *A = Op0->getOperand(0), *B = Op0->getOperand(1);
Value *C = Op1->getOperand(0), *D = Op1->getOperand(1);
// Use left distributivity, i.e. "X op' (Y op Z) = (X op' Y) op (X op' Z)".
// Does the instruction have the form "(A op' B) op (A op' D)" or, in the
@ -484,6 +490,10 @@ static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
match(Op1, m_Not(m_Specific(Op0))))
return Constant::getAllOnesValue(Op0->getType());
/// i1 add -> xor.
if (!MaxRecurse && Op0->getType()->isIntegerTy(1))
return SimplifyXorInst(Op0, Op1, TD, DT, MaxRecurse-1);
// Try some generic simplifications for associative operations.
if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, TD, DT,
MaxRecurse))
@ -543,6 +553,10 @@ static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
match(Op0, m_Add(m_Specific(Op1), m_Value(X))))
return X;
/// i1 sub -> xor.
if (!MaxRecurse && Op0->getType()->isIntegerTy(1))
return SimplifyXorInst(Op0, Op1, TD, DT, MaxRecurse-1);
// Mul distributes over Sub. Try some generic simplifications based on this.
if (Value *V = FactorizeBinOp(Instruction::Sub, Op0, Op1, Instruction::Mul,
TD, DT, MaxRecurse))
@ -565,6 +579,69 @@ Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, TD, DT, RecursionLimit);
}
/// SimplifyMulInst - Given operands for a Mul, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
const DominatorTree *DT, unsigned MaxRecurse) {
if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
Constant *Ops[] = { CLHS, CRHS };
return ConstantFoldInstOperands(Instruction::Mul, CLHS->getType(),
Ops, 2, TD);
}
// Canonicalize the constant to the RHS.
std::swap(Op0, Op1);
}
// X * undef -> 0
if (isa<UndefValue>(Op1))
return Constant::getNullValue(Op0->getType());
// X * 0 -> 0
if (match(Op1, m_Zero()))
return Op1;
// X * 1 -> X
if (match(Op1, m_One()))
return Op0;
/// i1 mul -> and.
if (!MaxRecurse && Op0->getType()->isIntegerTy(1))
return SimplifyAndInst(Op0, Op1, TD, DT, MaxRecurse-1);
// Try some generic simplifications for associative operations.
if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, TD, DT,
MaxRecurse))
return V;
// Mul distributes over Add. Try some generic simplifications based on this.
if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
TD, DT, MaxRecurse))
return V;
// If the operation is with the result of a select instruction, check whether
// operating on either branch of the select always yields the same value.
if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, TD, DT,
MaxRecurse))
return V;
// If the operation is with the result of a phi instruction, check whether
// operating on all incoming values of the phi always yields the same value.
if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, TD, DT,
MaxRecurse))
return V;
return 0;
}
Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
const DominatorTree *DT) {
return ::SimplifyMulInst(Op0, Op1, TD, DT, RecursionLimit);
}
/// SimplifyAndInst - Given operands for an And, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
@ -1087,15 +1164,16 @@ static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
const TargetData *TD, const DominatorTree *DT,
unsigned MaxRecurse) {
switch (Opcode) {
case Instruction::And: return SimplifyAndInst(LHS, RHS, TD, DT, MaxRecurse);
case Instruction::Or: return SimplifyOrInst(LHS, RHS, TD, DT, MaxRecurse);
case Instruction::Xor: return SimplifyXorInst(LHS, RHS, TD, DT, MaxRecurse);
case Instruction::Add: return SimplifyAddInst(LHS, RHS, /* isNSW */ false,
/* isNUW */ false, TD, DT,
MaxRecurse);
case Instruction::Sub: return SimplifySubInst(LHS, RHS, /* isNSW */ false,
/* isNUW */ false, TD, DT,
MaxRecurse);
case Instruction::Mul: return SimplifyMulInst(LHS, RHS, TD, DT, MaxRecurse);
case Instruction::And: return SimplifyAndInst(LHS, RHS, TD, DT, MaxRecurse);
case Instruction::Or: return SimplifyOrInst(LHS, RHS, TD, DT, MaxRecurse);
case Instruction::Xor: return SimplifyXorInst(LHS, RHS, TD, DT, MaxRecurse);
default:
if (Constant *CLHS = dyn_cast<Constant>(LHS))
if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
@ -1168,6 +1246,9 @@ Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD,
cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
TD, DT);
break;
case Instruction::Mul:
Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), TD, DT);
break;
case Instruction::And:
Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, DT);
break;

9
lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
View File

@ -14,6 +14,7 @@
#include "InstCombine.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Support/PatternMatch.h"
using namespace llvm;
using namespace PatternMatch;
@ -50,8 +51,8 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) {
bool Changed = SimplifyAssociativeOrCommutative(I);
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (isa<UndefValue>(Op1)) // undef * X -> 0
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
if (Value *V = SimplifyMulInst(Op0, Op1, TD))
return ReplaceInstUsesWith(I, V);
// Simplify mul instructions with a constant RHS.
if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
@ -64,10 +65,6 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) {
return BinaryOperator::CreateMul(SI->getOperand(0),
ConstantExpr::getShl(CI, ShOp));
if (CI->isZero())
return ReplaceInstUsesWith(I, Op1C); // X * 0 == 0
if (CI->equalsInt(1)) // X * 1 == X
return ReplaceInstUsesWith(I, Op0);
if (CI->isAllOnesValue()) // X * -1 == 0 - X
return BinaryOperator::CreateNeg(Op0, I.getName());