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Added a slew of SimplifyInstruction floating-point optimizations, many of which take advantage of fast-math flags. Test cases included.

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fsub X, +0 ==> X
  fsub X, -0 ==> X, when we know X is not -0
  fsub +/-0.0, (fsub -0.0, X) ==> X
  fsub nsz +/-0.0, (fsub +/-0.0, X) ==> X
  fsub nnan ninf X, X ==> 0.0
  fadd nsz X, 0 ==> X
  fadd [nnan ninf] X, (fsub [nnan ninf] 0, X) ==> 0
    where nnan and ninf have to occur at least once somewhere in this expression
  fmul X, 1.0 ==> X



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169940 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Michael Ilseman
2012-12-12 00:27:46 +00:00
parent 1d4b150704
commit 09ee250e72
4 changed files with 230 additions and 10 deletions
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119
lib/Analysis/InstructionSimplify.cpp
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@ -853,6 +853,85 @@ Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
RecursionLimit);
}
/// Given operands for an FAdd, see if we can fold the result. If not, this
/// returns null.
static Value *SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const Query &Q, unsigned MaxRecurse) {
if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
Constant *Ops[] = { CLHS, CRHS };
return ConstantFoldInstOperands(Instruction::FAdd, CLHS->getType(),
Ops, Q.TD, Q.TLI);
}
// Canonicalize the constant to the RHS.
std::swap(Op0, Op1);
}
// fadd X, -0 ==> X
if (match(Op1, m_NegZero()))
return Op0;
// fadd X, 0 ==> X, when we know X is not -0
if (match(Op1, m_Zero()) &&
(FMF.noSignedZeros() || CannotBeNegativeZero(Op0)))
return Op0;
// fadd [nnan ninf] X, (fsub [nnan ninf] 0, X) ==> 0
// where nnan and ninf have to occur at least once somewhere in this
// expression
Value *SubOp = 0;
if (match(Op1, m_FSub(m_AnyZero(), m_Specific(Op0))))
SubOp = Op1;
else if (match(Op0, m_FSub(m_AnyZero(), m_Specific(Op1))))
SubOp = Op0;
if (SubOp) {
Instruction *FSub = cast<Instruction>(SubOp);
if ((FMF.noNaNs() || FSub->hasNoNaNs()) &&
(FMF.noInfs() || FSub->hasNoInfs()))
return Constant::getNullValue(Op0->getType());
}
return 0;
}
/// Given operands for an FSub, see if we can fold the result. If not, this
/// returns null.
static Value *SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const Query &Q, unsigned MaxRecurse) {
if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
Constant *Ops[] = { CLHS, CRHS };
return ConstantFoldInstOperands(Instruction::FSub, CLHS->getType(),
Ops, Q.TD, Q.TLI);
}
}
// fsub X, 0 ==> X
if (match(Op1, m_Zero()))
return Op0;
// fsub X, -0 ==> X, when we know X is not -0
if (match(Op1, m_NegZero()) &&
(FMF.noSignedZeros() || CannotBeNegativeZero(Op0)))
return Op0;
// fsub 0, (fsub -0.0, X) ==> X
Value *X;
if (match(Op0, m_AnyZero())) {
if (match(Op1, m_FSub(m_NegZero(), m_Value(X))))
return X;
if (FMF.noSignedZeros() && match(Op1, m_FSub(m_AnyZero(), m_Value(X))))
return X;
}
// fsub nnan ninf x, x ==> 0.0
if (FMF.noNaNs() && FMF.noInfs() && Op0 == Op1)
return Constant::getNullValue(Op0->getType());
return 0;
}
/// Given the operands for an FMul, see if we can fold the result
static Value *SimplifyFMulInst(Value *Op0, Value *Op1,
FastMathFlags FMF,
@ -864,18 +943,18 @@ static Value *SimplifyFMulInst(Value *Op0, Value *Op1,
return ConstantFoldInstOperands(Instruction::FMul, CLHS->getType(),
Ops, Q.TD, Q.TLI);
}
// Canonicalize the constant to the RHS.
std::swap(Op0, Op1);
}
// Check for some fast-math optimizations
if (FMF.noNaNs()) {
if (FMF.noSignedZeros()) {
// fmul N S 0, x ==> 0
if (match(Op0, m_Zero()))
return Op0;
if (match(Op1, m_Zero()))
return Op1;
}
}
// fmul X, 1.0 ==> X
if (match(Op1, m_FPOne()))
return Op0;
// fmul nnan nsz X, 0 ==> 0
if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op1, m_AnyZero()))
return Op1;
return 0;
}
@ -945,6 +1024,18 @@ static Value *SimplifyMulInst(Value *Op0, Value *Op1, const Query &Q,
return 0;
}
Value *llvm::SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const DataLayout *TD, const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifyFAddInst(Op0, Op1, FMF, Query (TD, TLI, DT), RecursionLimit);
}
Value *llvm::SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const DataLayout *TD, const TargetLibraryInfo *TLI,
const DominatorTree *DT) {
return ::SimplifyFSubInst(Op0, Op1, FMF, Query (TD, TLI, DT), RecursionLimit);
}
Value *llvm::SimplifyFMulInst(Value *Op0, Value *Op1,
FastMathFlags FMF,
const DataLayout *TD,
@ -2789,12 +2880,20 @@ Value *llvm::SimplifyInstruction(Instruction *I, const DataLayout *TD,
default:
Result = ConstantFoldInstruction(I, TD, TLI);
break;
case Instruction::FAdd:
Result = SimplifyFAddInst(I->getOperand(0), I->getOperand(1),
I->getFastMathFlags(), TD, TLI, DT);
break;
case Instruction::Add:
Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
cast<BinaryOperator>(I)->hasNoSignedWrap(),
cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
TD, TLI, DT);
break;
case Instruction::FSub:
Result = SimplifyFSubInst(I->getOperand(0), I->getOperand(1),
I->getFastMathFlags(), TD, TLI, DT);
break;
case Instruction::Sub:
Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
cast<BinaryOperator>(I)->hasNoSignedWrap(),