[SimplifyLibCalls] powf(x, sitofp(n)) -> powi(x, n)
Summary:
Partially solves https://bugs.llvm.org/show_bug.cgi?id=42190
Reviewers: spatel, nikic, efriedma
Reviewed By: efriedma
Subscribers: efriedma, nikic, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63038
llvm-svn: 364940
diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
index b5f8b39..79b1b86 100644
--- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -1322,12 +1322,12 @@
APFloat BaseR = APFloat(1.0);
BaseR.convert(BaseF->getSemantics(), APFloat::rmTowardZero, &Ignored);
BaseR = BaseR / *BaseF;
- bool IsInteger = BaseF->isInteger(),
- IsReciprocal = BaseR.isInteger();
+ bool IsInteger = BaseF->isInteger(), IsReciprocal = BaseR.isInteger();
const APFloat *NF = IsReciprocal ? &BaseR : BaseF;
APSInt NI(64, false);
if ((IsInteger || IsReciprocal) &&
- !NF->convertToInteger(NI, APFloat::rmTowardZero, &Ignored) &&
+ NF->convertToInteger(NI, APFloat::rmTowardZero, &Ignored) ==
+ APFloat::opOK &&
NI > 1 && NI.isPowerOf2()) {
double N = NI.logBase2() * (IsReciprocal ? -1.0 : 1.0);
Value *FMul = B.CreateFMul(Expo, ConstantFP::get(Ty, N), "mul");
@@ -1410,12 +1410,22 @@
return Sqrt;
}
+static Value *createPowWithIntegerExponent(Value *Base, Value *Expo, Module *M,
+ IRBuilder<> &B) {
+ Value *Args[] = {Base, Expo};
+ Function *F = Intrinsic::getDeclaration(M, Intrinsic::powi, Base->getType());
+ return B.CreateCall(F, Args);
+}
+
Value *LibCallSimplifier::optimizePow(CallInst *Pow, IRBuilder<> &B) {
- Value *Base = Pow->getArgOperand(0), *Expo = Pow->getArgOperand(1);
+ Value *Base = Pow->getArgOperand(0);
+ Value *Expo = Pow->getArgOperand(1);
Function *Callee = Pow->getCalledFunction();
StringRef Name = Callee->getName();
Type *Ty = Pow->getType();
+ Module *M = Pow->getModule();
Value *Shrunk = nullptr;
+ bool AllowApprox = Pow->hasApproxFunc();
bool Ignored;
// Bail out if simplifying libcalls to pow() is disabled.
@@ -1428,8 +1438,8 @@
// Shrink pow() to powf() if the arguments are single precision,
// unless the result is expected to be double precision.
- if (UnsafeFPShrink &&
- Name == TLI->getName(LibFunc_pow) && hasFloatVersion(Name))
+ if (UnsafeFPShrink && Name == TLI->getName(LibFunc_pow) &&
+ hasFloatVersion(Name))
Shrunk = optimizeBinaryDoubleFP(Pow, B, true);
// Evaluate special cases related to the base.
@@ -1438,6 +1448,21 @@
if (match(Base, m_FPOne()))
return Base;
+ // powf(x, sitofp(e)) -> powi(x, e)
+ // powf(x, uitofp(e)) -> powi(x, e)
+ if (AllowApprox && (isa<SIToFPInst>(Expo) || isa<UIToFPInst>(Expo))) {
+ Value *IntExpo = cast<Instruction>(Expo)->getOperand(0);
+ Value *NewExpo = nullptr;
+ unsigned BitWidth = IntExpo->getType()->getPrimitiveSizeInBits();
+ if (isa<SIToFPInst>(Expo) && BitWidth == 32)
+ NewExpo = IntExpo;
+ else if (BitWidth < 32)
+ NewExpo = isa<SIToFPInst>(Expo) ? B.CreateSExt(IntExpo, B.getInt32Ty())
+ : B.CreateZExt(IntExpo, B.getInt32Ty());
+ if (NewExpo)
+ return createPowWithIntegerExponent(Base, NewExpo, M, B);
+ }
+
if (Value *Exp = replacePowWithExp(Pow, B))
return Exp;
@@ -1449,7 +1474,7 @@
// pow(x, 0.0) -> 1.0
if (match(Expo, m_SpecificFP(0.0)))
- return ConstantFP::get(Ty, 1.0);
+ return ConstantFP::get(Ty, 1.0);
// pow(x, 1.0) -> x
if (match(Expo, m_FPOne()))
@@ -1462,9 +1487,12 @@
if (Value *Sqrt = replacePowWithSqrt(Pow, B))
return Sqrt;
+ if (!AllowApprox)
+ return Shrunk;
+
// pow(x, n) -> x * x * x * ...
const APFloat *ExpoF;
- if (Pow->isFast() && match(Expo, m_APFloat(ExpoF))) {
+ if (match(Expo, m_APFloat(ExpoF))) {
// We limit to a max of 7 multiplications, thus the maximum exponent is 32.
// If the exponent is an integer+0.5 we generate a call to sqrt and an
// additional fmul.
@@ -1488,9 +1516,8 @@
if (!Expo2.isInteger())
return nullptr;
- Sqrt =
- getSqrtCall(Base, Pow->getCalledFunction()->getAttributes(),
- Pow->doesNotAccessMemory(), Pow->getModule(), B, TLI);
+ Sqrt = getSqrtCall(Base, Pow->getCalledFunction()->getAttributes(),
+ Pow->doesNotAccessMemory(), M, B, TLI);
}
// We will memoize intermediate products of the Addition Chain.
@@ -1513,6 +1540,14 @@
return FMul;
}
+
+ APSInt IntExpo(32, /*isUnsigned=*/false);
+ // powf(x, C) -> powi(x, C) iff C is a constant signed integer value
+ if (ExpoF->convertToInteger(IntExpo, APFloat::rmTowardZero, &Ignored) ==
+ APFloat::opOK) {
+ return createPowWithIntegerExponent(
+ Base, ConstantInt::get(B.getInt32Ty(), IntExpo), M, B);
+ }
}
return Shrunk;
@@ -3101,4 +3136,4 @@
FortifiedLibCallSimplifier::FortifiedLibCallSimplifier(
const TargetLibraryInfo *TLI, bool OnlyLowerUnknownSize)
- : TLI(TLI), OnlyLowerUnknownSize(OnlyLowerUnknownSize) {}
+ : TLI(TLI), OnlyLowerUnknownSize(OnlyLowerUnknownSize) {}
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