[InstCombine] Simplify pow(2.0, itofp(y)) to ldexp(1.0, y)
Simplify `pow(2.0, itofp(y))` to `ldexp(1.0, y)`.
Differential revision: https://reviews.llvm.org/D65979
llvm-svn: 369120
diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
index 2bee94c..7ff1f4a 100644
--- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -1284,9 +1284,25 @@
return InnerChain[Exp];
}
+// Return a properly extended 32-bit integer if the operation is an itofp.
+static Value *getIntToFPVal(Value *I2F, IRBuilder<> &B) {
+ if (isa<SIToFPInst>(I2F) || isa<UIToFPInst>(I2F)) {
+ Value *Op = cast<Instruction>(I2F)->getOperand(0);
+ // Make sure that the exponent fits inside an int32_t,
+ // thus avoiding any range issues that FP has not.
+ unsigned BitWidth = Op->getType()->getPrimitiveSizeInBits();
+ if (BitWidth < 32 ||
+ (BitWidth == 32 && isa<SIToFPInst>(I2F)))
+ return isa<SIToFPInst>(I2F) ? B.CreateSExt(Op, B.getInt32Ty())
+ : B.CreateZExt(Op, B.getInt32Ty());
+ }
+
+ return nullptr;
+}
+
/// Use exp{,2}(x * y) for pow(exp{,2}(x), y);
-/// exp2(n * x) for pow(2.0 ** n, x); exp10(x) for pow(10.0, x);
-/// exp2(log2(n) * x) for pow(n, x).
+/// ldexp(1.0, x) for pow(2.0, itofp(x)); exp2(n * x) for pow(2.0 ** n, x);
+/// exp10(x) for pow(10.0, x); exp2(log2(n) * x) for pow(n, x).
Value *LibCallSimplifier::replacePowWithExp(CallInst *Pow, IRBuilder<> &B) {
Value *Base = Pow->getArgOperand(0), *Expo = Pow->getArgOperand(1);
AttributeList Attrs = Pow->getCalledFunction()->getAttributes();
@@ -1368,6 +1384,16 @@
if (!match(Pow->getArgOperand(0), m_APFloat(BaseF)))
return nullptr;
+ // pow(2.0, itofp(x)) -> ldexp(1.0, x)
+ if (match(Base, m_SpecificFP(2.0)) &&
+ (isa<SIToFPInst>(Expo) || isa<UIToFPInst>(Expo)) &&
+ hasFloatFn(TLI, Ty, LibFunc_ldexp, LibFunc_ldexpf, LibFunc_ldexpl)) {
+ if (Value *ExpoI = getIntToFPVal(Expo, B))
+ return emitBinaryFloatFnCall(ConstantFP::get(Ty, 1.0), ExpoI, TLI,
+ LibFunc_ldexp, LibFunc_ldexpf, LibFunc_ldexpl,
+ B, Attrs);
+ }
+
// pow(2.0 ** n, x) -> exp2(n * x)
if (hasFloatFn(TLI, Ty, LibFunc_exp2, LibFunc_exp2f, LibFunc_exp2l)) {
APFloat BaseR = APFloat(1.0);
@@ -1605,16 +1631,8 @@
// powf(x, itofp(y)) -> powi(x, y)
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 *ExpoI = getIntToFPVal(Expo, B))
+ return createPowWithIntegerExponent(Base, ExpoI, M, B);
}
return Shrunk;
@@ -1635,20 +1653,12 @@
// Turn exp2(uitofp(x)) -> ldexp(1.0, zext(x)) if sizeof(x) < 32
if ((isa<SIToFPInst>(Op) || isa<UIToFPInst>(Op)) &&
hasFloatFn(TLI, Ty, LibFunc_ldexp, LibFunc_ldexpf, LibFunc_ldexpl)) {
- Instruction *OpC = cast<Instruction>(Op);
- Value *Exp = OpC->getOperand(0);
- unsigned BitWidth = Exp->getType()->getPrimitiveSizeInBits();
-
- if (BitWidth < 32 ||
- (BitWidth == 32 && isa<SIToFPInst>(Op))) {
- Exp = isa<SIToFPInst>(Op) ? B.CreateSExt(Exp, B.getInt32Ty())
- : B.CreateZExt(Exp, B.getInt32Ty());
-
+ if (Value *Exp = getIntToFPVal(Op, B))
return emitBinaryFloatFnCall(ConstantFP::get(Ty, 1.0), Exp, TLI,
LibFunc_ldexp, LibFunc_ldexpf, LibFunc_ldexpl,
B, CI->getCalledFunction()->getAttributes());
- }
}
+
return Ret;
}