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Optimize away fabs() calls when input is squared (known positive).

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Eliminate library calls and intrinsic calls to fabs when the input 
is a squared value.

Note that no unsafe-math / fast-math assumptions are needed for
this optimization.

Differential Revision: http://reviews.llvm.org/D5777



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219717 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Sanjay Patel
2014-10-14 20:43:11 +00:00
parent 40017084f7
commit 3f349b2ba8
3 changed files with 131 additions and 1 deletions
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31
lib/Transforms/Utils/SimplifyLibCalls.cpp
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@@ -1230,6 +1230,30 @@ Value *LibCallSimplifier::optimizeExp2(CallInst *CI, IRBuilder<> &B) {
return Ret;
}
Value *LibCallSimplifier::optimizeFabs(CallInst *CI, IRBuilder<> &B) {
Function *Callee = CI->getCalledFunction();
Value *Ret = nullptr;
if (Callee->getName() == "fabs" && TLI->has(LibFunc::fabsf)) {
Ret = optimizeUnaryDoubleFP(CI, B, false);
}
FunctionType *FT = Callee->getFunctionType();
// Make sure this has 1 argument of FP type which matches the result type.
if (FT->getNumParams() != 1 || FT->getReturnType() != FT->getParamType(0) ||
!FT->getParamType(0)->isFloatingPointTy())
return Ret;
Value *Op = CI->getArgOperand(0);
if (Instruction *I = dyn_cast<Instruction>(Op)) {
// Fold fabs(x * x) -> x * x; any squared FP value must already be positive.
if (I->getOpcode() == Instruction::FMul)
if (I->getOperand(0) == I->getOperand(1))
return Op;
}
return Ret;
}
static bool isTrigLibCall(CallInst *CI);
static void insertSinCosCall(IRBuilder<> &B, Function *OrigCallee, Value *Arg,
bool UseFloat, Value *&Sin, Value *&Cos,
@@ -1893,6 +1917,8 @@ Value *LibCallSimplifier::optimizeCall(CallInst *CI) {
return optimizePow(CI, Builder);
case Intrinsic::exp2:
return optimizeExp2(CI, Builder);
case Intrinsic::fabs:
return optimizeFabs(CI, Builder);
default:
return nullptr;
}
@@ -1965,6 +1991,10 @@ Value *LibCallSimplifier::optimizeCall(CallInst *CI) {
case LibFunc::exp2:
case LibFunc::exp2f:
return optimizeExp2(CI, Builder);
case LibFunc::fabsf:
case LibFunc::fabs:
case LibFunc::fabsl:
return optimizeFabs(CI, Builder);
case LibFunc::ffs:
case LibFunc::ffsl:
case LibFunc::ffsll:
@@ -1999,7 +2029,6 @@ Value *LibCallSimplifier::optimizeCall(CallInst *CI) {
case LibFunc::fputc:
return optimizeErrorReporting(CI, Builder, 1);
case LibFunc::ceil:
case LibFunc::fabs:
case LibFunc::floor:
case LibFunc::rint:
case LibFunc::round: