SimplifyLibCalls: Remove incorrect optimization of fabs

fabs(x * x) is not generally safe to assume x is positive if x is a NaN.
This is also less general than it could be, so this will be replaced
with a transformation on the intrinsic.

llvm-svn: 291359

1 files changed, 2 insertions, 10 deletions

diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
index c8f030f7eb8..11d54bcf4f8 100644
--- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -1189,19 +1189,11 @@ Value *LibCallSimplifier::optimizeExp2(CallInst *CI, IRBuilder<> &B) {
 
 Value *LibCallSimplifier::optimizeFabs(CallInst *CI, IRBuilder<> &B) {
   Function *Callee = CI->getCalledFunction();
-  Value *Ret = nullptr;
   StringRef Name = Callee->getName();
   if (Name == "fabs" && hasFloatVersion(Name))
-    Ret = optimizeUnaryDoubleFP(CI, B, false);
+    return optimizeUnaryDoubleFP(CI, B, false);
 
-  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;
+  return nullptr;
 }
 
 Value *LibCallSimplifier::optimizeFMinFMax(CallInst *CI, IRBuilder<> &B) {