[SimplifyLibCalls] don't drop fast-math-flags on trig reflection folds (retry r339608)

Even though this code is below a function called optimizeFloatingPointLibCall(),
we apparently can't guarantee that we're dealing with FPMathOperators, so bail
out immediately if that's not true.

llvm-svn: 339618

diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
index eda3f05..a2e5f8d 100644 (file)
--- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -1124,7 +1124,12 @@ Value *LibCallSimplifier::optimizeCAbs(CallInst *CI, IRBuilder<> &B) {
 
 static Value *optimizeTrigReflections(CallInst *Call, LibFunc Func,
                                       IRBuilder<> &B) {
-  // FIXME: This drops FMF.
+  if (!isa<FPMathOperator>(Call))
+    return nullptr;
+  
+  IRBuilder<>::FastMathFlagGuard Guard(B);
+  B.setFastMathFlags(Call->getFastMathFlags());
+  
   // TODO: Add tan() and other calls.
   // TODO: Can this be shared to also handle LLVM intrinsics?
   Value *X;

diff --git a/llvm/test/Transforms/InstCombine/cos-1.ll b/llvm/test/Transforms/InstCombine/cos-1.ll
index daa193b..8c9a5d8 100644 (file)
--- a/llvm/test/Transforms/InstCombine/cos-1.ll
+++ b/llvm/test/Transforms/InstCombine/cos-1.ll
@@ -40,7 +40,7 @@ define float @cosf_negated_arg(float %x) {
 
 define float @cosf_negated_arg_FMF(float %x) {
 ; ANY-LABEL: @cosf_negated_arg_FMF(
-; ANY-NEXT:    [[COS:%.*]] = call float @cosf(float [[X:%.*]])
+; ANY-NEXT:    [[COS:%.*]] = call reassoc nnan float @cosf(float [[X:%.*]])
 ; ANY-NEXT:    ret float [[COS]]
 ;
   %neg = fsub float -0.0, %x
@@ -72,6 +72,17 @@ define float @sinf_negated_arg(float %x) {
   ret float %r
 }
 
+define float @sinf_negated_arg_FMF(float %x) {
+; ANY-LABEL: @sinf_negated_arg_FMF(
+; ANY-NEXT:    [[SIN:%.*]] = call nnan afn float @sinf(float [[X:%.*]])
+; ANY-NEXT:    [[TMP1:%.*]] = fsub nnan afn float -0.000000e+00, [[SIN]]
+; ANY-NEXT:    ret float [[TMP1]]
+;
+  %neg = fsub ninf float -0.0, %x
+  %r = call afn nnan float @sinf(float %neg)
+  ret float %r
+}
+
 declare void @use(double)
 
 define double @sin_negated_arg_extra_use(double %x) {