2 files changed, 46 insertions, 24 deletions

diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
index ef700499ef2..24345465cf7 100644
--- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -1354,11 +1354,13 @@ Value *LibCallSimplifier::optimizeLog(CallInst *CI, IRBuilder<> &B) {
       !FT->getParamType(0)->isFloatingPointTy())
     return Ret;
 
-  if (!canUseUnsafeFPMath(CI->getParent()->getParent()))
+  if (!CI->hasUnsafeAlgebra())
     return Ret;
   Value *Op1 = CI->getArgOperand(0);
   auto *OpC = dyn_cast<CallInst>(Op1);
-  if (!OpC)
+
+  // The earlier call must also be unsafe in order to do these transforms.
+  if (!OpC || !OpC->hasUnsafeAlgebra())
     return Ret;
 
   // log(pow(x,y)) -> y*log(x)
diff --git a/llvm/test/Transforms/InstCombine/log-pow.ll b/llvm/test/Transforms/InstCombine/log-pow.ll
index c5ca1688d34..a0c10d0a0b8 100644
--- a/llvm/test/Transforms/InstCombine/log-pow.ll
+++ b/llvm/test/Transforms/InstCombine/log-pow.ll
@@ -1,41 +1,61 @@
 ; RUN: opt < %s -instcombine -S | FileCheck %s
 
-define double @mylog(double %x, double %y) #0 {
-entry:
+define double @log_pow(double %x, double %y) {
+  %pow = call fast double @llvm.pow.f64(double %x, double %y)
+  %call = call fast double @log(double %pow)
+  ret double %call
+}
+
+; CHECK-LABEL: define double @log_pow(
+; CHECK-NEXT:  %log = call fast double @log(double %x)
+; CHECK-NEXT:  %mul = fmul fast double %log, %y
+; CHECK-NEXT:  ret double %mul
+
+define double @log_pow_not_fast(double %x, double %y) {
   %pow = call double @llvm.pow.f64(double %x, double %y)
-  %call = call double @log(double %pow) #0
+  %call = call fast double @log(double %pow)
   ret double %call
 }
 
-; CHECK-LABEL: define double @mylog(
-; CHECK:   %log = call fast double @log(double %x) #0
-; CHECK:   %mul = fmul fast double %log, %y
-; CHECK:   ret double %mul
-; CHECK: }
+; CHECK-LABEL: define double @log_pow_not_fast(
+; CHECK-NEXT:  %pow = call double @llvm.pow.f64(double %x, double %y)
+; CHECK-NEXT:  %call = call fast double @log(double %pow)
+; CHECK-NEXT:  ret double %call
 
-define double @test2(double ()* %fptr, double %p1) #0 {
+define double @function_pointer(double ()* %fptr, double %p1) {
   %call1 = call double %fptr()
   %pow = call double @log(double %call1)
   ret double %pow
 }
 
-; CHECK-LABEL: @test2
-; CHECK: log
+; CHECK-LABEL: @function_pointer
+; CHECK-NEXT:  %call1 = call double %fptr()
+; CHECK-NEXT:  %pow = call double @log(double %call1)
+; CHECK-NEXT:  ret double %pow
+
+define double @log_exp2(double %x) {
+  %call2 = call fast double @exp2(double %x)
+  %call3 = call fast double @log(double %call2)
+  ret double %call3
+}
+
+; CHECK-LABEL: @log_exp2
+; CHECK-NEXT:  %call2 = call fast double @exp2(double %x)
+; CHECK-NEXT:  %logmul = fmul fast double %x, 0x3FE62E42FEFA39EF
+; CHECK-NEXT:  ret double %logmul
 
-define double @test3(double %x) #0 {
-  %call2 = call double @exp2(double %x) #0
-  %call3 = call double @log(double %call2) #0
+define double @log_exp2_not_fast(double %x) {
+  %call2 = call double @exp2(double %x)
+  %call3 = call fast double @log(double %call2)
   ret double %call3
 }
 
-; CHECK-LABEL: @test3
-; CHECK:  %call2 = call double @exp2(double %x) #0
-; CHECK:  %logmul = fmul fast double %x, 0x3FE62E42FEFA39EF
-; CHECK:  ret double %logmul
-; CHECK: }
+; CHECK-LABEL: @log_exp2_not_fast
+; CHECK-NEXT:  %call2 = call double @exp2(double %x)
+; CHECK-NEXT:  %call3 = call fast double @log(double %call2)
+; CHECK-NEXT:  ret double %call3
 
-declare double @log(double) #0
-declare double @exp2(double) #0
+declare double @log(double)
+declare double @exp2(double)
 declare double @llvm.pow.f64(double, double)
 
-attributes #0 = { "unsafe-fp-math"="true" }