[llvm] r256964 - [LibCallSimplifier] use instruction-level fast-math-flags for tan/atan transform

[Sanjay Patel via llvm-commits]

Author: spatel
Date: Wed Jan  6 13:23:35 2016
New Revision: 256964

URL: http://llvm.org/viewvc/llvm-project?rev=256964&view=rev
Log:
[LibCallSimplifier] use instruction-level fast-math-flags for tan/atan transform

Modified:
    llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp
    llvm/trunk/test/Transforms/InstCombine/tan.ll

Modified: llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp?rev=256964&r1=256963&r2=256964&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp Wed Jan  6 13:23:35 2016
@@ -1457,6 +1457,7 @@ Value *LibCallSimplifier::optimizeSqrt(C
   return Ret;
 }
 
+// TODO: Generalize to handle any trig function and its inverse.
 Value *LibCallSimplifier::optimizeTan(CallInst *CI, IRBuilder<> &B) {
   Function *Callee = CI->getCalledFunction();
   Value *Ret = nullptr;
@@ -1471,13 +1472,15 @@ Value *LibCallSimplifier::optimizeTan(Ca
       !FT->getParamType(0)->isFloatingPointTy())
     return Ret;
 
-  if (!canUseUnsafeFPMath(CI->getParent()->getParent()))
-    return Ret;
   Value *Op1 = CI->getArgOperand(0);
   auto *OpC = dyn_cast<CallInst>(Op1);
   if (!OpC)
     return Ret;
 
+  // Both calls must allow unsafe optimizations in order to remove them.
+  if (!CI->hasUnsafeAlgebra() || !OpC->hasUnsafeAlgebra())
+    return Ret;
+
   // tan(atan(x)) -> x
   // tanf(atanf(x)) -> x
   // tanl(atanl(x)) -> x

Modified: llvm/trunk/test/Transforms/InstCombine/tan.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/tan.ll?rev=256964&r1=256963&r2=256964&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/tan.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/tan.ll Wed Jan  6 13:23:35 2016
@@ -1,24 +1,23 @@
 ; RUN: opt < %s -instcombine -S | FileCheck %s
 
-define float @mytan(float %x) #0 {
-entry:
-  %call = call float @atanf(float %x)
-  %call1 = call float @tanf(float %call)
+define float @mytan(float %x) {
+  %call = call fast float @atanf(float %x)
+  %call1 = call fast float @tanf(float %call)
   ret float %call1
 }
 
 ; CHECK-LABEL: define float @mytan(
 ; CHECK:   ret float %x
 
-define float @test2(float ()* %fptr) #0 {
-  %call1 = call float %fptr()
-  %tan = call float @tanf(float %call1)
+define float @test2(float ()* %fptr) {
+  %call1 = call fast float %fptr()
+  %tan = call fast float @tanf(float %call1)
   ret float %tan
 }
 
 ; CHECK-LABEL: @test2
 ; CHECK: tanf
 
-declare float @tanf(float) #0
-declare float @atanf(float) #0
-attributes #0 = { "unsafe-fp-math"="true" }
+declare float @tanf(float)
+declare float @atanf(float)
+