[llvm] r257414 - [LibCallSimplifier] use instruction-level fast-math-flags to transform log calls

[Sanjay Patel via llvm-commits]

Author: spatel
Date: Mon Jan 11 17:31:48 2016
New Revision: 257414

URL: http://llvm.org/viewvc/llvm-project?rev=257414&view=rev
Log:
[LibCallSimplifier] use instruction-level fast-math-flags to transform log calls

Also, add tests to verify that we're checking 'fast' on both calls of each transform pair,
tighten the CHECK lines, and give the tests more meaningful names.

This is a continuation of:
http://reviews.llvm.org/rL255555
http://reviews.llvm.org/rL256871
http://reviews.llvm.org/rL256964
http://reviews.llvm.org/rL257400
http://reviews.llvm.org/rL257404


Modified:
    llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp
    llvm/trunk/test/Transforms/InstCombine/log-pow.ll

Modified: llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp?rev=257414&r1=257413&r2=257414&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp Mon Jan 11 17:31:48 2016
@@ -1354,11 +1354,13 @@ Value *LibCallSimplifier::optimizeLog(Ca
       !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)

Modified: llvm/trunk/test/Transforms/InstCombine/log-pow.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/log-pow.ll?rev=257414&r1=257413&r2=257414&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/log-pow.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/log-pow.ll Mon Jan 11 17:31:48 2016
@@ -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
+}
 
-define double @test3(double %x) #0 {
-  %call2 = call double @exp2(double %x) #0
-  %call3 = call double @log(double %call2) #0
+; 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 @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" }