[PATCH] D98235: [InstCombine][SimplifyLibCalls] An extra sqrtf was produced because of transformations in optimizePow function

[Sanjay Patel via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG7c49f3c75be9: [InstCombine][SimplifyLibCalls] An extra sqrtf was produced because of… (authored by vdsered, committed by spatel).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D98235/new/

https://reviews.llvm.org/D98235

Files:
  llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
  llvm/test/Transforms/InstCombine/pow-4.ll


Index: llvm/test/Transforms/InstCombine/pow-4.ll
===================================================================
--- llvm/test/Transforms/InstCombine/pow-4.ll
+++ llvm/test/Transforms/InstCombine/pow-4.ll
@@ -1,7 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt -instcombine -S < %s                        | FileCheck %s --check-prefixes=CHECK,SQRT
 ; RUN: opt -instcombine -S < %s -disable-builtin sqrt  | FileCheck %s --check-prefixes=CHECK,NOSQRT
-
 declare double @llvm.pow.f64(double, double)
 declare float @llvm.pow.f32(float, float)
 declare <2 x double> @llvm.pow.v2f64(<2 x double>, <2 x double>)
@@ -235,12 +234,10 @@
 }
 
 ; (float)pow((double)(float)x, 0.5)
-; FIXME: One call to `sqrtf` would suffice (PR47613).
 define float @shrink_pow_libcall_half(float %x) {
 ; SQRT-LABEL: @shrink_pow_libcall_half(
-; SQRT-NEXT:    [[SQRTF:%.*]] = call fast float @sqrtf(float [[X:%.*]])
-; SQRT-NEXT:    [[SQRTF1:%.*]] = call fast float @sqrtf(float [[X]])
-; SQRT-NEXT:    ret float [[SQRTF1]]
+; SQRT-NEXT:    [[SQRTF:%.*]] = call fast float @sqrtf(float [[X]])
+; SQRT-NEXT:    ret float [[SQRTF]]
 ;
 ; NOSQRT-LABEL: @shrink_pow_libcall_half(
 ; NOSQRT-NEXT:    [[SQRTF:%.*]] = call fast float @sqrtf(float [[X:%.*]])
Index: llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
===================================================================
--- llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -1704,20 +1704,12 @@
   StringRef Name = Callee->getName();
   Type *Ty = Pow->getType();
   Module *M = Pow->getModule();
-  Value *Shrunk = nullptr;
   bool AllowApprox = Pow->hasApproxFunc();
   bool Ignored;
 
   // Propagate the math semantics from the call to any created instructions.
   IRBuilderBase::FastMathFlagGuard Guard(B);
   B.setFastMathFlags(Pow->getFastMathFlags());
-
-  // Shrink pow() to powf() if the arguments are single precision,
-  // unless the result is expected to be double precision.
-  if (UnsafeFPShrink && Name == TLI->getName(LibFunc_pow) &&
-      hasFloatVersion(Name))
-    Shrunk = optimizeBinaryDoubleFP(Pow, B, true);
-
   // Evaluate special cases related to the base.
 
   // pow(1.0, x) -> 1.0
@@ -1818,7 +1810,15 @@
       return createPowWithIntegerExponent(Base, ExpoI, M, B);
   }
 
-  return Shrunk;
+  // Shrink pow() to powf() if the arguments are single precision,
+  // unless the result is expected to be double precision.
+  if (UnsafeFPShrink && Name == TLI->getName(LibFunc_pow) &&
+      hasFloatVersion(Name)) {
+    if (Value *Shrunk = optimizeBinaryDoubleFP(Pow, B, true))
+      return Shrunk;
+  }
+
+  return nullptr;
 }
 
 Value *LibCallSimplifier::optimizeExp2(CallInst *CI, IRBuilderBase &B) {


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