[PATCH] Allow constant folding of copysign

[Karthik Bhat]

Hi arsenm,

Hi All,
This is a small patch which enables const folding a call to copysign whenever possible.
Could someone please review the same?
Thanks
Karthik Bhat

http://llvm-reviews.chandlerc.com/D2975

Files:
  lib/Analysis/ConstantFolding.cpp
  test/Transforms/InstCombine/copysign.ll

Index: lib/Analysis/ConstantFolding.cpp
===================================================================
--- lib/Analysis/ConstantFolding.cpp
+++ lib/Analysis/ConstantFolding.cpp
@@ -1195,6 +1195,7 @@
   case Intrinsic::cttz:
   case Intrinsic::fma:
   case Intrinsic::fmuladd:
+  case Intrinsic::copysign:
   case Intrinsic::sadd_with_overflow:
   case Intrinsic::uadd_with_overflow:
   case Intrinsic::ssub_with_overflow:
@@ -1538,6 +1539,12 @@
         if (F->getIntrinsicID() == Intrinsic::pow) {
           return ConstantFoldBinaryFP(pow, Op1V, Op2V, Ty);
         }
+        if (F->getIntrinsicID() == Intrinsic::copysign) {
+          APFloat V1 = Op1->getValueAPF();
+          APFloat V2 = Op2->getValueAPF();
+          V1.copySign(V2);
+          return ConstantFP::get(Ty->getContext(), V1);
+        }
         if (!TLI)
           return 0;
         if (Name == "pow" && TLI->has(LibFunc::pow))
Index: test/Transforms/InstCombine/copysign.ll
===================================================================
--- test/Transforms/InstCombine/copysign.ll
+++ test/Transforms/InstCombine/copysign.ll
@@ -0,0 +1,49 @@
+; RUN: opt -S -instcombine < %s | FileCheck %s
+
+declare float @llvm.copysign.f32(float, float) #0
+declare double @llvm.copysign.f64(double, double) #0
+
+; CHECK-LABEL: @constant_fold_copysign_f32_01
+; CHECK-NEXT: ret float -1.000000e+00
+define float @constant_fold_copysign_f32_01() #0 {
+  %x = call float @llvm.copysign.f32(float 1.0, float -2.0) #0
+  ret float %x
+}
+
+; CHECK-LABEL: @constant_fold_copysign_f32_02
+; CHECK-NEXT: ret float 2.000000e+00
+define float @constant_fold_copysign_f32_02() #0 {
+  %x = call float @llvm.copysign.f32(float -2.0, float 1.0) #0
+  ret float %x
+}
+
+; CHECK-LABEL: @constant_fold_copysign_f32_03
+; CHECK-NEXT: ret float -2.000000e+00
+define float @constant_fold_copysign_f32_03() #0 {
+  %x = call float @llvm.copysign.f32(float -2.0, float -1.0) #0
+  ret float %x
+}
+
+; CHECK-LABEL: @constant_fold_copysign_f64_01
+; CHECK-NEXT: ret double -1.000000e+00
+define double @constant_fold_copysign_f64_01() #0 {
+  %x = call double @llvm.copysign.f64(double 1.0, double -2.0) #0
+  ret double %x
+}
+
+; CHECK-LABEL: @constant_fold_copysign_f64_02
+; CHECK-NEXT: ret double 1.000000e+00
+define double @constant_fold_copysign_f64_02() #0 {
+  %x = call double @llvm.copysign.f64(double -1.0, double 2.0) #0
+  ret double %x
+}
+
+; CHECK-LABEL: @constant_fold_copysign_f64_03
+; CHECK-NEXT: ret double -1.000000e+00
+define double @constant_fold_copysign_f64_03() #0 {
+  %x = call double @llvm.copysign.f64(double -1.0, double -2.0) #0
+  ret double %x
+}
+
+
+attributes #0 = { nounwind readnone }
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