[llvm] 9cdcd81 - [InstCombine] enhance fold for copysign with known sign arg
Sanjay Patel via llvm-commits
llvm-commits at lists.llvm.org
Sun Dec 22 07:07:09 PST 2019
Author: Sanjay Patel
Date: 2019-12-22T10:07:01-05:00
New Revision: 9cdcd81d3f2e9c1c9ae1e054e24668d46bc08bfb
URL: https://github.com/llvm/llvm-project/commit/9cdcd81d3f2e9c1c9ae1e054e24668d46bc08bfb
DIFF: https://github.com/llvm/llvm-project/commit/9cdcd81d3f2e9c1c9ae1e054e24668d46bc08bfb.diff
LOG: [InstCombine] enhance fold for copysign with known sign arg
This is another optimization suggested in PRPR44153:
https://bugs.llvm.org/show_bug.cgi?id=44153
Added:
Modified:
llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
llvm/test/Transforms/InstCombine/copysign.ll
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 51006272646d..f556c5fd4aba 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -2286,18 +2286,22 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
break;
}
case Intrinsic::copysign: {
- const APFloat *C;
- if (match(II->getArgOperand(1), m_APFloat(C))) {
- // If we know the sign bit of the sign argument, reduce to FABS/FNABS:
- // copysign X, PosC --> fabs X
- // copysign X, NegC --> fneg (fabs X)
+ if (SignBitMustBeZero(II->getArgOperand(1), &TLI)) {
+ // If we know that the sign argument is positive, reduce to FABS:
+ // copysign X, Pos --> fabs X
Value *Fabs = Builder.CreateUnaryIntrinsic(Intrinsic::fabs,
II->getArgOperand(0), II);
- if (C->isNegative())
- Fabs = Builder.CreateFNegFMF(Fabs, II);
-
return replaceInstUsesWith(*II, Fabs);
}
+ // TODO: There should be a ValueTracking sibling like SignBitMustBeOne.
+ const APFloat *C;
+ if (match(II->getArgOperand(1), m_APFloat(C)) && C->isNegative()) {
+ // If we know that the sign argument is negative, reduce to FNABS:
+ // copysign X, Neg --> fneg (fabs X)
+ Value *Fabs = Builder.CreateUnaryIntrinsic(Intrinsic::fabs,
+ II->getArgOperand(0), II);
+ return replaceInstUsesWith(*II, Builder.CreateFNegFMF(Fabs, II));
+ }
break;
}
case Intrinsic::fabs: {
diff --git a/llvm/test/Transforms/InstCombine/copysign.ll b/llvm/test/Transforms/InstCombine/copysign.ll
index c769ccedc3c8..cc68b195a7e2 100644
--- a/llvm/test/Transforms/InstCombine/copysign.ll
+++ b/llvm/test/Transforms/InstCombine/copysign.ll
@@ -45,9 +45,8 @@ define <3 x double> @negative_sign_arg_vec_splat(<3 x double> %x) {
define float @known_positive_sign_arg(float %x, float %y) {
; CHECK-LABEL: @known_positive_sign_arg(
-; CHECK-NEXT: [[FABS:%.*]] = call float @llvm.fabs.f32(float [[Y:%.*]])
-; CHECK-NEXT: [[R:%.*]] = call ninf float @llvm.copysign.f32(float [[X:%.*]], float [[FABS]])
-; CHECK-NEXT: ret float [[R]]
+; CHECK-NEXT: [[TMP1:%.*]] = call ninf float @llvm.fabs.f32(float [[X:%.*]])
+; CHECK-NEXT: ret float [[TMP1]]
;
%fabs = call float @llvm.fabs.f32(float %y)
%r = call ninf float @llvm.copysign.f32(float %x, float %fabs)
@@ -56,9 +55,8 @@ define float @known_positive_sign_arg(float %x, float %y) {
define <3 x double> @known_positive_sign_arg_vec(<3 x double> %x, <3 x i32> %y) {
; CHECK-LABEL: @known_positive_sign_arg_vec(
-; CHECK-NEXT: [[YF:%.*]] = uitofp <3 x i32> [[Y:%.*]] to <3 x double>
-; CHECK-NEXT: [[R:%.*]] = call arcp <3 x double> @llvm.copysign.v3f64(<3 x double> [[X:%.*]], <3 x double> [[YF]])
-; CHECK-NEXT: ret <3 x double> [[R]]
+; CHECK-NEXT: [[TMP1:%.*]] = call arcp <3 x double> @llvm.fabs.v3f64(<3 x double> [[X:%.*]])
+; CHECK-NEXT: ret <3 x double> [[TMP1]]
;
%yf = uitofp <3 x i32> %y to <3 x double>
%r = call arcp <3 x double> @llvm.copysign.v3f64(<3 x double> %x, <3 x double> %yf)
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