[PATCH] D65898: [InstCombine] x /c fabs(x) -> copysign(1.0, x)

[Dávid Bolvanský via Phabricator via llvm-commits]

xbolva00 updated this revision to Diff 214383.
xbolva00 added a comment.

Use m_Deferred


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D65898/new/

https://reviews.llvm.org/D65898

Files:
  lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
  test/Transforms/InstCombine/fabs-copysign.ll


Index: test/Transforms/InstCombine/fabs-copysign.ll
===================================================================
--- test/Transforms/InstCombine/fabs-copysign.ll
+++ test/Transforms/InstCombine/fabs-copysign.ll
@@ -10,9 +10,8 @@
 
 define double @fabs_copysign(double %x) {
 ; CHECK-LABEL: @fabs_copysign(
-; CHECK-NEXT:    [[F:%.*]] = tail call double @llvm.fabs.f64(double [[X:%.*]])
-; CHECK-NEXT:    [[DIV:%.*]] = fdiv nnan ninf double [[X]], [[F]]
-; CHECK-NEXT:    ret double [[DIV]]
+; CHECK-NEXT:    [[TMP1:%.*]] = call nnan ninf double @llvm.copysign.f64(double 1.000000e+00, double [[X:%.*]])
+; CHECK-NEXT:    ret double [[TMP1]]
 ;
   %f = tail call double @llvm.fabs.f64(double %x)
   %div = fdiv nnan ninf double %x, %f
@@ -21,9 +20,8 @@
 
 define double @fabs_copysign_commuted(double %x) {
 ; CHECK-LABEL: @fabs_copysign_commuted(
-; CHECK-NEXT:    [[F:%.*]] = tail call double @llvm.fabs.f64(double [[X:%.*]])
-; CHECK-NEXT:    [[DIV:%.*]] = fdiv nnan ninf double [[F]], [[X]]
-; CHECK-NEXT:    ret double [[DIV]]
+; CHECK-NEXT:    [[TMP1:%.*]] = call nnan ninf double @llvm.copysign.f64(double 1.000000e+00, double [[X:%.*]])
+; CHECK-NEXT:    ret double [[TMP1]]
 ;
   %f = tail call double @llvm.fabs.f64(double %x)
   %div = fdiv nnan ninf double %f, %x
@@ -33,9 +31,8 @@
 
 define float @fabs_copysignf(float %x) {
 ; CHECK-LABEL: @fabs_copysignf(
-; CHECK-NEXT:    [[F:%.*]] = tail call float @llvm.fabs.f32(float [[X:%.*]])
-; CHECK-NEXT:    [[DIV:%.*]] = fdiv nnan ninf float [[X]], [[F]]
-; CHECK-NEXT:    ret float [[DIV]]
+; CHECK-NEXT:    [[TMP1:%.*]] = call nnan ninf float @llvm.copysign.f32(float 1.000000e+00, float [[X:%.*]])
+; CHECK-NEXT:    ret float [[TMP1]]
 ;
   %f = tail call float @llvm.fabs.f32(float %x)
   %div = fdiv nnan ninf float %x, %f
@@ -46,8 +43,8 @@
 ; CHECK-LABEL: @fabs_copysign_use(
 ; CHECK-NEXT:    [[F:%.*]] = tail call double @llvm.fabs.f64(double [[X:%.*]])
 ; CHECK-NEXT:    call void @use(double [[F]])
-; CHECK-NEXT:    [[DIV:%.*]] = fdiv nnan ninf double [[X]], [[F]]
-; CHECK-NEXT:    ret double [[DIV]]
+; CHECK-NEXT:    [[TMP1:%.*]] = call nnan ninf double @llvm.copysign.f64(double 1.000000e+00, double [[X]])
+; CHECK-NEXT:    ret double [[TMP1]]
 ;
   %f = tail call double @llvm.fabs.f64(double %x)
   call void @use(double %f)
Index: lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -1234,6 +1234,17 @@
     return &I;
   }
 
+  // X / fabs(X) -> copysign(1.0, X)
+  // fabs(X) / X -> copysign(1.0, X)
+  if (I.hasNoNaNs() && I.hasNoInfs() &&
+      (match(&I,
+             m_FDiv(m_Value(X), m_Intrinsic<Intrinsic::fabs>(m_Deferred(X)))) ||
+       match(&I, m_FDiv(m_Intrinsic<Intrinsic::fabs>(m_Value(X)),
+                        m_Deferred(X))))) {
+    Value *V = Builder.CreateBinaryIntrinsic(
+        Intrinsic::copysign, ConstantFP::get(I.getType(), 1.0), X, &I);
+    return replaceInstUsesWith(I, V);
+  }
   return nullptr;
 }
 


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D65898.214383.patch
Type: text/x-patch
Size: 3111 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20190809/38310e65/attachment.bin>