From 12f39e0fede92ca04c811660530e750585124ed2 Mon Sep 17 00:00:00 2001
From: Sanjay Patel <spatel@rotateright.com>
Date: Sun, 8 Dec 2019 10:05:28 -0500
Subject: [InstSimplify] fold copysign with negated operand

This is another transform suggested in PR44153:
https://bugs.llvm.org/show_bug.cgi?id=44153

The backend for some targets already manages to get
this if it converts copysign to bitwise logic.
---
 llvm/lib/Analysis/InstructionSimplify.cpp | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'llvm/lib/Analysis/InstructionSimplify.cpp')

diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 7942cb09e84..d151b78f04c 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -5090,6 +5090,9 @@ static Value *simplifyBinaryIntrinsic(Function *F, Value *Op0, Value *Op1,
     // copysign X, X --> X
     if (Op0 == Op1)
       return Op0;
+    // copysign -X, X --> X
+    if (match(Op0, m_FNeg(m_Specific(Op1))))
+      return Op1;
     break;
   case Intrinsic::maxnum:
   case Intrinsic::minnum:
-- 
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