From: Chris Lattner <sabre@nondot.org>
Date: Tue, 14 Dec 2004 20:08:06 +0000 (+0000)
Subject: Constant exprs are not efficiently negatable in practice.  This disables
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=0ce8580fcd23839b69eb36af7b0cb789be4b2763;p=oota-llvm.git

Constant exprs are not efficiently negatable in practice.  This disables
turning X - (constantexpr) into X + (-constantexpr) among other things.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@18935 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 807653b56d1..f78a14d4273 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -309,10 +309,9 @@ static inline Value *dyn_castNegVal(Value *V) {
   if (BinaryOperator::isNeg(V))
     return BinaryOperator::getNegArgument(cast<BinaryOperator>(V));
 
-  // Constants can be considered to be negated values if they can be folded...
-  if (Constant *C = dyn_cast<Constant>(V))
-    if (!isa<UndefValue>(C))
-      return ConstantExpr::getNeg(C);
+  // Constants can be considered to be negated values if they can be folded.
+  if (ConstantInt *C = dyn_cast<ConstantInt>(V))
+    return ConstantExpr::getNeg(C);
   return 0;
 }