From: Bill Wendling <isanbard@gmail.com>
Date: Mon, 1 Dec 2008 19:46:27 +0000 (+0000)
Subject: Use a simple comparison. Overflow on integer negation can only occur when the
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=c25c68305c5d595c5428f75280cfb56e4f623eb3;p=oota-llvm.git

Use a simple comparison. Overflow on integer negation can only occur when the
integer is "minint".


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60366 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 9c6ff8acc57..e4ddecf7563 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -2934,20 +2934,9 @@ Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
     if (Value *LHSNeg = dyn_castNegVal(Op0)) {
       if (ConstantInt *CI = dyn_cast<ConstantInt>(LHSNeg)) {
         ConstantInt *RHSNeg = cast<ConstantInt>(ConstantExpr::getNeg(RHS));
-        APInt RHSNegAPI(RHSNeg->getValue());
-
-        APInt NegOne = -APInt(RHSNeg->getBitWidth(), 1, true);
-        APInt TwoToExp(RHSNeg->getBitWidth(), 1 << (RHSNeg->getBitWidth() - 1));
-
-        if ((RHS->getValue().isNegative() &&
-             RHSNegAPI.slt(TwoToExp - 1)) ||
-            (RHS->getValue().isNonNegative() &&
-             RHSNegAPI.sgt(TwoToExp * NegOne))) {
+        if (RHS != RHSNeg) {
           ConstantInt *CINeg = cast<ConstantInt>(ConstantExpr::getNeg(CI));
-          APInt CINegAPI(CINeg->getValue());
-
-          if ((CI->getValue().isNegative() && CINegAPI.slt(TwoToExp - 1)) ||
-              (CI->getValue().isNonNegative() && CINegAPI.sgt(TwoToExp*NegOne)))
+          if (CI != CINeg)
             return BinaryOperator::CreateSDiv(LHSNeg,
                                               ConstantExpr::getNeg(RHS));
         }