From: Dan Gohman <gohman@apple.com>
Date: Sun, 11 Apr 2010 22:12:18 +0000 (+0000)
Subject: When creating a ConstantRange for [n,UINT_MAX], special case n == 0, because
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=bc7129f9dbc6651407134e80a4202adc2ef2511c;p=oota-llvm.git

When creating a ConstantRange for [n,UINT_MAX], special case n == 0, because
ConstantRange(0, 0) creates an empty range rather than a full one.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100993 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index c67cb71b303..44aa5082b1c 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -2920,9 +2920,10 @@ ScalarEvolution::getUnsignedRange(const SCEV *S) {
     // initial value.
     if (AddRec->hasNoUnsignedWrap())
       if (const SCEVConstant *C = dyn_cast<SCEVConstant>(AddRec->getStart()))
-        ConservativeResult =
-          ConstantRange(C->getValue()->getValue(),
-                        APInt(getTypeSizeInBits(C->getType()), 0));
+        if (!C->isZero())
+          ConservativeResult =
+            ConstantRange(C->getValue()->getValue(),
+                          APInt(getTypeSizeInBits(C->getType()), 0));
 
     // TODO: non-affine addrec
     if (AddRec->isAffine()) {