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Clarify comments in genLoopLimit. 

llvm-svn: 193292
This commit is contained in:
Andrew Trick 2013-10-24 00:43:38 +00:00
parent c89fc826b2
commit ada2356ac9
1 changed files with 4 additions and 3 deletions
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7
llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
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@ -1506,9 +1506,10 @@ static Value *genLoopLimit(PHINode *IndVar, const SCEV *IVCount, Loop *L,
// BECount = (IVEnd - IVInit - 1) => IVLimit = IVInit (postinc).
//
// Valid Cases: (1) both integers is most common; (2) both may be pointers
// for simple memset-style loops; (3) IVInit is an integer and IVCount is a
// pointer may occur when enable-iv-rewrite generates a canonical IV on top
// of case #2.
// for simple memset-style loops.
//
// IVInit integer and IVCount pointer would only occur if a canonical IV
// were generated on top of case #2, which is not expected.
const SCEV *IVLimit = 0;
// For unit stride, IVCount = Start + BECount with 2's complement overflow.