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Instead of testing whether an instruction dominates the loop preheader,

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test whether it properly dominates the loop header. This is equivalent
when the loop has a preheader, and has the advantage of working when
the loop doesn't have a preheader. Since IVUsers doesn't Require
LoopSimplify, the loop isn't guaranteed to have a preheader.

llvm-svn: 82899
This commit is contained in:
Dan Gohman 2009-09-27 15:30:00 +00:00
parent b84f5a3421
commit 16398e3bc0
1 changed files with 3 additions and 3 deletions
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6
lib/Analysis/IVUsers.cpp
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@ -121,11 +121,11 @@ static bool getSCEVStartAndStride(const SCEV *&SH, Loop *L, Loop *UseLoop,
Start = SE->getAddExpr(Start, AddRecStart);
// If stride is an instruction, make sure it dominates the loop preheader.
// If stride is an instruction, make sure it properly dominates the header.
// Otherwise we could end up with a use before def situation.
if (!isa<SCEVConstant>(AddRecStride)) {
BasicBlock *Preheader = L->getLoopPreheader();
if (!AddRecStride->dominates(Preheader, DT))
BasicBlock *Header = L->getHeader();
if (!AddRecStride->properlyDominates(Header, DT))
return false;
DEBUG(errs() << "[" << L->getHeader()->getName()