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Implement Transforms/IndVarsSimplify/complex-scev.ll, a case where we didn't

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recognize some simple affine IV's.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@27982 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-04-26 18:34:07 +00:00
parent 3e0d4b9810
commit 97156e7984
1 changed files with 25 additions and 0 deletions
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25
lib/Analysis/ScalarEvolution.cpp
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@ -1295,6 +1295,31 @@ SCEVHandle ScalarEvolutionsImpl::createNodeForPHI(PHINode *PN) {
SCEVHandle StartVal = getSCEV(PN->getIncomingValue(IncomingEdge));
SCEVHandle PHISCEV = SCEVAddRecExpr::get(StartVal, Accum, L);
// Okay, for the entire analysis of this edge we assumed the PHI
// to be symbolic. We now need to go back and update all of the
// entries for the scalars that use the PHI (except for the PHI
// itself) to use the new analyzed value instead of the "symbolic"
// value.
ReplaceSymbolicValueWithConcrete(PN, SymbolicName, PHISCEV);
return PHISCEV;
}
}
} else if (SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(BEValue)) {
// Otherwise, this could be a loop like this:
// i = 0; for (j = 1; ..; ++j) { .... i = j; }
// In this case, j = {1,+,1} and BEValue is j.
// Because the other in-value of i (0) fits the evolution of BEValue
// i really is an addrec evolution.
if (AddRec->getLoop() == L && AddRec->isAffine()) {
SCEVHandle StartVal = getSCEV(PN->getIncomingValue(IncomingEdge));
// If StartVal = j.start - j.stride, we can use StartVal as the
// initial step of the addrec evolution.
if (StartVal == SCEV::getMinusSCEV(AddRec->getOperand(0),
AddRec->getOperand(1))) {
SCEVHandle PHISCEV =
SCEVAddRecExpr::get(StartVal, AddRec->getOperand(1), L);
// Okay, for the entire analysis of this edge we assumed the PHI
// to be symbolic. We now need to go back and update all of the
// entries for the scalars that use the PHI (except for the PHI