From 97156e7984887461a7d4b3d60fe9eaef856b5140 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Wed, 26 Apr 2006 18:34:07 +0000 Subject: [PATCH] Implement Transforms/IndVarsSimplify/complex-scev.ll, a case where we didn't recognize some simple affine IV's. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@27982 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Analysis/ScalarEvolution.cpp | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index f0848569ddb..c6e32c53ab7 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -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(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 -- 2.34.1