diff options
Diffstat (limited to 'llvm/lib/Transforms')
| -rw-r--r-- | llvm/lib/Transforms/Scalar/IndVarSimplify.cpp | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp b/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp index 056886f80e6..aa722dbb286 100644 --- a/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp +++ b/llvm/lib/Transforms/Scalar/IndVarSimplify.cpp @@ -1989,7 +1989,34 @@ linearFunctionTestReplace(Loop *L, DEBUG(dbgs() << " Widen RHS:\t" << *ExitCnt << "\n"); } else { + // We try to extend trip count first. If that doesn't work we truncate IV. + // Zext(trunc(IV)) == IV implies equivalence of the following two: + // Trunc(IV) == ExitCnt and IV == zext(ExitCnt). Similarly for sext. If + // one of the two holds, extend the trip count, otherwise we truncate IV. + bool Extended = false; + const SCEV *IV = SE->getSCEV(CmpIndVar); + const SCEV *ZExtTrunc = + SE->getZeroExtendExpr(SE->getTruncateExpr(SE->getSCEV(CmpIndVar), + ExitCnt->getType()), + CmpIndVar->getType()); + + if (ZExtTrunc == IV) { + Extended = true; + ExitCnt = Builder.CreateZExt(ExitCnt, IndVar->getType(), + "wide.trip.count"); + } else { + const SCEV *SExtTrunc = + SE->getSignExtendExpr(SE->getTruncateExpr(SE->getSCEV(CmpIndVar), + ExitCnt->getType()), + CmpIndVar->getType()); + if (SExtTrunc == IV) { + Extended = true; + ExitCnt = Builder.CreateSExt(ExitCnt, IndVar->getType(), + "wide.trip.count"); + } + } + if (!Extended) CmpIndVar = Builder.CreateTrunc(CmpIndVar, ExitCnt->getType(), "lftr.wideiv"); } |
