diff options
Diffstat (limited to 'lib/Analysis/ScalarEvolution.cpp')
-rw-r--r-- | lib/Analysis/ScalarEvolution.cpp | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index 413b3b4..f0bc936 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -845,6 +845,13 @@ const SCEV *ScalarEvolution::getTruncateExpr(const SCEV *Op, return getAddRecExpr(Operands, AddRec->getLoop()); } + // As a special case, fold trunc(undef) to undef. We don't want to + // know too much about SCEVUnknowns, but this special case is handy + // and harmless. + if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Op)) + if (isa<UndefValue>(U->getValue())) + return getSCEV(UndefValue::get(Ty)); + // The cast wasn't folded; create an explicit cast node. We can reuse // the existing insert position since if we get here, we won't have // made any changes which would invalidate it. @@ -1163,6 +1170,13 @@ const SCEV *ScalarEvolution::getAnyExtendExpr(const SCEV *Op, return getAddRecExpr(Ops, AR->getLoop()); } + // As a special case, fold anyext(undef) to undef. We don't want to + // know too much about SCEVUnknowns, but this special case is handy + // and harmless. + if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Op)) + if (isa<UndefValue>(U->getValue())) + return getSCEV(UndefValue::get(Ty)); + // If the expression is obviously signed, use the sext cast value. if (isa<SCEVSMaxExpr>(Op)) return SExt; |