diff options
Diffstat (limited to 'contrib/llvm/lib/Analysis/IVUsers.cpp')
-rw-r--r-- | contrib/llvm/lib/Analysis/IVUsers.cpp | 23 |
1 files changed, 21 insertions, 2 deletions
diff --git a/contrib/llvm/lib/Analysis/IVUsers.cpp b/contrib/llvm/lib/Analysis/IVUsers.cpp index b33e2cb..5a06cdc 100644 --- a/contrib/llvm/lib/Analysis/IVUsers.cpp +++ b/contrib/llvm/lib/Analysis/IVUsers.cpp @@ -187,15 +187,34 @@ bool IVUsers::AddUsersImpl(Instruction *I, if (AddUserToIVUsers) { // Okay, we found a user that we cannot reduce. - IVUses.push_back(new IVStrideUse(this, User, I)); - IVStrideUse &NewUse = IVUses.back(); + IVStrideUse &NewUse = AddUser(User, I); // Autodetect the post-inc loop set, populating NewUse.PostIncLoops. // The regular return value here is discarded; instead of recording // it, we just recompute it when we need it. + const SCEV *OriginalISE = ISE; ISE = TransformForPostIncUse(NormalizeAutodetect, ISE, User, I, NewUse.PostIncLoops, *SE, *DT); + + // PostIncNormalization effectively simplifies the expression under + // pre-increment assumptions. Those assumptions (no wrapping) might not + // hold for the post-inc value. Catch such cases by making sure the + // transformation is invertible. + if (OriginalISE != ISE) { + const SCEV *DenormalizedISE = + TransformForPostIncUse(Denormalize, ISE, User, I, + NewUse.PostIncLoops, *SE, *DT); + + // If we normalized the expression, but denormalization doesn't give the + // original one, discard this user. + if (OriginalISE != DenormalizedISE) { + DEBUG(dbgs() << " DISCARDING (NORMALIZATION ISN'T INVERTIBLE): " + << *ISE << '\n'); + IVUses.pop_back(); + return false; + } + } DEBUG(if (SE->getSCEV(I) != ISE) dbgs() << " NORMALIZED TO: " << *ISE << '\n'); } |