[PATCH] D41981: [SROA] fix assetion failure

[Eli Friedman via Phabricator via llvm-commits]

efriedma accepted this revision.
efriedma added a comment.
This revision is now accepted and ready to land.

LGTM, but don't close PR35657 until you track down the miscompile.  (csmith should not be generating code with out-of-bounds accesses, so there's probably another bug somewhere.)



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Comment at: lib/Transforms/Scalar/SROA.cpp:3933
   AllocaInst *NewAI;
-  if (SliceTy == AI.getAllocatedType()) {
-    assert(P.beginOffset() == 0 &&
-           "Non-zero begin offset but same alloca type");
+  if (SliceTy == AI.getAllocatedType() && P.beginOffset() == 0) {
     NewAI = &AI;
----------------
Please add a comment explaining that beginOffset() != 0 can happen for out-of-bounds accesses.  (We want to transform anyway because we don't want undefined behavior in unreachable code to block optimizations in other code.)


https://reviews.llvm.org/D41981