[PATCH] D76669: [LoopVectorize] Fix crash on "getNoopOrZeroExtend cannot truncate!" (PR45259)

[Vedant Kumar via Phabricator via llvm-commits]

vsk created this revision.
vsk added reviewers: fhahn, nemanjai.
Herald added subscribers: javed.absar, hiraditya.

In `InnerLoopVectorizer::getOrCreateTripCount`, when the backedge taken
count is a SCEV add expression, its type is defined by the type of the
last operand of the add expression.

In the test case from PR45259, this last operand happens to be a
pointer, which (according to llvm::Type) does not have a primitive size
in bits. In this case, LoopVectorize fails to truncate the SCEV and
crashes as a result.

ISTM that the truncation really is needed, and that using
`ScalarEvolution::getTypeSizeInBits` makes the truncation work as
expected. As I'm not really familiar with this code, I'm not sure
whether this is an appropriate or sufficient fix -- any advice
appreciated.

https://bugs.llvm.org/show_bug.cgi?id=45259


https://reviews.llvm.org/D76669

Files:
  llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
  llvm/test/Transforms/LoopVectorize/pr45259.ll

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