[all-commits] [llvm/llvm-project] 7fb66d: [MemCpyOpt] Fix a variety of scalable-type crashes

[Fraser Cormack via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 7fb66d4035960b3c2797eae73d79b8478ff0348e
      https://github.com/llvm/llvm-project/commit/7fb66d4035960b3c2797eae73d79b8478ff0348e
  Author: Fraser Cormack <fraser at codeplay.com>
  Date:   2021-09-08 (Wed, 08 Sep 2021)

  Changed paths:
    M llvm/include/llvm/Transforms/Scalar/MemCpyOptimizer.h
    M llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
    A llvm/test/Transforms/MemCpyOpt/vscale-crashes.ll

  Log Message:
  -----------
  [MemCpyOpt] Fix a variety of scalable-type crashes

This patch fixes a variety of crashes resulting from the `MemCpyOptPass`
casting `TypeSize` to a constant integer, whether implicitly or
explicitly.

Since the `MemsetRanges` requires a constant size to work, all but one
of the fixes in this patch simply involve skipping the various
optimizations for scalable types as cleanly as possible.

The optimization of `byval` parameters, however, has been updated to
work on scalable types in theory. In practice, this optimization is only
valid when the length of the `memcpy` is known to be larger than the
scalable type size, which is currently never the case. This could
perhaps be done in the future using the `vscale_range` attribute.

Some implicit casts have been left as they were, under the knowledge
they are only called on aggregate types. These should never be
scalably-sized.

Reviewed By: nikic, tra

Differential Revision: https://reviews.llvm.org/D109329