[PATCH] D49200: [DAGCombine] Improve Load-Store Forwarding

[Peter Smith via Phabricator via llvm-commits]

peter.smith added a comment.

This commit (found via git bisect) looks like it is the cause of https://bugs.llvm.org/show_bug.cgi?id=39571 which is derived from the Linux kernel and is a regression from LLVM 7.0. We get an internal fault in instruction selection for ARM state for pre ARM-v7 architectures (test uses armv4t but it is reproducible on v5t and v6).

A test case and details of how to reproduce can be found in the PR. It is possible that this has exposed a limitation in the Arm backend or the optimisation may not be suitable for it. Would you be able to take a look?


Repository:
  rL LLVM

https://reviews.llvm.org/D49200