[all-commits] [llvm/llvm-project] 2153ca: [DAGCombiner] Stop visitEXTRACT_SUBVECTOR creating...

[paulwalker-arm via All-commits]

  Branch: refs/heads/release/13.x
  Home:   https://github.com/llvm/llvm-project
  Commit: 2153cad11ba252698c21d48723265ca7f4850a29
      https://github.com/llvm/llvm-project/commit/2153cad11ba252698c21d48723265ca7f4850a29
  Author: Paul Walker <paul.walker at arm.com>
  Date:   2021-08-16 (Mon, 16 Aug 2021)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    M llvm/test/CodeGen/AArch64/sve-fixed-length-masked-scatter.ll

  Log Message:
  -----------
  [DAGCombiner] Stop visitEXTRACT_SUBVECTOR creating illegal BITCASTs post legalisation.

visitEXTRACT_SUBVECTOR can sometimes create illegal BITCASTs when
removing "redundant" INSERT_SUBVECTOR operations.  This patch adds
an extra check to ensure such combines only occur after operation
legalisation if any resulting BITBAST is itself legal.

Differential Revision: https://reviews.llvm.org/D108086

(cherry picked from commit cd0e1964137f1cd7b508809ec80c7d9dcb3f0458)