[PATCH] D62910: [DAGCombine] MergeConsecutiveStores - improve non-temporal store handling (PR42123)

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon created this revision.
RKSimon added reviewers: niravd, efriedma, craig.topper, andreadb.
Herald added a project: LLVM.

This patch is the first step towards ensuring MergeConsecutiveStores correctly handles non-temporal stores:

1 - When merging stores we must ensure that they all have the same non-temporal flag. This is unlikely to occur, but can in strange cases where we're storing at the end of one page and the beginning of another.

2 - The merged store node must retain the non-temporal flag.

After this I need to improve alignment handling - in most cases we shouldn't merge nt-stores unless they are naturally aligned - either we just prevent it in all cases or we refactor canMergeStoresTo to include access to the alignment and MMO flags as well?


Repository:
  rL LLVM

https://reviews.llvm.org/D62910

Files:
  lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  test/CodeGen/X86/merge-consecutive-stores-nt.ll

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