[PATCH] D26367: Fix DAGCombiner match

[Evgeny Stupachenko via llvm-commits]

evstupac created this revision.
evstupac added reviewers: aschwaighofer, RKSimon, hfinkel.
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The patches fix (base, index, offset) match in DAGCombine to combine the following stores/loads (a, b, c char arrays):
for (i = 0; i < n; i += 2) {

  char c1 = c{*b];
  char c2 = c[*b + 1];
  a[i] = c1;
  a[i + 1] = c2;
  b++;

}
into (a, c, the same short arrays):
for (i = 0; i < n; i++) {

  short c1 = c{*b];
  a[i] = c1;
  b++;

}

Without the patch match returned the following (base, index, offset):
*(a + i) -> (a, i, 0)
*(a + i + 1) -> (a + i, undef, 1)
and loads/stores were not combined because of different base.


Repository:
  rL LLVM

https://reviews.llvm.org/D26367

Files:
  lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  test/CodeGen/X86/MergeConsecutiveStores.ll

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