[PATCH] D88420: [InstCombine] matchFunnelShift - support non-uniform constant vector shift amounts (PR46895)

[Sterling Augustine via Phabricator via llvm-commits]

saugustine added a comment.

Here is a relatively simple, self-contained testcase. Of interest is that the entire loop needs to be present, and completely unwound for this bug to show. It looks to me like either next_carry or carry is mis-calculated or stale on the ninth iteration which fills the second-to-last element.

  Failed
      Correct          Actual
   0: c71c71c71c71c9fc   c71c71c71c71c9fc
   1: 5b91f6e791f6e791   5b91f6e791f6e791
   2: 6000000000000005   6000000000000005
   3: 9e79e79e79e79ed8   9e79e79e79e79ed8
   4: 4bf2c78af2c7816e   4bf2c78af2c7816e
   5: a53d3d3d3d3d3d3d   a53d3d3d3d3d3d3d
   6: 7555555555555558   7555555555555558
   7: cf3cf3cf3cf3cfcd   cf3cf3cf3cf3cfcd
   8: d3cfa5effb5effcf   d3cfa5effb5effcf
   9: 0000000000000000   0000000000000001
  10: 0000000000000000   0000000000000000

F13340726: ppc_shift_test.c <https://reviews.llvm.org/F13340726>


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https://reviews.llvm.org/D88420