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| author | Craig Topper <craig.topper@intel.com> | 2018-02-06 21:47:04 +0000 |
|---|---|---|
| committer | Craig Topper <craig.topper@intel.com> | 2018-02-06 21:47:04 +0000 |
| commit | dfea544c846f36b515edf7dda629842a7f972351 (patch) | |
| tree | 365ce22a1ef79e7b661819c96c51cff505d46cc0 /llvm/lib/ExecutionEngine | |
| parent | 0cdc273ada3d1dadce945dafaa090d3b29054172 (diff) | |
| download | bcm5719-llvm-dfea544c846f36b515edf7dda629842a7f972351.tar.gz bcm5719-llvm-dfea544c846f36b515edf7dda629842a7f972351.zip | |
[X86] Add test cases that exercise the BSR/BSF optimization combineCMov.
combineCmov tries to remove compares against BSR/BSF if we can prove the input to the BSR/BSF are never zero.
As far as I can tell most of the time codegenprepare despeculates ctlz/cttz and gives us a cttz_zero_undef/ctlz_zero_undef which don't use a cmov.
So the only way I found to trigger this code is to show codegenprepare an illegal type which it won't despeculate.
I think we should be turning ctlz/cttz into ctlz_zero_undef/cttz_zero_undef for these cases before we ever get to operation legalization where the cmov is created. But wanted to add these tests so we don't regress.
llvm-svn: 324409
Diffstat (limited to 'llvm/lib/ExecutionEngine')
0 files changed, 0 insertions, 0 deletions
