The InstructionSelector on x64 was missing the ability to properly match
comparisons of memory operands with zero, i.e. it used to turn something
like
Word32Equal(Load[Uint8](o, i), Int32Constant(0))
into
movzbl reg, [o,i]
cmp 0, reg
even requiring a temporary register. Now with this change it generates
the proper
cmpb [o,i], 0
sequence.
R=sigurds@chromium.org
Bug: v8:8238
Change-Id: I52a71bbf95c85e11cb275f0f4a5726a6873cde95
Reviewed-on: https://chromium-review.googlesource.com/c/1281342
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56677}
1e586c3c70