[PATCH] D81375: [InstCombine] Simplify boolean Phis with const inputs using CFG
Max Kazantsev via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Wed Jun 17 01:34:54 PDT 2020
mkazantsev added a comment.
In D81375#2096608 <https://reviews.llvm.org/D81375#2096608>, @nikic wrote:
> Why is this being limited to phis used in ret and br?
There is a problem with selects:
if (cond)
/ \
... ...
\ /
p = phi [true] [false]
s = select p, v1, v2
The way how InstCombine currently works will turn it into
if (cond)
/ \
... ...
\ /
s = select cond, v1, v2
instead of
if (cond)
/ \
... ...
\ /
s = phi [v1] [v2]
This limitation is temporarily, until we know how to fix this (and maybe other similar) cases.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D81375/new/
https://reviews.llvm.org/D81375
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