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| author | Sanjay Patel <spatel@rotateright.com> | 2022-04-11 07:09:47 -0400 |
|---|---|---|
| committer | Sanjay Patel <spatel@rotateright.com> | 2022-04-11 07:44:58 -0400 |
| commit | 2ed15984b49a1af87be37ec8bd6ee3ab7f724767 (patch) | |
| tree | d308fa7929c340deaaee8637100719b72f931400 /llvm/lib/CodeGen/CodeGen.cpp | |
| parent | d6cf181a8df6a7925660b2332e3ab7dbcfd08145 (diff) | |
| download | llvm-2ed15984b49a1af87be37ec8bd6ee3ab7f724767.zip llvm-2ed15984b49a1af87be37ec8bd6ee3ab7f724767.tar.gz llvm-2ed15984b49a1af87be37ec8bd6ee3ab7f724767.tar.bz2 | |
[SDAG] try to reduce compare of funnel shift equal 0
fshl (or X, Y), X, C ==/!= 0 --> or (shl Y, C), X ==/!= 0
fshl X, (or X, Y), C ==/!= 0 --> or (srl Y, BW-C), X ==/!= 0
This is similar to an existing setcc-of-rotate fold, but the
matching requires more checks for the more general funnel op:
https://alive2.llvm.org/ce/z/Ab2jDd
We are effectively decomposing the funnel shift into logical
shifts, reassociating, and removing a shift.
This should get us the final improvements for x86-64 that were
originally shown in D111530
( https://github.com/llvm/llvm-project/issues/49541 );
x86-32 still shows some SHLD/SHRD, so the pattern is not
matching there yet.
Differential Revision: https://reviews.llvm.org/D122919
Diffstat (limited to 'llvm/lib/CodeGen/CodeGen.cpp')
0 files changed, 0 insertions, 0 deletions