[PATCH] D112095: [x86] add special-case lowering for usubsat for pre-SSE4

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon accepted this revision.
RKSimon added a comment.
This revision is now accepted and ready to land.

LGTM



================
Comment at: llvm/test/CodeGen/X86/psubus.ll:31
 
 ; This is logically equivalent to the above.
 
----------------
Please can you add a comment explaining the fold:
```
; usubsat X, (1 << (BW-1)) --> (X ^ (1 << (BW-1))) & (ashr X, (BW-1))
```


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  https://reviews.llvm.org/D112095/new/

https://reviews.llvm.org/D112095