[PATCH] D57401: [DAGCombiner] fold add/sub with bool operand based on target's boolean contents

Sanjay Patel via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Wed Jan 30 06:31:26 PST 2019


spatel marked an inline comment as done.
spatel added inline comments.


================
Comment at: test/CodeGen/PowerPC/select_const.ll:268-269
 }
 
+; FIXME: This could be addi 3, 3, 42
+
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efriedma wrote:
> This looks like a missing target-independent pattern; we're ending up with something like "42 - (cond & 1)" instead of "42 + cond".
Yes, we're missing a generic combine here, but I thought we had the 1 you mentioned. Ie, if I saw it correctly while glancing at it the first time, this requires an AssertSext to uncover. 

I'll have a closer look to avoid this, but I figured the other diffs were more realistic, so we might want to commit this patch first if it looks reasonable.


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