[PATCH] D64707: [x86] try harder to form LEA from ADD to avoid flag conflicts (PR40483)
Sanjay Patel via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Sun Jul 14 13:00:08 PDT 2019
spatel marked an inline comment as done.
spatel added inline comments.
================
Comment at: llvm/lib/Target/X86/X86ISelDAGToDAG.cpp:2487
+ };
+ if (isMathWithFlags(N.getOperand(0)) && isMathWithFlags(N.getOperand(1)))
+ Complexity++;
----------------
grandinj wrote:
> Should this not be an || condition ?
It could be || (and I tried that initially), but I saw possible regressions (missed load folding) with that logic.
Given that this is a heuristic, it's hard to determine statically when it will be profitable.
Ok if I add a TODO comment about extending this in a follow-up patch? If we can recover the load folding, I agree that using || would be better.
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https://reviews.llvm.org/D64707/new/
https://reviews.llvm.org/D64707
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