[PATCH] D64707: [x86] try harder to form LEA from ADD to avoid flag conflicts (PR40483)

[Noel Grandin via Phabricator via llvm-commits]

grandinj added inline comments.


================
Comment at: llvm/lib/Target/X86/X86ISelDAGToDAG.cpp:2487
+    };
+    if (isMathWithFlags(N.getOperand(0)) && isMathWithFlags(N.getOperand(1)))
+      Complexity++;
----------------
spatel wrote:
> 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.
Sounds reasonable (noting that I am just a bystander here, not a real reviewer)


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  https://reviews.llvm.org/D64707/new/

https://reviews.llvm.org/D64707