[PATCH] D107552: [InstCombine] Combine lshr of add that intends to get the carry as llvm.uadd.with.overflow

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added inline comments.


================
Comment at: llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp:1105
+    for (TruncInst *Trunc : Truncs) {
+      Trunc->replaceAllUsesWith(UAdd);
+    }
----------------
craig.topper wrote:
> craig.topper wrote:
> > We probably need to do something here to schedule the dead truncates to revisited to remove them. But I'm not sure.
> I think this should use InstCombinerImpl::replaceInstUsesWith rather than Instruction::replaceAllUsesWith. Then I think it should call InstCombinerImpl::eraseInstFromFunction.
> 
> @spatel or @lebedev.ri does that sound right?
Right, the pass-specific call should be used.
I don't think we need to call `eraseInstFromFunction()` explcitly,
that should be handled automatically once you return non-null from this function.
Generally, i would think not having an intermediate vector would be better, but not sure.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D107552/new/

https://reviews.llvm.org/D107552