[llvm] [AMDGPU][GlobalISel] Fold zext(carry) into add/sub-with-carry (PR #224093)

[Matt Arsenault via llvm-commits]

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@@ -393,6 +398,35 @@ bool AMDGPUPostLegalizerCombinerImpl::matchCombine_s_mul_u64(
   return false;
 }
 
+bool AMDGPUPostLegalizerCombinerImpl::isCarryOut(Register Reg) const {
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arsenm wrote:

Matchable in tablegen 

https://github.com/llvm/llvm-project/pull/224093