[llvm] [InstCombine] Improve bitfield addition (PR #77184)

[Yingwei Zheng via llvm-commits]

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@@ -3379,6 +3379,149 @@ Value *InstCombinerImpl::foldAndOrOfICmps(ICmpInst *LHS, ICmpInst *RHS,
   return foldAndOrOfICmpsUsingRanges(LHS, RHS, IsAnd);
 }
 
+struct BitFieldAddBitMask {
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dtcxzyw wrote:

Please add some comments for these structs.

https://github.com/llvm/llvm-project/pull/77184