[llvm] [DAGCombiner][AMDGPU] Track signedness in ByteProviders (PR #65995)

[Matt Arsenault via llvm-commits]

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@@ -61,13 +66,17 @@ template <typename ISelOp> class ByteProvider {
   // DestOffset
   int64_t SrcOffset = 0;
 
+  // Tracks whether or not the byte is treated as a signed operand -- useful
+  // for arithmetic combines.
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arsenm wrote:

I'm not sure I understand what this means. The signededness only means anything in the context of the instruction producing or reading it. Is this talking about the unrelated bytes that aren't being tracked?

https://github.com/llvm/llvm-project/pull/65995