[llvm] [IR] Add `samesign` flag to icmp instruction (PR #111419)

[via llvm-commits]

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@@ -1033,6 +1033,28 @@ class CmpInst : public Instruction {
   }
 };
 
+/// An icmp instruction, which can be marked as "samesign", indicating that the
+/// two operands have the same sign. This means that we can convert "slt/ult"
+/// to "ult", which enables more optimizations.
+class PossiblySameSignInst : public CmpInst {
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elhewaty wrote:

> I'd prefer to add hasSameSign/setSameSame directly to ICmpInst, instead of having the PossiblySameSignInst wrapper.

@nikic  Is there a specific reason for this?

https://github.com/llvm/llvm-project/pull/111419