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

[Nikita Popov via llvm-commits]

================
@@ -540,6 +540,10 @@ enum GetElementPtrOptionalFlags {
   GEP_NUW = 2,
 };
 
+/// PossiblySameSignOptionalFlags - Flags for serializing
+/// PossiblySameSignInst's SubclassOptionalData contents.
+enum PossiblySameSignInstOptionalFlags { PSSI_SAME_SIGN = 0 };
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nikic wrote:

```suggestion
enum ICmpOptionalFlags { ICMP_SAME_SIGN = 0 };
```

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