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

[via llvm-commits]

================
@@ -5482,6 +5482,8 @@ Error BitcodeReader::parseFunctionBody(Function *F) {
         if (!CmpInst::isIntPredicate(PredVal))
           return error("Invalid icmp predicate");
         I = new ICmpInst(PredVal, LHS, RHS);
+        if (Record[OpNum] & (1 << bitc::PSSI_SAME_SIGN))
+          cast<ICmpInst>(I)->setSameSign(true);
----------------
elhewaty wrote:

@nikic  I am working on it now. but I don't fully understand why we should record length.
can you please give a brief explanation of what the record does? 

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