[llvm] [CodeGen] Add preliminary plumbing for `samesign` flag (PR #112354)

[via llvm-commits]

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@@ -3640,6 +3640,10 @@ void SelectionDAGBuilder::visitICmp(const ICmpInst &I) {
   SDValue Op2 = getValue(I.getOperand(1));
   ISD::CondCode Opcode = getICmpCondCode(predicate);
 
+  SDNodeFlags Flags;
+  Flags.setSameSign(I.hasSameSign());
+  SelectionDAG::FlagInserter FlagsInserter(DAG, Flags);
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goldsteinn wrote:

I think this needs to be below the possible `getPtrExtOrTrunc` below.

https://github.com/llvm/llvm-project/pull/112354