[llvm] [TableGen] More generically handle tied source operands in CompressInstEmitter. (PR #146183)

[Rahul Joshi via llvm-commits]

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@@ -290,6 +285,28 @@ void CompressInstEmitter::addDagOperandMapping(const Record *Rec,
       } else {
         llvm_unreachable("Unhandled CompressPat argument type!");
       }
+
+      // Create a mapping between the operand name in the Dag (e.g. $rs1) and
+      // its index in the list of Dag operands and check that operands with the
+      // same name have the same type. For example in 'C_ADD $rs1, $rs2' we
+      // generate the mapping $rs1 --> 0, $rs2 ---> 1. If the operand appears
+      // twice in the (tied) same Dag we use the last occurrence for indexing.
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jurahul wrote:

suggestion: If the operand appears twice in the same Dag (i.e., tied)? 
Or something similar, the current (tied) seems misplaced.

https://github.com/llvm/llvm-project/pull/146183