[llvm] [Exegesis][RISCV] Add RISCV support for llvm-exegesis (PR #89047)

[Min-Yih Hsu via llvm-commits]

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@@ -335,10 +357,32 @@ static std::vector<unsigned> getOpcodesOrDie(const LLVMState &State) {
   std::vector<unsigned> Result;
   Result.reserve(Pieces.size());
   for (const StringRef &OpcodeName : Pieces) {
-    if (unsigned Opcode = ResolveName(OpcodeName))
+    if (unsigned Opcode = ResolveName(OpcodeName)) {
       Result.push_back(Opcode);
-    else
+      continue;
+    }
+    // Not a known opcode name; should be an opcode name range.
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mshockwave wrote:

Could we implement the parsing logics here as a custom command line parser for `OpcodeName`? https://llvm.org/docs/CommandLine.html#writing-a-custom-parser

https://github.com/llvm/llvm-project/pull/89047