[llvm] [llvm-objdump] Add triple support to `mcpu=help` (PR #165661)

[Ruoyu Qiu via llvm-commits]

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@@ -3533,6 +3533,35 @@ commaSeparatedValues(const llvm::opt::InputArgList &InputArgs, int ID) {
   return Values;
 }
 
+static void mcpuHelp() {
+  std::string Error;
+  Triple DummyTriple;
+
+  if (!TripleName.empty())
+    DummyTriple.setTriple(TripleName);
+  else {
+    // If the target triple is derived from the files, we display help message
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cabbaken wrote:

Additionally, I noticed that when using `-d + --triple + object file`, the final output will be arm help message no matter what the `--triple` is.
This seems like unexpected behavior and was quite misleading me at first.

https://github.com/llvm/llvm-project/pull/165661