[llvm] [tools][llc] Add `--save-stats` option (PR #163967)

[Jon Roelofs via llvm-commits]

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@@ -355,6 +366,50 @@ static std::unique_ptr<ToolOutputFile> GetOutputStream(const char *TargetName,
   return FDOut;
 }
 
+static int MaybeEnableStats() {
+  if (SaveStats.getNumOccurrences() > 0) {
+    if (SaveStats.empty() || SaveStats == "cwd" || SaveStats == "obj") {
+      llvm::EnableStatistics(false);
+    } else {
+      WithColor::error(errs(), "llc")
+          << "Invalid --save-stats value: " << SaveStats
+          << ", must be empty, 'cwd' or 'obj'\n";
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jroelofs wrote:

I _think_ if you make the `cl::opt` one of the enum-flavored ones, you get this sort of error handling for free.

https://github.com/llvm/llvm-project/pull/163967