[clang] [flang] Add IR Profile-Guided Optimization (IR PGO) support to the Flang compiler (PR #136098)

[Tarun Prabhu via cfe-commits]

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@@ -148,6 +148,55 @@ class CodeGenOptions : public CodeGenOptionsBase {
   /// OpenMP is enabled.
   using DoConcurrentMappingKind = flangomp::DoConcurrentMappingKind;
 
+  enum ProfileInstrKind {
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tarunprabhu wrote:

Can this enum be shared between `clang` and `flang`? There is precedent for doing this, for example with the `VectorLibrary` enum. That was moved to `llvm/include/llvm/Frontend/Driver/CodeGenOptions.h`. We could consider doing the same for this.

https://github.com/llvm/llvm-project/pull/136098