[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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@@ -130,6 +133,20 @@ static bool saveMLIRTempFile(const CompilerInvocation &ci,
 // Custom BeginSourceFileAction
 //===----------------------------------------------------------------------===//
 
+
+static llvm::cl::opt<llvm::PGOOptions::ColdFuncOpt> ClPGOColdFuncAttr(
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tarunprabhu wrote:

This was added in #89298 and is marked with a TODO in `clang/lib/CodeGen/BackendUtil.cpp` saying that it should be removed once a proper frontend driver option is added. @kiranchandramohan , Do we want to be replicating something experimental like this in flang as well?

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