Fix and reapply IR PGO support for Flang (#142892)

This PR resubmits the changes from #136098, which was previously
reverted due to a build failure during the linking stage:

```
undefined reference to `llvm::DebugInfoCorrelate'  
undefined reference to `llvm::ProfileCorrelate'
```

The root cause was that `llvm/lib/Frontend/Driver/CodeGenOptions.cpp`
references symbols from the `Instrumentation` component, but the
`LINK_COMPONENTS` in the `llvm/lib/Frontend/CMakeLists.txt` for
`LLVMFrontendDriver` did not include it. As a result, linking failed in
configurations where these components were not transitively linked.

### Fix:

This updated patch explicitly adds `Instrumentation` to
`LINK_COMPONENTS` in the relevant `llvm/lib/Frontend/CMakeLists.txt`
file to ensure the required symbols are properly resolved.

---------

Co-authored-by: ict-ql <168183727+ict-ql@users.noreply.github.com>
Co-authored-by: Chyaka <52224511+liliumshade@users.noreply.github.com>
Co-authored-by: Tarun Prabhu <tarunprabhu@gmail.com>

1 files changed, 1 insertions, 8 deletions

diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index 88b3a49..7e0a3cf 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -124,17 +124,10 @@ namespace clang {
 extern llvm::cl::opt<bool> ClSanitizeGuardChecks;
 }
 
-// Default filename used for profile generation.
-static std::string getDefaultProfileGenName() {
-  return DebugInfoCorrelate || ProfileCorrelate != InstrProfCorrelator::NONE
-             ? "default_%m.proflite"
-             : "default_%m.profraw";
-}
-
 // Path and name of file used for profile generation
 static std::string getProfileGenName(const CodeGenOptions &CodeGenOpts) {
   std::string FileName = CodeGenOpts.InstrProfileOutput.empty()
-                             ? getDefaultProfileGenName()
+                             ? llvm::driver::getDefaultProfileGenName()
                              : CodeGenOpts.InstrProfileOutput;
   if (CodeGenOpts.ContinuousProfileSync)
     FileName = "%c" + FileName;