[clang] [llvm] [InstrPGO] Instrument sampling profile based cold function (PR #109837)

[Ellis Hoag via cfe-commits]

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@@ -649,6 +649,24 @@ static void addPGOAndCoverageFlags(const ToolChain &TC, Compilation &C,
     }
   }
 
+  if (auto *ColdFuncCoverageArg = Args.getLastArg(
+          options::OPT_fprofile_generate_cold_function_coverage,
+          options::OPT_fprofile_generate_cold_function_coverage_EQ)) {
+    SmallString<128> Path(
+        ColdFuncCoverageArg->getOption().matches(
+            options::OPT_fprofile_generate_cold_function_coverage_EQ)
+            ? ColdFuncCoverageArg->getValue()
+            : "");
+    llvm::sys::path::append(Path, "default_%m.profraw");
+    CmdArgs.push_back("-mllvm");
+    CmdArgs.push_back(Args.MakeArgString(
+        Twine("--instrument-sample-cold-function-path=") + Path));
+    CmdArgs.push_back("-mllvm");
+    CmdArgs.push_back("--instrument-cold-function-coverage");
+    CmdArgs.push_back("-mllvm");
+    CmdArgs.push_back("--pgo-function-entry-coverage");
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ellishg wrote:

You probably want to add a driver test case for this change like
https://github.com/llvm/llvm-project/blob/2f4327294dccc27fc9d5febe71196f6f854d66ff/clang/test/Driver/fcs-profile-generate.c#L1-L4

https://github.com/llvm/llvm-project/pull/109837