[Clang] Provide default value for -fprofile-sample-use, -fprofile-auto

[mikolaj-pirog]

As in title. This matches the behavior of -fprofile-use, which when used without a path to the file, looks for default.profdata file in the current/supplied dir. Fixes #112391

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[llvmbot]

@llvm/pr-subscribers-clang-driver

@llvm/pr-subscribers-clang

Author: Mikołaj Piróg (mikolaj-pirog)

Changes

As in title. This matches the behavior of -fprofile-use, which when used without a path to the file, looks for default.profdata file in the current/supplied dir. Fixes #112391

---

Full diff: https://github.com/llvm/llvm-project/pull/112750.diff

1 Files Affected:

• (modified) clang/lib/Driver/ToolChains/Clang.cpp (+21)

diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 3fc39296f44281..2da8b604ebff62 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -594,6 +594,8 @@ static void addPGOAndCoverageFlags(const ToolChain &TC, Compilation &C,
         << PGOGenerateArg->getSpelling() << ProfileGenerateArg->getSpelling();
 
   auto *ProfileUseArg = getLastProfileUseArg(Args);
+  auto *ProfileSampleUseArg = Args.getLastArg(
+      options::OPT_fprofile_sample_use, options::OPT_fprofile_sample_use_EQ);
 
   if (PGOGenerateArg && ProfileUseArg)
     D.Diag(diag::err_drv_argument_not_allowed_with)
@@ -677,6 +679,25 @@ static void addPGOAndCoverageFlags(const ToolChain &TC, Compilation &C,
     }
   }
 
+  if (ProfileSampleUseArg) {
+    if ((ProfileSampleUseArg->getOption().matches(
+             options::OPT_fprofile_sample_use) ||
+         ProfileSampleUseArg->getOption().matches(
+             options::OPT_fprofile_sample_use_EQ))) {
+      SmallString<128> Path(ProfileSampleUseArg->getNumValues() == 0
+                                ? ""
+                                : ProfileSampleUseArg->getValue());
+      if (Path.empty() || llvm::sys::fs::is_directory(Path))
+        llvm::sys::path::append(Path, "default.profdata");
+
+      if (!llvm::sys::fs::exists(Path))
+        D.Diag(diag::err_drv_no_such_file) << Path;
+
+      CmdArgs.push_back(
+          Args.MakeArgString(Twine("-fprofile-sample-use=") + Path));
+    }
+  }
+
   bool EmitCovNotes = Args.hasFlag(options::OPT_ftest_coverage,
                                    options::OPT_fno_test_coverage, false) ||
                       Args.hasArg(options::OPT_coverage);

[mikolaj-pirog]

Pinging @MaskRay for review, I can't add reviewers in the dedicated gh section yet

[MaskRay]

Actually I think we should drop the accepted and ignored Flag form of -fprofile-sample-use and -fprofile-auto, which is misleading at the least. I have a pending patch, which I will upload at night.

For sample PGO, the profile file extension is usually .afdo, but I don't think it makes sense to have a default filename.

[mikolaj-pirog]

Actually I think we should drop the accepted and ignored Flag form of -fprofile-sample-use and -fprofile-auto, which is misleading at the least. I have a pending patch, which I will upload at night.

For sample PGO, the profile file extension is usually .afdo, but I don't think it makes sense to have a default filename.

I think this isn't the best solution, since it is inconsistent with the behavior of the -fprofile-use option. Why should -fprofile-use be accepted and -fprofile-sample-use rejected? TBH I think the whole looking for default filename isn't the best option, but to make things consistent it seems to easier to introduce this behavior for -fprofile-sample/auto-use rather than take it from -fprofile-use

[mikolaj-pirog]

Closing as #113528 fixed the issue