[clang] Move `-fprofile-instrument-use-path=` check to driver (#159667)

The frontend currently opens the path provided via
`-fprofile-instrument-use-path=` to learn the kind of the
instrumentation data and set the `CodeGenOptions::ProfileUse` value.
This happens during command-line parsing, where we don't have a
correctly configured VFS yet, so the behavior is quite different from
all other frontend inputs. We need to move this logic out of the
frontend command line parsing logic somewhere where we do have the
configured VFS.

The complication is that the `ProfileUse` flag is being used to set
preprocessor macros, and there isn't a great place between command line
parsing and preprocessor initialization to perform this logic.

This PR solves the issue by deducing the kind of instrumentation data
right in the driver and then passing it via a new flag to the frontend.
This shouldn't change observable behavior of Clang on the driver level,
and only affects the frontend command line interface, which is an
implementation detail anyway.

1 files changed, 9 insertions, 4 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index f6f7f22..8d019d4 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -493,10 +493,15 @@ CodeGenModule::CodeGenModule(ASTContext &C,
     auto ReaderOrErr = llvm::IndexedInstrProfReader::create(
         CodeGenOpts.ProfileInstrumentUsePath, *FS,
         CodeGenOpts.ProfileRemappingFile);
-    // We're checking for profile read errors in CompilerInvocation, so if
-    // there was an error it should've already been caught. If it hasn't been
-    // somehow, trip an assertion.
-    assert(ReaderOrErr);
+    if (auto E = ReaderOrErr.takeError()) {
+      unsigned DiagID = Diags.getCustomDiagID(
+          DiagnosticsEngine::Error, "Error in reading profile %0: %1");
+      llvm::handleAllErrors(std::move(E), [&](const llvm::ErrorInfoBase &EI) {
+        Diags.Report(DiagID)
+            << CodeGenOpts.ProfileInstrumentUsePath << EI.message();
+      });
+      return;
+    }
     PGOReader = std::move(ReaderOrErr.get());
   }