[llvm][clang] Use the VFS in GCOVProfilerPass (#161260)

This PR starts using the correct VFS in `GCOVProfilerPass` instead of
using the real FS directly. This matches compiler's behavior for other
input files.

clang/lib/CodeGen/BackendUtil.cpp

@@ -1090,8 +1090,9 @@ void EmitAssemblyHelper::RunOptimizationPipeline(
     if (std::optional<GCOVOptions> Options =
             getGCOVOptions(CodeGenOpts, LangOpts))
       PB.registerPipelineStartEPCallback(
-          [Options](ModulePassManager &MPM, OptimizationLevel Level) {
-            MPM.addPass(GCOVProfilerPass(*Options));
+          [this, Options](ModulePassManager &MPM, OptimizationLevel Level) {
+            MPM.addPass(
+                GCOVProfilerPass(*Options, CI.getVirtualFileSystemPtr()));
           });
     if (std::optional<InstrProfOptions> Options =
             getInstrProfOptions(CodeGenOpts, LangOpts))

llvm/include/llvm/Transforms/Instrumentation/GCOVProfiler.h

@@ -20,11 +20,15 @@ namespace llvm {
 /// The gcov-style instrumentation pass
 class GCOVProfilerPass : public PassInfoMixin<GCOVProfilerPass> {
 public:
-  GCOVProfilerPass(const GCOVOptions &Options = GCOVOptions::getDefault()) : GCOVOpts(Options) { }
+  GCOVProfilerPass(
+      const GCOVOptions &Options = GCOVOptions::getDefault(),
+      IntrusiveRefCntPtr<vfs::FileSystem> VFS = vfs::getRealFileSystem())
+      : GCOVOpts(Options), VFS(std::move(VFS)) {}
   LLVM_ABI PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
 
 private:
   GCOVOptions GCOVOpts;
+  IntrusiveRefCntPtr<vfs::FileSystem> VFS;
 };
 
 } // namespace llvm

llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp

@@ -35,6 +35,7 @@
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/Regex.h"
+#include "llvm/Support/VirtualFileSystem.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Transforms/Instrumentation/CFGMST.h"
 #include "llvm/Transforms/Instrumentation/GCOVProfiler.h"
@@ -92,8 +93,10 @@ class GCOVFunction;
 
 class GCOVProfiler {
 public:
-  GCOVProfiler() : GCOVProfiler(GCOVOptions::getDefault()) {}
-  GCOVProfiler(const GCOVOptions &Opts) : Options(Opts) {}
+  GCOVProfiler()
+      : GCOVProfiler(GCOVOptions::getDefault(), *vfs::getRealFileSystem()) {}
+  GCOVProfiler(const GCOVOptions &Opts, vfs::FileSystem &VFS)
+      : Options(Opts), VFS(VFS) {}
   bool
   runOnModule(Module &M, function_ref<BlockFrequencyInfo *(Function &F)> GetBFI,
               function_ref<BranchProbabilityInfo *(Function &F)> GetBPI,
@@ -110,6 +113,7 @@ public:
     os->write_zeros(4 - s.size() % 4);
   }
   void writeBytes(const char *Bytes, int Size) { os->write(Bytes, Size); }
+  vfs::FileSystem &getVirtualFileSystem() const { return VFS; }
 
 private:
   // Create the .gcno files for the Module based on DebugInfo.
@@ -166,6 +170,7 @@ private:
   std::vector<Regex> ExcludeRe;
   DenseSet<const BasicBlock *> ExecBlocks;
   StringMap<bool> InstrumentedFiles;
+  vfs::FileSystem &VFS;
 };
 
 struct BBInfo {
@@ -214,10 +219,10 @@ static StringRef getFunctionName(const DISubprogram *SP) {
 /// Prefer relative paths in the coverage notes. Clang also may split
 /// up absolute paths into a directory and filename component. When
 /// the relative path doesn't exist, reconstruct the absolute path.
-static SmallString<128> getFilename(const DIScope *SP) {
+static SmallString<128> getFilename(const DIScope *SP, vfs::FileSystem &VFS) {
   SmallString<128> Path;
   StringRef RelPath = SP->getFilename();
-  if (sys::fs::exists(RelPath))
+  if (VFS.exists(RelPath))
     Path = RelPath;
   else
     sys::path::append(Path, SP->getDirectory(), SP->getFilename());
@@ -357,7 +362,7 @@ namespace {
 
     void writeOut(uint32_t CfgChecksum) {
       write(GCOV_TAG_FUNCTION);
-      SmallString<128> Filename = getFilename(SP);
+      SmallString<128> Filename = getFilename(SP, P->getVirtualFileSystem());
       uint32_t BlockLen = 3 + wordsOfString(getFunctionName(SP));
       BlockLen += 1 + wordsOfString(Filename) + 4;
 
@@ -455,7 +460,7 @@ bool GCOVProfiler::isFunctionInstrumented(const Function &F) {
   if (FilterRe.empty() && ExcludeRe.empty()) {
     return true;
   }
-  SmallString<128> Filename = getFilename(F.getSubprogram());
+  SmallString<128> Filename = getFilename(F.getSubprogram(), VFS);
   auto It = InstrumentedFiles.find(Filename);
   if (It != InstrumentedFiles.end()) {
     return It->second;
@@ -467,7 +472,7 @@ bool GCOVProfiler::isFunctionInstrumented(const Function &F) {
   // Path can be
   // /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/bits/*.h so for
   // such a case we must get the real_path.
-  if (sys::fs::real_path(Filename, RealPath)) {
+  if (VFS.getRealPath(Filename, RealPath)) {
     // real_path can fail with path like "foo.c".
     RealFilename = Filename;
   } else {
@@ -524,9 +529,10 @@ std::string GCOVProfiler::mangleName(const DICompileUnit *CU,
   SmallString<128> Filename = CU->getFilename();
   sys::path::replace_extension(Filename, Notes ? "gcno" : "gcda");
   StringRef FName = sys::path::filename(Filename);
-  SmallString<128> CurPath;
-  if (sys::fs::current_path(CurPath))
+  ErrorOr<std::string> CWD = VFS.getCurrentWorkingDirectory();
+  if (!CWD)
     return std::string(FName);
+  SmallString<128> CurPath{*CWD};
   sys::path::append(CurPath, FName);
   return std::string(CurPath);
 }
@@ -554,7 +560,7 @@ bool GCOVProfiler::runOnModule(
 PreservedAnalyses GCOVProfilerPass::run(Module &M,
                                         ModuleAnalysisManager &AM) {
 
-  GCOVProfiler Profiler(GCOVOpts);
+  GCOVProfiler Profiler(GCOVOpts, *VFS);
   FunctionAnalysisManager &FAM =
       AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
 
@@ -789,7 +795,7 @@ bool GCOVProfiler::emitProfileNotes(
       // Add the function line number to the lines of the entry block
       // to have a counter for the function definition.
       uint32_t Line = SP->getLine();
-      auto Filename = getFilename(SP);
+      auto Filename = getFilename(SP, VFS);
 
       BranchProbabilityInfo *BPI = GetBPI(F);
       BlockFrequencyInfo *BFI = GetBFI(F);
@@ -881,7 +887,7 @@ bool GCOVProfiler::emitProfileNotes(
           if (SP != getDISubprogram(Scope))
             continue;
 
-          GCOVLines &Lines = Block.getFile(getFilename(Loc->getScope()));
+          GCOVLines &Lines = Block.getFile(getFilename(Loc->getScope(), VFS));
           Lines.addLine(Loc.getLine());
         }
         Line = 0;