Use -fdebug-compilation-dir to form absolute paths in coverage mappings

[rnk]

Summary

This allows users to explicitly request relative paths with
-fdebug-compilation-dir ..

Fixes PR43614

[vsk]

Thanks, lgtm!

In PR43614 I mentioned adding an extra argument to llvm-cov to specify the base directory. On second thought, the existing -path-equivalence option should make that unnecessary.

clang/test/CoverageMapping/debug-dir.cpp

15

Does the "[^/]" check work on Windows, or is something like "[^/\\]" necessary?

[rnk]

clang/test/CoverageMapping/debug-dir.cpp

15

It is insufficient on Windows, but the full string looks like "\01\0Dfoobar\5Cdebug-dir.cpp, so [^/\\] would match the \0D. If the \0D is the same across all systems, I could match that and it would suffice. As is, this will catch absolute paths on Unix only, which could be enough coverage.

[liaoyuke]

In D68733#1702609, @vsk wrote:

Thanks, lgtm!

In PR43614 I mentioned adding an extra argument to llvm-cov to specify the base directory. On second thought, the existing -path-equivalence option should make that unnecessary.

I just tested out this CL, and I don't think it's working correctly (even with -path-equivalence flag)

The command I used is:
/usr/local/google/home/liaoyuke/chromium/src/third_party/llvm-build/Release+Asserts/bin/llvm-cov show -format=html -output-dir=/usr/local/google/home/liaoyuke/chromium/src/out/output_test_path -instr-profile=/usr/local/google/home/liaoyuke/chromium/src/out/output_test_path/linux/coverage.profdata -path-equivalence=../..,/usr/local/google/home/liaoyuke/chromium/src out/coverage/base_unittests

And the generated html files are as following: https://imgur.com/gallery/dlgQXhy
Specifically, there are a few problems:

1. The index.html files still show relative paths, but I'm expecting an absolute path given that I passed in the -path-equivalence flag.
2. The file level line-by-line view's styling is completely off, there is no table and no highlights.
3. I also tried the "llvm-cov export" command, it seems that it doesn't respect the -path-equivalence flag at all, and the produced json still uses relative paths in them. (I'm guessing the root cause is the same as 1)

Am I using the -path-equivalence flag correctly? And any other suggestions to work this around?

[vsk]

In D68733#1723734, @liaoyuke wrote:

In D68733#1702609, @vsk wrote:

Thanks, lgtm!

In PR43614 I mentioned adding an extra argument to llvm-cov to specify the base directory. On second thought, the existing -path-equivalence option should make that unnecessary.

I just tested out this CL, and I don't think it's working correctly (even with -path-equivalence flag)

The command I used is:
/usr/local/google/home/liaoyuke/chromium/src/third_party/llvm-build/Release+Asserts/bin/llvm-cov show -format=html -output-dir=/usr/local/google/home/liaoyuke/chromium/src/out/output_test_path -instr-profile=/usr/local/google/home/liaoyuke/chromium/src/out/output_test_path/linux/coverage.profdata -path-equivalence=../..,/usr/local/google/home/liaoyuke/chromium/src out/coverage/base_unittests

Hi @liaoyuke, thanks for trying this out.

And the generated html files are as following: https://imgur.com/gallery/dlgQXhy
Specifically, there are a few problems:

1. The index.html files still show relative paths, but I'm expecting an absolute path given that I passed in the -path-equivalence flag.

I have a question about the option you passed: -path-equivalence=../..,<local-path>. If I read this patch correctly, the final coverage mapping will contain (what looks like) absolute paths which are just rooted at the debug compilation dir. So, why remap ../.. instead of <debug-compilation-dir>?

2. The file level line-by-line view's styling is completely off, there is no table and no highlights.

Interesting. Have you confirmed that the issue does not reproduce without -fdebug-compilation-dir/-path-equivalence?

3. I also tried the "llvm-cov export" command, it seems that it doesn't respect the -path-equivalence flag at all, and the produced json still uses relative paths in them. (I'm guessing the root cause is the same as 1)

Hm, actually this could be a bug in llvm-cov. Reading through the source, it looks like the path remapping is done before the exporter is created, but perhaps I've missed something.

Am I using the -path-equivalence flag correctly? And any other suggestions to work this around?

clang/lib/CodeGen/CoverageMappingGen.h

 class CoverageMappingModuleGen {
   CodeGenModule &CGM;
   CoverageSourceInfo &SourceInfo;
   llvm::SmallDenseMap<const FileEntry *, unsigned, 8> FileEntries;
   std::vector<llvm::Constant *> FunctionRecords;
   std::vector<llvm::Constant *> FunctionNames;
   llvm::StructType *FunctionRecordTy;
   std::vector<std::string> CoverageMappings;
+  SmallString<256> CWD;
+
+  /// Make the filename absolute, remove dots, and normalize slashes to local
+  /// path style.
+  std::string normalizeFilename(StringRef Filename);
 
 public:
-  CoverageMappingModuleGen(CodeGenModule &CGM, CoverageSourceInfo &SourceInfo)
-      : CGM(CGM), SourceInfo(SourceInfo), FunctionRecordTy(nullptr) {}
+  CoverageMappingModuleGen(CodeGenModule &CGM, CoverageSourceInfo &SourceInfo);
 
   CoverageSourceInfo &getSourceInfo() const {
     return SourceInfo;
   }
 
   /// Add a function's coverage mapping record to the collection of the
   /// function mapping records.
   void addFunctionMappingRecord(llvm::GlobalVariable *FunctionName,

clang/lib/CodeGen/CoverageMappingGen.cpp

 };
 
 std::string getCoverageSection(const CodeGenModule &CGM) {
   return llvm::getInstrProfSectionName(
       llvm::IPSK_covmap,
       CGM.getContext().getTargetInfo().getTriple().getObjectFormat());
 }
 
-std::string normalizeFilename(StringRef Filename) {
-  llvm::SmallString<256> Path(Filename);
-  llvm::sys::fs::make_absolute(Path);
-  llvm::sys::path::remove_dots(Path, /*remove_dot_dot=*/true);
-  return Path.str().str();
-}
-
 } // end anonymous namespace
 
 static void dump(llvm::raw_ostream &OS, StringRef FunctionName,
                  ArrayRef<CounterExpression> Expressions,
                  ArrayRef<CounterMappingRegion> Regions) {
   OS << FunctionName << ":\n";
   CounterMappingContext Ctx(Expressions);
   for (const auto &R : Regions) {
OS << "File " << R.FileID << ", " << R.LineStart << ":" << R.ColumnStart
        << " -> " << R.LineEnd << ":" << R.ColumnEnd << " = ";
     Ctx.dump(R.Count, OS);
     if (R.Kind == CounterMappingRegion::ExpansionRegion)
       OS << " (Expanded file = " << R.ExpandedFileID << ")";
     OS << "\n";
   }
 }
 
+CoverageMappingModuleGen::CoverageMappingModuleGen(
+    CodeGenModule &CGM, CoverageSourceInfo &SourceInfo)
+    : CGM(CGM), SourceInfo(SourceInfo), FunctionRecordTy(nullptr) {
+  // Honor -fdebug-compilation-dir in paths in coverage data. Otherwise, use the
+  // regular working directory when normalizing paths.
+  if (!CGM.getCodeGenOpts().DebugCompilationDir.empty())
+    CWD = CGM.getCodeGenOpts().DebugCompilationDir;
+  else
+    llvm::sys::fs::current_path(CWD);
+}
+
+std::string CoverageMappingModuleGen::normalizeFilename(StringRef Filename) {
+  llvm::SmallString<256> Path(Filename);
+  llvm::sys::fs::make_absolute(CWD, Path);
+  llvm::sys::path::remove_dots(Path, /*remove_dot_dot=*/true);
+  return Path.str().str();
+}
+
 void CoverageMappingModuleGen::addFunctionMappingRecord(
     llvm::GlobalVariable *NamePtr, StringRef NameValue, uint64_t FuncHash,
     const std::string &CoverageMapping, bool IsUsed) {
   llvm::LLVMContext &Ctx = CGM.getLLVMContext();
   if (!FunctionRecordTy) {
 #define COVMAP_FUNC_RECORD(Type, LLVMType, Name, Init) LLVMType,
     llvm::Type *FunctionRecordTypes[] = {
       #include "llvm/ProfileData/InstrProfData.inc"

clang/test/CoverageMapping/debug-dir.cpp

+// %s expands to an absolute path, so to test relative paths we need to create a
+// clean directory, put the source there, and cd into it.
+// RUN: rm -rf %t
+// RUN: mkdir -p %t/foobar
+// RUN: cd %t
+// RUN: cp %s foobar/debug-dir.cpp
+
+// RUN: %clang_cc1 -fprofile-instrument=clang -fcoverage-mapping -emit-llvm -main-file-name debug-dir.cpp foobar/debug-dir.cpp  -o - | FileCheck -check-prefix=ABSOLUTE %s
+//
+// ABSOLUTE: @__llvm_coverage_mapping = {{.*"\\01.*clang.*test.*CoverageMapping.*.*foobar.*debug-dir\.cpp}}
+
+// RUN: %clang_cc1 -fprofile-instrument=clang -fcoverage-mapping -emit-llvm -main-file-name debug-dir.cpp foobar/debug-dir.cpp -fdebug-compilation-dir . -o - | FileCheck -check-prefix=RELATIVE %s
+//
+// RELATIVE: @__llvm_coverage_mapping = {{.*"\\01[^/]*foobar.*debug-dir\.cpp}}
+
+void f1() {}