Reapply "Adapt gcov to changes in CFE."

This reverts commit r348203 and reapplies D55085 with an additional
GCOV bugfix to make the change NFC for relative file paths in .gcno files.

Thanks to Ilya Biryukov for additional testing!

Original commit message:

    Update Diagnostic handling for changes in CFE.

    The clang frontend no longer emits the current working directory for
    DIFiles containing an absolute path in the filename: and will move the
    common prefix between current working directory and the file into the
    directory: component.

    https://reviews.llvm.org/D55085

llvm-svn: 348512

llvm/include/llvm/IR/DiagnosticInfo.h

@@ -340,7 +340,7 @@ private:
 };
 
 class DiagnosticLocation {
-  StringRef Filename;
+  DIFile *File = nullptr;
   unsigned Line = 0;
   unsigned Column = 0;
 
@@ -349,8 +349,11 @@ public:
   DiagnosticLocation(const DebugLoc &DL);
   DiagnosticLocation(const DISubprogram *SP);
 
-  bool isValid() const { return !Filename.empty(); }
-  StringRef getFilename() const { return Filename; }
+  bool isValid() const { return File; }
+  /// Return the full path to the file.
+  std::string getAbsolutePath() const;
+  /// Return the file name relative to the compilation directory.
+  StringRef getRelativePath() const;
   unsigned getLine() const { return Line; }
   unsigned getColumn() const { return Column; }
 };
@@ -375,9 +378,13 @@ public:
   const std::string getLocationStr() const;
 
   /// Return location information for this diagnostic in three parts:
-  /// the source file name, line number and column.
-  void getLocation(StringRef *Filename, unsigned *Line, unsigned *Column) const;
+  /// the relative source file path, line number and column.
+  void getLocation(StringRef &RelativePath, unsigned &Line,
+                   unsigned &Column) const;
 
+  /// Return the absolute path tot the file.
+  std::string getAbsolutePath() const;
+  
   const Function &getFunction() const { return Fn; }
   DiagnosticLocation getLocation() const { return Loc; }
 

llvm/lib/IR/DiagnosticInfo.cpp

@@ -33,9 +33,10 @@
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/Path.h"
 #include "llvm/Support/Regex.h"
-#include "llvm/Support/raw_ostream.h"
 #include "llvm/Support/ScopedPrinter.h"
+#include "llvm/Support/raw_ostream.h"
 #include <atomic>
 #include <cassert>
 #include <memory>
@@ -106,7 +107,7 @@ void DiagnosticInfoPGOProfile::print(DiagnosticPrinter &DP) const {
 DiagnosticLocation::DiagnosticLocation(const DebugLoc &DL) {
   if (!DL)
     return;
-  Filename = DL->getFilename();
+  File = DL->getFile();
   Line = DL->getLine();
   Column = DL->getColumn();
 }
@@ -114,17 +115,36 @@ DiagnosticLocation::DiagnosticLocation(const DebugLoc &DL) {
 DiagnosticLocation::DiagnosticLocation(const DISubprogram *SP) {
   if (!SP)
     return;
-  Filename = SP->getFilename();
+  
+  File = SP->getFile();
   Line = SP->getScopeLine();
   Column = 0;
 }
 
-void DiagnosticInfoWithLocationBase::getLocation(StringRef *Filename,
-                                                 unsigned *Line,
-                                                 unsigned *Column) const {
-  *Filename = Loc.getFilename();
-  *Line = Loc.getLine();
-  *Column = Loc.getColumn();
+StringRef DiagnosticLocation::getRelativePath() const {
+  return File->getFilename();
+}
+
+std::string DiagnosticLocation::getAbsolutePath() const {
+  StringRef Name = File->getFilename();
+  if (sys::path::is_absolute(Name))
+    return Name;
+
+  SmallString<128> Path;
+  sys::path::append(Path, File->getDirectory(), Name);
+  return sys::path::remove_leading_dotslash(Path).str();
+}
+
+std::string DiagnosticInfoWithLocationBase::getAbsolutePath() const {
+  return Loc.getAbsolutePath();
+}
+
+void DiagnosticInfoWithLocationBase::getLocation(StringRef &RelativePath,
+                                                 unsigned &Line,
+                                                 unsigned &Column) const {
+  RelativePath = Loc.getRelativePath();
+  Line = Loc.getLine();
+  Column = Loc.getColumn();
 }
 
 const std::string DiagnosticInfoWithLocationBase::getLocationStr() const {
@@ -132,7 +152,7 @@ const std::string DiagnosticInfoWithLocationBase::getLocationStr() const {
   unsigned Line = 0;
   unsigned Column = 0;
   if (isLocationAvailable())
-    getLocation(&Filename, &Line, &Column);
+    getLocation(Filename, Line, Column);
   return (Filename + ":" + Twine(Line) + ":" + Twine(Column)).str();
 }
 
@@ -399,7 +419,7 @@ template <> struct MappingTraits<DiagnosticLocation> {
   static void mapping(IO &io, DiagnosticLocation &DL) {
     assert(io.outputting() && "input not yet implemented");
 
-    StringRef File = DL.getFilename();
+    StringRef File = DL.getRelativePath();
     unsigned Line = DL.getLine();
     unsigned Col = DL.getColumn();
 

llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp

@@ -180,6 +180,21 @@ static StringRef getFunctionName(const DISubprogram *SP) {
   return SP->getName();
 }
 
+/// Extract a filename for a DISubprogram.
+///
+/// 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.
+SmallString<128> getFilename(const DISubprogram *SP) {
+  SmallString<128> Path;
+  StringRef RelPath = SP->getFilename();
+  if (sys::fs::exists(RelPath))
+    Path = RelPath;
+  else
+    sys::path::append(Path, SP->getDirectory(), SP->getFilename());
+  return Path;
+}
+
 namespace {
   class GCOVRecord {
    protected:
@@ -256,7 +271,7 @@ namespace {
     }
 
    private:
-    StringRef Filename;
+    std::string Filename;
     SmallVector<uint32_t, 32> Lines;
   };
 
@@ -377,8 +392,9 @@ namespace {
 
     void writeOut() {
       writeBytes(FunctionTag, 4);
+      SmallString<128> Filename = getFilename(SP);
       uint32_t BlockLen = 1 + 1 + 1 + lengthOfGCOVString(getFunctionName(SP)) +
-                          1 + lengthOfGCOVString(SP->getFilename()) + 1;
+                          1 + lengthOfGCOVString(Filename) + 1;
       if (UseCfgChecksum)
         ++BlockLen;
       write(BlockLen);
@@ -387,7 +403,7 @@ namespace {
       if (UseCfgChecksum)
         write(CfgChecksum);
       writeGCOVString(getFunctionName(SP));
-      writeGCOVString(SP->getFilename());
+      writeGCOVString(Filename);
       write(SP->getLine());
 
       // Emit count of blocks.
@@ -466,7 +482,7 @@ bool GCOVProfiler::isFunctionInstrumented(const Function &F) {
   if (FilterRe.empty() && ExcludeRe.empty()) {
     return true;
   }
-  const StringRef Filename = F.getSubprogram()->getFilename();
+  SmallString<128> Filename = getFilename(F.getSubprogram());
   auto It = InstrumentedFiles.find(Filename);
   if (It != InstrumentedFiles.end()) {
     return It->second;
@@ -688,7 +704,8 @@ void 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();
-      Func.getBlock(&EntryBlock).getFile(SP->getFilename()).addLine(Line);
+      auto Filename = getFilename(SP);
+      Func.getBlock(&EntryBlock).getFile(Filename).addLine(Line);
 
       for (auto &BB : F) {
         GCOVBlock &Block = Func.getBlock(&BB);
@@ -719,7 +736,7 @@ void GCOVProfiler::emitProfileNotes() {
           if (SP != getDISubprogram(Loc.getScope()))
             continue;
 
-          GCOVLines &Lines = Block.getFile(SP->getFilename());
+          GCOVLines &Lines = Block.getFile(Filename);
           Lines.addLine(Loc.getLine());
         }
         Line = 0;

llvm/test/CodeGen/AMDGPU/vi-removed-intrinsics.ll

@@ -17,7 +17,7 @@ attributes #1 = { nounwind }
 !llvm.module.flags = !{!2, !3}
 
 !0 = distinct !DICompileUnit(language: DW_LANG_OpenCL, file: !1, isOptimized: false, runtimeVersion: 0, emissionKind: NoDebug)
-!1 = !DIFile(filename: "foo.cl", directory: "/dev/null")
+!1 = !DIFile(filename: "foo.cl", directory: ".")
 !2 = !{i32 2, !"Dwarf Version", i32 4}
 !3 = !{i32 2, !"Debug Info Version", i32 3}
 !4 = !DILocation(line: 1, column: 42, scope: !5)