Take DW_AT_comp_dir from $PWD when it's present and starts with a '/'. This is

closer to what GCC does, except that GCC also checks that the inodes for $PWD
and '.' match.

llvm-svn: 142633

clang/include/clang/Driver/CC1Options.td

@@ -110,6 +110,8 @@ def disable_llvm_verifier : Flag<"-disable-llvm-verifier">,
   HelpText<"Don't run the LLVM IR verifier pass">;
 def disable_red_zone : Flag<"-disable-red-zone">,
   HelpText<"Do not emit code that uses the red zone.">;
+def fdebug_compilation_dir : Separate<"-fdebug-compilation-dir">,
+  HelpText<"The compilation directory to embed in the debug info.">;
 def dwarf_debug_flags : Separate<"-dwarf-debug-flags">,
   HelpText<"The string to embed in the Dwarf debug flags record.">;
 def fforbid_guard_variables : Flag<"-fforbid-guard-variables">,

clang/include/clang/Frontend/CodeGenOptions.h

@@ -115,6 +115,9 @@ public:
   /// Enable additional debugging information.
   std::string DebugPass;
 
+  /// The string to embed in debug information as the current working directory.
+  std::string DebugCompilationDir;
+
   /// The string to embed in the debug information for the compile unit, if
   /// non-empty.
   std::string DwarfDebugFlags;

clang/lib/CodeGen/CGDebugInfo.cpp

@@ -250,6 +250,9 @@ unsigned CGDebugInfo::getColumnNumber(SourceLocation Loc) {
 }
 
 StringRef CGDebugInfo::getCurrentDirname() {
+  if (!CGM.getCodeGenOpts().DebugCompilationDir.empty())
+    return CGM.getCodeGenOpts().DebugCompilationDir;
+
   if (!CWDName.empty())
     return CWDName;
   llvm::SmallString<256> CWD;

clang/lib/Driver/Tools.cpp

@@ -1625,6 +1625,16 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   if (ShouldDisableDwarfDirectory(Args, getToolChain()))
     CmdArgs.push_back("-fno-dwarf-directory-asm");
 
+  if (const char *pwd = ::getenv("PWD")) {
+    // GCC also verifies that stat(pwd) and stat(".") have the same inode
+    // number. Not doing those because stats are slow, but we could.
+    if (pwd[0] == '/') {
+      std::string CompDir = pwd;
+      CmdArgs.push_back("-fdebug-compilation-dir");
+      CmdArgs.push_back(Args.MakeArgString(CompDir));
+    }
+  }
+
   if (Arg *A = Args.getLastArg(options::OPT_ftemplate_depth_)) {
     CmdArgs.push_back("-ftemplate-depth");
     CmdArgs.push_back(A->getValue(Args));

clang/lib/Frontend/CompilerInvocation.cpp

@@ -131,6 +131,10 @@ static void CodeGenOptsToArgs(const CodeGenOptions &Opts,
     Res.push_back("-disable-llvm-optzns");
   if (Opts.DisableRedZone)
     Res.push_back("-disable-red-zone");
+  if (!Opts.DebugCompilationDir.empty()) {
+    Res.push_back("-fdebug-compilation-dir");
+    Res.push_back(Opts.DebugCompilationDir);
+  }
   if (!Opts.DwarfDebugFlags.empty()) {
     Res.push_back("-dwarf-debug-flags");
     Res.push_back(Opts.DwarfDebugFlags);
@@ -1071,6 +1075,7 @@ static void ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
   Opts.EmitGcovArcs = Args.hasArg(OPT_femit_coverage_data);
   Opts.EmitGcovNotes = Args.hasArg(OPT_femit_coverage_notes);
   Opts.CoverageFile = Args.getLastArgValue(OPT_coverage_file);
+  Opts.DebugCompilationDir = Args.getLastArgValue(OPT_fdebug_compilation_dir);
 
   if (Arg *A = Args.getLastArg(OPT_fobjc_dispatch_method_EQ)) {
     StringRef Name = A->getValue(Args);

clang/test/CodeGen/debug-info-compilation-dir.c

@@ -0,0 +1,4 @@
+// RUN: %clang_cc1 -fdebug-compilation-dir /nonsense -emit-llvm -g %s -o - | \
+// RUN:   grep nonsense
+
+// RUN: %clang_cc1 -emit-llvm -g %s -o - | grep %S

clang/test/Driver/debug.c

@@ -0,0 +1,8 @@
+// RUN: %clang -### -g %s -c 2>&1 | grep '"-fdebug-compilation-dir" "'%S'"'
+// RUN: PWD=/foo %clang -### -g %s -c 2>&1 | grep '"-fdebug-compilation-dir" "/foo"'
+
+// This test uses grep instead of FileCheck so that we get %S -> dirname
+// substitution.
+
+// "PWD=/foo gcc" wouldn't necessarily work. You would need to pick a different
+// path to the same directory (try a symlink).