On Mar 29, 2013, at 4:12 PM, Nick Lewycky <[email protected]> wrote:
> On 28 March 2013 10:24, Chad Rosier <[email protected]> wrote: > Hi Nick, > I've run into a bug with -fdebug-compilation-dir and I was hoping you could > help me come up with a solution. > Specifically, could tell me how gcc behaves when stat(pwd) and stat(.) > differ? I'm running into this very case. If > you need a test case, I'd be happy to provide one. Also, do you know why gcc > prefers ::getenv("PWD") as > opposed to something like getcwd()? > > Great questions! The comment in gcc/libiberty says "Use the PWD environment > variable if it's set correctly, since this is faster and gives more uniform > answers to the user." > > When stat(pwd) and stat(.) differ in inode or dev, gcc calls getcwd(). > Specifically, gcc checks for the presence of the PWD environment variable, > that its value starts with a '/' character, that they can stat $PWD and stat > ".", and that the inode and containing devices match. If any of those fail, > it falls back to getcwd, complete with a loop to determine the path length > (in the absence of MAXPATHLEN). If getcwd fails, the debug info will contain > "." for the path. > > Hope that helps! Yes it does. Thanks so much, Nick. > > Nick > > > Chad > > > On Oct 20, 2011, at 7:32 PM, Nick Lewycky <[email protected]> wrote: > >> Author: nicholas >> Date: Thu Oct 20 21:32:14 2011 >> New Revision: 142633 >> >> URL: http://llvm.org/viewvc/llvm-project?rev=142633&view=rev >> Log: >> 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. >> >> Added: >> cfe/trunk/test/CodeGen/debug-info-compilation-dir.c >> cfe/trunk/test/Driver/debug.c >> Modified: >> cfe/trunk/include/clang/Driver/CC1Options.td >> cfe/trunk/include/clang/Frontend/CodeGenOptions.h >> cfe/trunk/lib/CodeGen/CGDebugInfo.cpp >> cfe/trunk/lib/Driver/Tools.cpp >> cfe/trunk/lib/Frontend/CompilerInvocation.cpp >> >> Modified: cfe/trunk/include/clang/Driver/CC1Options.td >> URL: >> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Driver/CC1Options.td?rev=142633&r1=142632&r2=142633&view=diff >> ============================================================================== >> --- cfe/trunk/include/clang/Driver/CC1Options.td (original) >> +++ cfe/trunk/include/clang/Driver/CC1Options.td Thu Oct 20 21:32:14 2011 >> @@ -110,6 +110,8 @@ >> 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">, >> >> Modified: cfe/trunk/include/clang/Frontend/CodeGenOptions.h >> URL: >> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Frontend/CodeGenOptions.h?rev=142633&r1=142632&r2=142633&view=diff >> ============================================================================== >> --- cfe/trunk/include/clang/Frontend/CodeGenOptions.h (original) >> +++ cfe/trunk/include/clang/Frontend/CodeGenOptions.h Thu Oct 20 21:32:14 >> 2011 >> @@ -115,6 +115,9 @@ >> /// 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; >> >> Modified: cfe/trunk/lib/CodeGen/CGDebugInfo.cpp >> URL: >> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGDebugInfo.cpp?rev=142633&r1=142632&r2=142633&view=diff >> ============================================================================== >> --- cfe/trunk/lib/CodeGen/CGDebugInfo.cpp (original) >> +++ cfe/trunk/lib/CodeGen/CGDebugInfo.cpp Thu Oct 20 21:32:14 2011 >> @@ -250,6 +250,9 @@ >> } >> >> StringRef CGDebugInfo::getCurrentDirname() { >> + if (!CGM.getCodeGenOpts().DebugCompilationDir.empty()) >> + return CGM.getCodeGenOpts().DebugCompilationDir; >> + >> if (!CWDName.empty()) >> return CWDName; >> llvm::SmallString<256> CWD; >> >> Modified: cfe/trunk/lib/Driver/Tools.cpp >> URL: >> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/Tools.cpp?rev=142633&r1=142632&r2=142633&view=diff >> ============================================================================== >> --- cfe/trunk/lib/Driver/Tools.cpp (original) >> +++ cfe/trunk/lib/Driver/Tools.cpp Thu Oct 20 21:32:14 2011 >> @@ -1625,6 +1625,16 @@ >> 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)); >> >> Modified: cfe/trunk/lib/Frontend/CompilerInvocation.cpp >> URL: >> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Frontend/CompilerInvocation.cpp?rev=142633&r1=142632&r2=142633&view=diff >> ============================================================================== >> --- cfe/trunk/lib/Frontend/CompilerInvocation.cpp (original) >> +++ cfe/trunk/lib/Frontend/CompilerInvocation.cpp Thu Oct 20 21:32:14 2011 >> @@ -131,6 +131,10 @@ >> 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 @@ >> 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); >> >> Added: cfe/trunk/test/CodeGen/debug-info-compilation-dir.c >> URL: >> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/debug-info-compilation-dir.c?rev=142633&view=auto >> ============================================================================== >> --- cfe/trunk/test/CodeGen/debug-info-compilation-dir.c (added) >> +++ cfe/trunk/test/CodeGen/debug-info-compilation-dir.c Thu Oct 20 21:32:14 >> 2011 >> @@ -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 >> >> Added: cfe/trunk/test/Driver/debug.c >> URL: >> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Driver/debug.c?rev=142633&view=auto >> ============================================================================== >> --- cfe/trunk/test/Driver/debug.c (added) >> +++ cfe/trunk/test/Driver/debug.c Thu Oct 20 21:32:14 2011 >> @@ -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). >> >> >> _______________________________________________ >> cfe-commits mailing list >> [email protected] >> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits > > > _______________________________________________ > cfe-commits mailing list > [email protected] > http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
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