[cfe-commits] r142633 - in /cfe/trunk: include/clang/Driver/CC1Options.td include/clang/Frontend/CodeGenOptions.h lib/CodeGen/CGDebugInfo.cpp lib/Driver/Tools.cpp lib/Frontend/CompilerInvocation.cpp test/CodeGen/debug-info-compilation-dir.c test/Driver/debug.c
Nick Lewycky
nlewycky at google.com
Fri Mar 29 16:12:57 PDT 2013
On 28 March 2013 10:24, Chad Rosier <mcrosier at apple.com> 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!
Nick
> Chad
>
>
> On Oct 20, 2011, at 7:32 PM, Nick Lewycky <nicholas at mxc.ca> 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).
>
>
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