[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
Chad Rosier
mcrosier at apple.com
Tue Apr 2 10:00:50 PDT 2013
On Mar 29, 2013, at 4:12 PM, Nick Lewycky <nlewycky at google.com> wrote:
> 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!
Yes it does. Thanks so much, Nick.
>
> 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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