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Pull in r196874 from upstream llvm trunk:

Fix a crash that occurs when PWD is invalid.

  MCJIT needs to be able to run in hostile environments, even when PWD
  is invalid. There's no need to crash MCJIT in this case.

  The obvious fix is to simply leave MCContext's CompilationDir empty
  when PWD can't be determined. This way, MCJIT clients,
  and other clients that link with LLVM don't need a valid working directory.

  If we do want to guarantee valid CompilationDir, that should be done
  only for clients of getCompilationDir(). This is as simple as checking
  for an empty string.

  The only current use of getCompilationDir is EmitGenDwarfInfo, which
  won't conceivably run with an invalid working dir. However, in the
  purely hypothetically and untestable case that this happens, the
  AT_comp_dir will be omitted from the compilation_unit DIE.

This should help fix assertions occurring with ports-mgmt/tinderbox,
when it is using jails, and sometimes invalidates clang's current
working directory.

Reported by:	decke
MFC after:	2 weeks
X-MFC-With:	r261991
This commit is contained in:
Dimitry Andric 2014-02-28 17:12:31 +00:00
parent 29c5be8f2b
commit a1509b8a0e
Notes: svn2git 2020-12-20 02:59:44 +00:00
svn path=/head/; revision=262611
3 changed files with 9 additions and 5 deletions
contrib/llvm

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@ -278,6 +278,7 @@ namespace llvm {
/// This can be overridden by clients which want to control the reported
/// compilation directory and have it be something other than the current
/// working directory.
/// Returns an empty string if the current directory cannot be determined.
StringRef getCompilationDir() const { return CompilationDir; }
/// \brief Set the compilation directory for DW_AT_comp_dir

View File

@ -47,8 +47,8 @@ MCContext::MCContext(const MCAsmInfo *mai, const MCRegisterInfo *mri,
AllowTemporaryLabels(true), DwarfCompileUnitID(0), AutoReset(DoAutoReset) {
error_code EC = llvm::sys::fs::current_path(CompilationDir);
assert(!EC && "Could not determine the current directory");
(void)EC;
if (EC)
CompilationDir.clear();
MachOUniquingMap = 0;
ELFUniquingMap = 0;

View File

@ -467,7 +467,8 @@ static void EmitGenDwarfAbbrev(MCStreamer *MCOS) {
EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
EmitAbbrev(MCOS, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr);
EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
EmitAbbrev(MCOS, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string);
if (!context.getCompilationDir().empty())
EmitAbbrev(MCOS, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string);
StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
if (!DwarfDebugFlags.empty())
EmitAbbrev(MCOS, dwarf::DW_AT_APPLE_flags, dwarf::DW_FORM_string);
@ -643,8 +644,10 @@ static void EmitGenDwarfInfo(MCStreamer *MCOS,
MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
// AT_comp_dir, the working directory the assembly was done in.
MCOS->EmitBytes(context.getCompilationDir());
MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
if (!context.getCompilationDir().empty()) {
MCOS->EmitBytes(context.getCompilationDir());
MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
}
// AT_APPLE_flags, the command line arguments of the assembler tool.
StringRef DwarfDebugFlags = context.getDwarfDebugFlags();