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[dump_syms/Mac] New -x option to prefer extern names when there's a mismatch

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When built with -gmlt, .dSYMs are (by design) missing the
`DW_AT_linkage_name` which Breakpad uses to fill out the
(name-mangled) function names.

Thankfully, the .dSYM contains both the old-school LC_SYMTAB command
containing the STABS-format symbols (which include the fully-qualified
C++ symbol names we want, but no actual compilation unit data), as
well as the LC_SEGMENT_64 containing the __DWARF segment with the
minimal -gmlt debug information (which excludes the name-mangled C++
symbols).

Unfortunately, since the .dSYM's STABS does not define compilation
units, the usual path in `StabsReader` ignores all the fully-qualified
C++ symbol names for the functions:

https://chromium.googlesource.com/breakpad/breakpad/+/bd9d94c70843620adeebcd73c243001237c6d426/src/common/stabs_reader.cc#100

Fortunately, when built for macOS platforms (`HAVE_MACH_O_NLIST_H`),
`StabsReader` supports storing all the STABS-format symbols as
`Extern`s, regardless of whether or not they're in a compilation unit:

https://chromium.googlesource.com/breakpad/breakpad/+/bd9d94c70843620adeebcd73c243001237c6d426/src/common/stabs_reader.cc#119

Currently, when there's both a `Function` and an `Extern` with the same address, `Module` discards the `Extern`:

https://chromium.googlesource.com/breakpad/breakpad/+/bd9d94c70843620adeebcd73c243001237c6d426/src/common/module.cc#161

This CL adds a new `-x` option to the Mac `dump_syms` which prefers
the Extern function name if there's a mismatch.

Bug: https://bugs.chromium.org/p/google-breakpad/issues/detail?id=883
Change-Id: I0d32adc64fbf567600b0a5ca63c71c422b7f0f8c
Reviewed-on: https://chromium-review.googlesource.com/c/breakpad/breakpad/+/4453650
Reviewed-by: Joshua Peraza <jperaza@chromium.org>
This commit is contained in:
Ben Hamilton 2023-04-21 12:02:42 -06:00 • committed by Joshua Peraza
parent 16cee17997
commit f548d75c9f
8 changed files with 123 additions and 18 deletions
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13
src/common/dwarf_cu_to_module_unittest.cc
View file

@ -267,6 +267,10 @@ class CUFixtureBase {
void TestFunction(int i, const string& name,
Module::Address address, Module::Address size);
// Test that the I'th function (ordered by address) in the module
// this.module_ has the given prefer_extern_name.
void TestFunctionPreferExternName(int i, bool prefer_extern_name);
// Test that the number of source lines owned by the I'th function
// in the module this.module_ is equal to EXPECTED.
void TestLineCount(int i, size_t expected);
@ -615,6 +619,15 @@ void CUFixtureBase::TestFunction(int i, const string& name,
EXPECT_EQ(0U, function->parameter_size);
}
void CUFixtureBase::TestFunctionPreferExternName(int i,
bool prefer_extern_name) {
FillFunctions();
ASSERT_LT((size_t)i, functions_.size());
Module::Function* function = functions_[i];
EXPECT_EQ(prefer_extern_name, function->prefer_extern_name);
}
void CUFixtureBase::TestLineCount(int i, size_t expected) {
FillFunctions();
ASSERT_LT((size_t) i, functions_.size());