This amends commit 00be3578e0841dd9abe408e5b4946180de0bf46b to demangle symbol
names in global descriptors. We keep the mangled name for the `__odr_gen_asan_*`
variables and the runtime __cxa_demangle call site change (which fixed possible
leaks for other scenarios: non-fatal diagnostics).
compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cpp uses
an undefined weak `__cxa_demangle` which does not pull in an archive definition.
A -static-libstdc++ executable link does not get demangled names.
Unfortunately this means we cannot rely on runtime demangling.
See compiler-rt/test/asan/TestCases/global-demangle.cpp
The runtime calls `MaybeDemangleGlobalName` for error reporting and
`__cxxabiv1::__cxa_demangle` is called if available, so demanging Itanium
mangled names in global metadata is unnecessary and wastes data size.
Add `MaybeDemangleGlobalName` in ODR violation detection to support demangled
names in a suppressions file. `MaybeDemangleGlobalName` may call
`DemangleCXXABI` and leak memory. Use an internal allocation to prevent lsan
leak (in case there is no fatal asan error).
The debug feature `report_globals=2` prints information for all instrumented
global variables. `MaybeDemangleGlobalName` would be slow, so don't do that.
The output looks like `Added Global[0x56448f092d60]: beg=0x56448fa66d60 size=4/32 name=_ZL13test_global_2`
and I think the mangled name is fine.
Other mangled schemes e.g. Windows (see win-string-literal.ll) remain the
current behavior.
Reviewed By: hctim
Differential Revision: https://reviews.llvm.org/D138095
This enables odr indicators on all platforms and private aliases on non-Windows.
Note that GCC also uses private aliases: this fixes bogus
`The following global variable is not properly aligned.` errors for interposed global variables
Fix https://github.com/google/sanitizers/issues/398
Fix https://github.com/google/sanitizers/issues/1017
Fix https://github.com/llvm/llvm-project/issues/36893 (we can restore D46665)
Global variables of non-hasExactDefinition() linkages (i.e.
linkonce/linkonce_odr/weak/weak_odr/common/external_weak) are not instrumented.
If an instrumented variable gets interposed to an uninstrumented variable due to
symbol interposition (e.g. in issue 36893, _ZTS1A in foo.so is resolved to _ZTS1A in
the executable), there may be a bogus error.
With private aliases, the register code will not resolve to a definition in
another module, and thus prevent the issue.
Cons: minor size increase. This is mainly due to extra `__odr_asan_gen_*` symbols.
(ELF) In addition, in relocatable files private aliases replace some relocations
referencing global symbols with .L symbols and may introduce some STT_SECTION symbols.
For lld, with -g0, the size increase is 0.07~0.09% for many configurations I
have tested: -O0, -O1, -O2, -O3, -O2 -ffunction-sections -fdata-sections
-Wl,--gc-sections. With -g1 or above, the size increase ratio will be even smaller.
This patch obsoletes D92078.
Don't migrate Windows for now: the static data member of a specialization
`std::num_put<char>::id` is a weak symbol, as well as its ODR indicator.
Unfortunately, link.exe (and lld without -lldmingw) generally doesn't support
duplicate weak definitions (weak symbols in different TUs likely pick different
defined external symbols and conflict).
Differential Revision: https://reviews.llvm.org/D137227
