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4b63a536ee
When resuming execution, DW_CFA_GNU_args_size from the current frame
must be added back to the stack pointer. Clang now generates these frequently
at -O3. A simple repro for x86_64, that will crash with clang ~3.9 or newer:
void f(int, int,int,int,int,int,int,int,int);
int main() {
try {
f(0,1,2,3,4,5,6,7,8);
} catch (int) {
return 0;
}
return 1;
}
Where f is something that throws an int, but in a different translation unit to
prevent optimization.
This results in cfi instructions before the call:
.cfi_escape 0x2e, 0x20
Grabbing the args_size means fully parsing the cfi in the current frame, which
is unfortunate because it means nearly twice the work at each step. The logic
to grab args_size can be in unw_step or get_proc_info (since this is always
called before resuming in stack unwinding). Putting it in get_proc_info allows
the more common unw_step code to remain fast.
It would potentially fit in nicely with a proc info cache (as mentioned in the
if0 comment block)
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|---|---|---|
| .. | ||
| aarch64 | ||
| arm | ||
| coredump | ||
| dwarf | ||
| hppa | ||
| ia64 | ||
| mi | ||
| mips | ||
| ppc | ||
| ppc32 | ||
| ppc64 | ||
| ptrace | ||
| setjmp | ||
| sh | ||
| tilegx | ||
| unwind | ||
| x86 | ||
| x86_64 | ||
| elf32.c | ||
| elf32.h | ||
| elf64.c | ||
| elf64.h | ||
| elfxx.c | ||
| elfxx.h | ||
| libunwind-generic.pc.in | ||
| Makefile.am | ||
| os-freebsd.c | ||
| os-hpux.c | ||
| os-linux.c | ||
| os-linux.h | ||
| os-qnx.c | ||