[PATCH] D34149: [ASAN] ASAN is not properly calling libbacktrace to symbolize program

[Denis Khalikov via Phabricator via llvm-commits]

denis13 added inline comments.


================
Comment at: lib/sanitizer_common/sanitizer_symbolizer_libbacktrace.cc:113
   SymbolizeCodeCallbackArg *cdata = (SymbolizeCodeCallbackArg *)vdata;
+  if (function == NULL && cdata->frames_symbolized)
+    return 0;
----------------
m.ostapenko wrote:
> Hm, still can't get this. As far as I can understand, this callback is called before **SymbolizeCodeCallback** and `cdata->frames_symbolized > 0` becomes true only if somewhere before we executed line 121 where we have `function != NULL`. So, the situation with `(!function && cdata->frames_symbolized > 0)` corresponds to inlined calls (when multiple locations correspond to one PC), right? But in this case, won't we miss **filename** and **lineno** for that inlined functions? Or perhaps I'm missing something?
Thanks for question.

This fix  cover situation with code written on assembler as it mentioned in PR sanitizer/81081
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81081.

In this case we don't have any information about inlined this function or not, because we don't have specific debug info generated by compiler. All debug info generated by "as" and for that reason doesn't contain any tag which represents function (DW_TAG_subprogram).

In other case this code 

```
if (function == NULL && cdata->frames_symbolized)
```

cover situation with function was inlined and we can't find valid address


```
2585 static int
2586 report_inlined_functions (uintptr_t pc, struct function *function,
2587                           backtrace_full_callback callback, void *data,
2588                           const char **filename, int *lineno)
2589 {
2590   struct function_addrs *function_addrs;
2591   struct function *inlined;
2592   int ret;
2593 
2594   if (function->function_addrs_count == 0)
2595     return 0;
2596 
2597   function_addrs = ((struct function_addrs *)
2598                     bsearch (&pc, function->function_addrs,
2599                              function->function_addrs_count,
2600                              sizeof (struct function_addrs),
2601                              function_addrs_search));
2602   if (function_addrs == NULL)
2603     return 0;
2604 
2605   while (((size_t) (function_addrs - function->function_addrs) + 1
2606           < function->function_addrs_count)
2607          && pc >= (function_addrs + 1)->low
2608          && pc < (function_addrs + 1)->high)
2609     ++function_addrs;
2610 

```




https://reviews.llvm.org/D34149