[asan] Avoid two compiler-synthesized calls to memset & memcpy

[rnk]

Summary

Otherwise the tests hang on Windows attempting to report nested errors.

[vitalybuka]

compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_win.cc

39

How does this help to avoid memset?

[rnk]

compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_win.cc

39

Actually, I think the boolean is unnecessary. The constructor has to be user-provided. If it's compiler-synthesized, then the compiler zeros out the memory before calling the constructor, as in this code:

struct Foo {
  Foo()
#ifdef USER_CTOR
  {}
#else
  = default;
#endif
  int x = 0;
};
Foo *getit() { return new Foo(); }

I'll simplify it.

compiler-rt/lib/asan/asan_globals.cc

int GetGlobalsForAddress(uptr addr, Global *globals, u32 *reg_sites,
   if (!flags()->report_globals) return 0;
   BlockingMutexLock lock(&mu_for_globals);
   int res = 0;
   for (ListOfGlobals *l = list_of_all_globals; l; l = l->next) {
     const Global &g = *l->g;
     if (flags()->report_globals >= 2)
       ReportGlobal(g, "Search");
     if (IsAddressNearGlobal(addr, g)) {
-#if defined(__GNUC__) && defined(__sparc__)
       internal_memcpy(&globals[res], &g, sizeof(g));
-#else
-      globals[res] = g;
-#endif
       if (reg_sites)
         reg_sites[res] = FindRegistrationSite(&g);
       res++;
-      if (res == max_globals) break;
+      if (res == max_globals)
+        break;
     }
   }
   return res;
 }
 
 enum GlobalSymbolState {
   UNREGISTERED = 0,
   REGISTERED = 1

compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_win.cc

 decltype(::SymSetOptions) *SymSetOptions;
 decltype(::SymSetSearchPathW) *SymSetSearchPathW;
 decltype(::UnDecorateSymbolName) *UnDecorateSymbolName;
 
 namespace {
 
 class WinSymbolizerTool : public SymbolizerTool {
  public:
+  WinSymbolizerTool(bool avoid_memset) {
+    (void)avoid_memset;  // Avoids a compiler-synthesized call to memset.
+  }
   bool SymbolizePC(uptr addr, SymbolizedStack *stack) override;
   bool SymbolizeData(uptr addr, DataInfo *info) override {
     return false;
   }
   const char *Demangle(const char *name) override;
 };
 
 bool is_dbghelp_initialized = false;
if (path) {
     if (user_path && user_path[0] == '\0') {
       VReport(2, "External symbolizer is explicitly disabled.\n");
     } else {
       VReport(2, "External symbolizer is not present.\n");
     }
   }
 
   // Add the dbghelp based symbolizer.
-  list->push_back(new(*allocator) WinSymbolizerTool());
+  list->push_back(new(*allocator) WinSymbolizerTool(/*avoid_memset=*/true));
 }
 
 Symbolizer *Symbolizer::PlatformInit() {
   IntrusiveList<SymbolizerTool> list;
   list.clear();
   ChooseSymbolizerTools(&list, &symbolizer_allocator_);
 
   return new(symbolizer_allocator_) Symbolizer(list);