[asan] Move __asan_handle_no_return to public header

[mcgrathr]

Summary

Heretofore asan_handle_no_return was used only by interceptors,
i.e. code private to the ASan runtime. However, on systems without
interceptors, code like libc++abi is built with -fsanitize=address
itself and should call asan_handle_no_return directly from
__cxa_throw so that no interceptor is required.

[mcgrathr]

This is necessary for D36599 to (re-)land.

[vitalybuka]

As now it's going to be apart of API, please add a test

[mcgrathr]

Added test case.

[mcgrathr]

In D36811#843915, @vitalybuka wrote:

As now it's going to be apart of API, please add a test

Done.

[vitalybuka]

Thank you!

compiler-rt/trunk/include/sanitizer/asan_interface.h

#endif
   // the fake frame and sets beg/end to the boundaries of this fake frame.
   // Otherwise returns NULL and does not touch beg/end.
   // If beg/end are NULL, they are not touched.
   // This function may be called from a thread other than the owner of
   // fake_stack, but the owner thread need to be alive.
   void *__asan_addr_is_in_fake_stack(void *fake_stack, void *addr, void **beg,
                                      void **end);
 
+  // Performs cleanup before a [[noreturn]] function.  Must be called
+  // before things like _exit and execl to avoid false positives on stack.
+  void __asan_handle_no_return(void);
+
 #ifdef __cplusplus
 }  // extern "C"
 #endif
 
 #endif  // SANITIZER_ASAN_INTERFACE_H

compiler-rt/trunk/lib/asan/tests/asan_interface_test.cc

for (size_t i = 0; i < 4000000; i++) {
     size_t idx = i % kNumMallocs;
     EXPECT_TRUE(__sanitizer_get_ownership(pointers[idx]));
     EXPECT_EQ(sizes[idx], __sanitizer_get_allocated_size(pointers[idx]));
   }
   for (size_t i = 0, n = pointers.size(); i < n; i++)
     free(pointers[i]);
 }
 
+TEST(AddressSanitizerInterface, HandleNoReturnTest) {
+  char array[40];
+  __asan_poison_memory_region(array, sizeof(array));
+  BAD_ACCESS(array, 20);
+  __asan_handle_no_return();
+  // It unpoisons the whole thread stack.
+  GOOD_ACCESS(array, 20);
+}