[PATCH] D54344: [Clang][CodeGen][CXX]: Workaround __attribute((no_destroy)) crash/incorrect code generation.

[Kristina Brooks via Phabricator via cfe-commits]

kristina added a comment.

I've managed to isolate enough to make for a testcase. Is that too broad or is it okay to attach as is?

The following triggers the assert:

  namespace util {
  	template <typename T>
  	class test_vector
  	{
  	public:
  		test_vector(unsigned c)
  			: Used(0), TotalSize(sizeof(T) * c)
  		{
  			// Intentional
  			Storage = (T*)(new T[TotalSize]);
  		}
  		~test_vector() {
  			delete[] Storage;
  		}
  		char* data() {
  			return Storage;
  		}
  		unsigned size() {
  			return TotalSize;
  		}
  		void push_back(T one_thing) {
  			Storage[Used++] = one_thing;
  		}
  	private:
  		unsigned Used;
  		unsigned TotalSize;
  		T*       Storage;
  	};
  }
  
  volatile int do_not_optimize_me = 0;
  
  namespace os {
  	using char_vec_t = util::test_vector<char>;
  	
  	class logger_base
  	{
  	public:
  		constexpr logger_base() = default;
  	protected:
  		char_vec_t* NamePtr = nullptr;
  		char_vec_t  Name    = char_vec_t(10);
  	};
  	
  	class logger : public logger_base
  	{
  	public:
  		void stuff(const char* fmt, int something) {
  			do_not_optimize_me = something + fmt[0];
  		}
  		logger()
  		{
  			Name = char_vec_t(8);
  			Name.push_back('a');
  		}
  		
  		logger(const char* name)
  		{
  			Name = util::test_vector<char>(__builtin_strlen(name));
  			Name.push_back(name[0]);
  			Name.push_back(name[1]);
  		}
  	};
  }
  
  #define TOPLEVEL_LOGGER(_var_name, _category_const)               \
  	namespace { constexpr char $__##_var_name[] = _category_const; \
  	__attribute((no_destroy)) os::logger _var_name ($__##_var_name) ; }
  
  TOPLEVEL_LOGGER(s_log, "something");
  
  class some_class {
  public:
  	some_class(int some_value) {
  		do_not_optimize_me = some_value;
  		s_log.stuff("wawawa", 5 + do_not_optimize_me);
  	}
  	~some_class() = default;
  };
  
  static some_class s_ctor(1);


https://reviews.llvm.org/D54344