Re: How the gdb function throw_error works?

On 06/27/2013 11:19 AM, Terry Guo wrote:
> Hi there,
>
> Function value_of_dwarf_block_entry in file dwarf2loc.c has a call to
> function throw_error which seems will print out some error messages to
> gdb user. I am pretty sure that the throw_error will be called in the

Function 'error' prints error messages, but throw_error may not. 
NO_ENTRY_VALUE_ERROR is caught by the callers of 
value_of_dwarf_block_entry, IIUC.  For example, see stack.c:read_frame_arg:

       TRY_CATCH (except, RETURN_MASK_ERROR)
	{
	  const struct symbol_computed_ops *ops;

	  ops = SYMBOL_COMPUTED_OPS (sym);
	  entryval = ops->read_variable_at_entry (sym, frame);
	}
       if (!entryval)
	{
	  entryval_error = alloca (strlen (except.message) + 1);
	  strcpy (entryval_error, except.message);
	}

       if (except.error == NO_ENTRY_VALUE_ERROR
	  || (entryval && value_optimized_out (entryval)))
	{
	  entryval = NULL;
	  entryval_error = NULL;
	}

Function pointer 'read_variable_at_entry' calls value_of_dwarf_block_entry.

-- 
Yao (齐尧)