Introduce value_at_non_lval

In some cases, while a value might be read from memory, gdb should not
record the value as being equivalent to that memory.

In Ada, the inferior call code will call ada_convert_actual -- and
here, if the argument is already in memory, that address will simply
be reused.  However, for a call like "f(g())", the result of "g" might
be on the stack and thus overwritten by the call to "f".

This patch introduces a new function that is like value_at but that
ensures that the result is non-lvalue.
This commit is contained in:
Tom Tromey 2022-09-09 12:50:33 -06:00
parent 43f2b4583f
commit 7f22044a6b
2 changed files with 14 additions and 0 deletions

View file

@ -1019,6 +1019,16 @@ value_at (struct type *type, CORE_ADDR addr)
return get_value_at (type, addr, 0);
}
/* See value.h. */
struct value *
value_at_non_lval (struct type *type, CORE_ADDR addr)
{
struct value *result = value_at (type, addr);
VALUE_LVAL (result) = not_lval;
return result;
}
/* Return a lazy value with type TYPE located at ADDR (cf. value_at).
The type of the created value may differ from the passed type TYPE.
Make sure to retrieve the returned values's new type after this call

View file

@ -711,6 +711,10 @@ extern struct value *value_from_component_bitsize (struct value *whole,
extern struct value *value_at (struct type *type, CORE_ADDR addr);
extern struct value *value_at_lazy (struct type *type, CORE_ADDR addr);
/* Like value_at, but ensures that the result is marked not_lval.
This can be important if the memory is "volatile". */
extern struct value *value_at_non_lval (struct type *type, CORE_ADDR addr);
extern struct value *value_from_contents_and_address_unresolved
(struct type *, const gdb_byte *, CORE_ADDR);
extern struct value *value_from_contents_and_address (struct type *,