#include "gdb_assert.h"
#include "dictionary.h"
#include "reggroups.h"
+#include "regcache.h"
/* Prototypes for exported functions. */
void _initialize_stack (void);
-void return_command (char *, int);
-
/* Prototypes for local functions. */
static void down_command (char *, int);
return_command (char *retval_exp, int from_tty)
{
struct symbol *thisfun;
- CORE_ADDR selected_frame_addr;
- CORE_ADDR selected_frame_pc;
- struct frame_info *frame;
struct value *return_value = NULL;
+ const char *query_prefix = "";
- if (deprecated_selected_frame == NULL)
+ /* FIXME: cagney/2003-10-20: Perform a minimal existance test on the
+ target. If that fails, error out. For the moment don't rely on
+ get_selected_frame as it's error message is the the singularly
+ obscure "No registers". */
+ if (!target_has_registers)
error ("No selected frame.");
- thisfun = get_frame_function (deprecated_selected_frame);
- selected_frame_addr = get_frame_base (deprecated_selected_frame);
- selected_frame_pc = get_frame_pc (deprecated_selected_frame);
-
- /* Compute the return value (if any -- possibly getting errors here). */
+ thisfun = get_frame_function (get_selected_frame ());
+ /* Compute the return value. If the computation triggers an error,
+ let it bail. If the return type can't be handled, set
+ RETURN_VALUE to NULL, and QUERY_PREFIX to an informational
+ message. */
if (retval_exp)
{
struct type *return_type = NULL;
+ /* Compute the return value. Should the computation fail, this
+ call throws an error. */
return_value = parse_and_eval (retval_exp);
- /* Cast return value to the return type of the function. */
+ /* Cast return value to the return type of the function. Should
+ the cast fail, this call throws an error. */
if (thisfun != NULL)
return_type = TYPE_TARGET_TYPE (SYMBOL_TYPE (thisfun));
if (return_type == NULL)
return_type = builtin_type_int;
return_value = value_cast (return_type, return_value);
- /* Make sure we have fully evaluated it, since
- it might live in the stack frame we're about to pop. */
+ /* Make sure the value is fully evaluated. It may live in the
+ stack frame we're about to pop. */
if (VALUE_LAZY (return_value))
value_fetch_lazy (return_value);
- }
-
- /* If interactive, require confirmation. */
- if (from_tty)
- {
- if (thisfun != 0)
+ /* Check that this architecture can handle the function's return
+ type. In the case of "struct convention", still do the
+ "return", just also warn the user. */
+ if (gdbarch_return_value_p (current_gdbarch))
{
- if (!query ("Make %s return now? ", SYMBOL_PRINT_NAME (thisfun)))
- {
- error ("Not confirmed.");
- /* NOTREACHED */
- }
+ if (gdbarch_return_value (current_gdbarch, return_type,
+ NULL, NULL, NULL)
+ == RETURN_VALUE_REGISTER_CONVENTION)
+ return_value = NULL;
}
- else if (!query ("Make selected stack frame return now? "))
- error ("Not confirmed.");
+ else
+ {
+ /* NOTE: cagney/2003-10-20: The double check is to ensure
+ that the STORE_RETURN_VALUE call, further down, is not
+ applied to a struct or union return-value. It wasn't
+ allowed previously, so don't start allowing it now. An
+ ABI that uses "register convention" to return small
+ structures and should implement the "return_value"
+ architecture method. */
+ if (using_struct_return (return_type, 0)
+ || TYPE_CODE (return_type) == TYPE_CODE_STRUCT
+ || TYPE_CODE (return_type) == TYPE_CODE_UNION)
+ return_value = NULL;
+ }
+ if (return_value == NULL)
+ query_prefix = "\
+The location at which to store the function's return value is unknown.\n";
}
- /* FIXME: cagney/2003-01-18: Rather than pop each frame in turn,
- this code should just go straight to the relevant frame and pop
- that. */
-
- /* Do the real work. Pop until the specified frame is current. We
- use this method because the deprecated_selected_frame is not
- valid after a frame_pop(). The pc comparison makes this work
- even if the selected frame shares its fp with another frame. */
-
- /* FIXME: cagney/32003-03-12: This code should use frame_id_eq().
- Unfortunatly, that function doesn't yet include the PC in any
- frame ID comparison. */
+ /* Does an interactive user really want to do this? Include
+ information, such as how well GDB can handle the return value, in
+ the query message. */
+ if (from_tty)
+ {
+ int confirmed;
+ if (thisfun == NULL)
+ confirmed = query ("%sMake selected stack frame return now? ",
+ query_prefix);
+ else
+ confirmed = query ("%sMake %s return now? ", query_prefix,
+ SYMBOL_PRINT_NAME (thisfun));
+ if (!confirmed)
+ error ("Not confirmed");
+ }
- while (selected_frame_addr != get_frame_base (frame = get_current_frame ())
- || selected_frame_pc != get_frame_pc (frame))
- frame_pop (get_current_frame ());
+ /* NOTE: cagney/2003-01-18: Is this silly? Rather than pop each
+ frame in turn, should this code just go straight to the relevant
+ frame and pop that? */
- /* Then pop that frame. */
+ /* First discard all frames inner-to the selected frame (making the
+ selected frame current). */
+ {
+ struct frame_id selected_id = get_frame_id (get_selected_frame ());
+ while (!frame_id_eq (selected_id, get_frame_id (get_current_frame ())))
+ {
+ if (frame_id_inner (selected_id, get_frame_id (get_current_frame ())))
+ /* Caught in the safety net, oops! We've gone way past the
+ selected frame. */
+ error ("Problem while popping stack frames (corrupt stack?)");
+ frame_pop (get_current_frame ());
+ }
+ }
+ /* Second discard the selected frame (which is now also the current
+ frame). */
frame_pop (get_current_frame ());
- /* Compute the return value (if any) and store in the place
- for return values. */
-
- if (retval_exp)
- set_return_value (return_value);
-
- /* If we are at the end of a call dummy now, pop the dummy frame too. */
+ /* Store RETURN_VAUE in the just-returned register set. */
+ if (return_value != NULL)
+ {
+ struct type *return_type = VALUE_TYPE (return_value);
+ if (!gdbarch_return_value_p (current_gdbarch))
+ {
+ STORE_RETURN_VALUE (return_type, current_regcache,
+ VALUE_CONTENTS (return_value));
+ }
+ else
+ {
+ gdb_assert (gdbarch_return_value (current_gdbarch, return_type,
+ NULL, NULL, NULL)
+ == RETURN_VALUE_REGISTER_CONVENTION);
+ gdbarch_return_value (current_gdbarch, return_type, current_regcache,
+ VALUE_CONTENTS (return_value), NULL);
+ }
+ }
- /* FIXME: cagney/2003-01-18: This is silly. Instead of popping all
- the frames except the dummy, and then, as an afterthought,
- popping the dummy frame, this code should just pop through to the
- dummy frame. */
-
+ /* If we are at the end of a call dummy now, pop the dummy frame
+ too. */
+ /* NOTE: cagney/2003-01-18: Is this silly? Instead of popping all
+ the frames in sequence, should this code just pop the dummy frame
+ directly? */
if (CALL_DUMMY_HAS_COMPLETED (read_pc(), read_sp (),
get_frame_base (get_current_frame ())))
frame_pop (get_current_frame ());
/* If interactive, print the frame that is now current. */
-
if (from_tty)
frame_command ("0", 1);
else
== RETURN_VALUE_STRUCT_CONVENTION);
}
-/* Store VAL so it will be returned if a function returns now.
- Does not verify that VAL's type matches what the current
- function wants to return. */
-
-void
-set_return_value (struct value *val)
-{
- struct type *type = check_typedef (VALUE_TYPE (val));
- enum type_code code = TYPE_CODE (type);
-
- if (code == TYPE_CODE_ERROR)
- error ("Function return type unknown.");
-
- if (gdbarch_return_value_p (current_gdbarch))
- {
- switch (gdbarch_return_value (current_gdbarch, type, NULL, NULL, NULL))
- {
- case RETURN_VALUE_REGISTER_CONVENTION:
- /* Success. The architecture can deal with it, write it to
- the regcache. */
- gdbarch_return_value (current_gdbarch, type, current_regcache,
- VALUE_CONTENTS (val), NULL);
- return;
- case RETURN_VALUE_STRUCT_CONVENTION:
- /* Failure. For the moment, assume that it is not possible
- to find the location, on the stack, at which the "struct
- return" value should be stored. Only a warning because
- an error aborts the "return" command leaving GDB in a
- weird state. */
- warning ("Location of return value unknown");
- return;
- }
- }
-
-
- if (code == TYPE_CODE_STRUCT
- || code == TYPE_CODE_UNION) /* FIXME, implement struct return. */
- /* FIXME: cagney/2003-10-20: This should be an internal-warning.
- The problem is that while GDB's core supports "struct return"
- using "register convention", many architectures haven't been
- updated to implement the mechanisms needed to make it work.
- It's a warning, and not an error, as otherwize it will jump out
- of the "return" command leaving both GDB and the user in a very
- confused state. */
- {
- warning ("This architecture does not support specifying a struct or union return-value.");
- return;
- }
-
- STORE_RETURN_VALUE (type, current_regcache, VALUE_CONTENTS (val));
-}
-\f
void
_initialize_values (void)
{
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