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Introduce ada_var_value_operation

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This adds class ada_var_value_operation, which implements OP_VAR_VALUE
for Ada.

gdb/ChangeLog
2021-03-08  Tom Tromey  <tom@tromey.com>

	* ada-lang.c (ada_var_value_operation::evaluate_for_cast)
	(ada_var_value_operation::evaluate): New methods.
	* ada-exp.h (class ada_var_value_operation): New.
This commit is contained in:
Tom Tromey
2021-03-08 07:27:57 -07:00
parent 60fa02ca6f
commit 99a3b1e77b
3 changed files with 139 additions and 0 deletions
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6
gdb/ChangeLog
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@@ -1,3 +1,9 @@
2021-03-08 Tom Tromey <tom@tromey.com>
* ada-lang.c (ada_var_value_operation::evaluate_for_cast)
(ada_var_value_operation::evaluate): New methods.
* ada-exp.h (class ada_var_value_operation): New.
2021-03-08 Tom Tromey <tom@tromey.com>
* ada-lang.c (ada_unop_atr_operation::evaluate): New method.

21
gdb/ada-exp.h
View File

@@ -283,6 +283,27 @@ public:
{ return std::get<1> (m_storage); }
};
/* Variant of var_value_operation for Ada. */
class ada_var_value_operation
: public var_value_operation
{
public:
using var_value_operation::var_value_operation;
value *evaluate (struct type *expect_type,
struct expression *exp,
enum noside noside) override;
value *evaluate_for_cast (struct type *expect_type,
struct expression *exp,
enum noside noside) override;
protected:
using operation::do_generate_ax;
};
} /* namespace expr */
#endif /* ADA_EXP_H */

112
gdb/ada-lang.c
View File

@@ -10553,6 +10553,118 @@ ada_unop_atr_operation::evaluate (struct type *expect_type,
val, type_arg, std::get<2> (m_storage));
}
value *
ada_var_value_operation::evaluate_for_cast (struct type *expect_type,
struct expression *exp,
enum noside noside)
{
value *val = evaluate_var_value (noside,
std::get<1> (m_storage),
std::get<0> (m_storage));
val = ada_value_cast (expect_type, val);
/* Follow the Ada language semantics that do not allow taking
an address of the result of a cast (view conversion in Ada). */
if (VALUE_LVAL (val) == lval_memory)
{
if (value_lazy (val))
value_fetch_lazy (val);
VALUE_LVAL (val) = not_lval;
}
return val;
}
value *
ada_var_value_operation::evaluate (struct type *expect_type,
struct expression *exp,
enum noside noside)
{
symbol *sym = std::get<0> (m_storage);
if (SYMBOL_DOMAIN (sym) == UNDEF_DOMAIN)
/* Only encountered when an unresolved symbol occurs in a
context other than a function call, in which case, it is
invalid. */
error (_("Unexpected unresolved symbol, %s, during evaluation"),
sym->print_name ());
if (noside == EVAL_AVOID_SIDE_EFFECTS)
{
struct type *type = static_unwrap_type (SYMBOL_TYPE (sym));
/* Check to see if this is a tagged type. We also need to handle
the case where the type is a reference to a tagged type, but
we have to be careful to exclude pointers to tagged types.
The latter should be shown as usual (as a pointer), whereas
a reference should mostly be transparent to the user. */
if (ada_is_tagged_type (type, 0)
|| (type->code () == TYPE_CODE_REF
&& ada_is_tagged_type (TYPE_TARGET_TYPE (type), 0)))
{
/* Tagged types are a little special in the fact that the real
type is dynamic and can only be determined by inspecting the
object's tag. This means that we need to get the object's
value first (EVAL_NORMAL) and then extract the actual object
type from its tag.
Note that we cannot skip the final step where we extract
the object type from its tag, because the EVAL_NORMAL phase
results in dynamic components being resolved into fixed ones.
This can cause problems when trying to print the type
description of tagged types whose parent has a dynamic size:
We use the type name of the "_parent" component in order
to print the name of the ancestor type in the type description.
If that component had a dynamic size, the resolution into
a fixed type would result in the loss of that type name,
thus preventing us from printing the name of the ancestor
type in the type description. */
value *arg1 = var_value_operation::evaluate (nullptr, exp,
EVAL_NORMAL);
if (type->code () != TYPE_CODE_REF)
{
struct type *actual_type;
actual_type = type_from_tag (ada_value_tag (arg1));
if (actual_type == NULL)
/* If, for some reason, we were unable to determine
the actual type from the tag, then use the static
approximation that we just computed as a fallback.
This can happen if the debugging information is
incomplete, for instance. */
actual_type = type;
return value_zero (actual_type, not_lval);
}
else
{
/* In the case of a ref, ada_coerce_ref takes care
of determining the actual type. But the evaluation
should return a ref as it should be valid to ask
for its address; so rebuild a ref after coerce. */
arg1 = ada_coerce_ref (arg1);
return value_ref (arg1, TYPE_CODE_REF);
}
}
/* Records and unions for which GNAT encodings have been
generated need to be statically fixed as well.
Otherwise, non-static fixing produces a type where
all dynamic properties are removed, which prevents "ptype"
from being able to completely describe the type.
For instance, a case statement in a variant record would be
replaced by the relevant components based on the actual
value of the discriminants. */
if ((type->code () == TYPE_CODE_STRUCT
&& dynamic_template_type (type) != NULL)
|| (type->code () == TYPE_CODE_UNION
&& ada_find_parallel_type (type, "___XVU") != NULL))
return value_zero (to_static_fixed_type (type), not_lval);
}
value *arg1 = var_value_operation::evaluate (expect_type, exp, noside);
return ada_to_fixed_value (arg1);
}
}
/* Implement the evaluate_exp routine in the exp_descriptor structure