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[Ada] Cache all static structures and reset cache during resolution 

Currently, ada-lang.c:template_to_static_fixed_type (working on
structure types only) caches its result into the unused TYPE_TARGET_TYPE
field. This introduces inconsistencies when the input type is
specialized, for instance during type resolution: the cached static
fixed type is copied along with the original type, but it's no longer
adapted to the copy once the copy is modified:
template_to_static_fixed_type has to compute another static fixed type
for it.

This change first introduces a cache reset during type resolution for
structure types so that this inconsistency does not happen anymore. It
also makes template_to_static_fixed_type smarter with respect to types
that do not need static fixed copies so that less computations is done
in general.

This inconsistency was spotted thanks to code reading, not because of
any sort of failure and we did not manage to exhibit a failure yet, so
no testcase for this.

gdb/ChangeLog:

	* ada-lang.c (template_to_static_fixed_type): Return input type
	when it is already fixed. Cache the input type itself when not
	creating a static fixed copy. Make it explicit that we never
	molestate the input type.
	* gdbtypes.c (resolve_dynamic_struct): Reset the
	TYPE_TARGET_TYPE field for resolved copies.
This commit is contained in:
Pierre-Marie de Rodat 2015-04-27 11:06:07 +02:00
parent 460efde16c
commit 9e19566105
3 changed files with 47 additions and 18 deletions
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9
gdb/ChangeLog
View File

@ -1,3 +1,12 @@
2015-04-27 Pierre-Marie de Rodat <derodat@adacore.com>
* ada-lang.c (template_to_static_fixed_type): Return input type
when it is already fixed. Cache the input type itself when not
creating a static fixed copy. Make it explicit that we never
molestate the input type.
* gdbtypes.c (resolve_dynamic_struct): Reset the
TYPE_TARGET_TYPE field for resolved copies.
2015-04-27 Joel Brobecker <brobecker@adacore.com>
* ada-lang.c (ada_is_tagged_type): Add call to ada_check_typedef.

52
gdb/ada-lang.c
View File

@ -8171,11 +8171,21 @@ template_to_static_fixed_type (struct type *type0)
int nfields;
int f;
/* No need no do anything if the input type is already fixed. */
if (TYPE_FIXED_INSTANCE (type0))
return type0;
/* Likewise if we already have computed the static approximation. */
if (TYPE_TARGET_TYPE (type0) != NULL)
return TYPE_TARGET_TYPE (type0);
nfields = TYPE_NFIELDS (type0);
/* Don't clone TYPE0 until we are sure we are going to need a copy. */
type = type0;
nfields = TYPE_NFIELDS (type0);
/* Whether or not we cloned TYPE0, cache the result so that we don't do
recompute all over next time. */
TYPE_TARGET_TYPE (type0) = type;
for (f = 0; f < nfields; f += 1)
{
@ -8189,24 +8199,30 @@ template_to_static_fixed_type (struct type *type0)
}
else
new_type = static_unwrap_type (field_type);
if (type == type0 && new_type != field_type)
{
TYPE_TARGET_TYPE (type0) = type = alloc_type_copy (type0);
TYPE_CODE (type) = TYPE_CODE (type0);
INIT_CPLUS_SPECIFIC (type);
TYPE_NFIELDS (type) = nfields;
TYPE_FIELDS (type) = (struct field *)
TYPE_ALLOC (type, nfields * sizeof (struct field));
memcpy (TYPE_FIELDS (type), TYPE_FIELDS (type0),
sizeof (struct field) * nfields);
TYPE_NAME (type) = ada_type_name (type0);
TYPE_TAG_NAME (type) = NULL;
TYPE_FIXED_INSTANCE (type) = 1;
TYPE_LENGTH (type) = 0;
}
TYPE_FIELD_TYPE (type, f) = new_type;
TYPE_FIELD_NAME (type, f) = TYPE_FIELD_NAME (type0, f);
if (new_type != field_type)
{
/* Clone TYPE0 only the first time we get a new field type. */
if (type == type0)
{
TYPE_TARGET_TYPE (type0) = type = alloc_type_copy (type0);
TYPE_CODE (type) = TYPE_CODE (type0);
INIT_CPLUS_SPECIFIC (type);
TYPE_NFIELDS (type) = nfields;
TYPE_FIELDS (type) = (struct field *)
TYPE_ALLOC (type, nfields * sizeof (struct field));
memcpy (TYPE_FIELDS (type), TYPE_FIELDS (type0),
sizeof (struct field) * nfields);
TYPE_NAME (type) = ada_type_name (type0);
TYPE_TAG_NAME (type) = NULL;
TYPE_FIXED_INSTANCE (type) = 1;
TYPE_LENGTH (type) = 0;
}
TYPE_FIELD_TYPE (type, f) = new_type;
TYPE_FIELD_NAME (type, f) = TYPE_FIELD_NAME (type0, f);
}
}
return type;
}

4
gdb/gdbtypes.c
View File

@ -2013,6 +2013,10 @@ resolve_dynamic_struct (struct type *type,
TYPE_LENGTH (resolved_type)
= (resolved_type_bit_length + TARGET_CHAR_BIT - 1) / TARGET_CHAR_BIT;
/* The Ada language uses this field as a cache for static fixed types: reset
it as RESOLVED_TYPE must have its own static fixed type. */
TYPE_TARGET_TYPE (resolved_type) = NULL;
return resolved_type;
}