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C++ alias analysis improvement.

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2002-03-06  Dan Nicolaescu  <dann@ics.uci.edu>
            Daniel Berlin  <dan@dberlin.org>

        C++ alias analysis improvement.
	* alias.c (record_component_aliases): Record aliases for base
        classes too.
	* cp/cp-lang.c (ok_to_generate_alias_set_for_type): New function.
	(cxx_get_alias_set): Use it.

Co-Authored-By: Daniel Berlin <dberlin@dberlin.org>

From-SVN: r50587
This commit is contained in:
Dan Nicolaescu 2002-03-11 18:01:54 +00:00 committed by David Edelsohn
parent ff080abaf5
commit 61eece67a6
4 changed files with 79 additions and 3 deletions
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7
gcc/ChangeLog
View File

@ -1,3 +1,10 @@
2002-03-11 Dan Nicolaescu <dann@ics.uci.edu>
Daniel Berlin <dan@dberlin.org>
C++ alias analysis improvement.
* alias.c (record_component_aliases): Record aliases for base
classes too.
2002-03-11 Ulrich Weigand <uweigand@de.ibm.com>
* config/s390/s390.h (REG_ALLOC_ORDER): Add missing register.

11
gcc/alias.c
View File

@ -679,6 +679,17 @@ record_component_aliases (type)
case RECORD_TYPE:
case UNION_TYPE:
case QUAL_UNION_TYPE:
/* Recursively record aliases for the base classes, if there are any */
if (TYPE_BINFO (type) != NULL && TYPE_BINFO_BASETYPES (type) != NULL)
{
int i;
for (i = 0; i < TREE_VEC_LENGTH (TYPE_BINFO_BASETYPES (type)); i++)
{
tree binfo = TREE_VEC_ELT (TYPE_BINFO_BASETYPES (type), i);
record_alias_subset (superset,
get_alias_set (BINFO_TYPE (binfo)));
}
}
for (field = TYPE_FIELDS (type); field != 0; field = TREE_CHAIN (field))
if (TREE_CODE (field) == FIELD_DECL && ! DECL_NONADDRESSABLE_P (field))
record_alias_subset (superset, get_alias_set (TREE_TYPE (field)));

6
gcc/cp/ChangeLog
View File

@ -1,3 +1,9 @@
2002-03-11 Dan Nicolaescu <dann@ics.uci.edu>
Daniel Berlin <dan@dberlin.org>
* cp-lang.c (ok_to_generate_alias_set_for_type): New function.
(cxx_get_alias_set): Use it.
2002-03-10 Kaveh R. Ghazi <ghazi@caip.rutgers.edu>
* cp-tree.h (stabilize_expr): Prototype.

58
gcc/cp/cp-lang.c
View File

@ -29,6 +29,7 @@ Boston, MA 02111-1307, USA. */
#include "langhooks-def.h"
static HOST_WIDE_INT cxx_get_alias_set PARAMS ((tree));
static bool ok_to_generate_alias_set_for_type PARAMS ((tree));
#undef LANG_HOOKS_NAME
#define LANG_HOOKS_NAME "GNU C++"
@ -99,15 +100,66 @@ static HOST_WIDE_INT cxx_get_alias_set PARAMS ((tree));
/* Each front end provides its own hooks, for toplev.c. */
const struct lang_hooks lang_hooks = LANG_HOOKS_INITIALIZER;
/* Check if a C++ type is safe for aliasing.
Return TRUE if T safe for aliasing FALSE otherwise. */
static bool
ok_to_generate_alias_set_for_type (t)
tree t;
{
if (TYPE_PTRMEMFUNC_P (t))
return true;
if (AGGREGATE_TYPE_P (t))
{
if ((TREE_CODE (t) == RECORD_TYPE) || (TREE_CODE (t) == UNION_TYPE))
{
tree fields;
/* PODs are safe. */
if (! CLASSTYPE_NON_POD_P(t))
return true;
/* Classes with virtual baseclasses are not. */
if (TYPE_USES_VIRTUAL_BASECLASSES (t))
return false;
/* Recursively check the base classes. */
if (TYPE_BINFO (t) != NULL && TYPE_BINFO_BASETYPES (t) != NULL)
{
int i;
for (i = 0; i < TREE_VEC_LENGTH (TYPE_BINFO_BASETYPES (t)); i++)
{
tree binfo = TREE_VEC_ELT (TYPE_BINFO_BASETYPES (t), i);
if (!ok_to_generate_alias_set_for_type (BINFO_TYPE (binfo)))
return false;
}
}
/* Check all the fields. */
for (fields = TYPE_FIELDS (t); fields; fields = TREE_CHAIN (fields))
{
if (TREE_CODE (fields) != FIELD_DECL)
continue;
if (! ok_to_generate_alias_set_for_type (TREE_TYPE (fields)))
return false;
}
return true;
}
else if (TREE_CODE (t) == ARRAY_TYPE)
return ok_to_generate_alias_set_for_type (TREE_TYPE (t));
else
/* This should never happen, we dealt with all the aggregate
types that can appear in C++ above. */
abort ();
}
else
return true;
}
/* Special routine to get the alias set for C++. */
static HOST_WIDE_INT
cxx_get_alias_set (t)
tree t;
{
/* It's not yet safe to use alias sets for classes in C++ because
the TYPE_FIELDs list for a class doesn't mention base classes. */
if (AGGREGATE_TYPE_P (t))
/* It's not yet safe to use alias sets for classes in C++. */
if (!ok_to_generate_alias_set_for_type(t))
return 0;
return c_common_get_alias_set (t);