--- /dev/null
+/* Type based alias analysis.
+ Copyright (C) 2004, 2005, 2006, 2007, 2008 Free Software Foundation,
+ Inc.
+ Contributed by Kenneth Zadeck <zadeck@naturalbridge.com>
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
+
+/* This pass determines which types in the program contain only
+ instances that are completely encapsulated by the compilation unit.
+ Those types that are encapsulated must also pass the further
+ requirement that there be no bad operations on any instances of
+ those types.
+
+ A great deal of freedom in compilation is allowed for the instances
+ of those types that pass these conditions.
+*/
+
+/* The code in this module is called by the ipa pass manager. It
+ should be one of the later passes since its information is used by
+ the rest of the compilation. */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "tree.h"
+#include "tree-flow.h"
+#include "tree-inline.h"
+#include "tree-pass.h"
+#include "langhooks.h"
+#include "pointer-set.h"
+#include "ggc.h"
+#include "ipa-utils.h"
+#include "ipa-type-escape.h"
+#include "c-common.h"
+#include "gimple.h"
+#include "cgraph.h"
+#include "output.h"
+#include "flags.h"
+#include "timevar.h"
+#include "diagnostic.h"
+#include "langhooks.h"
+
+/* Some of the aliasing is called very early, before this phase is
+ called. To assure that this is not a problem, we keep track of if
+ this phase has been run. */
+static bool initialized = false;
+
+/* Scratch bitmap for avoiding work. */
+static bitmap been_there_done_that;
+static bitmap bitmap_tmp;
+
+/* There are two levels of escape that types can undergo.
+
+ EXPOSED_PARAMETER - some instance of the variable is
+ passed by value into an externally visible function or some
+ instance of the variable is passed out of an externally visible
+ function as a return value. In this case any of the fields of the
+ variable that are pointer types end up having their types marked as
+ FULL_ESCAPE.
+
+ FULL_ESCAPE - when bad things happen to good types. One of the
+ following things happens to the type: (a) either an instance of the
+ variable has its address passed to an externally visible function,
+ (b) the address is taken and some bad cast happens to the address
+ or (c) explicit arithmetic is done to the address.
+*/
+
+enum escape_t
+{
+ EXPOSED_PARAMETER,
+ FULL_ESCAPE
+};
+
+/* The following two bit vectors global_types_* correspond to
+ previous cases above. During the analysis phase, a bit is set in
+ one of these vectors if an operation of the offending class is
+ discovered to happen on the associated type. */
+
+static bitmap global_types_exposed_parameter;
+static bitmap global_types_full_escape;
+
+/* All of the types seen in this compilation unit. */
+static bitmap global_types_seen;
+/* Reverse map to take a canon uid and map it to a canon type. Uid's
+ are never manipulated unless they are associated with a canon
+ type. */
+static splay_tree uid_to_canon_type;
+
+/* Internal structure of type mapping code. This maps a canon type
+ name to its canon type. */
+static splay_tree all_canon_types;
+
+/* Map from type clones to the single canon type. */
+static splay_tree type_to_canon_type;
+
+/* A splay tree of bitmaps. An element X in the splay tree has a bit
+ set in its bitmap at TYPE_UID (TYPE_MAIN_VARIANT (Y)) if there was
+ an operation in the program of the form "&X.Y". */
+static splay_tree uid_to_addressof_down_map;
+
+/* A splay tree of bitmaps. An element Y in the splay tree has a bit
+ set in its bitmap at TYPE_UID (TYPE_MAIN_VARIANT (X)) if there was
+ an operation in the program of the form "&X.Y". */
+static splay_tree uid_to_addressof_up_map;
+
+/* Tree to hold the subtype maps used to mark subtypes of escaped
+ types. */
+static splay_tree uid_to_subtype_map;
+
+/* Records tree nodes seen in cgraph_create_edges. Simply using
+ walk_tree_without_duplicates doesn't guarantee each node is visited
+ once because it gets a new htab upon each recursive call from
+ scan_for_refs. */
+static struct pointer_set_t *visited_nodes;
+
+/* Visited stmts by walk_use_def_chains function because it's called
+ recursively. */
+static struct pointer_set_t *visited_stmts;
+
+static bitmap_obstack ipa_obstack;
+
+/* Static functions from this file that are used
+ before being defined. */
+static unsigned int look_for_casts (tree);
+static bool is_cast_from_non_pointer (tree, gimple, void *);
+
+/* Get the name of TYPE or return the string "<UNNAMED>". */
+static const char*
+get_name_of_type (tree type)
+{
+ tree name = TYPE_NAME (type);
+
+ if (!name)
+ /* Unnamed type, do what you like here. */
+ return "<UNNAMED>";
+
+ /* It will be a TYPE_DECL in the case of a typedef, otherwise, an
+ identifier_node */
+ if (TREE_CODE (name) == TYPE_DECL)
+ {
+ /* Each DECL has a DECL_NAME field which contains an
+ IDENTIFIER_NODE. (Some decls, most often labels, may have
+ zero as the DECL_NAME). */
+ if (DECL_NAME (name))
+ return IDENTIFIER_POINTER (DECL_NAME (name));
+ else
+ /* Unnamed type, do what you like here. */
+ return "<UNNAMED>";
+ }
+ else if (TREE_CODE (name) == IDENTIFIER_NODE)
+ return IDENTIFIER_POINTER (name);
+ else
+ return "<UNNAMED>";
+}
+
+struct type_brand_s
+{
+ const char* name;
+ int seq;
+};
+
+/* Splay tree comparison function on type_brand_s structures. */
+
+static int
+compare_type_brand (splay_tree_key sk1, splay_tree_key sk2)
+{
+ struct type_brand_s * k1 = (struct type_brand_s *) sk1;
+ struct type_brand_s * k2 = (struct type_brand_s *) sk2;
+
+ int value = strcmp(k1->name, k2->name);
+ if (value == 0)
+ return k2->seq - k1->seq;
+ else
+ return value;
+}
+
+/* All of the "unique_type" code is a hack to get around the sleazy
+ implementation used to compile more than file. Currently gcc does
+ not get rid of multiple instances of the same type that have been
+ collected from different compilation units. */
+/* This is a trivial algorithm for removing duplicate types. This
+ would not work for any language that used structural equivalence as
+ the basis of its type system. */
+/* Return TYPE if no type compatible with TYPE has been seen so far,
+ otherwise return a type compatible with TYPE that has already been
+ processed. */
+
+static tree
+discover_unique_type (tree type)
+{
+ struct type_brand_s * brand = XNEW (struct type_brand_s);
+ int i = 0;
+ splay_tree_node result;
+
+ brand->name = get_name_of_type (type);
+
+ while (1)
+ {
+ brand->seq = i++;
+ result = splay_tree_lookup (all_canon_types, (splay_tree_key) brand);
+
+ if (result)
+ {
+ /* Create an alias since this is just the same as
+ other_type. */
+ tree other_type = (tree) result->value;
+ if (types_compatible_p (type, other_type))
+ {
+ free (brand);
+ /* Insert this new type as an alias for other_type. */
+ splay_tree_insert (type_to_canon_type,
+ (splay_tree_key) type,
+ (splay_tree_value) other_type);
+ return other_type;
+ }
+ /* Not compatible, look for next instance with same name. */
+ }
+ else
+ {
+ /* No more instances, create new one since this is the first
+ time we saw this type. */
+ brand->seq = i++;
+ /* Insert the new brand. */
+ splay_tree_insert (all_canon_types,
+ (splay_tree_key) brand,
+ (splay_tree_value) type);
+
+ /* Insert this new type as an alias for itself. */
+ splay_tree_insert (type_to_canon_type,
+ (splay_tree_key) type,
+ (splay_tree_value) type);
+
+ /* Insert the uid for reverse lookup; */
+ splay_tree_insert (uid_to_canon_type,
+ (splay_tree_key) TYPE_UID (type),
+ (splay_tree_value) type);
+
+ bitmap_set_bit (global_types_seen, TYPE_UID (type));
+ return type;
+ }
+ }
+}
+
+/* Return true if TYPE is one of the type classes that we are willing
+ to analyze. This skips the goofy types like arrays of pointers to
+ methods. */
+static bool
+type_to_consider (tree type)
+{
+ /* Strip the *'s off. */
+ type = TYPE_MAIN_VARIANT (type);
+ while (POINTER_TYPE_P (type) || TREE_CODE (type) == ARRAY_TYPE)
+ type = TYPE_MAIN_VARIANT (TREE_TYPE (type));
+
+ switch (TREE_CODE (type))
+ {
+ case BOOLEAN_TYPE:
+ case COMPLEX_TYPE:
+ case ENUMERAL_TYPE:
+ case INTEGER_TYPE:
+ case QUAL_UNION_TYPE:
+ case REAL_TYPE:
+ case FIXED_POINT_TYPE:
+ case RECORD_TYPE:
+ case UNION_TYPE:
+ case VECTOR_TYPE:
+ case VOID_TYPE:
+ return true;
+
+ default:
+ return false;
+ }
+}
+
+/* Get the canon type of TYPE. If SEE_THRU_PTRS is true, remove all
+ the POINTER_TOs and if SEE_THRU_ARRAYS is true, remove all of the
+ ARRAY_OFs and POINTER_TOs. */
+
+static tree
+get_canon_type (tree type, bool see_thru_ptrs, bool see_thru_arrays)
+{
+ splay_tree_node result;
+ /* Strip the *'s off. */
+ if (!type || !type_to_consider (type))
+ return NULL;
+
+ type = TYPE_MAIN_VARIANT (type);
+ if (see_thru_arrays)
+ while (POINTER_TYPE_P (type) || TREE_CODE (type) == ARRAY_TYPE)
+ type = TYPE_MAIN_VARIANT (TREE_TYPE (type));
+
+ else if (see_thru_ptrs)
+ while (POINTER_TYPE_P (type))
+ type = TYPE_MAIN_VARIANT (TREE_TYPE (type));
+
+ result = splay_tree_lookup (type_to_canon_type, (splay_tree_key) type);
+
+ if (result == NULL)
+ return discover_unique_type (type);
+ else return (tree) result->value;
+}
+
+/* Same as GET_CANON_TYPE, except return the TYPE_ID rather than the
+ TYPE. */
+
+static int
+get_canon_type_uid (tree type, bool see_thru_ptrs, bool see_thru_arrays)
+{
+ type = get_canon_type (type, see_thru_ptrs, see_thru_arrays);
+ if (type)
+ return TYPE_UID(type);
+ else return 0;
+}
+
+/* Return 0 if TYPE is a record or union type. Return a positive
+ number if TYPE is a pointer to a record or union. The number is
+ the number of pointer types stripped to get to the record or union
+ type. Return -1 if TYPE is none of the above. */
+
+int
+ipa_type_escape_star_count_of_interesting_type (tree type)
+{
+ int count = 0;
+ /* Strip the *'s off. */
+ if (!type)
+ return -1;
+ type = TYPE_MAIN_VARIANT (type);
+ while (POINTER_TYPE_P (type))
+ {
+ type = TYPE_MAIN_VARIANT (TREE_TYPE (type));
+ count++;
+ }
+
+ /* We are interested in records, and unions only. */
+ if (TREE_CODE (type) == RECORD_TYPE
+ || TREE_CODE (type) == QUAL_UNION_TYPE
+ || TREE_CODE (type) == UNION_TYPE)
+ return count;
+ else
+ return -1;
+}
+
+
+/* Return 0 if TYPE is a record or union type. Return a positive
+ number if TYPE is a pointer to a record or union. The number is
+ the number of pointer types stripped to get to the record or union
+ type. Return -1 if TYPE is none of the above. */
+
+int
+ipa_type_escape_star_count_of_interesting_or_array_type (tree type)
+{
+ int count = 0;
+ /* Strip the *'s off. */
+ if (!type)
+ return -1;
+ type = TYPE_MAIN_VARIANT (type);
+ while (POINTER_TYPE_P (type) || TREE_CODE (type) == ARRAY_TYPE)
+ {
+ type = TYPE_MAIN_VARIANT (TREE_TYPE (type));
+ count++;
+ }
+
+ /* We are interested in records, and unions only. */
+ if (TREE_CODE (type) == RECORD_TYPE
+ || TREE_CODE (type) == QUAL_UNION_TYPE
+ || TREE_CODE (type) == UNION_TYPE)
+ return count;
+ else
+ return -1;
+}
+
+
+/* Return true if the record, or union TYPE passed in escapes this
+ compilation unit. Note that all of the pointer-to's are removed
+ before testing since these may not be correct. */
+
+bool
+ipa_type_escape_type_contained_p (tree type)
+{
+ if (!initialized)
+ return false;
+ return !bitmap_bit_p (global_types_full_escape,
+ get_canon_type_uid (type, true, false));
+}
+
+/* Return true if a modification to a field of type FIELD_TYPE cannot
+ clobber a record of RECORD_TYPE. */
+
+bool
+ipa_type_escape_field_does_not_clobber_p (tree record_type, tree field_type)
+{
+ splay_tree_node result;
+ int uid;
+
+ if (!initialized)
+ return false;
+
+ /* Strip off all of the pointer tos on the record type. Strip the
+ same number of pointer tos from the field type. If the field
+ type has fewer, it could not have been aliased. */
+ record_type = TYPE_MAIN_VARIANT (record_type);
+ field_type = TYPE_MAIN_VARIANT (field_type);
+ while (POINTER_TYPE_P (record_type))
+ {
+ record_type = TYPE_MAIN_VARIANT (TREE_TYPE (record_type));
+ if (POINTER_TYPE_P (field_type))
+ field_type = TYPE_MAIN_VARIANT (TREE_TYPE (field_type));
+ else
+ /* However, if field_type is a union, this quick test is not
+ correct since one of the variants of the union may be a
+ pointer to type and we cannot see across that here. So we
+ just strip the remaining pointer tos off the record type
+ and fall thru to the more precise code. */
+ if (TREE_CODE (field_type) == QUAL_UNION_TYPE
+ || TREE_CODE (field_type) == UNION_TYPE)
+ {
+ while (POINTER_TYPE_P (record_type))
+ record_type = TYPE_MAIN_VARIANT (TREE_TYPE (record_type));
+ break;
+ }
+ else
+ return true;
+ }
+
+ record_type = get_canon_type (record_type, true, true);
+ /* The record type must be contained. The field type may
+ escape. */
+ if (!ipa_type_escape_type_contained_p (record_type))
+ return false;
+
+ uid = TYPE_UID (record_type);
+ result = splay_tree_lookup (uid_to_addressof_down_map, (splay_tree_key) uid);
+
+ if (result)
+ {
+ bitmap field_type_map = (bitmap) result->value;
+ uid = get_canon_type_uid (field_type, true, true);
+ /* If the bit is there, the address was taken. If not, it
+ wasn't. */
+ return !bitmap_bit_p (field_type_map, uid);
+ }
+ else
+ /* No bitmap means no addresses were taken. */
+ return true;
+}
+
+
+/* Add TYPE to the suspect type set. Return true if the bit needed to
+ be marked. */
+
+static tree
+mark_type (tree type, enum escape_t escape_status)
+{
+ bitmap map = NULL;
+ int uid;
+
+ type = get_canon_type (type, true, true);
+ if (!type)
+ return NULL;
+
+ switch (escape_status)
+ {
+ case EXPOSED_PARAMETER:
+ map = global_types_exposed_parameter;
+ break;
+ case FULL_ESCAPE:
+ map = global_types_full_escape;
+ break;
+ }
+
+ uid = TYPE_UID (type);
+ if (bitmap_bit_p (map, uid))
+ return type;
+ else
+ {
+ bitmap_set_bit (map, uid);
+ if (escape_status == FULL_ESCAPE)
+ {
+ /* Efficiency hack. When things are bad, do not mess around
+ with this type anymore. */
+ bitmap_set_bit (global_types_exposed_parameter, uid);
+ }
+ }
+ return type;
+}
+
+/* Add interesting TYPE to the suspect type set. If the set is
+ EXPOSED_PARAMETER and the TYPE is a pointer type, the set is
+ changed to FULL_ESCAPE. */
+
+static void
+mark_interesting_type (tree type, enum escape_t escape_status)
+{
+ if (!type) return;
+ if (ipa_type_escape_star_count_of_interesting_type (type) >= 0)
+ {
+ if ((escape_status == EXPOSED_PARAMETER)
+ && POINTER_TYPE_P (type))
+ /* EXPOSED_PARAMETERs are only structs or unions are passed by
+ value. Anything passed by reference to an external
+ function fully exposes the type. */
+ mark_type (type, FULL_ESCAPE);
+ else
+ mark_type (type, escape_status);
+ }
+}
+
+/* Return true if PARENT is supertype of CHILD. Both types must be
+ known to be structures or unions. */
+
+static bool
+parent_type_p (tree parent, tree child)
+{
+ int i;
+ tree binfo, base_binfo;
+ if (TYPE_BINFO (parent))
+ for (binfo = TYPE_BINFO (parent), i = 0;
+ BINFO_BASE_ITERATE (binfo, i, base_binfo); i++)
+ {
+ tree binfotype = BINFO_TYPE (base_binfo);
+ if (binfotype == child)
+ return true;
+ else if (parent_type_p (binfotype, child))
+ return true;
+ }
+ if (TREE_CODE (parent) == UNION_TYPE
+ || TREE_CODE (parent) == QUAL_UNION_TYPE)
+ {
+ tree field;
+ /* Search all of the variants in the union to see if one of them
+ is the child. */
+ for (field = TYPE_FIELDS (parent);
+ field;
+ field = TREE_CHAIN (field))
+ {
+ tree field_type;
+ if (TREE_CODE (field) != FIELD_DECL)
+ continue;
+
+ field_type = TREE_TYPE (field);
+ if (field_type == child)
+ return true;
+ }
+
+ /* If we did not find it, recursively ask the variants if one of
+ their children is the child type. */
+ for (field = TYPE_FIELDS (parent);
+ field;
+ field = TREE_CHAIN (field))
+ {
+ tree field_type;
+ if (TREE_CODE (field) != FIELD_DECL)
+ continue;
+
+ field_type = TREE_TYPE (field);
+ if (TREE_CODE (field_type) == RECORD_TYPE
+ || TREE_CODE (field_type) == QUAL_UNION_TYPE
+ || TREE_CODE (field_type) == UNION_TYPE)
+ if (parent_type_p (field_type, child))
+ return true;
+ }
+ }
+
+ if (TREE_CODE (parent) == RECORD_TYPE)
+ {
+ tree field;
+ for (field = TYPE_FIELDS (parent);
+ field;
+ field = TREE_CHAIN (field))
+ {
+ tree field_type;
+ if (TREE_CODE (field) != FIELD_DECL)
+ continue;
+
+ field_type = TREE_TYPE (field);
+ if (field_type == child)
+ return true;
+ /* You can only cast to the first field so if it does not
+ match, quit. */
+ if (TREE_CODE (field_type) == RECORD_TYPE
+ || TREE_CODE (field_type) == QUAL_UNION_TYPE
+ || TREE_CODE (field_type) == UNION_TYPE)
+ {
+ if (parent_type_p (field_type, child))
+ return true;
+ else
+ break;
+ }
+ }
+ }
+ return false;
+}
+
+/* Return the number of pointer tos for TYPE and return TYPE with all
+ of these stripped off. */
+
+static int
+count_stars (tree* type_ptr)
+{
+ tree type = *type_ptr;
+ int i = 0;
+ type = TYPE_MAIN_VARIANT (type);
+ while (POINTER_TYPE_P (type))
+ {
+ type = TYPE_MAIN_VARIANT (TREE_TYPE (type));
+ i++;
+ }
+
+ *type_ptr = type;
+ return i;
+}
+
+enum cast_type {
+ CT_UP = 0x1,
+ CT_DOWN = 0x2,
+ CT_SIDEWAYS = 0x4,
+ CT_USELESS = 0x8,
+ CT_FROM_P_BAD = 0x10,
+ CT_FROM_NON_P = 0x20,
+ CT_TO_NON_INTER = 0x40,
+ CT_FROM_MALLOC = 0x80,
+ CT_NO_CAST = 0x100
+};
+
+/* Check the cast FROM_TYPE to TO_TYPE. This function requires that
+ the two types have already passed the
+ ipa_type_escape_star_count_of_interesting_type test. */
+
+static enum cast_type
+check_cast_type (tree to_type, tree from_type)
+{
+ int to_stars = count_stars (&to_type);
+ int from_stars = count_stars (&from_type);
+ if (to_stars != from_stars)
+ return CT_SIDEWAYS;
+
+ if (to_type == from_type)
+ return CT_USELESS;
+
+ if (parent_type_p (to_type, from_type)) return CT_UP;
+ if (parent_type_p (from_type, to_type)) return CT_DOWN;
+ return CT_SIDEWAYS;
+}
+
+/* This function returns nonzero if VAR is result of call
+ to malloc function. */
+
+static bool
+is_malloc_result (tree var)
+{
+ gimple def_stmt;
+
+ if (!var)
+ return false;
+
+ if (SSA_NAME_IS_DEFAULT_DEF (var))
+ return false;
+
+ def_stmt = SSA_NAME_DEF_STMT (var);
+
+ if (!is_gimple_call (def_stmt))
+ return false;
+
+ if (var != gimple_call_lhs (def_stmt))
+ return false;
+
+ return ((gimple_call_flags (def_stmt) & ECF_MALLOC) != 0);
+
+}
+
+/* Check a cast FROM this variable, TO_TYPE. Mark the escaping types
+ if appropriate. Returns cast_type as detected. */
+
+static enum cast_type
+check_cast (tree to_type, tree from)
+{
+ tree from_type = get_canon_type (TREE_TYPE (from), false, false);
+ bool to_interesting_type, from_interesting_type;
+ enum cast_type cast = CT_NO_CAST;
+
+ to_type = get_canon_type (to_type, false, false);
+ if (!from_type || !to_type || from_type == to_type)
+ return cast;
+
+ to_interesting_type =
+ ipa_type_escape_star_count_of_interesting_type (to_type) >= 0;
+ from_interesting_type =
+ ipa_type_escape_star_count_of_interesting_type (from_type) >= 0;
+
+ if (to_interesting_type)
+ if (from_interesting_type)
+ {
+ /* Both types are interesting. This can be one of four types
+ of cast: useless, up, down, or sideways. We do not care
+ about up or useless. Sideways casts are always bad and
+ both sides get marked as escaping. Downcasts are not
+ interesting here because if type is marked as escaping, all
+ of its subtypes escape. */
+ cast = check_cast_type (to_type, from_type);
+ switch (cast)
+ {
+ case CT_UP:
+ case CT_USELESS:
+ case CT_DOWN:
+ break;
+
+ case CT_SIDEWAYS:
+ mark_type (to_type, FULL_ESCAPE);
+ mark_type (from_type, FULL_ESCAPE);
+ break;
+
+ default:
+ break;
+ }
+ }
+ else
+ {
+ /* This code excludes two cases from marking as escaped:
+
+ 1. if this is a cast of index of array of structures/unions
+ that happens before accessing array element, we should not
+ mark it as escaped.
+ 2. if this is a cast from the local that is a result from a
+ call to malloc, do not mark the cast as bad.
+
+ */
+
+ if (POINTER_TYPE_P (to_type) && !POINTER_TYPE_P (from_type))
+ cast = CT_FROM_NON_P;
+ else if (TREE_CODE (from) == SSA_NAME
+ && is_malloc_result (from))
+ cast = CT_FROM_MALLOC;
+ else
+ {
+ cast = CT_FROM_P_BAD;
+ mark_type (to_type, FULL_ESCAPE);
+ }
+ }
+ else if (from_interesting_type)
+ {
+ mark_type (from_type, FULL_ESCAPE);
+ cast = CT_TO_NON_INTER;
+ }
+
+ return cast;
+}
+
+
+/* Scan assignment statement S to see if there are any casts within it. */
+
+static unsigned int
+look_for_casts_stmt (gimple s)
+{
+ unsigned int cast = 0;
+
+ gcc_assert (is_gimple_assign (s));
+
+ if (gimple_assign_cast_p (s))
+ {
+ tree castfromvar = gimple_assign_rhs1 (s);
+ cast |= check_cast (TREE_TYPE (gimple_assign_lhs (s)), castfromvar);
+ }
+ else
+ {
+ size_t i;
+ for (i = 0; i < gimple_num_ops (s); i++)
+ cast |= look_for_casts (gimple_op (s, i));
+ }
+
+ if (!cast)
+ cast = CT_NO_CAST;
+
+ return cast;
+}
+
+
+typedef struct cast
+{
+ int type;
+ gimple stmt;
+} cast_t;
+
+/* This function is a callback for walk_use_def_chains function called
+ from is_array_access_through_pointer_and_index. */
+
+static bool
+is_cast_from_non_pointer (tree var, gimple def_stmt, void *data)
+{
+ if (!def_stmt || !var)
+ return false;
+
+ if (gimple_code (def_stmt) == GIMPLE_PHI)
+ return false;
+
+ if (SSA_NAME_IS_DEFAULT_DEF (var))
+ return false;
+
+ if (is_gimple_assign (def_stmt))
+ {
+ use_operand_p use_p;
+ ssa_op_iter iter;
+ unsigned int cast = look_for_casts_stmt (def_stmt);
+
+ /* Check that only one cast happened, and it's of non-pointer
+ type. */
+ if ((cast & CT_FROM_NON_P) == (CT_FROM_NON_P)
+ && (cast & ~(CT_FROM_NON_P)) == 0)
+ {
+ ((cast_t *)data)->stmt = def_stmt;
+ ((cast_t *)data)->type++;
+
+ FOR_EACH_SSA_USE_OPERAND (use_p, def_stmt, iter, SSA_OP_ALL_USES)
+ {
+ walk_use_def_chains (USE_FROM_PTR (use_p),
+ is_cast_from_non_pointer, data, false);
+ if (((cast_t*)data)->type == -1)
+ break;
+ }
+ }
+ /* Check that there is no cast, or cast is not harmful. */
+ else if ((cast & CT_NO_CAST) == (CT_NO_CAST)
+ || (cast & CT_DOWN) == (CT_DOWN)
+ || (cast & CT_UP) == (CT_UP)
+ || (cast & CT_USELESS) == (CT_USELESS)
+ || (cast & CT_FROM_MALLOC) == (CT_FROM_MALLOC))
+ {
+ FOR_EACH_SSA_USE_OPERAND (use_p, def_stmt, iter, SSA_OP_ALL_USES)
+ {
+ walk_use_def_chains (USE_FROM_PTR (use_p),
+ is_cast_from_non_pointer, data, false);
+ if (((cast_t*)data)->type == -1)
+ break;
+ }
+ }
+ /* The cast is harmful. */
+ else
+ ((cast_t *)data)->type = -1;
+ }
+
+ if (((cast_t*)data)->type == -1)
+ return true;
+
+ return false;
+}
+
+/* When array element a_p[i] is accessed through the pointer a_p
+ and index i, it's translated into the following sequence
+ in gimple:
+
+ i.1_5 = (unsigned int) i_1;
+ D.1605_6 = i.1_5 * 16;
+ D.1606_7 = (struct str_t *) D.1605_6;
+ a_p.2_8 = a_p;
+ D.1608_9 = D.1606_7 + a_p.2_8;
+
+ OP0 and OP1 are of the same pointer types and stand for
+ D.1606_7 and a_p.2_8 or vise versa.
+
+ This function checks that:
+
+ 1. one of OP0 and OP1 (D.1606_7) has passed only one cast from
+ non-pointer type (D.1606_7 = (struct str_t *) D.1605_6;).
+
+ 2. one of OP0 and OP1 which has passed the cast from
+ non-pointer type (D.1606_7), is actually generated by multiplication of
+ index by size of type to which both OP0 and OP1 point to
+ (in this case D.1605_6 = i.1_5 * 16; ).
+
+ 3. an address of def of the var to which was made cast (D.1605_6)
+ was not taken.(How can it happen?)
+
+ The following items are checked implicitly by the end of algorithm:
+
+ 4. one of OP0 and OP1 (a_p.2_8) have never been cast
+ (because if it was cast to pointer type, its type, that is also
+ the type of OP0 and OP1, will be marked as escaped during
+ analysis of casting stmt (when check_cast() is called
+ from scan_for_refs for this stmt)).
+
+ 5. defs of OP0 and OP1 are not passed into externally visible function
+ (because if they are passed then their type, that is also the type of OP0
+ and OP1, will be marked and escaped during check_call function called from
+ scan_for_refs with call stmt).
+
+ In total, 1-5 guaranty that it's an access to array by pointer and index.
+
+*/
+
+bool
+is_array_access_through_pointer_and_index (enum tree_code code, tree op0,
+ tree op1, tree *base, tree *offset,
+ gimple *offset_cast_stmt)
+{
+ tree before_cast;
+ gimple before_cast_def_stmt;
+ cast_t op0_cast, op1_cast;
+
+ *base = NULL;
+ *offset = NULL;
+ *offset_cast_stmt = NULL;
+
+ /* Check 1. */
+ if (code == POINTER_PLUS_EXPR)
+ {
+ tree op0type = TYPE_MAIN_VARIANT (TREE_TYPE (op0));
+ tree op1type = TYPE_MAIN_VARIANT (TREE_TYPE (op1));
+
+ /* One of op0 and op1 is of pointer type and the other is numerical. */
+ if (POINTER_TYPE_P (op0type) && NUMERICAL_TYPE_CHECK (op1type))
+ {
+ *base = op0;
+ *offset = op1;
+ }
+ else if (POINTER_TYPE_P (op1type) && NUMERICAL_TYPE_CHECK (op0type))
+ {
+ *base = op1;
+ *offset = op0;
+ }
+ else
+ return false;
+ }
+ else
+ {
+ /* Init data for walk_use_def_chains function. */
+ op0_cast.type = op1_cast.type = 0;
+ op0_cast.stmt = op1_cast.stmt = NULL;
+
+ visited_stmts = pointer_set_create ();
+ walk_use_def_chains (op0, is_cast_from_non_pointer,(void *)(&op0_cast),
+ false);
+ pointer_set_destroy (visited_stmts);
+
+ visited_stmts = pointer_set_create ();
+ walk_use_def_chains (op1, is_cast_from_non_pointer,(void *)(&op1_cast),
+ false);
+ pointer_set_destroy (visited_stmts);
+
+ if (op0_cast.type == 1 && op1_cast.type == 0)
+ {
+ *base = op1;
+ *offset = op0;
+ *offset_cast_stmt = op0_cast.stmt;
+ }
+ else if (op0_cast.type == 0 && op1_cast.type == 1)
+ {
+ *base = op0;
+ *offset = op1;
+ *offset_cast_stmt = op1_cast.stmt;
+ }
+ else
+ return false;
+ }
+
+ /* Check 2.
+ offset_cast_stmt is of the form:
+ D.1606_7 = (struct str_t *) D.1605_6; */
+
+ if (*offset_cast_stmt)
+ {
+ before_cast = SINGLE_SSA_TREE_OPERAND (*offset_cast_stmt, SSA_OP_USE);
+ if (!before_cast)
+ return false;
+
+ if (SSA_NAME_IS_DEFAULT_DEF (before_cast))
+ return false;
+
+ before_cast_def_stmt = SSA_NAME_DEF_STMT (before_cast);
+ if (!before_cast_def_stmt)
+ return false;
+ }
+ else
+ before_cast_def_stmt = SSA_NAME_DEF_STMT (*offset);
+
+ /* before_cast_def_stmt should be of the form:
+ D.1605_6 = i.1_5 * 16; */
+
+ if (is_gimple_assign (before_cast_def_stmt))
+ {
+ /* We expect temporary here. */
+ if (!is_gimple_reg (gimple_assign_lhs (before_cast_def_stmt)))
+ return false;
+
+ if (gimple_assign_rhs_code (before_cast_def_stmt) == MULT_EXPR)
+ {
+ tree arg0 = gimple_assign_rhs1 (before_cast_def_stmt);
+ tree arg1 = gimple_assign_rhs2 (before_cast_def_stmt);
+ tree unit_size =
+ TYPE_SIZE_UNIT (TREE_TYPE (TYPE_MAIN_VARIANT (TREE_TYPE (op0))));
+
+ if (!(CONSTANT_CLASS_P (arg0)
+ && simple_cst_equal (arg0, unit_size))
+ && !(CONSTANT_CLASS_P (arg1)
+ && simple_cst_equal (arg1, unit_size)))
+ return false;
+ }
+ else
+ return false;
+ }
+ else
+ return false;
+
+ /* Check 3.
+ check that address of D.1605_6 was not taken.
+ FIXME: if D.1605_6 is gimple reg than it cannot be addressable. */
+
+ return true;
+}
+
+/* Register the parameter and return types of function FN. The type
+ ESCAPES if the function is visible outside of the compilation
+ unit. */
+static void
+check_function_parameter_and_return_types (tree fn, bool escapes)
+{
+ tree arg;
+
+ if (TYPE_ARG_TYPES (TREE_TYPE (fn)))
+ {
+ for (arg = TYPE_ARG_TYPES (TREE_TYPE (fn));
+ arg && TREE_VALUE (arg) != void_type_node;
+ arg = TREE_CHAIN (arg))
+ {
+ tree type = get_canon_type (TREE_VALUE (arg), false, false);
+ if (escapes)
+ mark_interesting_type (type, EXPOSED_PARAMETER);
+ }
+ }
+ else
+ {
+ /* FIXME - According to Geoff Keating, we should never have to
+ do this; the front ends should always process the arg list
+ from the TYPE_ARG_LIST. However, Geoff is wrong, this code
+ does seem to be live. */
+
+ for (arg = DECL_ARGUMENTS (fn); arg; arg = TREE_CHAIN (arg))
+ {
+ tree type = get_canon_type (TREE_TYPE (arg), false, false);
+ if (escapes)
+ mark_interesting_type (type, EXPOSED_PARAMETER);
+ }
+ }
+ if (escapes)
+ {
+ tree type = get_canon_type (TREE_TYPE (TREE_TYPE (fn)), false, false);
+ mark_interesting_type (type, EXPOSED_PARAMETER);
+ }
+}
+
+/* Return true if the variable T is the right kind of static variable to
+ perform compilation unit scope escape analysis. */
+
+static inline void
+has_proper_scope_for_analysis (tree t)
+{
+ /* If the variable has the "used" attribute, treat it as if it had a
+ been touched by the devil. */
+ tree type = get_canon_type (TREE_TYPE (t), false, false);
+ if (!type) return;
+
+ if (lookup_attribute ("used", DECL_ATTRIBUTES (t)))
+ {
+ mark_interesting_type (type, FULL_ESCAPE);
+ return;
+ }
+
+ /* Do not want to do anything with volatile except mark any
+ function that uses one to be not const or pure. */
+ if (TREE_THIS_VOLATILE (t))
+ return;
+
+ /* Do not care about a local automatic that is not static. */
+ if (!TREE_STATIC (t) && !DECL_EXTERNAL (t))
+ return;
+
+ if (DECL_EXTERNAL (t) || TREE_PUBLIC (t))
+ {
+ /* If the front end set the variable to be READONLY and
+ constant, we can allow this variable in pure or const
+ functions but the scope is too large for our analysis to set
+ these bits ourselves. */
+
+ if (TREE_READONLY (t)
+ && DECL_INITIAL (t)
+ && is_gimple_min_invariant (DECL_INITIAL (t)))
+ ; /* Read of a constant, do not change the function state. */
+ else
+ {
+ /* The type escapes for all public and externs. */
+ mark_interesting_type (type, FULL_ESCAPE);
+ }
+ }
+}
+
+/* If T is a VAR_DECL for a static that we are interested in, add the
+ uid to the bitmap. */
+
+static void
+check_operand (tree t)
+{
+ if (!t) return;
+
+ /* This is an assignment from a function, register the types as
+ escaping. */
+ if (TREE_CODE (t) == FUNCTION_DECL)
+ check_function_parameter_and_return_types (t, true);
+
+ else if (TREE_CODE (t) == VAR_DECL)
+ has_proper_scope_for_analysis (t);
+}
+
+/* Examine tree T for references. */
+
+static void
+check_tree (tree t)
+{
+ if ((TREE_CODE (t) == EXC_PTR_EXPR) || (TREE_CODE (t) == FILTER_EXPR))
+ return;
+
+ /* We want to catch here also REALPART_EXPR and IMAGEPART_EXPR,
+ but they already included in handled_component_p. */
+ while (handled_component_p (t))
+ {
+ if (TREE_CODE (t) == ARRAY_REF)
+ check_operand (TREE_OPERAND (t, 1));
+ t = TREE_OPERAND (t, 0);
+ }
+
+ if (INDIRECT_REF_P (t))
+/* || TREE_CODE (t) == MEM_REF) */
+ check_tree (TREE_OPERAND (t, 0));
+
+ if (SSA_VAR_P (t) || (TREE_CODE (t) == FUNCTION_DECL))
+ {
+ check_operand (t);
+ if (DECL_P (t) && DECL_INITIAL (t))
+ check_tree (DECL_INITIAL (t));
+ }
+}
+
+/* Create an address_of edge FROM_TYPE.TO_TYPE. */
+static void
+mark_interesting_addressof (tree to_type, tree from_type)
+{
+ int from_uid;
+ int to_uid;
+ bitmap type_map;
+ splay_tree_node result;
+
+ from_type = get_canon_type (from_type, false, false);
+ to_type = get_canon_type (to_type, false, false);
+
+ if (!from_type || !to_type)
+ return;
+
+ from_uid = TYPE_UID (from_type);
+ to_uid = TYPE_UID (to_type);
+
+ gcc_assert (ipa_type_escape_star_count_of_interesting_type (from_type) == 0);
+
+ /* Process the Y into X map pointer. */
+ result = splay_tree_lookup (uid_to_addressof_down_map,
+ (splay_tree_key) from_uid);
+
+ if (result)
+ type_map = (bitmap) result->value;
+ else
+ {
+ type_map = BITMAP_ALLOC (&ipa_obstack);
+ splay_tree_insert (uid_to_addressof_down_map,
+ from_uid,
+ (splay_tree_value)type_map);
+ }
+ bitmap_set_bit (type_map, TYPE_UID (to_type));
+
+ /* Process the X into Y reverse map pointer. */
+ result =
+ splay_tree_lookup (uid_to_addressof_up_map, (splay_tree_key) to_uid);
+
+ if (result)
+ type_map = (bitmap) result->value;
+ else
+ {
+ type_map = BITMAP_ALLOC (&ipa_obstack);
+ splay_tree_insert (uid_to_addressof_up_map,
+ to_uid,
+ (splay_tree_value)type_map);
+ }
+ bitmap_set_bit (type_map, TYPE_UID (from_type));
+}
+
+/* Scan tree T to see if there are any addresses taken in within T. */
+
+static void
+look_for_address_of (tree t)
+{
+ if (TREE_CODE (t) == ADDR_EXPR)
+ {
+ tree x = get_base_var (t);
+ tree cref = TREE_OPERAND (t, 0);
+
+ /* If we have an expression of the form "&a.b.c.d", mark a.b,
+ b.c and c.d. as having its address taken. */
+ tree fielddecl = NULL_TREE;
+ while (cref!= x)
+ {
+ if (TREE_CODE (cref) == COMPONENT_REF)
+ {
+ fielddecl = TREE_OPERAND (cref, 1);
+ mark_interesting_addressof (TREE_TYPE (fielddecl),
+ DECL_FIELD_CONTEXT (fielddecl));
+ }
+ else if (TREE_CODE (cref) == ARRAY_REF)
+ get_canon_type (TREE_TYPE (cref), false, false);
+
+ cref = TREE_OPERAND (cref, 0);
+ }
+
+ if (TREE_CODE (x) == VAR_DECL)
+ has_proper_scope_for_analysis (x);
+ }
+}
+
+
+/* Scan tree T to see if there are any casts within it. */
+
+static unsigned int
+look_for_casts (tree t)
+{
+ unsigned int cast = 0;
+
+ if (is_gimple_cast (t) || TREE_CODE (t) == VIEW_CONVERT_EXPR)
+ {
+ tree castfromvar = TREE_OPERAND (t, 0);
+ cast = cast | check_cast (TREE_TYPE (t), castfromvar);
+ }
+ else
+ while (handled_component_p (t))
+ {
+ t = TREE_OPERAND (t, 0);
+ if (TREE_CODE (t) == VIEW_CONVERT_EXPR)
+ {
+ /* This may be some part of a component ref.
+ IE it may be a.b.VIEW_CONVERT_EXPR<weird_type>(c).d, AFAIK.
+ castfromref will give you a.b.c, not a. */
+ tree castfromref = TREE_OPERAND (t, 0);
+ cast = cast | check_cast (TREE_TYPE (t), castfromref);
+ }
+ else if (TREE_CODE (t) == COMPONENT_REF)
+ get_canon_type (TREE_TYPE (TREE_OPERAND (t, 1)), false, false);
+ }
+
+ if (!cast)
+ cast = CT_NO_CAST;
+ return cast;
+}
+
+/* Check to see if T is a read or address of operation on a static var
+ we are interested in analyzing. */
+
+static void
+check_rhs_var (tree t)
+{
+ look_for_address_of (t);
+ check_tree (t);
+}
+
+/* Check to see if T is an assignment to a static var we are
+ interested in analyzing. */
+
+static void
+check_lhs_var (tree t)
+{
+ check_tree (t);
+}
+
+/* This is a scaled down version of get_asm_expr_operands from
+ tree_ssa_operands.c. The version there runs much later and assumes
+ that aliasing information is already available. Here we are just
+ trying to find if the set of inputs and outputs contain references
+ or address of operations to local. FN is the function being
+ analyzed and STMT is the actual asm statement. */
+
+static void
+check_asm (gimple stmt)
+{
+ size_t i;
+
+ for (i = 0; i < gimple_asm_noutputs (stmt); i++)
+ check_lhs_var (gimple_asm_output_op (stmt, i));
+
+ for (i = 0; i < gimple_asm_ninputs (stmt); i++)
+ check_rhs_var (gimple_asm_input_op (stmt, i));
+
+ /* There is no code here to check for asm memory clobbers. The
+ casual maintainer might think that such code would be necessary,
+ but that appears to be wrong. In other parts of the compiler,
+ the asm memory clobbers are assumed to only clobber variables
+ that are addressable. All types with addressable instances are
+ assumed to already escape. So, we are protected here. */
+}
+
+
+/* Check the parameters of function call to CALL to mark the
+ types that pass across the function boundary. Also check to see if
+ this is either an indirect call, a call outside the compilation
+ unit. */
+
+static void
+check_call (gimple call)
+{
+ tree callee_t = gimple_call_fndecl (call);
+ struct cgraph_node* callee;
+ enum availability avail = AVAIL_NOT_AVAILABLE;
+ size_t i;
+
+ for (i = 0; i < gimple_call_num_args (call); i++)
+ check_rhs_var (gimple_call_arg (call, i));
+
+ if (callee_t)
+ {
+ tree arg_type;
+ tree last_arg_type = NULL;
+ callee = cgraph_node(callee_t);
+ avail = cgraph_function_body_availability (callee);
+
+ /* Check that there are no implicit casts in the passing of
+ parameters. */
+ if (TYPE_ARG_TYPES (TREE_TYPE (callee_t)))
+ {
+ for (arg_type = TYPE_ARG_TYPES (TREE_TYPE (callee_t)), i = 0;
+ arg_type && TREE_VALUE (arg_type) != void_type_node;
+ arg_type = TREE_CHAIN (arg_type), i++)
+ {
+ tree operand = gimple_call_arg (call, i);
+ if (operand)
+ {
+ last_arg_type = TREE_VALUE(arg_type);
+ check_cast (last_arg_type, operand);
+ }
+ else
+ /* The code reaches here for some unfortunate
+ builtin functions that do not have a list of
+ argument types. */
+ break;
+ }
+ }
+ else
+ {
+ /* FIXME - According to Geoff Keating, we should never
+ have to do this; the front ends should always process
+ the arg list from the TYPE_ARG_LIST. */
+ for (arg_type = DECL_ARGUMENTS (callee_t), i = 0;
+ arg_type;
+ arg_type = TREE_CHAIN (arg_type), i++)
+ {
+ tree operand = gimple_call_arg (call, i);
+ if (operand)
+ {
+ last_arg_type = TREE_TYPE (arg_type);
+ check_cast (last_arg_type, operand);
+ }
+ else
+ /* The code reaches here for some unfortunate
+ builtin functions that do not have a list of
+ argument types. */
+ break;
+ }
+ }
+
+ /* In the case where we have a var_args function, we need to
+ check the remaining parameters against the last argument. */
+ arg_type = last_arg_type;
+ for ( ; i < gimple_call_num_args (call); i++)
+ {
+ tree operand = gimple_call_arg (call, i);
+ if (arg_type)
+ check_cast (arg_type, operand);
+ else
+ {
+ /* The code reaches here for some unfortunate
+ builtin functions that do not have a list of
+ argument types. Most of these functions have
+ been marked as having their parameters not
+ escape, but for the rest, the type is doomed. */
+ tree type = get_canon_type (TREE_TYPE (operand), false, false);
+ mark_interesting_type (type, FULL_ESCAPE);
+ }
+ }
+ }
+
+ /* The callee is either unknown (indirect call) or there is just no
+ scannable code for it (external call) . We look to see if there
+ are any bits available for the callee (such as by declaration or
+ because it is builtin) and process solely on the basis of those
+ bits. */
+ if (avail == AVAIL_NOT_AVAILABLE || avail == AVAIL_OVERWRITABLE)
+ {
+ /* If this is a direct call to an external function, mark all of
+ the parameter and return types. */
+ for (i = 0; i < gimple_call_num_args (call); i++)
+ {
+ tree operand = gimple_call_arg (call, i);
+ tree type = get_canon_type (TREE_TYPE (operand), false, false);
+ mark_interesting_type (type, EXPOSED_PARAMETER);
+ }
+
+ if (callee_t)
+ {
+ tree type =
+ get_canon_type (TREE_TYPE (TREE_TYPE (callee_t)), false, false);
+ mark_interesting_type (type, EXPOSED_PARAMETER);
+ }
+ }
+}
+
+/* CODE is the operation on OP0 and OP1. OP0 is the operand that we
+ *know* is a pointer type. OP1 may be a pointer type. */
+static bool
+okay_pointer_operation (enum tree_code code, tree op0, tree op1)
+{
+ tree op0type = TYPE_MAIN_VARIANT (TREE_TYPE (op0));
+
+ switch (code)
+ {
+ case MULT_EXPR:
+ /* Multiplication does not change alignment. */
+ return true;
+ break;
+ case MINUS_EXPR:
+ case PLUS_EXPR:
+ case POINTER_PLUS_EXPR:
+ {
+ tree base, offset;
+ gimple offset_cast_stmt;
+
+ if (POINTER_TYPE_P (op0type)
+ && TREE_CODE (op0) == SSA_NAME
+ && TREE_CODE (op1) == SSA_NAME
+ && is_array_access_through_pointer_and_index (code, op0, op1,
+ &base,
+ &offset,
+ &offset_cast_stmt))
+ return true;
+ else
+ {
+ tree size_of_op0_points_to = TYPE_SIZE_UNIT (TREE_TYPE (op0type));
+
+ if (CONSTANT_CLASS_P (op1)
+ && size_of_op0_points_to
+ && multiple_of_p (TREE_TYPE (size_of_op0_points_to),
+ op1, size_of_op0_points_to))
+ return true;
+
+ if (CONSTANT_CLASS_P (op0)
+ && size_of_op0_points_to
+ && multiple_of_p (TREE_TYPE (size_of_op0_points_to),
+ op0, size_of_op0_points_to))
+ return true;
+ }
+ }
+ break;
+ default:
+ return false;
+ }
+ return false;
+}
+
+
+
+/* Helper for scan_for_refs. Check the operands of an assignment to
+ mark types that may escape. */
+
+static void
+check_assign (gimple t)
+{
+ /* First look on the lhs and see what variable is stored to */
+ check_lhs_var (gimple_assign_lhs (t));
+
+ /* For the purposes of figuring out what the cast affects */
+
+ /* Next check the operands on the rhs to see if they are ok. */
+ switch (TREE_CODE_CLASS (gimple_assign_rhs_code (t)))
+ {
+ case tcc_binary:
+ {
+ tree op0 = gimple_assign_rhs1 (t);
+ tree type0 = get_canon_type (TREE_TYPE (op0), false, false);
+ tree op1 = gimple_assign_rhs2 (t);
+ tree type1 = get_canon_type (TREE_TYPE (op1), false, false);
+
+ /* If this is pointer arithmetic of any bad sort, then
+ we need to mark the types as bad. For binary
+ operations, no binary operator we currently support
+ is always "safe" in regard to what it would do to
+ pointers for purposes of determining which types
+ escape, except operations of the size of the type.
+ It is possible that min and max under the right set
+ of circumstances and if the moon is in the correct
+ place could be safe, but it is hard to see how this
+ is worth the effort. */
+ if (type0 && POINTER_TYPE_P (type0)
+ && !okay_pointer_operation (gimple_assign_rhs_code (t), op0, op1))
+ mark_interesting_type (type0, FULL_ESCAPE);
+
+ if (type1 && POINTER_TYPE_P (type1)
+ && !okay_pointer_operation (gimple_assign_rhs_code (t), op1, op0))
+ mark_interesting_type (type1, FULL_ESCAPE);
+
+ look_for_casts (op0);
+ look_for_casts (op1);
+ check_rhs_var (op0);
+ check_rhs_var (op1);
+ }
+ break;
+
+ case tcc_unary:
+ {
+ tree op0 = gimple_assign_rhs1 (t);
+ tree type0 = get_canon_type (TREE_TYPE (op0), false, false);
+
+ /* For unary operations, if the operation is NEGATE or ABS on
+ a pointer, this is also considered pointer arithmetic and
+ thus, bad for business. */
+ if (type0
+ && POINTER_TYPE_P (type0)
+ && (TREE_CODE (op0) == NEGATE_EXPR
+ || TREE_CODE (op0) == ABS_EXPR))
+ mark_interesting_type (type0, FULL_ESCAPE);
+
+ check_rhs_var (op0);
+ look_for_casts (op0);
+ }
+ break;
+
+ case tcc_reference:
+ look_for_casts (gimple_assign_rhs1 (t));
+ check_rhs_var (gimple_assign_rhs1 (t));
+ break;
+
+ case tcc_declaration:
+ check_rhs_var (gimple_assign_rhs1 (t));
+ break;
+
+ case tcc_expression:
+ if (gimple_assign_rhs_code (t) == ADDR_EXPR)
+ {
+ tree rhs = gimple_assign_rhs1 (t);
+ look_for_casts (TREE_OPERAND (rhs, 0));
+ check_rhs_var (rhs);
+ }
+ break;
+
+ default:
+ break;
+ }
+}
+
+
+/* Scan statement T for references to types and mark anything
+ interesting. */
+
+static void
+scan_for_refs (gimple t)
+{
+ switch (gimple_code (t))
+ {
+ case GIMPLE_ASSIGN:
+ check_assign (t);
+ break;
+
+ case GIMPLE_CALL:
+ /* If this is a call to malloc, squirrel away the result so we
+ do mark the resulting cast as being bad. */
+ check_call (t);
+ break;
+
+ case GIMPLE_ASM:
+ check_asm (t);
+ break;
+
+ default:
+ break;
+ }
+
+ return;
+}
+
+
+/* The init routine for analyzing global static variable usage. See
+ comments at top for description. */
+static void
+ipa_init (void)
+{
+ bitmap_obstack_initialize (&ipa_obstack);
+ global_types_exposed_parameter = BITMAP_ALLOC (&ipa_obstack);
+ global_types_full_escape = BITMAP_ALLOC (&ipa_obstack);
+ global_types_seen = BITMAP_ALLOC (&ipa_obstack);
+
+ uid_to_canon_type = splay_tree_new (splay_tree_compare_ints, 0, 0);
+ all_canon_types = splay_tree_new (compare_type_brand, 0, 0);
+ type_to_canon_type = splay_tree_new (splay_tree_compare_pointers, 0, 0);
+ uid_to_subtype_map = splay_tree_new (splay_tree_compare_ints, 0, 0);
+ uid_to_addressof_down_map = splay_tree_new (splay_tree_compare_ints, 0, 0);
+ uid_to_addressof_up_map = splay_tree_new (splay_tree_compare_ints, 0, 0);
+
+ /* There are some shared nodes, in particular the initializers on
+ static declarations. We do not need to scan them more than once
+ since all we would be interested in are the addressof
+ operations. */
+ visited_nodes = pointer_set_create ();
+ initialized = true;
+}
+
+/* Check out the rhs of a static or global initialization VNODE to see
+ if any of them contain addressof operations. Note that some of
+ these variables may not even be referenced in the code in this
+ compilation unit but their right hand sides may contain references
+ to variables defined within this unit. */
+
+static void
+analyze_variable (struct varpool_node *vnode)
+{
+ tree global = vnode->decl;
+ tree type = get_canon_type (TREE_TYPE (global), false, false);
+
+ /* If this variable has exposure beyond the compilation unit, add
+ its type to the global types. */
+
+ if (vnode->externally_visible)
+ mark_interesting_type (type, FULL_ESCAPE);
+
+ gcc_assert (TREE_CODE (global) == VAR_DECL);
+
+ if (DECL_INITIAL (global))
+ check_tree (DECL_INITIAL (global));
+}
+
+/* This is the main routine for finding the reference patterns for
+ global variables within a function FN. */
+
+static void
+analyze_function (struct cgraph_node *fn)
+{
+ tree decl = fn->decl;
+ check_function_parameter_and_return_types (decl,
+ fn->local.externally_visible);
+ if (dump_file)
+ fprintf (dump_file, "\n local analysis of %s", cgraph_node_name (fn));
+
+ {
+ struct function *this_cfun = DECL_STRUCT_FUNCTION (decl);
+ basic_block this_block;
+
+ FOR_EACH_BB_FN (this_block, this_cfun)
+ {
+ gimple_stmt_iterator gsi;
+ for (gsi = gsi_start_bb (this_block); !gsi_end_p (gsi); gsi_next (&gsi))
+ scan_for_refs (gsi_stmt (gsi));
+ }
+ }
+
+ /* There may be const decls with interesting right hand sides. */
+ if (DECL_STRUCT_FUNCTION (decl))
+ {
+ tree step;
+ for (step = DECL_STRUCT_FUNCTION (decl)->local_decls;
+ step;
+ step = TREE_CHAIN (step))
+ {
+ tree var = TREE_VALUE (step);
+ if (TREE_CODE (var) == VAR_DECL
+ && DECL_INITIAL (var)
+ && !TREE_STATIC (var))
+ check_tree (DECL_INITIAL (var));
+ get_canon_type (TREE_TYPE (var), false, false);
+ }
+ }
+}
+
+\f
+
+/* Convert a type_UID into a type. */
+static tree
+type_for_uid (int uid)
+{
+ splay_tree_node result =
+ splay_tree_lookup (uid_to_canon_type, (splay_tree_key) uid);
+
+ if (result)
+ return (tree) result->value;
+ else return NULL;
+}
+
+/* Return a bitmap with the subtypes of the type for UID. If it
+ does not exist, return either NULL or a new bitmap depending on the
+ value of CREATE. */
+
+static bitmap
+subtype_map_for_uid (int uid, bool create)
+{
+ splay_tree_node result = splay_tree_lookup (uid_to_subtype_map,
+ (splay_tree_key) uid);
+
+ if (result)
+ return (bitmap) result->value;
+ else if (create)
+ {
+ bitmap subtype_map = BITMAP_ALLOC (&ipa_obstack);
+ splay_tree_insert (uid_to_subtype_map,
+ uid,
+ (splay_tree_value)subtype_map);
+ return subtype_map;
+ }
+ else return NULL;
+}
+
+/* Mark all of the supertypes and field types of TYPE as being seen.
+ Also accumulate the subtypes for each type so that
+ close_types_full_escape can mark a subtype as escaping if the
+ supertype escapes. */
+
+static void
+close_type_seen (tree type)
+{
+ tree field;
+ int i, uid;
+ tree binfo, base_binfo;
+
+ /* See thru all pointer tos and array ofs. */
+ type = get_canon_type (type, true, true);
+ if (!type)
+ return;
+
+ uid = TYPE_UID (type);
+
+ if (bitmap_bit_p (been_there_done_that, uid))
+ return;
+ bitmap_set_bit (been_there_done_that, uid);
+
+ /* If we are doing a language with a type hierarchy, mark all of
+ the superclasses. */
+ if (TYPE_BINFO (type))
+ for (binfo = TYPE_BINFO (type), i = 0;
+ BINFO_BASE_ITERATE (binfo, i, base_binfo); i++)
+ {
+ tree binfo_type = BINFO_TYPE (base_binfo);
+ bitmap subtype_map = subtype_map_for_uid
+ (TYPE_UID (TYPE_MAIN_VARIANT (binfo_type)), true);
+ bitmap_set_bit (subtype_map, uid);
+ close_type_seen (get_canon_type (binfo_type, true, true));
+ }
+
+ /* If the field is a struct or union type, mark all of the
+ subfields. */
+ for (field = TYPE_FIELDS (type);
+ field;
+ field = TREE_CHAIN (field))
+ {
+ tree field_type;
+ if (TREE_CODE (field) != FIELD_DECL)
+ continue;
+
+ field_type = TREE_TYPE (field);
+ if (ipa_type_escape_star_count_of_interesting_or_array_type (field_type) >= 0)
+ close_type_seen (get_canon_type (field_type, true, true));
+ }
+}
+
+/* Take a TYPE that has been passed by value to an external function
+ and mark all of the fields that have pointer types as escaping. For
+ any of the non pointer types that are structures or unions,
+ recurse. TYPE is never a pointer type. */
+
+static void
+close_type_exposed_parameter (tree type)
+{
+ tree field;
+ int uid;
+
+ type = get_canon_type (type, false, false);
+ if (!type)
+ return;
+ uid = TYPE_UID (type);
+ gcc_assert (!POINTER_TYPE_P (type));
+
+ if (bitmap_bit_p (been_there_done_that, uid))
+ return;
+ bitmap_set_bit (been_there_done_that, uid);
+
+ /* If the field is a struct or union type, mark all of the
+ subfields. */
+ for (field = TYPE_FIELDS (type);
+ field;
+ field = TREE_CHAIN (field))
+ {
+ tree field_type;
+
+ if (TREE_CODE (field) != FIELD_DECL)
+ continue;
+
+ field_type = get_canon_type (TREE_TYPE (field), false, false);
+ mark_interesting_type (field_type, EXPOSED_PARAMETER);
+
+ /* Only recurse for non pointer types of structures and unions. */
+ if (ipa_type_escape_star_count_of_interesting_type (field_type) == 0)
+ close_type_exposed_parameter (field_type);
+ }
+}
+
+/* The next function handles the case where a type fully escapes.
+ This means that not only does the type itself escape,
+
+ a) the type of every field recursively escapes
+ b) the type of every subtype escapes as well as the super as well
+ as all of the pointer to types for each field.
+
+ Note that pointer to types are not marked as escaping. If the
+ pointed to type escapes, the pointer to type also escapes.
+
+ Take a TYPE that has had the address taken for an instance of it
+ and mark all of the types for its fields as having their addresses
+ taken. */
+
+static void
+close_type_full_escape (tree type)
+{
+ tree field;
+ unsigned int i;
+ int uid;
+ tree binfo, base_binfo;
+ bitmap_iterator bi;
+ bitmap subtype_map;
+ splay_tree_node address_result;
+
+ /* Strip off any pointer or array types. */
+ type = get_canon_type (type, true, true);
+ if (!type)
+ return;
+ uid = TYPE_UID (type);
+
+ if (bitmap_bit_p (been_there_done_that, uid))
+ return;
+ bitmap_set_bit (been_there_done_that, uid);
+
+ subtype_map = subtype_map_for_uid (uid, false);
+
+ /* If we are doing a language with a type hierarchy, mark all of
+ the superclasses. */
+ if (TYPE_BINFO (type))
+ for (binfo = TYPE_BINFO (type), i = 0;
+ BINFO_BASE_ITERATE (binfo, i, base_binfo); i++)
+ {
+ tree binfotype = BINFO_TYPE (base_binfo);
+ binfotype = mark_type (binfotype, FULL_ESCAPE);
+ close_type_full_escape (binfotype);
+ }
+
+ /* Mark as escaped any types that have been down casted to
+ this type. */
+ if (subtype_map)
+ EXECUTE_IF_SET_IN_BITMAP (subtype_map, 0, i, bi)
+ {
+ tree subtype = type_for_uid (i);
+ subtype = mark_type (subtype, FULL_ESCAPE);
+ close_type_full_escape (subtype);
+ }
+
+ /* If the field is a struct or union type, mark all of the
+ subfields. */
+ for (field = TYPE_FIELDS (type);
+ field;
+ field = TREE_CHAIN (field))
+ {
+ tree field_type;
+ if (TREE_CODE (field) != FIELD_DECL)
+ continue;
+
+ field_type = TREE_TYPE (field);
+ if (ipa_type_escape_star_count_of_interesting_or_array_type (field_type) >= 0)
+ {
+ field_type = mark_type (field_type, FULL_ESCAPE);
+ close_type_full_escape (field_type);
+ }
+ }
+
+ /* For all of the types A that contain this type B and were part of
+ an expression like "&...A.B...", mark the A's as escaping. */
+ address_result = splay_tree_lookup (uid_to_addressof_up_map,
+ (splay_tree_key) uid);
+ if (address_result)
+ {
+ bitmap containing_classes = (bitmap) address_result->value;
+ EXECUTE_IF_SET_IN_BITMAP (containing_classes, 0, i, bi)
+ {
+ close_type_full_escape (type_for_uid (i));
+ }
+ }
+}
+
+/* Transitively close the addressof bitmap for the type with UID.
+ This means that if we had a.b and b.c, a would have both b and c in
+ its maps. */
+
+static bitmap
+close_addressof_down (int uid)
+{
+ bitmap_iterator bi;
+ splay_tree_node result =
+ splay_tree_lookup (uid_to_addressof_down_map, (splay_tree_key) uid);
+ bitmap map = NULL;
+ bitmap new_map;
+ unsigned int i;
+
+ if (result)
+ map = (bitmap) result->value;
+ else
+ return NULL;
+
+ if (bitmap_bit_p (been_there_done_that, uid))
+ return map;
+ bitmap_set_bit (been_there_done_that, uid);
+
+ /* If the type escapes, get rid of the addressof map, it will not be
+ needed. */
+ if (bitmap_bit_p (global_types_full_escape, uid))
+ {
+ BITMAP_FREE (map);
+ splay_tree_remove (uid_to_addressof_down_map, (splay_tree_key) uid);
+ return NULL;
+ }
+
+ /* The new_map will have all of the bits for the enclosed fields and
+ will have the unique id version of the old map. */
+ new_map = BITMAP_ALLOC (&ipa_obstack);
+
+ EXECUTE_IF_SET_IN_BITMAP (map, 0, i, bi)
+ {
+ bitmap submap = close_addressof_down (i);
+ bitmap_set_bit (new_map, i);
+ if (submap)
+ bitmap_ior_into (new_map, submap);
+ }
+ result->value = (splay_tree_value) new_map;
+
+ BITMAP_FREE (map);
+ return new_map;
+}
+
+\f
+/* The main entry point for type escape analysis. */
+
+static unsigned int
+type_escape_execute (void)
+{
+ struct cgraph_node *node;
+ struct varpool_node *vnode;
+ unsigned int i;
+ bitmap_iterator bi;
+ splay_tree_node result;
+
+ ipa_init ();
+
+ /* Process all of the variables first. */
+ FOR_EACH_STATIC_VARIABLE (vnode)
+ analyze_variable (vnode);
+
+ /* Process all of the functions next.
+
+ We do not want to process any of the clones so we check that this
+ is a master clone. However, we do need to process any
+ AVAIL_OVERWRITABLE functions (these are never clones) because
+ they may cause a type variable to escape.
+ */
+ for (node = cgraph_nodes; node; node = node->next)
+ if (node->analyzed
+ && (cgraph_is_master_clone (node)
+ || (cgraph_function_body_availability (node) == AVAIL_OVERWRITABLE)))
+ analyze_function (node);
+
+
+ pointer_set_destroy (visited_nodes);
+ visited_nodes = NULL;
+
+ /* Do all of the closures to discover which types escape the
+ compilation unit. */
+
+ been_there_done_that = BITMAP_ALLOC (&ipa_obstack);
+ bitmap_tmp = BITMAP_ALLOC (&ipa_obstack);
+
+ /* Examine the types that we have directly seen in scanning the code
+ and add to that any contained types or superclasses. */
+
+ bitmap_copy (bitmap_tmp, global_types_seen);
+ EXECUTE_IF_SET_IN_BITMAP (bitmap_tmp, 0, i, bi)
+ {
+ tree type = type_for_uid (i);
+ /* Only look at records and unions and pointer tos. */
+ if (ipa_type_escape_star_count_of_interesting_or_array_type (type) >= 0)
+ close_type_seen (type);
+ }
+ bitmap_clear (been_there_done_that);
+
+ /* Examine all of the types passed by value and mark any enclosed
+ pointer types as escaping. */
+ bitmap_copy (bitmap_tmp, global_types_exposed_parameter);
+ EXECUTE_IF_SET_IN_BITMAP (bitmap_tmp, 0, i, bi)
+ {
+ close_type_exposed_parameter (type_for_uid (i));
+ }
+ bitmap_clear (been_there_done_that);
+
+ /* Close the types for escape. If something escapes, then any
+ enclosed types escape as well as any subtypes. */
+ bitmap_copy (bitmap_tmp, global_types_full_escape);
+ EXECUTE_IF_SET_IN_BITMAP (bitmap_tmp, 0, i, bi)
+ {
+ close_type_full_escape (type_for_uid (i));
+ }
+ bitmap_clear (been_there_done_that);
+
+ /* Before this pass, the uid_to_addressof_down_map for type X
+ contained an entry for Y if there had been an operation of the
+ form &X.Y. This step adds all of the fields contained within Y
+ (recursively) to X's map. */
+
+ result = splay_tree_min (uid_to_addressof_down_map);
+ while (result)
+ {
+ int uid = result->key;
+ /* Close the addressof map, i.e. copy all of the transitive
+ substructures up to this level. */
+ close_addressof_down (uid);
+ result = splay_tree_successor (uid_to_addressof_down_map, uid);
+ }
+
+ /* Do not need the array types and pointer types in the persistent
+ data structures. */
+ result = splay_tree_min (all_canon_types);
+ while (result)
+ {
+ tree type = (tree) result->value;
+ tree key = (tree) result->key;
+ if (POINTER_TYPE_P (type)
+ || TREE_CODE (type) == ARRAY_TYPE)
+ {
+ splay_tree_remove (all_canon_types, (splay_tree_key) result->key);
+ splay_tree_remove (type_to_canon_type, (splay_tree_key) type);
+ splay_tree_remove (uid_to_canon_type, (splay_tree_key) TYPE_UID (type));
+ bitmap_clear_bit (global_types_seen, TYPE_UID (type));
+ }
+ result = splay_tree_successor (all_canon_types, (splay_tree_key) key);
+ }
+
+ if (dump_file)
+ {
+ EXECUTE_IF_SET_IN_BITMAP (global_types_seen, 0, i, bi)
+ {
+ /* The pointer types are in the global_types_full_escape
+ bitmap but not in the backwards map. They also contain
+ no useful information since they are not marked. */
+ tree type = type_for_uid (i);
+ fprintf(dump_file, "type %d ", i);
+ print_generic_expr (dump_file, type, 0);
+ if (bitmap_bit_p (global_types_full_escape, i))
+ fprintf(dump_file, " escaped\n");
+ else
+ fprintf(dump_file, " contained\n");
+ }
+ }
+
+ /* Get rid of uid_to_addressof_up_map and its bitmaps. */
+ result = splay_tree_min (uid_to_addressof_up_map);
+ while (result)
+ {
+ int uid = (int)result->key;
+ bitmap bm = (bitmap)result->value;
+
+ BITMAP_FREE (bm);
+ splay_tree_remove (uid_to_addressof_up_map, (splay_tree_key) uid);
+ result = splay_tree_successor (uid_to_addressof_up_map, uid);
+ }
+
+ /* Get rid of the subtype map. */
+ result = splay_tree_min (uid_to_subtype_map);
+ while (result)
+ {
+ bitmap b = (bitmap)result->value;
+ BITMAP_FREE(b);
+ splay_tree_remove (uid_to_subtype_map, result->key);
+ result = splay_tree_min (uid_to_subtype_map);
+ }
+ splay_tree_delete (uid_to_subtype_map);
+ uid_to_subtype_map = NULL;
+
+ BITMAP_FREE (global_types_exposed_parameter);
+ BITMAP_FREE (been_there_done_that);
+ BITMAP_FREE (bitmap_tmp);
+ return 0;
+}
+
+static bool
+gate_type_escape_vars (void)
+{
+ return (flag_ipa_type_escape
+ /* Don't bother doing anything if the program has errors. */
+ && !(errorcount || sorrycount));
+}
+
+struct simple_ipa_opt_pass pass_ipa_type_escape =
+{
+ {
+ SIMPLE_IPA_PASS,
+ "type-escape-var", /* name */
+ gate_type_escape_vars, /* gate */
+ type_escape_execute, /* execute */
+ NULL, /* sub */
+ NULL, /* next */
+ 0, /* static_pass_number */
+ TV_IPA_TYPE_ESCAPE, /* tv_id */
+ 0, /* properties_required */
+ 0, /* properties_provided */
+ 0, /* properties_destroyed */
+ 0, /* todo_flags_start */
+ 0 /* todo_flags_finish */
+ }
+};
projects / msp430-gcc.git / blobdiff