/* Alias analysis for trees.
- Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
+ Copyright (C) 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
Contributed by Diego Novillo <dnovillo@redhat.com>
This file is part of GCC.
#include "function.h"
#include "diagnostic.h"
#include "tree-dump.h"
-#include "tree-gimple.h"
+#include "gimple.h"
#include "tree-flow.h"
#include "tree-inline.h"
#include "tree-pass.h"
Lastly, we delete partitions with no symbols, and clean up after
ourselves. */
+
+/* Alias information used by compute_may_aliases and its helpers. */
+struct alias_info
+{
+ /* SSA names visited while collecting points-to information. If bit I
+ is set, it means that SSA variable with version I has already been
+ visited. */
+ sbitmap ssa_names_visited;
+
+ /* Array of SSA_NAME pointers processed by the points-to collector. */
+ VEC(tree,heap) *processed_ptrs;
+
+ /* ADDRESSABLE_VARS contains all the global variables and locals that
+ have had their address taken. */
+ struct alias_map_d **addressable_vars;
+ size_t num_addressable_vars;
+
+ /* POINTERS contains all the _DECL pointers with unique memory tags
+ that have been referenced in the program. */
+ struct alias_map_d **pointers;
+ size_t num_pointers;
+
+ /* Variables that have been written to directly (i.e., not through a
+ pointer dereference). */
+ struct pointer_set_t *written_vars;
+
+ /* Pointers that have been used in an indirect store operation. */
+ struct pointer_set_t *dereferenced_ptrs_store;
+
+ /* Pointers that have been used in an indirect load operation. */
+ struct pointer_set_t *dereferenced_ptrs_load;
+};
+
+
/* Structure to map a variable to its alias set. */
struct alias_map_d
{
/* Local functions. */
static void compute_flow_insensitive_aliasing (struct alias_info *);
static void dump_alias_stats (FILE *);
-static bool may_alias_p (tree, alias_set_type, tree, alias_set_type, bool);
static tree create_memory_tag (tree type, bool is_type_tag);
static tree get_smt_for (tree, struct alias_info *);
static tree get_nmt_for (tree);
static void delete_alias_info (struct alias_info *);
static void compute_flow_sensitive_aliasing (struct alias_info *);
static void setup_pointers_and_addressables (struct alias_info *);
+static void update_alias_info (struct alias_info *);
static void create_global_var (void);
static void maybe_create_global_var (void);
static void set_pt_anything (tree);
slot = pointer_map_insert (map, var);
if (*slot == NULL)
{
- stats = pool_alloc (mem_sym_stats_pool);
+ stats = (struct mem_sym_stats_d *) pool_alloc (mem_sym_stats_pool);
memset (stats, 0, sizeof (*stats));
stats->var = var;
*slot = (void *) stats;
mpt = memory_partition (var);
- if (!MTAG_P (var))
- var_ann (var)->call_clobbered = false;
-
- bitmap_clear_bit (gimple_call_clobbered_vars (cfun), DECL_UID (var));
+ clear_call_clobbered (var);
TREE_ADDRESSABLE (var) = 0;
if (mpt)
VEC_free (tree, heap, taglist);
}
-/* Set up the initial variable clobbers and globalness.
+/* Set up the initial variable clobbers, call-uses and globalness.
When this function completes, only tags whose aliases need to be
clobbered will be set clobbered. Tags clobbered because they
contain call clobbered vars are handled in compute_tag_properties. */
referenced_var_iterator rvi;
tree var;
tree ptr;
+ bool any_pt_anything = false;
+ enum escape_type pt_anything_mask = 0;
FOR_EACH_REFERENCED_VAR (var, rvi)
{
}
}
+ if (!clobber_what_escaped ())
+ {
+ any_pt_anything = true;
+ pt_anything_mask |= ESCAPE_TO_CALL;
+ }
+
+ compute_call_used_vars ();
+
for (i = 0; VEC_iterate (tree, ai->processed_ptrs, i, ptr); i++)
{
struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr);
tree tag = symbol_mem_tag (SSA_NAME_VAR (ptr));
-
- if (pi->value_escapes_p)
+
+ /* A pointer that only escapes via a function return does not
+ add to the call clobber or call used solution.
+ To exclude ESCAPE_TO_PURE_CONST we would need to track
+ call used variables separately or compute those properly
+ in the operand scanner. */
+ if (pi->value_escapes_p
+ && pi->escape_mask & ~ESCAPE_TO_RETURN)
{
/* If PTR escapes then its associated memory tags and
pointed-to variables are call-clobbered. */
if (tag)
mark_call_clobbered (tag, pi->escape_mask);
-
- if (pi->pt_vars)
- {
- bitmap_iterator bi;
- unsigned int j;
- EXECUTE_IF_SET_IN_BITMAP (pi->pt_vars, 0, j, bi)
- {
- tree alias = referenced_var (j);
-
- /* If you clobber one part of a structure, you
- clobber the entire thing. While this does not make
- the world a particularly nice place, it is necessary
- in order to allow C/C++ tricks that involve
- pointer arithmetic to work. */
- if (!unmodifiable_var_p (alias))
- mark_call_clobbered (alias, pi->escape_mask);
- }
- }
}
/* If the name tag is call clobbered, so is the symbol tag
So removing this code and fixing all the bugs would be nice.
It is the cause of a bunch of clobbering. */
if ((pi->pt_global_mem || pi->pt_anything)
- && pi->is_dereferenced && pi->name_mem_tag)
+ && pi->memory_tag_needed && pi->name_mem_tag)
{
mark_call_clobbered (pi->name_mem_tag, ESCAPE_IS_GLOBAL);
MTAG_GLOBAL (pi->name_mem_tag) = true;
}
if ((pi->pt_global_mem || pi->pt_anything)
- && pi->is_dereferenced
+ && pi->memory_tag_needed
&& tag)
{
mark_call_clobbered (tag, ESCAPE_IS_GLOBAL);
MTAG_GLOBAL (tag) = true;
}
}
+
+ /* If a pt_anything pointer escaped we need to mark all addressable
+ variables call clobbered. */
+ if (any_pt_anything)
+ {
+ bitmap_iterator bi;
+ unsigned int j;
+
+ EXECUTE_IF_SET_IN_BITMAP (gimple_addressable_vars (cfun), 0, j, bi)
+ {
+ tree var = referenced_var (j);
+ if (!unmodifiable_var_p (var))
+ mark_call_clobbered (var, pt_anything_mask);
+ }
+ }
}
/* Compute which variables need to be marked call clobbered because
count_mem_refs (long *num_vuses_p, long *num_vdefs_p,
long *num_partitioned_p, long *num_unpartitioned_p)
{
- block_stmt_iterator bsi;
+ gimple_stmt_iterator gsi;
basic_block bb;
long num_vdefs, num_vuses, num_partitioned, num_unpartitioned;
referenced_var_iterator rvi;
if (num_vuses_p || num_vdefs_p)
FOR_EACH_BB (bb)
- for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
+ for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
{
- tree stmt = bsi_stmt (bsi);
- if (stmt_references_memory_p (stmt))
+ gimple stmt = gsi_stmt (gsi);
+ if (gimple_references_memory_p (stmt))
{
num_vuses += NUM_SSA_OPERANDS (stmt, SSA_OP_VUSE);
num_vdefs += NUM_SSA_OPERANDS (stmt, SSA_OP_VDEF);
recorded by this function, see compute_memory_partitions). */
void
-update_mem_sym_stats_from_stmt (tree var, tree stmt, long num_direct_reads,
+update_mem_sym_stats_from_stmt (tree var, gimple stmt, long num_direct_reads,
long num_direct_writes)
{
mem_sym_stats_t stats;
stats = get_mem_sym_stats_for (var);
stats->num_direct_reads += num_direct_reads;
- stats->frequency_reads += ((long) bb_for_stmt (stmt)->frequency
+ stats->frequency_reads += ((long) gimple_bb (stmt)->frequency
* num_direct_reads);
stats->num_direct_writes += num_direct_writes;
- stats->frequency_writes += ((long) bb_for_stmt (stmt)->frequency
+ stats->frequency_writes += ((long) gimple_bb (stmt)->frequency
* num_direct_writes);
}
if (ptr
&& POINTER_TYPE_P (TREE_TYPE (ptr))
&& (pi = SSA_NAME_PTR_INFO (ptr)) != NULL
- && pi->is_dereferenced)
+ && pi->memory_tag_needed)
{
unsigned j;
bitmap_iterator bj;
timevar_pop (TV_MEMORY_PARTITIONING);
}
-
/* Compute may-alias information for every variable referenced in function
FNDECL.
address of V escapes the current function, making V call-clobbered
(i.e., whether &V is stored in a global variable or if its passed as a
function call argument). */
- compute_points_to_sets (ai);
+ compute_points_to_sets ();
+
+ /* Update various related attributes like escaped addresses,
+ pointer dereferences for loads and stores. This is used
+ when creating name tags and alias sets. */
+ update_alias_info (ai);
/* Collect all pointers and addressable variables, compute alias sets,
create memory tags for pointers and promote variables whose address is
/* Populate all virtual operands and newly promoted register operands. */
{
- block_stmt_iterator bsi;
+ gimple_stmt_iterator gsi;
basic_block bb;
FOR_EACH_BB (bb)
- for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
- update_stmt_if_modified (bsi_stmt (bsi));
+ for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ update_stmt_if_modified (gsi_stmt (gsi));
}
/* Debugging dumps. */
struct count_ptr_d
{
tree ptr;
- unsigned count;
+ unsigned num_stores;
+ unsigned num_loads;
};
static tree
count_ptr_derefs (tree *tp, int *walk_subtrees, void *data)
{
- struct count_ptr_d *count_p = (struct count_ptr_d *) data;
+ struct walk_stmt_info *wi_p = (struct walk_stmt_info *) data;
+ struct count_ptr_d *count_p = (struct count_ptr_d *) wi_p->info;
/* Do not walk inside ADDR_EXPR nodes. In the expression &ptr->fld,
pointer 'ptr' is *not* dereferenced, it is simply used to compute
}
if (INDIRECT_REF_P (*tp) && TREE_OPERAND (*tp, 0) == count_p->ptr)
- count_p->count++;
+ {
+ if (wi_p->is_lhs)
+ count_p->num_stores++;
+ else
+ count_p->num_loads++;
+ }
return NULL_TREE;
}
stored in *NUM_STORES_P and *NUM_LOADS_P. */
void
-count_uses_and_derefs (tree ptr, tree stmt, unsigned *num_uses_p,
+count_uses_and_derefs (tree ptr, gimple stmt, unsigned *num_uses_p,
unsigned *num_loads_p, unsigned *num_stores_p)
{
ssa_op_iter i;
find all the indirect and direct uses of x_1 inside. The only
shortcut we can take is the fact that GIMPLE only allows
INDIRECT_REFs inside the expressions below. */
- if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
- || (TREE_CODE (stmt) == RETURN_EXPR
- && TREE_CODE (TREE_OPERAND (stmt, 0)) == GIMPLE_MODIFY_STMT)
- || TREE_CODE (stmt) == ASM_EXPR
- || TREE_CODE (stmt) == CALL_EXPR)
+ if (is_gimple_assign (stmt)
+ || gimple_code (stmt) == GIMPLE_RETURN
+ || gimple_code (stmt) == GIMPLE_ASM
+ || is_gimple_call (stmt))
{
- tree lhs, rhs;
+ struct walk_stmt_info wi;
+ struct count_ptr_d count;
- if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
- {
- lhs = GIMPLE_STMT_OPERAND (stmt, 0);
- rhs = GIMPLE_STMT_OPERAND (stmt, 1);
- }
- else if (TREE_CODE (stmt) == RETURN_EXPR)
- {
- tree e = TREE_OPERAND (stmt, 0);
- lhs = GIMPLE_STMT_OPERAND (e, 0);
- rhs = GIMPLE_STMT_OPERAND (e, 1);
- }
- else if (TREE_CODE (stmt) == ASM_EXPR)
- {
- lhs = ASM_OUTPUTS (stmt);
- rhs = ASM_INPUTS (stmt);
- }
- else
- {
- lhs = NULL_TREE;
- rhs = stmt;
- }
+ count.ptr = ptr;
+ count.num_stores = 0;
+ count.num_loads = 0;
- if (lhs
- && (TREE_CODE (lhs) == TREE_LIST
- || EXPR_P (lhs)
- || GIMPLE_STMT_P (lhs)))
- {
- struct count_ptr_d count;
- count.ptr = ptr;
- count.count = 0;
- walk_tree (&lhs, count_ptr_derefs, &count, NULL);
- *num_stores_p = count.count;
- }
+ memset (&wi, 0, sizeof (wi));
+ wi.info = &count;
+ walk_gimple_op (stmt, count_ptr_derefs, &wi);
- if (rhs
- && (TREE_CODE (rhs) == TREE_LIST
- || EXPR_P (rhs)
- || GIMPLE_STMT_P (rhs)))
- {
- struct count_ptr_d count;
- count.ptr = ptr;
- count.count = 0;
- walk_tree (&rhs, count_ptr_derefs, &count, NULL);
- *num_loads_p = count.count;
- }
+ *num_stores_p = count.num_stores;
+ *num_loads_p = count.num_loads;
}
gcc_assert (*num_uses_p >= *num_loads_p + *num_stores_p);
bitmap_set_bit (all_nmts, DECL_UID (var));
/* Since we are about to re-discover call-clobbered
- variables, clear the call-clobbered flag. Variables that
- are intrinsically call-clobbered (globals, local statics,
- etc) will not be marked by the aliasing code, so we can't
- remove them from CALL_CLOBBERED_VARS.
-
- NB: STRUCT_FIELDS are still call clobbered if they are for a
- global variable, so we *don't* clear their call clobberedness
- just because they are tags, though we will clear it if they
- aren't for global variables. */
- if (TREE_CODE (var) == NAME_MEMORY_TAG
- || TREE_CODE (var) == SYMBOL_MEMORY_TAG
- || TREE_CODE (var) == MEMORY_PARTITION_TAG
- || !is_global_var (var))
- clear_call_clobbered (var);
+ variables, clear the call-clobbered flag. */
+ clear_call_clobbered (var);
}
+ /* There should be no call-clobbered variable left. */
+ gcc_assert (bitmap_empty_p (gimple_call_clobbered_vars (cfun)));
+
+ /* Clear the call-used variables. */
+ bitmap_clear (gimple_call_used_vars (cfun));
+
/* Clear flow-sensitive points-to information from each SSA name. */
for (i = 1; i < num_ssa_names; i++)
{
pi->pt_anything = 0;
pi->pt_null = 0;
pi->value_escapes_p = 0;
+ pi->memory_tag_needed = 0;
pi->is_dereferenced = 0;
if (pi->pt_vars)
bitmap_clear (pi->pt_vars);
struct alias_info *ai;
referenced_var_iterator rvi;
tree var;
+ static bool alias_bitmap_obstack_initialized;
ai = XCNEW (struct alias_info);
ai->ssa_names_visited = sbitmap_alloc (num_ssa_names);
/* Next time, we will need to reset alias information. */
cfun->gimple_df->aliases_computed_p = true;
- if (alias_bitmap_obstack.elements != NULL)
+ if (alias_bitmap_obstack_initialized)
bitmap_obstack_release (&alias_bitmap_obstack);
bitmap_obstack_initialize (&alias_bitmap_obstack);
+ alias_bitmap_obstack_initialized = true;
return ai;
}
pi = SSA_NAME_PTR_INFO (ptr);
- if (pi->pt_anything || !pi->is_dereferenced)
+ if (pi->pt_anything || !pi->memory_tag_needed)
{
/* No name tags for pointers that have not been
dereferenced or point to an arbitrary location. */
tree ptr;
timevar_push (TV_FLOW_SENSITIVE);
- set_used_smts ();
for (i = 0; VEC_iterate (tree, ai->processed_ptrs, i, ptr); i++)
{
static void
compute_flow_insensitive_aliasing (struct alias_info *ai)
{
+ referenced_var_iterator rvi;
+ tree var;
size_t i;
timevar_push (TV_FLOW_INSENSITIVE);
add_may_alias (tag1, tag2);
}
}
+
+ /* We have to add all HEAP variables to all SMTs aliases bitmaps.
+ As we don't know which effective type the HEAP will have we cannot
+ do better here and we need the conflicts with obfuscated pointers
+ (a simple (*(int[n] *)ptr)[i] will do, with ptr from a VLA array
+ allocation). */
+ for (i = 0; i < ai->num_pointers; i++)
+ {
+ struct alias_map_d *p_map = ai->pointers[i];
+ tree tag = symbol_mem_tag (p_map->var);
+
+ FOR_EACH_REFERENCED_VAR (var, rvi)
+ {
+ if (var_ann (var)->is_heapvar)
+ add_may_alias (tag, var);
+ }
+ }
+
timevar_pop (TV_FLOW_INSENSITIVE);
}
}
+/* Update related alias information kept in AI. This is used when
+ building name tags, alias sets and deciding grouping heuristics.
+ STMT is the statement to process. This function also updates
+ ADDRESSABLE_VARS. */
+
+static void
+update_alias_info_1 (gimple stmt, struct alias_info *ai)
+{
+ bitmap addr_taken;
+ use_operand_p use_p;
+ ssa_op_iter iter;
+ bool stmt_dereferences_ptr_p;
+ enum escape_type stmt_escape_type = is_escape_site (stmt);
+ struct mem_ref_stats_d *mem_ref_stats = gimple_mem_ref_stats (cfun);
+
+ stmt_dereferences_ptr_p = false;
+
+ if (stmt_escape_type == ESCAPE_TO_CALL
+ || stmt_escape_type == ESCAPE_TO_PURE_CONST)
+ {
+ mem_ref_stats->num_call_sites++;
+ if (stmt_escape_type == ESCAPE_TO_PURE_CONST)
+ mem_ref_stats->num_pure_const_call_sites++;
+ }
+ else if (stmt_escape_type == ESCAPE_TO_ASM)
+ mem_ref_stats->num_asm_sites++;
+
+ /* Mark all the variables whose address are taken by the statement. */
+ addr_taken = gimple_addresses_taken (stmt);
+ if (addr_taken)
+ bitmap_ior_into (gimple_addressable_vars (cfun), addr_taken);
+
+ /* Process each operand use. For pointers, determine whether they
+ are dereferenced by the statement, or whether their value
+ escapes, etc. */
+ FOR_EACH_PHI_OR_STMT_USE (use_p, stmt, iter, SSA_OP_USE)
+ {
+ tree op, var;
+ var_ann_t v_ann;
+ struct ptr_info_def *pi;
+ unsigned num_uses, num_loads, num_stores;
+
+ op = USE_FROM_PTR (use_p);
+
+ /* If STMT is a PHI node, OP may be an ADDR_EXPR. If so, add it
+ to the set of addressable variables. */
+ if (TREE_CODE (op) == ADDR_EXPR)
+ {
+ bitmap addressable_vars = gimple_addressable_vars (cfun);
+
+ gcc_assert (gimple_code (stmt) == GIMPLE_PHI);
+ gcc_assert (addressable_vars);
+
+ /* PHI nodes don't have annotations for pinning the set
+ of addresses taken, so we collect them here.
+
+ FIXME, should we allow PHI nodes to have annotations
+ so that they can be treated like regular statements?
+ Currently, they are treated as second-class
+ statements. */
+ add_to_addressable_set (TREE_OPERAND (op, 0), &addressable_vars);
+ continue;
+ }
+
+ /* Ignore constants (they may occur in PHI node arguments). */
+ if (TREE_CODE (op) != SSA_NAME)
+ continue;
+
+ var = SSA_NAME_VAR (op);
+ v_ann = var_ann (var);
+
+ /* The base variable of an SSA name must be a GIMPLE register, and thus
+ it cannot be aliased. */
+ gcc_assert (!may_be_aliased (var));
+
+ /* We are only interested in pointers. */
+ if (!POINTER_TYPE_P (TREE_TYPE (op)))
+ continue;
+
+ pi = get_ptr_info (op);
+
+ /* Add OP to AI->PROCESSED_PTRS, if it's not there already. */
+ if (!TEST_BIT (ai->ssa_names_visited, SSA_NAME_VERSION (op)))
+ {
+ SET_BIT (ai->ssa_names_visited, SSA_NAME_VERSION (op));
+ VEC_safe_push (tree, heap, ai->processed_ptrs, op);
+ }
+
+ /* If STMT is a PHI node, then it will not have pointer
+ dereferences and it will not be an escape point. */
+ if (gimple_code (stmt) == GIMPLE_PHI)
+ continue;
+
+ /* Determine whether OP is a dereferenced pointer, and if STMT
+ is an escape point, whether OP escapes. */
+ count_uses_and_derefs (op, stmt, &num_uses, &num_loads, &num_stores);
+
+ /* For directly dereferenced pointers we can apply
+ TBAA-pruning to their points-to set. We may not count the
+ implicit dereferences &PTR->FLD here. */
+ if (num_loads + num_stores > 0)
+ pi->is_dereferenced = 1;
+
+ /* Handle a corner case involving address expressions of the
+ form '&PTR->FLD'. The problem with these expressions is that
+ they do not represent a dereference of PTR. However, if some
+ other transformation propagates them into an INDIRECT_REF
+ expression, we end up with '*(&PTR->FLD)' which is folded
+ into 'PTR->FLD'.
+
+ So, if the original code had no other dereferences of PTR,
+ the aliaser will not create memory tags for it, and when
+ &PTR->FLD gets propagated to INDIRECT_REF expressions, the
+ memory operations will receive no VDEF/VUSE operands.
+
+ One solution would be to have count_uses_and_derefs consider
+ &PTR->FLD a dereference of PTR. But that is wrong, since it
+ is not really a dereference but an offset calculation.
+
+ What we do here is to recognize these special ADDR_EXPR
+ nodes. Since these expressions are never GIMPLE values (they
+ are not GIMPLE invariants), they can only appear on the RHS
+ of an assignment and their base address is always an
+ INDIRECT_REF expression. */
+ if (is_gimple_assign (stmt)
+ && gimple_assign_rhs_code (stmt) == ADDR_EXPR
+ && !is_gimple_val (gimple_assign_rhs1 (stmt)))
+ {
+ /* If the RHS if of the form &PTR->FLD and PTR == OP, then
+ this represents a potential dereference of PTR. */
+ tree rhs = gimple_assign_rhs1 (stmt);
+ tree base = get_base_address (TREE_OPERAND (rhs, 0));
+ if (TREE_CODE (base) == INDIRECT_REF
+ && TREE_OPERAND (base, 0) == op)
+ num_loads++;
+ }
+
+ if (num_loads + num_stores > 0)
+ {
+ /* Mark OP as dereferenced. In a subsequent pass,
+ dereferenced pointers that point to a set of
+ variables will be assigned a name tag to alias
+ all the variables OP points to. */
+ pi->memory_tag_needed = 1;
+
+ /* ??? For always executed direct dereferences we can
+ apply TBAA-pruning to their escape set. */
+
+ /* If this is a store operation, mark OP as being
+ dereferenced to store, otherwise mark it as being
+ dereferenced to load. */
+ if (num_stores > 0)
+ pointer_set_insert (ai->dereferenced_ptrs_store, var);
+ else
+ pointer_set_insert (ai->dereferenced_ptrs_load, var);
+
+ /* Update the frequency estimate for all the dereferences of
+ pointer OP. */
+ update_mem_sym_stats_from_stmt (op, stmt, num_loads, num_stores);
+
+ /* Indicate that STMT contains pointer dereferences. */
+ stmt_dereferences_ptr_p = true;
+ }
+
+ if (stmt_escape_type != NO_ESCAPE && num_loads + num_stores < num_uses)
+ {
+ /* If STMT is an escape point and STMT contains at
+ least one direct use of OP, then the value of OP
+ escapes and so the pointed-to variables need to
+ be marked call-clobbered. */
+ pi->value_escapes_p = 1;
+ pi->escape_mask |= stmt_escape_type;
+
+ /* If the statement makes a function call, assume
+ that pointer OP will be dereferenced in a store
+ operation inside the called function. */
+ if (is_gimple_call (stmt)
+ || stmt_escape_type == ESCAPE_STORED_IN_GLOBAL)
+ {
+ pointer_set_insert (ai->dereferenced_ptrs_store, var);
+ pi->memory_tag_needed = 1;
+ }
+ }
+ }
+
+ if (gimple_code (stmt) == GIMPLE_PHI)
+ return;
+
+ /* Mark stored variables in STMT as being written to and update the
+ memory reference stats for all memory symbols referenced by STMT. */
+ if (gimple_references_memory_p (stmt))
+ {
+ unsigned i;
+ bitmap_iterator bi;
+
+ mem_ref_stats->num_mem_stmts++;
+
+ /* Notice that we only update memory reference stats for symbols
+ loaded and stored by the statement if the statement does not
+ contain pointer dereferences and it is not a call/asm site.
+ This is to avoid double accounting problems when creating
+ memory partitions. After computing points-to information,
+ pointer dereference statistics are used to update the
+ reference stats of the pointed-to variables, so here we
+ should only update direct references to symbols.
+
+ Indirect references are not updated here for two reasons: (1)
+ The first time we compute alias information, the sets
+ LOADED/STORED are empty for pointer dereferences, (2) After
+ partitioning, LOADED/STORED may have references to
+ partitions, not the original pointed-to variables. So, if we
+ always counted LOADED/STORED here and during partitioning, we
+ would count many symbols more than once.
+
+ This does cause some imprecision when a statement has a
+ combination of direct symbol references and pointer
+ dereferences (e.g., MEMORY_VAR = *PTR) or if a call site has
+ memory symbols in its argument list, but these cases do not
+ occur so frequently as to constitute a serious problem. */
+ if (gimple_stored_syms (stmt))
+ EXECUTE_IF_SET_IN_BITMAP (gimple_stored_syms (stmt), 0, i, bi)
+ {
+ tree sym = referenced_var (i);
+ pointer_set_insert (ai->written_vars, sym);
+ if (!stmt_dereferences_ptr_p
+ && stmt_escape_type != ESCAPE_TO_CALL
+ && stmt_escape_type != ESCAPE_TO_PURE_CONST
+ && stmt_escape_type != ESCAPE_TO_ASM)
+ update_mem_sym_stats_from_stmt (sym, stmt, 0, 1);
+ }
+
+ if (!stmt_dereferences_ptr_p
+ && gimple_loaded_syms (stmt)
+ && stmt_escape_type != ESCAPE_TO_CALL
+ && stmt_escape_type != ESCAPE_TO_PURE_CONST
+ && stmt_escape_type != ESCAPE_TO_ASM)
+ EXECUTE_IF_SET_IN_BITMAP (gimple_loaded_syms (stmt), 0, i, bi)
+ update_mem_sym_stats_from_stmt (referenced_var (i), stmt, 1, 0);
+ }
+}
+
+/* Update various related attributes like escaped addresses,
+ pointer dereferences for loads and stores. This is used
+ when creating name tags and alias sets. */
+
+static void
+update_alias_info (struct alias_info *ai)
+{
+ basic_block bb;
+
+ FOR_EACH_BB (bb)
+ {
+ gimple_stmt_iterator gsi;
+ gimple phi;
+
+ for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ {
+ phi = gsi_stmt (gsi);
+ if (is_gimple_reg (PHI_RESULT (phi)))
+ update_alias_info_1 (phi, ai);
+ }
+
+ for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ update_alias_info_1 (gsi_stmt (gsi), ai);
+ }
+}
+
/* Create memory tags for all the dereferenced pointers and build the
ADDRESSABLE_VARS and POINTERS arrays used for building the may-alias
sets. Based on the address escape and points-to information collected
VAR_ALIAS_SET is the alias set for VAR. */
-static bool
+bool
may_alias_p (tree ptr, alias_set_type mem_alias_set,
tree var, alias_set_type var_alias_set,
bool alias_set_only)
/* The star count is -1 if the type at the end of the
pointer_to chain is not a record or union type. */
- if (!alias_set_only
- && ipa_type_escape_star_count_of_interesting_type (var_type) >= 0)
+ if (!alias_set_only &&
+ 0 /* FIXME tuples ipa_type_escape_star_count_of_interesting_type (var_type) >= 0*/)
{
int ptr_star_count = 0;
-
+
/* ipa_type_escape_star_count_of_interesting_type is a
little too restrictive for the pointer type, need to
allow pointers to primitive types as long as those
return true;
}
+/* Return true, if PTR may point to a global variable. */
+
+bool
+may_point_to_global_var (tree ptr)
+{
+ struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr);
+
+ /* If we do not have points-to information for this variable,
+ we have to punt. */
+ if (!pi
+ || !pi->name_mem_tag)
+ return true;
+
+ /* The name memory tag is marked as global variable if the points-to
+ set contains a global variable. */
+ return is_global_var (pi->name_mem_tag);
+}
/* Add ALIAS to the set of variables that may alias VAR. */
struct ptr_info_def *pi = get_ptr_info (ptr);
pi->pt_anything = 1;
+ /* Anything includes global memory. */
+ pi->pt_global_mem = 1;
pi->pt_vars = NULL;
/* The pointer used to have a name tag, but we now found it pointing
if none. */
enum escape_type
-is_escape_site (tree stmt)
+is_escape_site (gimple stmt)
{
- tree call = get_call_expr_in (stmt);
- if (call != NULL_TREE)
+ if (is_gimple_call (stmt))
{
- if (!TREE_SIDE_EFFECTS (call))
+ if (gimple_call_flags (stmt) & (ECF_PURE | ECF_CONST))
return ESCAPE_TO_PURE_CONST;
return ESCAPE_TO_CALL;
}
- else if (TREE_CODE (stmt) == ASM_EXPR)
+ else if (gimple_code (stmt) == GIMPLE_ASM)
return ESCAPE_TO_ASM;
- else if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
+ else if (is_gimple_assign (stmt))
{
- tree lhs = GIMPLE_STMT_OPERAND (stmt, 0);
+ tree lhs = gimple_assign_lhs (stmt);
/* Get to the base of _REF nodes. */
if (TREE_CODE (lhs) != SSA_NAME)
if (lhs == NULL_TREE)
return ESCAPE_UNKNOWN;
- if (TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == NOP_EXPR
- || TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == CONVERT_EXPR
- || TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == VIEW_CONVERT_EXPR)
+ if (gimple_assign_cast_p (stmt))
{
- tree from
- = TREE_TYPE (TREE_OPERAND (GIMPLE_STMT_OPERAND (stmt, 1), 0));
- tree to = TREE_TYPE (GIMPLE_STMT_OPERAND (stmt, 1));
+ tree from = TREE_TYPE (gimple_assign_rhs1 (stmt));
+ tree to = TREE_TYPE (lhs);
/* If the RHS is a conversion between a pointer and an integer, the
pointer escapes since we can't track the integer. */
if (TREE_CODE (lhs) == SSA_NAME)
return NO_ESCAPE;
+ /* If the LHS is a non-global decl, it isn't a non-local memory store.
+ If the LHS escapes, the RHS escape is dealt with in the PTA solver. */
+ if (DECL_P (lhs)
+ && !is_global_var (lhs))
+ return NO_ESCAPE;
+
/* FIXME: LHS is not an SSA_NAME. Even if it's an assignment to a
local variables we cannot be sure if it will escape, because we
don't have information about objects not in SSA form. Need to
Applications (OOPSLA), pp. 1-19, 1999. */
return ESCAPE_STORED_IN_GLOBAL;
}
- else if (TREE_CODE (stmt) == RETURN_EXPR)
+ else if (gimple_code (stmt) == GIMPLE_RETURN)
return ESCAPE_TO_RETURN;
return NO_ESCAPE;
tmp_var = build_decl (code, create_tmp_var_name (prefix), type);
- /* Make the variable writable. */
+ /* Memory tags are always writable and non-static. */
TREE_READONLY (tmp_var) = 0;
+ TREE_STATIC (tmp_var) = 0;
/* It doesn't start out global. */
MTAG_GLOBAL (tmp_var) = 0;
- TREE_STATIC (tmp_var) = 0;
TREE_USED (tmp_var) = 1;
return tmp_var;
TREE_THIS_VOLATILE (tag) |= TREE_THIS_VOLATILE (tag_type);
/* Make sure that the symbol tag has the same alias set as the
- pointed-to type. */
- gcc_assert (tag_set == get_alias_set (tag));
+ pointed-to type or at least accesses through the pointer will
+ alias that set. The latter can happen after the vectorizer
+ created pointers of vector type. */
+ gcc_assert (tag_set == get_alias_set (tag)
+ || alias_set_subset_of (tag_set, get_alias_set (tag)));
return tag;
}
return pi;
}
-
/* Dump points-to information for SSA_NAME PTR into FILE. */
void
if (pi->is_dereferenced)
fprintf (file, ", is dereferenced");
+ else if (pi->memory_tag_needed)
+ fprintf (file, ", is dereferenced in call");
if (pi->value_escapes_p)
fprintf (file, ", its value escapes");
it needs to traverse the whole CFG looking for pointer SSA_NAMEs. */
void
-dump_points_to_info (FILE *file)
+dump_points_to_info (FILE *file ATTRIBUTE_UNUSED)
{
basic_block bb;
- block_stmt_iterator si;
+ gimple_stmt_iterator si;
ssa_op_iter iter;
const char *fname =
lang_hooks.decl_printable_name (current_function_decl, 2);
/* Dump points-to information for every pointer defined in the program. */
FOR_EACH_BB (bb)
{
- tree phi;
-
- for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
+ for (si = gsi_start_phis (bb); !gsi_end_p (si); gsi_next (&si))
{
+ gimple phi = gsi_stmt (si);
tree ptr = PHI_RESULT (phi);
if (POINTER_TYPE_P (TREE_TYPE (ptr)))
dump_points_to_info_for (file, ptr);
}
- for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
+ for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si))
{
- tree stmt = bsi_stmt (si);
+ gimple stmt = gsi_stmt (si);
tree def;
FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
if (TREE_CODE (def) == SSA_NAME
dump_may_aliases_for (stderr, var);
}
-
/* Return true if VAR may be aliased. */
bool
/* Globally visible variables can have their addresses taken by other
translation units. */
if (MTAG_P (var)
- && (MTAG_GLOBAL (var) || TREE_PUBLIC (var)))
+ && MTAG_GLOBAL (var))
return true;
else if (!MTAG_P (var)
&& (DECL_EXTERNAL (var) || TREE_PUBLIC (var)))
if (!TREE_STATIC (var))
return false;
- /* If we're in unit-at-a-time mode, then we must have seen all
- occurrences of address-of operators, and so we can trust
- TREE_ADDRESSABLE. Otherwise we can only be sure the variable
- isn't addressable if it's local to the current function. */
- if (flag_unit_at_a_time)
- return false;
-
- if (decl_function_context (var) == current_function_decl)
- return false;
-
- return true;
+ return false;
}
/* The following is based on code in add_stmt_operand to ensure that the
return tag;
}
-/* Create a new symbol tag for PTR. Construct the may-alias list of this type
- tag so that it has the aliasing of VAR, or of the relevant subvars of VAR
- according to the location accessed by EXPR.
+/* Create a new symbol tag for PTR. Construct the may-alias list of
+ this type tag so that it has the aliasing of VAR according to the
+ location accessed by EXPR.
- Note, the set of aliases represented by the new symbol tag are not marked
- for renaming. */
+ Note, the set of aliases represented by the new symbol tag are not
+ marked for renaming. */
void
new_type_alias (tree ptr, tree var, tree expr)
ali = add_may_alias_for_new_tag (tag, var);
set_symbol_mem_tag (ptr, ali);
- TREE_READONLY (tag) = TREE_READONLY (var);
MTAG_GLOBAL (tag) = is_global_var (var);
}
-/* ??? Stub. */
-
-static unsigned int
-create_structure_vars (void)
-{
- return TODO_rebuild_alias;
-}
-
-static bool
-gate_structure_vars (void)
-{
- return flag_tree_salias != 0;
-}
-
-struct gimple_opt_pass pass_create_structure_vars =
-{
- {
- GIMPLE_PASS,
- "salias", /* name */
- gate_structure_vars, /* gate */
- create_structure_vars, /* execute */
- NULL, /* sub */
- NULL, /* next */
- 0, /* static_pass_number */
- 0, /* tv_id */
- PROP_cfg, /* properties_required */
- 0, /* properties_provided */
- 0, /* properties_destroyed */
- 0, /* todo_flags_start */
- TODO_dump_func /* todo_flags_finish */
- }
-};
/* Reset the call_clobbered flags on our referenced vars. In
theory, this only needs to be done for globals. */
}
};
-static bool
-gate_build_alias (void)
-{
- return !gate_structure_vars();
-}
+/* A dummy pass to cause aliases to be computed via TODO_rebuild_alias. */
struct gimple_opt_pass pass_build_alias =
{
{
GIMPLE_PASS,
- "build_alias", /* name */
- gate_build_alias, /* gate */
+ "alias", /* name */
+ NULL, /* gate */
NULL, /* execute */
NULL, /* sub */
NULL, /* next */
PROP_alias, /* properties_provided */
0, /* properties_destroyed */
0, /* todo_flags_start */
- TODO_rebuild_alias /* todo_flags_finish */
+ TODO_rebuild_alias | TODO_dump_func /* todo_flags_finish */
}
};
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