/* Rewrite a program in Normal form into SSA.
- Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
+ Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
Contributed by Diego Novillo <dnovillo@redhat.com>
This file is part of GCC.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING. If not, write to
-the Free Software Foundation, 59 Temple Place - Suite 330,
-Boston, MA 02111-1307, USA. */
+the Free Software Foundation, 51 Franklin Street, Fifth Floor,
+Boston, MA 02110-1301, USA. */
#include "config.h"
#include "system.h"
#include "hard-reg-set.h"
#include "basic-block.h"
#include "output.h"
-#include "errors.h"
#include "expr.h"
#include "function.h"
#include "diagnostic.h"
#include "bitmap.h"
#include "tree-flow.h"
-#include "tree-simple.h"
+#include "tree-gimple.h"
#include "tree-inline.h"
#include "varray.h"
#include "timevar.h"
-#include "tree-alias-common.h"
#include "hashtab.h"
#include "tree-dump.h"
#include "tree-pass.h"
#include "cfgloop.h"
#include "domwalk.h"
+#include "ggc.h"
+#include "params.h"
/* This file builds the SSA form for a function as described in:
R. Cytron, J. Ferrante, B. Rosen, M. Wegman, and K. Zadeck. Efficiently
Graph. ACM Transactions on Programming Languages and Systems,
13(4):451-490, October 1991. */
+/* True if the code is in ssa form. */
+bool in_ssa_p;
/* Structure to map a variable VAR to the set of blocks that contain
definitions for VAR. */
Ith block contains a definition of VAR. */
bitmap def_blocks;
+ /* Blocks that contain a PHI node for VAR. */
+ bitmap phi_blocks;
+
/* Blocks where VAR is live-on-entry. Similar semantics as
DEF_BLOCKS. */
bitmap livein_blocks;
};
+
/* Each entry in DEF_BLOCKS contains an element of type STRUCT
DEF_BLOCKS_D, mapping a variable VAR to a bitmap describing all the
basic blocks where VAR is defined (assigned a new value). It also
computing PHI pruning heuristics. */
static htab_t def_blocks;
+/* Stack of trees used to restore the global currdefs to its original
+ state after completing rewriting of a block and its dominator
+ children. Its elements have the following properties:
+
+ - An SSA_NAME indicates that the current definition of the
+ underlying variable should be set to the given SSA_NAME.
+
+ - A _DECL node indicates that the underlying variable has no
+ current definition.
+
+ - A NULL node is used to mark the last node associated with the
+ current block.
+
+ - A NULL node at the top entry is used to mark the last node
+ associated with the current block. */
+static VEC(tree,heap) *block_defs_stack;
+
+/* Basic block vectors used in this file ought to be allocated in the
+ heap. We use pointer vector, because ints can be easily passed by
+ value. */
+DEF_VEC_I(int);
+DEF_VEC_ALLOC_I(int,heap);
+
+/* Set of existing SSA names being replaced by update_ssa. */
+static sbitmap old_ssa_names;
+
+/* Set of new SSA names being added by update_ssa. Note that both
+ NEW_SSA_NAMES and OLD_SSA_NAMES are dense bitmaps because most of
+ the operations done on them are presence tests. */
+static sbitmap new_ssa_names;
+
+/* Symbols whose SSA form needs to be updated or created for the first
+ time. */
+static bitmap syms_to_rename;
+
+/* Set of SSA names that have been marked to be released after they
+ were registered in the replacement table. They will be finally
+ released after we finish updating the SSA web. */
+static bitmap names_to_release;
+
+/* Growth factor for NEW_SSA_NAMES and OLD_SSA_NAMES. These sets need
+ to grow as the callers to register_new_name_mapping will typically
+ create new names on the fly. FIXME. Currently set to 1/3 to avoid
+ frequent reallocations but still need to find a reasonable growth
+ strategy. */
+#define NAME_SETS_GROWTH_FACTOR (MAX (3, num_ssa_names / 3))
+
+/* Tuple used to represent replacement mappings. */
+struct repl_map_d
+{
+ tree name;
+ bitmap set;
+};
+
+/* NEW -> OLD_SET replacement table. If we are replacing several
+ existing SSA names O_1, O_2, ..., O_j with a new name N_i,
+ then REPL_TBL[N_i] = { O_1, O_2, ..., O_j }. */
+static htab_t repl_tbl;
+
+/* true if register_new_name_mapping needs to initialize the data
+ structures needed by update_ssa. */
+static bool need_to_initialize_update_ssa_p = true;
+
+/* true if update_ssa needs to update virtual operands. */
+static bool need_to_update_vops_p = false;
+
+/* Statistics kept by update_ssa to use in the virtual mapping
+ heuristic. If the number of virtual mappings is beyond certain
+ threshold, the updater will switch from using the mappings into
+ renaming the virtual symbols from scratch. In some cases, the
+ large number of name mappings for virtual names causes significant
+ slowdowns in the PHI insertion code. */
+struct update_ssa_stats_d
+{
+ unsigned num_virtual_mappings;
+ unsigned num_total_mappings;
+ bitmap virtual_symbols;
+ unsigned num_virtual_symbols;
+};
+static struct update_ssa_stats_d update_ssa_stats;
+
/* Global data to attach to the main dominator walk structure. */
struct mark_def_sites_global_data
{
- /* This sbitmap contains the variables which are set before they
- are used in a basic block. We keep it as a global variable
- solely to avoid the overhead of allocating and deallocating
- the bitmap. */
- sbitmap kills;
+ /* This bitmap contains the variables which are set before they
+ are used in a basic block. */
+ bitmap kills;
+
+ /* Bitmap of names to rename. */
+ sbitmap names_to_rename;
+
+ /* Set of blocks that mark_def_sites deems interesting for the
+ renamer to process. */
+ sbitmap interesting_blocks;
};
-struct rewrite_block_data
+
+/* Information stored for SSA names. */
+struct ssa_name_info
{
- varray_type block_defs;
+ /* This field indicates whether or not the variable may need PHI nodes.
+ See the enum's definition for more detailed information about the
+ states. */
+ ENUM_BITFIELD (need_phi_state) need_phi_state : 2;
+
+ /* The actual definition of the ssa name. */
+ tree current_def;
+};
+
+
+/* The main entry point to the SSA renamer (rewrite_blocks) may be
+ called several times to do different, but related, tasks.
+ Initially, we need it to rename the whole program into SSA form.
+ At other times, we may need it to only rename into SSA newly
+ exposed symbols. Finally, we can also call it to incrementally fix
+ an already built SSA web. */
+enum rewrite_mode {
+ /* Convert the whole function into SSA form. */
+ REWRITE_ALL,
+
+ /* Incrementally update the SSA web by replacing existing SSA
+ names with new ones. See update_ssa for details. */
+ REWRITE_UPDATE
};
-/* Local functions. */
-static void rewrite_finalize_block (struct dom_walk_data *, basic_block);
-static void rewrite_initialize_block_local_data (struct dom_walk_data *,
- basic_block, bool);
-static void rewrite_initialize_block (struct dom_walk_data *, basic_block);
-static void rewrite_add_phi_arguments (struct dom_walk_data *, basic_block);
-static void mark_def_sites (struct dom_walk_data *walk_data,
- basic_block bb, block_stmt_iterator);
-static void mark_def_sites_initialize_block (struct dom_walk_data *walk_data,
- basic_block bb);
-static void compute_global_livein (bitmap, bitmap);
-static void set_def_block (tree, basic_block);
-static void set_livein_block (tree, basic_block);
-static bool prepare_operand_for_rename (tree *op_p, size_t *uid_p);
-static void insert_phi_nodes (bitmap *);
-static void rewrite_stmt (struct dom_walk_data *, basic_block,
- block_stmt_iterator);
-static inline void rewrite_operand (tree *);
-static void insert_phi_nodes_for (tree, bitmap *, varray_type *);
-static tree get_reaching_def (tree);
-static hashval_t def_blocks_hash (const void *);
-static int def_blocks_eq (const void *, const void *);
-static void def_blocks_free (void *);
-static int debug_def_blocks_r (void **, void *);
-static inline struct def_blocks_d *get_def_blocks_for (tree);
-static inline struct def_blocks_d *find_def_blocks_for (tree);
-static void htab_statistics (FILE *, htab_t);
+/* Use TREE_VISITED to keep track of which statements we want to
+ rename. When renaming a subset of the variables, not all
+ statements will be processed. This is decided in mark_def_sites. */
+#define REWRITE_THIS_STMT(T) TREE_VISITED (T)
+
+/* Use the unsigned flag to keep track of which statements we want to
+ visit when marking new definition sites. This is slightly
+ different than REWRITE_THIS_STMT: it's used by update_ssa to
+ distinguish statements that need to have both uses and defs
+ processed from those that only need to have their defs processed.
+ Statements that define new SSA names only need to have their defs
+ registered, but they don't need to have their uses renamed. */
+#define REGISTER_DEFS_IN_THIS_STMT(T) (T)->common.unsigned_flag
+
+
+/* Prototypes for debugging functions. */
+extern void dump_tree_ssa (FILE *);
+extern void debug_tree_ssa (void);
+extern void debug_def_blocks (void);
+extern void dump_tree_ssa_stats (FILE *);
+extern void debug_tree_ssa_stats (void);
+void dump_update_ssa (FILE *);
+void debug_update_ssa (void);
+void dump_names_replaced_by (FILE *, tree);
+void debug_names_replaced_by (tree);
+
+/* Get the information associated with NAME. */
+
+static inline struct ssa_name_info *
+get_ssa_name_ann (tree name)
+{
+ if (!SSA_NAME_AUX (name))
+ SSA_NAME_AUX (name) = xcalloc (1, sizeof (struct ssa_name_info));
+
+ return (struct ssa_name_info *) SSA_NAME_AUX (name);
+}
+
+
+/* Gets phi_state field for VAR. */
+
+static inline enum need_phi_state
+get_phi_state (tree var)
+{
+ if (TREE_CODE (var) == SSA_NAME)
+ return get_ssa_name_ann (var)->need_phi_state;
+ else
+ return var_ann (var)->need_phi_state;
+}
+
+
+/* Sets phi_state field for VAR to STATE. */
+
+static inline void
+set_phi_state (tree var, enum need_phi_state state)
+{
+ if (TREE_CODE (var) == SSA_NAME)
+ get_ssa_name_ann (var)->need_phi_state = state;
+ else
+ var_ann (var)->need_phi_state = state;
+}
+
+
+/* Return the current definition for VAR. */
+
+tree
+get_current_def (tree var)
+{
+ if (TREE_CODE (var) == SSA_NAME)
+ return get_ssa_name_ann (var)->current_def;
+ else
+ return var_ann (var)->current_def;
+}
+
+
+/* Sets current definition of VAR to DEF. */
+
+void
+set_current_def (tree var, tree def)
+{
+ if (TREE_CODE (var) == SSA_NAME)
+ get_ssa_name_ann (var)->current_def = def;
+ else
+ var_ann (var)->current_def = def;
+}
+
/* Compute global livein information given the set of blockx where
an object is locally live at the start of the block (LIVEIN)
to include global livein (i.e., it modifies the underlying bitmap
for LIVEIN). */
-static void
+void
compute_global_livein (bitmap livein, bitmap def_blocks)
{
basic_block bb, *worklist, *tos;
+ unsigned i;
+ bitmap_iterator bi;
tos = worklist
= (basic_block *) xmalloc (sizeof (basic_block) * (last_basic_block + 1));
- /* Initialize the worklist. */
- FOR_EACH_BB (bb)
+ EXECUTE_IF_SET_IN_BITMAP (livein, 0, i, bi)
{
- if (bitmap_bit_p (livein, bb->index))
- *tos++ = bb;
+ *tos++ = BASIC_BLOCK (i);
}
/* Iterate until the worklist is empty. */
while (tos != worklist)
{
edge e;
+ edge_iterator ei;
/* Pull a block off the worklist. */
bb = *--tos;
/* For each predecessor block. */
- for (e = bb->pred; e; e = e->pred_next)
+ FOR_EACH_EDGE (e, ei, bb->preds)
{
basic_block pred = e->src;
int pred_index = pred->index;
}
-/* Block initialization routine for mark_def_sites. Clear the
- KILLS bitmap at the start of each block. */
-
-static void
-mark_def_sites_initialize_block (struct dom_walk_data *walk_data,
- basic_block bb ATTRIBUTE_UNUSED)
-{
- struct mark_def_sites_global_data *gd = walk_data->global_data;
- sbitmap kills = gd->kills;
-
- sbitmap_zero (kills);
-}
-
-
-/* Call back for walk_dominator_tree used to collect definition sites
- for every variable in the function. For every statement S in block
- BB:
-
- 1- Variables defined by S in DEF_OPS(S) are marked in the bitmap
- WALK_DATA->GLOBAL_DATA->KILLS.
-
- 2- If S uses a variable VAR and there is no preceding kill of VAR,
- then it is marked in marked in the LIVEIN_BLOCKS bitmap
- associated with VAR.
-
- This information is used to determine which variables are live
- across block boundaries to reduce the number of PHI nodes
- we create. */
+/* Return the set of blocks where variable VAR is defined and the blocks
+ where VAR is live on entry (livein). If no entry is found in
+ DEF_BLOCKS, a new one is created and returned. */
-static void
-mark_def_sites (struct dom_walk_data *walk_data,
- basic_block bb,
- block_stmt_iterator bsi)
+static inline struct def_blocks_d *
+get_def_blocks_for (tree var)
{
- struct mark_def_sites_global_data *gd = walk_data->global_data;
- sbitmap kills = gd->kills;
- vdef_optype vdefs;
- vuse_optype vuses;
- def_optype defs;
- use_optype uses;
- size_t i, uid;
- tree stmt;
- stmt_ann_t ann;
-
- /* Mark all the blocks that have definitions for each variable in the
- VARS_TO_RENAME bitmap. */
- stmt = bsi_stmt (bsi);
- get_stmt_operands (stmt);
- ann = stmt_ann (stmt);
-
- /* If a variable is used before being set, then the variable is live
- across a block boundary, so mark it live-on-entry to BB. */
- uses = USE_OPS (ann);
- for (i = 0; i < NUM_USES (uses); i++)
- {
- tree *use_p = USE_OP_PTR (uses, i);
-
- if (prepare_operand_for_rename (use_p, &uid)
- && !TEST_BIT (kills, uid))
- set_livein_block (*use_p, bb);
- }
-
- /* Similarly for virtual uses. */
- vuses = VUSE_OPS (ann);
- for (i = 0; i < NUM_VUSES (vuses); i++)
- {
- tree *use_p = VUSE_OP_PTR (vuses, i);
-
- if (prepare_operand_for_rename (use_p, &uid)
- && !TEST_BIT (kills, uid))
- set_livein_block (*use_p, bb);
- }
+ struct def_blocks_d db, *db_p;
+ void **slot;
- /* Note that virtual definitions are irrelevant for computing KILLS
- because a VDEF does not constitute a killing definition of the
- variable. However, the operand of a virtual definitions is a use
- of the variable, so it may cause the variable to be considered
- live-on-entry. */
- vdefs = VDEF_OPS (ann);
- for (i = 0; i < NUM_VDEFS (vdefs); i++)
+ db.var = var;
+ slot = htab_find_slot (def_blocks, (void *) &db, INSERT);
+ if (*slot == NULL)
{
- size_t dummy;
-
- if (prepare_operand_for_rename (VDEF_OP_PTR (vdefs, i), &uid)
- && prepare_operand_for_rename (VDEF_RESULT_PTR (vdefs, i), &dummy))
- {
- VDEF_RESULT (vdefs, i) = VDEF_OP (vdefs, i);
-
- if (!TEST_BIT (kills, uid))
- set_livein_block (VDEF_OP (vdefs, i), bb);
- set_def_block (VDEF_RESULT (vdefs, i), bb);
- }
+ db_p = XNEW (struct def_blocks_d);
+ db_p->var = var;
+ db_p->def_blocks = BITMAP_ALLOC (NULL);
+ db_p->phi_blocks = BITMAP_ALLOC (NULL);
+ db_p->livein_blocks = BITMAP_ALLOC (NULL);
+ *slot = (void *) db_p;
}
+ else
+ db_p = (struct def_blocks_d *) *slot;
- /* Now process the definition made by this statement. Mark the
- variables in KILLS. */
- defs = DEF_OPS (ann);
- for (i = 0; i < NUM_DEFS (defs); i++)
- {
- tree *def_p = DEF_OP_PTR (defs, i);
-
- if (prepare_operand_for_rename (def_p, &uid))
- {
- set_def_block (*def_p, bb);
- SET_BIT (kills, uid);
- }
- }
+ return db_p;
}
-/* Mark block BB as the definition site for variable VAR. */
+/* Mark block BB as the definition site for variable VAR. PHI_P is true if
+ VAR is defined by a PHI node. */
static void
-set_def_block (tree var, basic_block bb)
+set_def_block (tree var, basic_block bb, bool phi_p)
{
struct def_blocks_d *db_p;
- enum need_phi_state state = var_ann (var)->need_phi_state;
+ enum need_phi_state state;
+ state = get_phi_state (var);
db_p = get_def_blocks_for (var);
/* Set the bit corresponding to the block where VAR is defined. */
bitmap_set_bit (db_p->def_blocks, bb->index);
+ if (phi_p)
+ bitmap_set_bit (db_p->phi_blocks, bb->index);
- /* Keep track of whether or not we may need to insert phi nodes.
+ /* Keep track of whether or not we may need to insert PHI nodes.
If we are in the UNKNOWN state, then this is the first definition
of VAR. Additionally, we have not seen any uses of VAR yet, so
- we do not need a phi node for this variable at this time (i.e.,
+ we do not need a PHI node for this variable at this time (i.e.,
transition to NEED_PHI_STATE_NO).
If we are in any other state, then we either have multiple definitions
definition(s). In this case we may need a PHI node, so enter
state NEED_PHI_STATE_MAYBE. */
if (state == NEED_PHI_STATE_UNKNOWN)
- var_ann (var)->need_phi_state = NEED_PHI_STATE_NO;
+ set_phi_state (var, NEED_PHI_STATE_NO);
else
- var_ann (var)->need_phi_state = NEED_PHI_STATE_MAYBE;
+ set_phi_state (var, NEED_PHI_STATE_MAYBE);
}
set_livein_block (tree var, basic_block bb)
{
struct def_blocks_d *db_p;
- enum need_phi_state state = var_ann (var)->need_phi_state;
+ enum need_phi_state state = get_phi_state (var);
db_p = get_def_blocks_for (var);
/* Set the bit corresponding to the block where VAR is live in. */
bitmap_set_bit (db_p->livein_blocks, bb->index);
- /* Keep track of whether or not we may need to insert phi nodes.
+ /* Keep track of whether or not we may need to insert PHI nodes.
If we reach here in NEED_PHI_STATE_NO, see if this use is dominated
by the single block containing the definition(s) of this variable. If
if (def_block_index == -1
|| ! dominated_by_p (CDI_DOMINATORS, bb,
BASIC_BLOCK (def_block_index)))
- var_ann (var)->need_phi_state = NEED_PHI_STATE_MAYBE;
+ set_phi_state (var, NEED_PHI_STATE_MAYBE);
}
else
- var_ann (var)->need_phi_state = NEED_PHI_STATE_MAYBE;
+ set_phi_state (var, NEED_PHI_STATE_MAYBE);
}
-/* If the operand pointed by OP_P needs to be renamed, strip away SSA_NAME
- wrappers (if needed) and return true. The unique ID for the operand's
- variable will be stored in *UID_P. */
+/* Return true if symbol SYM is marked for renaming. */
-static bool
-prepare_operand_for_rename (tree *op_p, size_t *uid_p)
+static inline bool
+symbol_marked_for_renaming (tree sym)
{
- tree var = (TREE_CODE (*op_p) != SSA_NAME) ? *op_p : SSA_NAME_VAR (*op_p);
- *uid_p = var_ann (var)->uid;
-
- /* Ignore variables that don't need to be renamed. */
- if (vars_to_rename && !bitmap_bit_p (vars_to_rename, *uid_p))
- return false;
-
- /* The variable needs to be renamed. If it already had an
- SSA_NAME, strip it off. This way, the SSA rename pass
- doesn't need to deal with existing SSA names. */
- if (TREE_CODE (*op_p) == SSA_NAME)
- {
- if (default_def (SSA_NAME_VAR (*op_p)) != *op_p)
- release_ssa_name (*op_p);
- *op_p = var;
- }
-
- return true;
+ gcc_assert (DECL_P (sym));
+ return bitmap_bit_p (syms_to_rename, DECL_UID (sym));
}
-/* Helper for insert_phi_nodes. If VAR needs PHI nodes, insert them
- at the dominance frontier (DFS) of blocks defining VAR. */
+/* Return true if NAME is in OLD_SSA_NAMES. */
-static inline
-void insert_phi_nodes_1 (tree var, bitmap *dfs, varray_type *work_stack)
+static inline bool
+is_old_name (tree name)
{
- var_ann_t ann = var_ann (var);
- if (ann->need_phi_state != NEED_PHI_STATE_NO)
- insert_phi_nodes_for (var, dfs, work_stack);
+ unsigned ver = SSA_NAME_VERSION (name);
+ return ver < new_ssa_names->n_bits && TEST_BIT (old_ssa_names, ver);
}
-/* Insert PHI nodes at the dominance frontier of blocks with variable
- definitions. DFS contains the dominance frontier information for
- the flowgraph. PHI nodes will only be inserted at the dominance
- frontier of definition blocks for variables whose NEED_PHI_STATE
- annotation is marked as ``maybe'' or ``unknown'' (computed by
- mark_def_sites). */
+/* Return true if NAME is in NEW_SSA_NAMES. */
-static void
-insert_phi_nodes (bitmap *dfs)
+static inline bool
+is_new_name (tree name)
{
- size_t i;
- varray_type work_stack;
-
- timevar_push (TV_TREE_INSERT_PHI_NODES);
-
- /* Array WORK_STACK is a stack of CFG blocks. Each block that contains
- an assignment or PHI node will be pushed to this stack. */
- VARRAY_BB_INIT (work_stack, last_basic_block, "work_stack");
-
- /* Iterate over all variables in VARS_TO_RENAME. For each variable, add
- to the work list all the blocks that have a definition for the
- variable. PHI nodes will be added to the dominance frontier blocks of
- each definition block. */
- if (vars_to_rename)
- EXECUTE_IF_SET_IN_BITMAP (vars_to_rename, 0, i,
- insert_phi_nodes_1 (referenced_var (i), dfs, &work_stack));
- else
- for (i = 0; i < num_referenced_vars; i++)
- insert_phi_nodes_1 (referenced_var (i), dfs, &work_stack);
-
- timevar_pop (TV_TREE_INSERT_PHI_NODES);
+ unsigned ver = SSA_NAME_VERSION (name);
+ return ver < new_ssa_names->n_bits && TEST_BIT (new_ssa_names, ver);
}
-/* Perform a depth-first traversal of the dominator tree looking for
- variables to rename. BB is the block where to start searching.
- Renaming is a five step process:
-
- 1- Every definition made by PHI nodes at the start of the blocks is
- registered as the current definition for the corresponding variable.
-
- 2- Every statement in BB is rewritten. USE and VUSE operands are
- rewritten with their corresponding reaching definition. DEF and
- VDEF targets are registered as new definitions.
-
- 3- All the PHI nodes in successor blocks of BB are visited. The
- argument corresponding to BB is replaced with its current reaching
- definition.
-
- 4- Recursively rewrite every dominator child block of BB.
+/* Hashing and equality functions for REPL_TBL. */
- 5- Restore (in reverse order) the current reaching definition for every
- new definition introduced in this block. This is done so that when
- we return from the recursive call, all the current reaching
- definitions are restored to the names that were valid in the
- dominator parent of BB. */
+static hashval_t
+repl_map_hash (const void *p)
+{
+ return htab_hash_pointer ((const void *)((const struct repl_map_d *)p)->name);
+}
-/* Initialize the local stacks.
-
- BLOCK_DEFS is used to save all the existing reaching definitions for
- the new SSA names introduced in this block. Before registering a
- new definition for a variable, the existing reaching definition is
- pushed into this stack so that we can restore it in Step 5. */
+static int
+repl_map_eq (const void *p1, const void *p2)
+{
+ return ((const struct repl_map_d *)p1)->name
+ == ((const struct repl_map_d *)p2)->name;
+}
static void
-rewrite_initialize_block_local_data (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
- basic_block bb ATTRIBUTE_UNUSED,
- bool recycled ATTRIBUTE_UNUSED)
+repl_map_free (void *p)
{
-#ifdef ENABLE_CHECKING
- struct rewrite_block_data *bd
- = (struct rewrite_block_data *)VARRAY_TOP_GENERIC_PTR (walk_data->block_data_stack);
-
- /* We get cleared memory from the allocator, so if the memory is
- not cleared, then we are re-using a previously allocated entry. In
- that case, we can also re-use the underlying virtal arrays. Just
- make sure we clear them before using them! */
- if (recycled && bd->block_defs && VARRAY_ACTIVE_SIZE (bd->block_defs) > 0)
- abort ();
-#endif
+ BITMAP_FREE (((struct repl_map_d *)p)->set);
+ free (p);
}
-/* SSA Rewriting Step 1. Initialization, create a block local stack
- of reaching definitions for new SSA names produced in this block
- (BLOCK_DEFS). Register new definitions for every PHI node in the
- block. */
+/* Return the names replaced by NEW (i.e., REPL_TBL[NEW].SET). */
-static void
-rewrite_initialize_block (struct dom_walk_data *walk_data, basic_block bb)
+static inline bitmap
+names_replaced_by (tree new)
{
- tree phi;
- struct rewrite_block_data *bd
- = (struct rewrite_block_data *)VARRAY_TOP_GENERIC_PTR (walk_data->block_data_stack);
+ struct repl_map_d m;
+ void **slot;
- if (dump_file && (dump_flags & TDF_DETAILS))
- fprintf (dump_file, "\n\nRenaming block #%d\n\n", bb->index);
+ m.name = new;
+ slot = htab_find_slot (repl_tbl, (void *) &m, NO_INSERT);
- /* Step 1. Register new definitions for every PHI node in the block.
- Conceptually, all the PHI nodes are executed in parallel and each PHI
- node introduces a new version for the associated variable. */
- for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
- {
- tree result = PHI_RESULT (phi);
+ /* If N was not registered in the replacement table, return NULL. */
+ if (slot == NULL || *slot == NULL)
+ return NULL;
- register_new_def (result, &bd->block_defs);
- }
+ return ((struct repl_map_d *) *slot)->set;
}
-/* SSA Rewriting Step 3. Visit all the successor blocks of BB looking for
- PHI nodes. For every PHI node found, add a new argument containing the
- current reaching definition for the variable and the edge through which
- that definition is reaching the PHI node. */
+/* Add OLD to REPL_TBL[NEW].SET. */
-static void
-rewrite_add_phi_arguments (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
- basic_block bb)
+static inline void
+add_to_repl_tbl (tree new, tree old)
{
- edge e;
+ struct repl_map_d m, *mp;
+ void **slot;
- for (e = bb->succ; e; e = e->succ_next)
+ m.name = new;
+ slot = htab_find_slot (repl_tbl, (void *) &m, INSERT);
+ if (*slot == NULL)
{
- tree phi;
-
- for (phi = phi_nodes (e->dest); phi; phi = TREE_CHAIN (phi))
- {
- tree currdef;
-
- /* If this PHI node has already been rewritten, then there is
- nothing to do for this PHI or any following PHIs since we
- always add new PHI nodes at the start of the PHI chain. */
- if (PHI_REWRITTEN (phi))
- break;
-
- currdef = get_reaching_def (SSA_NAME_VAR (PHI_RESULT (phi)));
- add_phi_arg (&phi, currdef, e);
- }
+ mp = XNEW (struct repl_map_d);
+ mp->name = new;
+ mp->set = BITMAP_ALLOC (NULL);
+ *slot = (void *) mp;
}
+ else
+ mp = (struct repl_map_d *) *slot;
+
+ bitmap_set_bit (mp->set, SSA_NAME_VERSION (old));
}
-/* SSA Rewriting Step 5. Restore the current reaching definition for each
- variable referenced in the block (in reverse order). */
+
+/* Add a new mapping NEW -> OLD REPL_TBL. Every entry N_i in REPL_TBL
+ represents the set of names O_1 ... O_j replaced by N_i. This is
+ used by update_ssa and its helpers to introduce new SSA names in an
+ already formed SSA web. */
static void
-rewrite_finalize_block (struct dom_walk_data *walk_data,
- basic_block bb ATTRIBUTE_UNUSED)
+add_new_name_mapping (tree new, tree old)
{
- struct rewrite_block_data *bd
- = (struct rewrite_block_data *)VARRAY_TOP_GENERIC_PTR (walk_data->block_data_stack);
+ timevar_push (TV_TREE_SSA_INCREMENTAL);
+
+ /* OLD and NEW must be different SSA names for the same symbol. */
+ gcc_assert (new != old && SSA_NAME_VAR (new) == SSA_NAME_VAR (old));
- /* Step 5. Restore the current reaching definition for each variable
- referenced in the block (in reverse order). */
- while (bd->block_defs && VARRAY_ACTIVE_SIZE (bd->block_defs) > 0)
+ /* We may need to grow NEW_SSA_NAMES and OLD_SSA_NAMES because our
+ caller may have created new names since the set was created. */
+ if (new_ssa_names->n_bits <= num_ssa_names - 1)
{
- tree tmp = VARRAY_TOP_TREE (bd->block_defs);
- tree saved_def, var;
+ unsigned int new_sz = num_ssa_names + NAME_SETS_GROWTH_FACTOR;
+ new_ssa_names = sbitmap_resize (new_ssa_names, new_sz, 0);
+ old_ssa_names = sbitmap_resize (old_ssa_names, new_sz, 0);
+ }
- VARRAY_POP (bd->block_defs);
- if (TREE_CODE (tmp) == SSA_NAME)
- {
- saved_def = tmp;
- var = SSA_NAME_VAR (saved_def);
- }
- else
+ /* If this mapping is for virtual names, we will need to update
+ virtual operands. */
+ if (!is_gimple_reg (new))
+ {
+ tree sym;
+ size_t uid;
+
+ need_to_update_vops_p = true;
+
+ /* Keep counts of virtual mappings and symbols to use in the
+ virtual mapping heuristic. If we have large numbers of
+ virtual mappings for a relatively low number of symbols, it
+ will make more sense to rename the symbols from scratch.
+ Otherwise, the insertion of PHI nodes for each of the old
+ names in these mappings will be very slow. */
+ sym = SSA_NAME_VAR (new);
+ uid = DECL_UID (sym);
+ update_ssa_stats.num_virtual_mappings++;
+ if (!bitmap_bit_p (update_ssa_stats.virtual_symbols, uid))
{
- saved_def = NULL;
- var = tmp;
+ bitmap_set_bit (update_ssa_stats.virtual_symbols, uid);
+ update_ssa_stats.num_virtual_symbols++;
}
-
- var_ann (var)->current_def = saved_def;
}
-}
+ /* Update the REPL_TBL table. */
+ add_to_repl_tbl (new, old);
-/* Dump SSA information to FILE. */
+ /* If OLD had already been registered as a new name, then all the
+ names that OLD replaces should also be replaced by NEW. */
+ if (is_new_name (old))
+ bitmap_ior_into (names_replaced_by (new), names_replaced_by (old));
-void
-dump_tree_ssa (FILE *file)
-{
- basic_block bb;
- const char *funcname
- = (*lang_hooks.decl_printable_name) (current_function_decl, 2);
+ /* Register NEW and OLD in NEW_SSA_NAMES and OLD_SSA_NAMES,
+ respectively. */
+ SET_BIT (new_ssa_names, SSA_NAME_VERSION (new));
+ SET_BIT (old_ssa_names, SSA_NAME_VERSION (old));
- fprintf (file, "SSA information for %s\n\n", funcname);
+ /* Update mapping counter to use in the virtual mapping heuristic. */
+ update_ssa_stats.num_total_mappings++;
- FOR_EACH_BB (bb)
- {
- dump_bb (bb, file, 0);
- fputs (" ", file);
- print_generic_stmt (file, phi_nodes (bb), dump_flags);
- fputs ("\n\n", file);
- }
+ timevar_pop (TV_TREE_SSA_INCREMENTAL);
}
-/* Dump SSA information to stderr. */
+/* Call back for walk_dominator_tree used to collect definition sites
+ for every variable in the function. For every statement S in block
+ BB:
-void
-debug_tree_ssa (void)
-{
- dump_tree_ssa (stderr);
-}
+ 1- Variables defined by S in the DEFS of S are marked in the bitmap
+ WALK_DATA->GLOBAL_DATA->KILLS.
+ 2- If S uses a variable VAR and there is no preceding kill of VAR,
+ then it is marked in the LIVEIN_BLOCKS bitmap associated with VAR.
-/* Dump SSA statistics on FILE. */
+ This information is used to determine which variables are live
+ across block boundaries to reduce the number of PHI nodes
+ we create. */
-void
-dump_tree_ssa_stats (FILE *file)
+static void
+mark_def_sites (struct dom_walk_data *walk_data,
+ basic_block bb,
+ block_stmt_iterator bsi)
{
- fprintf (file, "\nHash table statistics:\n");
-
- fprintf (file, " def_blocks: ");
- htab_statistics (file, def_blocks);
-
- fprintf (file, "\n");
-}
-
+ struct mark_def_sites_global_data *gd =
+ (struct mark_def_sites_global_data *) walk_data->global_data;
+ bitmap kills = gd->kills;
+ tree stmt, def;
+ use_operand_p use_p;
+ def_operand_p def_p;
+ ssa_op_iter iter;
-/* Dump SSA statistics on stderr. */
+ stmt = bsi_stmt (bsi);
+ update_stmt_if_modified (stmt);
-void
-debug_tree_ssa_stats (void)
-{
- dump_tree_ssa_stats (stderr);
-}
+ REGISTER_DEFS_IN_THIS_STMT (stmt) = 0;
+ REWRITE_THIS_STMT (stmt) = 0;
+ /* If a variable is used before being set, then the variable is live
+ across a block boundary, so mark it live-on-entry to BB. */
+ FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter,
+ SSA_OP_USE | SSA_OP_VUSE | SSA_OP_VMUSTKILL)
+ {
+ tree sym = USE_FROM_PTR (use_p);
+ gcc_assert (DECL_P (sym));
+ if (!bitmap_bit_p (kills, DECL_UID (sym)))
+ set_livein_block (sym, bb);
+ REWRITE_THIS_STMT (stmt) = 1;
+ }
+
+ /* Note that virtual definitions are irrelevant for computing KILLS
+ because a V_MAY_DEF does not constitute a killing definition of the
+ variable. However, the operand of a virtual definitions is a use
+ of the variable, so it may cause the variable to be considered
+ live-on-entry. */
+ FOR_EACH_SSA_MAYDEF_OPERAND (def_p, use_p, stmt, iter)
+ {
+ tree sym = USE_FROM_PTR (use_p);
+ gcc_assert (DECL_P (sym));
+ set_livein_block (sym, bb);
+ set_def_block (sym, bb, false);
+ REGISTER_DEFS_IN_THIS_STMT (stmt) = 1;
+ REWRITE_THIS_STMT (stmt) = 1;
+ }
-/* Dump statistics for the hash table HTAB. */
+ /* Now process the defs and must-defs made by this statement. */
+ FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF | SSA_OP_VMUSTDEF)
+ {
+ gcc_assert (DECL_P (def));
+ set_def_block (def, bb, false);
+ bitmap_set_bit (kills, DECL_UID (def));
+ REGISTER_DEFS_IN_THIS_STMT (stmt) = 1;
+ }
-static void
-htab_statistics (FILE *file, htab_t htab)
-{
- fprintf (file, "size %ld, %ld elements, %f collision/search ratio\n",
- (long) htab_size (htab),
- (long) htab_elements (htab),
- htab_collisions (htab));
+ /* If we found the statement interesting then also mark the block BB
+ as interesting. */
+ if (REWRITE_THIS_STMT (stmt) || REGISTER_DEFS_IN_THIS_STMT (stmt))
+ SET_BIT (gd->interesting_blocks, bb->index);
}
-/* Insert PHI nodes for variable VAR using the dominance frontier
- information given in DFS. */
+/* Given a set of blocks with variable definitions (DEF_BLOCKS),
+ return a bitmap with all the blocks in the iterated dominance
+ frontier of the blocks in DEF_BLOCKS. DFS contains dominance
+ frontier information as returned by compute_dominance_frontiers.
+
+ The resulting set of blocks are the potential sites where PHI nodes
+ are needed. The caller is responsible from freeing the memory
+ allocated for the return value. */
-static void
-insert_phi_nodes_for (tree var, bitmap *dfs, varray_type *work_stack)
+static bitmap
+find_idf (bitmap def_blocks, bitmap *dfs)
{
- struct def_blocks_d *def_map;
+ bitmap_iterator bi;
+ unsigned bb_index;
+ VEC(int,heap) *work_stack;
bitmap phi_insertion_points;
- int bb_index;
-
- def_map = find_def_blocks_for (var);
- if (def_map == NULL)
- return;
- phi_insertion_points = BITMAP_XMALLOC ();
+ work_stack = VEC_alloc (int, heap, n_basic_blocks);
+ phi_insertion_points = BITMAP_ALLOC (NULL);
- EXECUTE_IF_SET_IN_BITMAP (def_map->def_blocks, 0, bb_index,
- {
- VARRAY_PUSH_BB (*work_stack, BASIC_BLOCK (bb_index));
- });
+ /* Seed the work list with all the blocks in DEF_BLOCKS. */
+ EXECUTE_IF_SET_IN_BITMAP (def_blocks, 0, bb_index, bi)
+ /* We use VEC_quick_push here for speed. This is safe because we
+ know that the number of definition blocks is no greater than
+ the number of basic blocks, which is the initial capacity of
+ WORK_STACK. */
+ VEC_quick_push (int, work_stack, bb_index);
/* Pop a block off the worklist, add every block that appears in
- the original block's dfs that we have not already processed to
+ the original block's DF that we have not already processed to
the worklist. Iterate until the worklist is empty. Blocks
which are added to the worklist are potential sites for
- PHI nodes.
-
- The iteration step could be done during PHI insertion just as
- easily. We do it here for historical reasons -- we used to have
- a heuristic which used the potential PHI insertion points to
- determine if fully pruned or semi pruned SSA form was appropriate.
-
- We now always use fully pruned SSA form. */
- while (VARRAY_ACTIVE_SIZE (*work_stack) > 0)
+ PHI nodes. */
+ while (VEC_length (int, work_stack) > 0)
{
- basic_block bb = VARRAY_TOP_BB (*work_stack);
- int bb_index = bb->index;
- int dfs_index;
+ bb_index = VEC_pop (int, work_stack);
- VARRAY_POP (*work_stack);
-
- EXECUTE_IF_AND_COMPL_IN_BITMAP (dfs[bb_index],
- phi_insertion_points,
- 0, dfs_index,
- {
- basic_block bb = BASIC_BLOCK (dfs_index);
+ /* Since the registration of NEW -> OLD name mappings is done
+ separately from the call to update_ssa, when updating the SSA
+ form, the basic blocks where new and/or old names are defined
+ may have disappeared by CFG cleanup calls. In this case,
+ we may pull a non-existing block from the work stack. */
+ gcc_assert (bb_index < (unsigned) last_basic_block);
- VARRAY_PUSH_BB (*work_stack, bb);
- bitmap_set_bit (phi_insertion_points, dfs_index);
- });
+ EXECUTE_IF_AND_COMPL_IN_BITMAP (dfs[bb_index], phi_insertion_points,
+ 0, bb_index, bi)
+ {
+ /* Use a safe push because if there is a definition of VAR
+ in every basic block, then WORK_STACK may eventually have
+ more than N_BASIC_BLOCK entries. */
+ VEC_safe_push (int, heap, work_stack, bb_index);
+ bitmap_set_bit (phi_insertion_points, bb_index);
+ }
}
- /* Now compute global livein for this variable. Note this modifies
- def_map->livein_blocks. */
- compute_global_livein (def_map->livein_blocks, def_map->def_blocks);
-
- /* And insert the PHI nodes. */
- EXECUTE_IF_AND_IN_BITMAP (phi_insertion_points, def_map->livein_blocks,
- 0, bb_index,
- {
- create_phi_node (var, BASIC_BLOCK (bb_index));
- });
+ VEC_free (int, heap, work_stack);
- BITMAP_XFREE (phi_insertion_points);
+ return phi_insertion_points;
}
-/* SSA Rewriting Step 2. Rewrite every variable used in each statement in
- the block with its immediate reaching definitions. Update the current
- definition of a variable when a new real or virtual definition is found. */
-static void
-rewrite_stmt (struct dom_walk_data *walk_data,
- basic_block bb ATTRIBUTE_UNUSED,
- block_stmt_iterator si)
+/* Return the set of blocks where variable VAR is defined and the blocks
+ where VAR is live on entry (livein). Return NULL, if no entry is
+ found in DEF_BLOCKS. */
+
+static inline struct def_blocks_d *
+find_def_blocks_for (tree var)
{
- size_t i;
- stmt_ann_t ann;
- tree stmt;
- vuse_optype vuses;
- vdef_optype vdefs;
- def_optype defs;
- use_optype uses;
- struct rewrite_block_data *bd;
+ struct def_blocks_d dm;
+ dm.var = var;
+ return (struct def_blocks_d *) htab_find (def_blocks, &dm);
+}
- bd = VARRAY_TOP_GENERIC_PTR (walk_data->block_data_stack);
- stmt = bsi_stmt (si);
- ann = stmt_ann (stmt);
+/* Retrieve or create a default definition for symbol SYM. */
- if (dump_file && (dump_flags & TDF_DETAILS))
+static inline tree
+get_default_def_for (tree sym)
+{
+ tree ddef = default_def (sym);
+
+ if (ddef == NULL_TREE)
{
- fprintf (dump_file, "Renaming statement ");
- print_generic_stmt (dump_file, stmt, TDF_SLIM);
- fprintf (dump_file, "\n");
+ ddef = make_ssa_name (sym, build_empty_stmt ());
+ set_default_def (sym, ddef);
}
-#if defined ENABLE_CHECKING
- /* We have just scanned the code for operands. No statement should
- be modified. */
- if (ann->modified)
- abort ();
-#endif
+ return ddef;
+}
- defs = DEF_OPS (ann);
- uses = USE_OPS (ann);
- vuses = VUSE_OPS (ann);
- vdefs = VDEF_OPS (ann);
- /* Step 1. Rewrite USES and VUSES in the statement. */
- for (i = 0; i < NUM_USES (uses); i++)
- rewrite_operand (USE_OP_PTR (uses, i));
+/* Insert PHI nodes for variable VAR using the iterated dominance
+ frontier given in PHI_INSERTION_POINTS. If UPDATE_P is true, this
+ function assumes that the caller is incrementally updating the SSA
+ form, in which case (1) VAR is assumed to be an SSA name, (2) a new
+ SSA name is created for VAR's symbol, and, (3) all the arguments
+ for the newly created PHI node are set to VAR.
- /* Rewrite virtual uses in the statement. */
- for (i = 0; i < NUM_VUSES (vuses); i++)
- rewrite_operand (VUSE_OP_PTR (vuses, i));
+ PHI_INSERTION_POINTS is updated to reflect nodes that already had a
+ PHI node for VAR. On exit, only the nodes that received a PHI node
+ for VAR will be present in PHI_INSERTION_POINTS. */
- /* Step 2. Register the statement's DEF and VDEF operands. */
- for (i = 0; i < NUM_DEFS (defs); i++)
- {
- tree *def_p = DEF_OP_PTR (defs, i);
+static void
+insert_phi_nodes_for (tree var, bitmap phi_insertion_points, bool update_p)
+{
+ unsigned bb_index;
+ edge e;
+ tree phi;
+ basic_block bb;
+ bitmap_iterator bi;
+ struct def_blocks_d *def_map;
- if (TREE_CODE (*def_p) != SSA_NAME)
- *def_p = make_ssa_name (*def_p, stmt);
+ def_map = find_def_blocks_for (var);
+ gcc_assert (def_map);
- /* FIXME: We shouldn't be registering new defs if the variable
- doesn't need to be renamed. */
- register_new_def (*def_p, &bd->block_defs);
- }
+ /* Remove the blocks where we already have PHI nodes for VAR. */
+ bitmap_and_compl_into (phi_insertion_points, def_map->phi_blocks);
+
+ /* Now compute global livein for this variable. Note this modifies
+ def_map->livein_blocks. */
+ compute_global_livein (def_map->livein_blocks, def_map->def_blocks);
- /* Register new virtual definitions made by the statement. */
- for (i = 0; i < NUM_VDEFS (vdefs); i++)
+ /* And insert the PHI nodes. */
+ EXECUTE_IF_AND_IN_BITMAP (phi_insertion_points, def_map->livein_blocks,
+ 0, bb_index, bi)
{
- rewrite_operand (VDEF_OP_PTR (vdefs, i));
+ bb = BASIC_BLOCK (bb_index);
- if (TREE_CODE (VDEF_RESULT (vdefs, i)) != SSA_NAME)
- *VDEF_RESULT_PTR (vdefs, i)
- = make_ssa_name (VDEF_RESULT (vdefs, i), stmt);
+ if (update_p && TREE_CODE (var) == SSA_NAME)
+ {
+ /* If we are rewriting SSA names, create the LHS of the PHI
+ node by duplicating VAR. This is useful in the case of
+ pointers, to also duplicate pointer attributes (alias
+ information, in particular). */
+ edge_iterator ei;
+ tree new_lhs;
+
+ phi = create_phi_node (var, bb);
+ new_lhs = duplicate_ssa_name (var, phi);
+ SET_PHI_RESULT (phi, new_lhs);
+ add_new_name_mapping (new_lhs, var);
+
+ /* Add VAR to every argument slot of PHI. We need VAR in
+ every argument so that rewrite_update_phi_arguments knows
+ which name is this PHI node replacing. If VAR is a
+ symbol marked for renaming, this is not necessary, the
+ renamer will use the symbol on the LHS to get its
+ reaching definition. */
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ add_phi_arg (phi, var, e);
+ }
+ else
+ {
+ tree sym = DECL_P (var) ? var : SSA_NAME_VAR (var);
+ phi = create_phi_node (sym, bb);
+ }
- /* FIXME: We shouldn't be registering new defs if the variable
- doesn't need to be renamed. */
- register_new_def (VDEF_RESULT (vdefs, i), &bd->block_defs);
+ /* Mark this PHI node as interesting for update_ssa. */
+ REGISTER_DEFS_IN_THIS_STMT (phi) = 1;
+ REWRITE_THIS_STMT (phi) = 1;
}
}
-/* Replace the operand pointed by OP_P with its immediate reaching
- definition. */
+/* Insert PHI nodes at the dominance frontier of blocks with variable
+ definitions. DFS contains the dominance frontier information for
+ the flowgraph. PHI nodes will only be inserted at the dominance
+ frontier of definition blocks for variables whose NEED_PHI_STATE
+ annotation is marked as ``maybe'' or ``unknown'' (computed by
+ mark_def_sites). */
-static inline void
-rewrite_operand (tree *op_p)
+static void
+insert_phi_nodes (bitmap *dfs)
{
- if (TREE_CODE (*op_p) != SSA_NAME)
- *op_p = get_reaching_def (*op_p);
+ referenced_var_iterator rvi;
+ tree var;
+
+ timevar_push (TV_TREE_INSERT_PHI_NODES);
+
+ FOR_EACH_REFERENCED_VAR (var, rvi)
+ {
+ struct def_blocks_d *def_map;
+ bitmap idf;
+
+ def_map = find_def_blocks_for (var);
+ if (def_map == NULL)
+ continue;
+
+ if (get_phi_state (var) != NEED_PHI_STATE_NO)
+ {
+ idf = find_idf (def_map->def_blocks, dfs);
+ insert_phi_nodes_for (var, idf, false);
+ BITMAP_FREE (idf);
+ }
+ }
+
+ timevar_pop (TV_TREE_INSERT_PHI_NODES);
}
/* Register DEF (an SSA_NAME) to be a new definition for its underlying
variable (SSA_NAME_VAR (DEF)) and push VAR's current reaching definition
- into the stack pointed by BLOCK_DEFS_P. */
+ into the stack pointed to by BLOCK_DEFS_P. */
void
-register_new_def (tree def, varray_type *block_defs_p)
+register_new_def (tree def, VEC(tree,heap) **block_defs_p)
{
tree var = SSA_NAME_VAR (def);
tree currdef;
This is the same test to prune the set of variables which may
need PHI nodes. So we just use that information since it's already
computed and available for us to use. */
- if (var_ann (var)->need_phi_state == NEED_PHI_STATE_NO)
+ if (get_phi_state (var) == NEED_PHI_STATE_NO)
{
- var_ann (var)->current_def = def;
+ set_current_def (var, def);
return;
}
- currdef = var_ann (var)->current_def;
- if (! *block_defs_p)
- VARRAY_TREE_INIT (*block_defs_p, 20, "block_defs");
+ currdef = get_current_def (var);
/* Push the current reaching definition into *BLOCK_DEFS_P. This stack is
later used by the dominator tree callbacks to restore the reaching
definitions for all the variables defined in the block after a recursive
visit to all its immediately dominated blocks. If there is no current
reaching definition, then just record the underlying _DECL node. */
- VARRAY_PUSH_TREE (*block_defs_p, currdef ? currdef : var);
+ VEC_safe_push (tree, heap, *block_defs_p, currdef ? currdef : var);
/* Set the current reaching definition for VAR to be DEF. */
- var_ann (var)->current_def = def;
+ set_current_def (var, def);
+}
+
+
+/* Perform a depth-first traversal of the dominator tree looking for
+ variables to rename. BB is the block where to start searching.
+ Renaming is a five step process:
+
+ 1- Every definition made by PHI nodes at the start of the blocks is
+ registered as the current definition for the corresponding variable.
+
+ 2- Every statement in BB is rewritten. USE and VUSE operands are
+ rewritten with their corresponding reaching definition. DEF and
+ VDEF targets are registered as new definitions.
+
+ 3- All the PHI nodes in successor blocks of BB are visited. The
+ argument corresponding to BB is replaced with its current reaching
+ definition.
+
+ 4- Recursively rewrite every dominator child block of BB.
+
+ 5- Restore (in reverse order) the current reaching definition for every
+ new definition introduced in this block. This is done so that when
+ we return from the recursive call, all the current reaching
+ definitions are restored to the names that were valid in the
+ dominator parent of BB. */
+
+/* SSA Rewriting Step 1. Initialization, create a block local stack
+ of reaching definitions for new SSA names produced in this block
+ (BLOCK_DEFS). Register new definitions for every PHI node in the
+ block. */
+
+static void
+rewrite_initialize_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
+ basic_block bb)
+{
+ tree phi;
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, "\n\nRenaming block #%d\n\n", bb->index);
+
+ /* Mark the unwind point for this block. */
+ VEC_safe_push (tree, heap, block_defs_stack, NULL_TREE);
+
+ /* Step 1. Register new definitions for every PHI node in the block.
+ Conceptually, all the PHI nodes are executed in parallel and each PHI
+ node introduces a new version for the associated variable. */
+ for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
+ {
+ tree result = PHI_RESULT (phi);
+ register_new_def (result, &block_defs_stack);
+ }
}
static tree
get_reaching_def (tree var)
{
- tree default_d, currdef_var;
+ tree currdef_var, avar;
/* Lookup the current reaching definition for VAR. */
- default_d = NULL_TREE;
- currdef_var = var_ann (var)->current_def;
+ currdef_var = get_current_def (var);
/* If there is no reaching definition for VAR, create and register a
default definition for it (if needed). */
if (currdef_var == NULL_TREE)
{
- default_d = default_def (var);
- if (default_d == NULL_TREE)
- {
- default_d = make_ssa_name (var, build_empty_stmt ());
- set_default_def (var, default_d);
- }
- var_ann (var)->current_def = default_d;
+ avar = DECL_P (var) ? var : SSA_NAME_VAR (var);
+ currdef_var = get_default_def_for (avar);
+ set_current_def (var, currdef_var);
}
/* Return the current reaching definition for VAR, or the default
definition, if we had to create one. */
- return (currdef_var) ? currdef_var : default_d;
+ return currdef_var;
}
-/* Hashing and equality functions for DEF_BLOCKS. */
-
-static hashval_t
-def_blocks_hash (const void *p)
-{
- return htab_hash_pointer
- ((const void *)((const struct def_blocks_d *)p)->var);
-}
+/* SSA Rewriting Step 2. Rewrite every variable used in each statement in
+ the block with its immediate reaching definitions. Update the current
+ definition of a variable when a new real or virtual definition is found. */
-static int
-def_blocks_eq (const void *p1, const void *p2)
+static void
+rewrite_stmt (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
+ basic_block bb ATTRIBUTE_UNUSED,
+ block_stmt_iterator si)
{
- return ((const struct def_blocks_d *)p1)->var
- == ((const struct def_blocks_d *)p2)->var;
-}
+ tree stmt;
+ use_operand_p use_p;
+ def_operand_p def_p;
+ ssa_op_iter iter;
-/* Free memory allocated by one entry in DEF_BLOCKS. */
+ stmt = bsi_stmt (si);
-static void
-def_blocks_free (void *p)
-{
- struct def_blocks_d *entry = p;
- BITMAP_XFREE (entry->def_blocks);
- BITMAP_XFREE (entry->livein_blocks);
- free (entry);
-}
+ /* If mark_def_sites decided that we don't need to rewrite this
+ statement, ignore it. */
+ if (!REWRITE_THIS_STMT (stmt) && !REGISTER_DEFS_IN_THIS_STMT (stmt))
+ return;
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, "Renaming statement ");
+ print_generic_stmt (dump_file, stmt, TDF_SLIM);
+ fprintf (dump_file, "\n");
+ }
-/* Dump the DEF_BLOCKS hash table on stderr. */
+ /* Step 1. Rewrite USES and VUSES in the statement. */
+ if (REWRITE_THIS_STMT (stmt))
+ FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter,
+ SSA_OP_ALL_USES|SSA_OP_ALL_KILLS)
+ {
+ tree var = USE_FROM_PTR (use_p);
+ gcc_assert (DECL_P (var));
+ SET_USE (use_p, get_reaching_def (var));
+ }
-void
-debug_def_blocks (void)
-{
- htab_traverse (def_blocks, debug_def_blocks_r, NULL);
+ /* Step 2. Register the statement's DEF and VDEF operands. */
+ if (REGISTER_DEFS_IN_THIS_STMT (stmt))
+ FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, iter, SSA_OP_ALL_DEFS)
+ {
+ tree var = DEF_FROM_PTR (def_p);
+ gcc_assert (DECL_P (var));
+ SET_DEF (def_p, make_ssa_name (var, stmt));
+ register_new_def (DEF_FROM_PTR (def_p), &block_defs_stack);
+ }
}
-/* Callback for htab_traverse to dump the DEF_BLOCKS hash table. */
-static int
-debug_def_blocks_r (void **slot, void *data ATTRIBUTE_UNUSED)
+/* SSA Rewriting Step 3. Visit all the successor blocks of BB looking for
+ PHI nodes. For every PHI node found, add a new argument containing the
+ current reaching definition for the variable and the edge through which
+ that definition is reaching the PHI node. */
+
+static void
+rewrite_add_phi_arguments (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
+ basic_block bb)
{
- unsigned long i;
- struct def_blocks_d *db_p = (struct def_blocks_d *) *slot;
-
- fprintf (stderr, "VAR: ");
- print_generic_expr (stderr, db_p->var, dump_flags);
- fprintf (stderr, ", DEF_BLOCKS: { ");
- EXECUTE_IF_SET_IN_BITMAP (db_p->def_blocks, 0, i,
- fprintf (stderr, "%ld ", i));
- fprintf (stderr, "}");
- fprintf (stderr, ", LIVEIN_BLOCKS: { ");
- EXECUTE_IF_SET_IN_BITMAP (db_p->livein_blocks, 0, i,
- fprintf (stderr, "%ld ", i));
- fprintf (stderr, "}\n");
+ edge e;
+ edge_iterator ei;
- return 1;
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ {
+ tree phi;
+
+ for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi))
+ {
+ tree currdef;
+ currdef = get_reaching_def (SSA_NAME_VAR (PHI_RESULT (phi)));
+ add_phi_arg (phi, currdef, e);
+ }
+ }
}
-/* Return the set of blocks where variable VAR is defined and the blocks
- where VAR is live on entry (livein). Return NULL, if no entry is
- found in DEF_BLOCKS. */
+/* Called after visiting basic block BB. Restore CURRDEFS to its
+ original value. */
+
+static void
+rewrite_finalize_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
+ basic_block bb ATTRIBUTE_UNUSED)
+{
+ /* Restore CURRDEFS to its original state. */
+ while (VEC_length (tree, block_defs_stack) > 0)
+ {
+ tree tmp = VEC_pop (tree, block_defs_stack);
+ tree saved_def, var;
+
+ if (tmp == NULL_TREE)
+ break;
+
+ /* If we recorded an SSA_NAME, then make the SSA_NAME the current
+ definition of its underlying variable. If we recorded anything
+ else, it must have been an _DECL node and its current reaching
+ definition must have been NULL. */
+ if (TREE_CODE (tmp) == SSA_NAME)
+ {
+ saved_def = tmp;
+ var = SSA_NAME_VAR (saved_def);
+ }
+ else
+ {
+ saved_def = NULL;
+ var = tmp;
+ }
+
+ set_current_def (var, saved_def);
+ }
+}
+
+
+/* Dump SSA information to FILE. */
+
+void
+dump_tree_ssa (FILE *file)
+{
+ basic_block bb;
+ const char *funcname
+ = lang_hooks.decl_printable_name (current_function_decl, 2);
+
+ fprintf (file, "SSA information for %s\n\n", funcname);
+
+ FOR_EACH_BB (bb)
+ {
+ dump_bb (bb, file, 0);
+ fputs (" ", file);
+ print_generic_stmt (file, phi_nodes (bb), dump_flags);
+ fputs ("\n\n", file);
+ }
+}
+
+
+/* Dump SSA information to stderr. */
+
+void
+debug_tree_ssa (void)
+{
+ dump_tree_ssa (stderr);
+}
+
+
+/* Dump statistics for the hash table HTAB. */
+
+static void
+htab_statistics (FILE *file, htab_t htab)
+{
+ fprintf (file, "size %ld, %ld elements, %f collision/search ratio\n",
+ (long) htab_size (htab),
+ (long) htab_elements (htab),
+ htab_collisions (htab));
+}
+
+
+/* Dump SSA statistics on FILE. */
+
+void
+dump_tree_ssa_stats (FILE *file)
+{
+ fprintf (file, "\nHash table statistics:\n");
+
+ fprintf (file, " def_blocks: ");
+ htab_statistics (file, def_blocks);
+
+ fprintf (file, "\n");
+}
+
+
+/* Dump SSA statistics on stderr. */
+
+void
+debug_tree_ssa_stats (void)
+{
+ dump_tree_ssa_stats (stderr);
+}
+
+
+/* Hashing and equality functions for DEF_BLOCKS. */
+
+static hashval_t
+def_blocks_hash (const void *p)
+{
+ return htab_hash_pointer
+ ((const void *)((const struct def_blocks_d *)p)->var);
+}
+
+static int
+def_blocks_eq (const void *p1, const void *p2)
+{
+ return ((const struct def_blocks_d *)p1)->var
+ == ((const struct def_blocks_d *)p2)->var;
+}
+
+
+/* Free memory allocated by one entry in DEF_BLOCKS. */
+
+static void
+def_blocks_free (void *p)
+{
+ struct def_blocks_d *entry = (struct def_blocks_d *) p;
+ BITMAP_FREE (entry->def_blocks);
+ BITMAP_FREE (entry->phi_blocks);
+ BITMAP_FREE (entry->livein_blocks);
+ free (entry);
+}
+
+
+/* Callback for htab_traverse to dump the DEF_BLOCKS hash table. */
+
+static int
+debug_def_blocks_r (void **slot, void *data ATTRIBUTE_UNUSED)
+{
+ struct def_blocks_d *db_p = (struct def_blocks_d *) *slot;
+
+ fprintf (stderr, "VAR: ");
+ print_generic_expr (stderr, db_p->var, dump_flags);
+ bitmap_print (stderr, db_p->def_blocks, ", DEF_BLOCKS: { ", "}");
+ bitmap_print (stderr, db_p->livein_blocks, ", LIVEIN_BLOCKS: { ", "}\n");
+
+ return 1;
+}
+
+
+/* Dump the DEF_BLOCKS hash table on stderr. */
+
+void
+debug_def_blocks (void)
+{
+ htab_traverse (def_blocks, debug_def_blocks_r, NULL);
+}
+
+
+/* Register NEW_NAME to be the new reaching definition for OLD_NAME. */
+
+static inline void
+register_new_update_single (tree new_name, tree old_name)
+{
+ tree currdef = get_current_def (old_name);
+
+ /* Push the current reaching definition into *BLOCK_DEFS_P.
+ This stack is later used by the dominator tree callbacks to
+ restore the reaching definitions for all the variables
+ defined in the block after a recursive visit to all its
+ immediately dominated blocks. */
+ VEC_reserve (tree, heap, block_defs_stack, 2);
+ VEC_quick_push (tree, block_defs_stack, currdef);
+ VEC_quick_push (tree, block_defs_stack, old_name);
+
+ /* Set the current reaching definition for OLD_NAME to be
+ NEW_NAME. */
+ set_current_def (old_name, new_name);
+}
+
+
+/* Register NEW_NAME to be the new reaching definition for all the
+ names in OLD_NAMES. Used by the incremental SSA update routines to
+ replace old SSA names with new ones. */
+
+static inline void
+register_new_update_set (tree new_name, bitmap old_names)
+{
+ bitmap_iterator bi;
+ unsigned i;
+
+ EXECUTE_IF_SET_IN_BITMAP (old_names, 0, i, bi)
+ register_new_update_single (new_name, ssa_name (i));
+}
+
+
+/* Initialization of block data structures for the incremental SSA
+ update pass. Create a block local stack of reaching definitions
+ for new SSA names produced in this block (BLOCK_DEFS). Register
+ new definitions for every PHI node in the block. */
+
+static void
+rewrite_update_init_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
+ basic_block bb)
+{
+ edge e;
+ edge_iterator ei;
+ tree phi;
+ bool is_abnormal_phi;
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, "\n\nRegistering new PHI nodes in block #%d\n\n",
+ bb->index);
+
+ /* Mark the unwind point for this block. */
+ VEC_safe_push (tree, heap, block_defs_stack, NULL_TREE);
+
+ /* Mark the LHS if any of the arguments flows through an abnormal
+ edge. */
+ is_abnormal_phi = false;
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ if (e->flags & EDGE_ABNORMAL)
+ {
+ is_abnormal_phi = true;
+ break;
+ }
+
+ /* If any of the PHI nodes is a replacement for a name in
+ OLD_SSA_NAMES or it's one of the names in NEW_SSA_NAMES, then
+ register it as a new definition for its corresponding name. Also
+ register definitions for names whose underlying symbols are
+ marked for renaming. */
+ for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
+ {
+ tree lhs, lhs_sym;
+
+ if (!REGISTER_DEFS_IN_THIS_STMT (phi))
+ continue;
+
+ lhs = PHI_RESULT (phi);
+ lhs_sym = SSA_NAME_VAR (lhs);
+
+ if (symbol_marked_for_renaming (lhs_sym))
+ register_new_update_single (lhs, lhs_sym);
+ else
+ {
+ /* If LHS is a new name, register a new definition for all
+ the names replaced by LHS. */
+ if (is_new_name (lhs))
+ register_new_update_set (lhs, names_replaced_by (lhs));
+
+ /* If LHS is an OLD name, register it as a new definition
+ for itself. */
+ if (is_old_name (lhs))
+ register_new_update_single (lhs, lhs);
+ }
+
+ if (is_abnormal_phi)
+ SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs) = 1;
+ }
+}
+
+
+/* Called after visiting block BB. Unwind BLOCK_DEFS_STACK to restore
+ the current reaching definition of every name re-written in BB to
+ the original reaching definition before visiting BB. This
+ unwinding must be done in the opposite order to what is done in
+ register_new_update_set. */
+
+static void
+rewrite_update_fini_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
+ basic_block bb ATTRIBUTE_UNUSED)
+{
+ while (VEC_length (tree, block_defs_stack) > 0)
+ {
+ tree var = VEC_pop (tree, block_defs_stack);
+ tree saved_def;
+
+ /* NULL indicates the unwind stop point for this block (see
+ rewrite_update_init_block). */
+ if (var == NULL)
+ return;
+
+ saved_def = VEC_pop (tree, block_defs_stack);
+ set_current_def (var, saved_def);
+ }
+}
+
+
+/* If the operand pointed to by USE_P is a name in OLD_SSA_NAMES or
+ it is a symbol marked for renaming, replace it with USE_P's current
+ reaching definition. */
+
+static inline void
+maybe_replace_use (use_operand_p use_p)
+{
+ tree rdef = NULL_TREE;
+ tree use = USE_FROM_PTR (use_p);
+ tree sym = DECL_P (use) ? use : SSA_NAME_VAR (use);
+
+ if (symbol_marked_for_renaming (sym))
+ rdef = get_reaching_def (sym);
+ else if (is_old_name (use))
+ rdef = get_reaching_def (use);
+
+ if (rdef && rdef != use)
+ SET_USE (use_p, rdef);
+}
+
+
+/* If the operand pointed to by DEF_P is an SSA name in NEW_SSA_NAMES
+ or OLD_SSA_NAMES, or if it is a symbol marked for renaming,
+ register it as the current definition for the names replaced by
+ DEF_P. */
+
+static inline void
+maybe_register_def (def_operand_p def_p, tree stmt)
+{
+ tree def = DEF_FROM_PTR (def_p);
+ tree sym = DECL_P (def) ? def : SSA_NAME_VAR (def);
+
+ /* If DEF is a naked symbol that needs renaming, create a
+ new name for it. */
+ if (symbol_marked_for_renaming (sym))
+ {
+ if (DECL_P (def))
+ {
+ def = make_ssa_name (def, stmt);
+ SET_DEF (def_p, def);
+ }
+
+ register_new_update_single (def, sym);
+ }
+ else
+ {
+ /* If DEF is a new name, register it as a new definition
+ for all the names replaced by DEF. */
+ if (is_new_name (def))
+ register_new_update_set (def, names_replaced_by (def));
+
+ /* If DEF is an old name, register DEF as a new
+ definition for itself. */
+ if (is_old_name (def))
+ register_new_update_single (def, def);
+ }
+}
+
+
+/* Update every variable used in the statement pointed-to by SI. The
+ statement is assumed to be in SSA form already. Names in
+ OLD_SSA_NAMES used by SI will be updated to their current reaching
+ definition. Names in OLD_SSA_NAMES or NEW_SSA_NAMES defined by SI
+ will be registered as a new definition for their corresponding name
+ in OLD_SSA_NAMES. */
+
+static void
+rewrite_update_stmt (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
+ basic_block bb ATTRIBUTE_UNUSED,
+ block_stmt_iterator si)
+{
+ stmt_ann_t ann;
+ tree stmt;
+ use_operand_p use_p;
+ def_operand_p def_p;
+ ssa_op_iter iter;
+
+ stmt = bsi_stmt (si);
+ ann = stmt_ann (stmt);
+
+ /* Only update marked statements. */
+ if (!REWRITE_THIS_STMT (stmt) && !REGISTER_DEFS_IN_THIS_STMT (stmt))
+ return;
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, "Updating SSA information for statement ");
+ print_generic_stmt (dump_file, stmt, TDF_SLIM);
+ fprintf (dump_file, "\n");
+ }
+
+ /* Rewrite USES included in OLD_SSA_NAMES and USES whose underlying
+ symbol is marked for renaming. */
+ if (REWRITE_THIS_STMT (stmt))
+ {
+ FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE)
+ maybe_replace_use (use_p);
+
+ if (need_to_update_vops_p)
+ FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter,
+ SSA_OP_VIRTUAL_USES | SSA_OP_VIRTUAL_KILLS)
+ maybe_replace_use (use_p);
+ }
+
+ /* Register definitions of names in NEW_SSA_NAMES and OLD_SSA_NAMES.
+ Also register definitions for names whose underlying symbol is
+ marked for renaming. */
+ if (REGISTER_DEFS_IN_THIS_STMT (stmt))
+ {
+ FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, iter, SSA_OP_DEF)
+ maybe_register_def (def_p, stmt);
+
+ if (need_to_update_vops_p)
+ FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, iter, SSA_OP_VIRTUAL_DEFS)
+ maybe_register_def (def_p, stmt);
+ }
+}
+
+
+/* Replace the operand pointed to by USE_P with USE's current reaching
+ definition. */
+
+static inline void
+replace_use (use_operand_p use_p, tree use)
+{
+ tree rdef = get_reaching_def (use);
+ if (rdef != use)
+ SET_USE (use_p, rdef);
+}
+
+
+/* Visit all the successor blocks of BB looking for PHI nodes. For
+ every PHI node found, check if any of its arguments is in
+ OLD_SSA_NAMES. If so, and if the argument has a current reaching
+ definition, replace it. */
+
+static void
+rewrite_update_phi_arguments (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
+ basic_block bb)
+{
+ edge e;
+ edge_iterator ei;
+
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ {
+ tree phi;
+
+ for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi))
+ {
+ tree arg;
+ use_operand_p arg_p;
+
+ /* Skip PHI nodes that are not marked for rewrite. */
+ if (!REWRITE_THIS_STMT (phi))
+ continue;
+
+ arg_p = PHI_ARG_DEF_PTR_FROM_EDGE (phi, e);
+ arg = USE_FROM_PTR (arg_p);
+
+ if (arg && !DECL_P (arg) && TREE_CODE (arg) != SSA_NAME)
+ continue;
+
+ if (arg == NULL_TREE)
+ {
+ /* When updating a PHI node for a recently introduced
+ symbol we may find NULL arguments. That's why we
+ take the symbol from the LHS of the PHI node. */
+ replace_use (arg_p, SSA_NAME_VAR (PHI_RESULT (phi)));
+ }
+ else
+ {
+ tree sym = DECL_P (arg) ? arg : SSA_NAME_VAR (arg);
+
+ if (symbol_marked_for_renaming (sym))
+ replace_use (arg_p, sym);
+ else if (is_old_name (arg))
+ replace_use (arg_p, arg);
+ }
+
+ if (e->flags & EDGE_ABNORMAL)
+ SSA_NAME_OCCURS_IN_ABNORMAL_PHI (USE_FROM_PTR (arg_p)) = 1;
+ }
+ }
+}
+
+
+/* Rewrite the actual blocks, statements, and PHI arguments, to be in SSA
+ form.
+
+ ENTRY indicates the block where to start. Every block dominated by
+ ENTRY will be rewritten.
+
+ WHAT indicates what actions will be taken by the renamer (see enum
+ rewrite_mode).
+
+ BLOCKS are the set of interesting blocks for the dominator walker
+ to process. If this set is NULL, then all the nodes dominated
+ by ENTRY are walked. Otherwise, blocks dominated by ENTRY that
+ are not present in BLOCKS are ignored. */
+
+static void
+rewrite_blocks (basic_block entry, enum rewrite_mode what, sbitmap blocks)
+{
+ struct dom_walk_data walk_data;
+
+ /* Rewrite all the basic blocks in the program. */
+ timevar_push (TV_TREE_SSA_REWRITE_BLOCKS);
+
+ /* Setup callbacks for the generic dominator tree walker. */
+ memset (&walk_data, 0, sizeof (walk_data));
+
+ walk_data.dom_direction = CDI_DOMINATORS;
+ walk_data.interesting_blocks = blocks;
+
+ if (what == REWRITE_UPDATE)
+ walk_data.before_dom_children_before_stmts = rewrite_update_init_block;
+ else
+ walk_data.before_dom_children_before_stmts = rewrite_initialize_block;
+
+ if (what == REWRITE_ALL)
+ walk_data.before_dom_children_walk_stmts = rewrite_stmt;
+ else if (what == REWRITE_UPDATE)
+ walk_data.before_dom_children_walk_stmts = rewrite_update_stmt;
+ else
+ gcc_unreachable ();
+
+ if (what == REWRITE_ALL)
+ walk_data.before_dom_children_after_stmts = rewrite_add_phi_arguments;
+ else if (what == REWRITE_UPDATE)
+ walk_data.before_dom_children_after_stmts = rewrite_update_phi_arguments;
+ else
+ gcc_unreachable ();
+
+ if (what == REWRITE_ALL)
+ walk_data.after_dom_children_after_stmts = rewrite_finalize_block;
+ else if (what == REWRITE_UPDATE)
+ walk_data.after_dom_children_after_stmts = rewrite_update_fini_block;
+ else
+ gcc_unreachable ();
+
+ block_defs_stack = VEC_alloc (tree, heap, 10);
+
+ /* Initialize the dominator walker. */
+ init_walk_dominator_tree (&walk_data);
+
+ /* Recursively walk the dominator tree rewriting each statement in
+ each basic block. */
+ walk_dominator_tree (&walk_data, entry);
+
+ /* Finalize the dominator walker. */
+ fini_walk_dominator_tree (&walk_data);
+
+ /* Debugging dumps. */
+ if (dump_file && (dump_flags & TDF_STATS))
+ {
+ dump_dfa_stats (dump_file);
+ if (def_blocks)
+ dump_tree_ssa_stats (dump_file);
+ }
+
+ if (def_blocks)
+ {
+ htab_delete (def_blocks);
+ def_blocks = NULL;
+ }
+
+ VEC_free (tree, heap, block_defs_stack);
+
+ timevar_pop (TV_TREE_SSA_REWRITE_BLOCKS);
+}
-static inline struct def_blocks_d *
-find_def_blocks_for (tree var)
+
+/* Block initialization routine for mark_def_sites. Clear the
+ KILLS bitmap at the start of each block. */
+
+static void
+mark_def_sites_initialize_block (struct dom_walk_data *walk_data,
+ basic_block bb ATTRIBUTE_UNUSED)
{
- struct def_blocks_d dm;
- dm.var = var;
- return (struct def_blocks_d *) htab_find (def_blocks, &dm);
+ struct mark_def_sites_global_data *gd =
+ (struct mark_def_sites_global_data *) walk_data->global_data;
+ bitmap kills = gd->kills;
+ bitmap_clear (kills);
+}
+
+
+/* Mark the definition site blocks for each variable, so that we know
+ where the variable is actually live.
+
+ INTERESTING_BLOCKS will be filled in with all the blocks that
+ should be processed by the renamer. It is assumed to be
+ initialized and zeroed by the caller. */
+
+static void
+mark_def_site_blocks (sbitmap interesting_blocks)
+{
+ struct dom_walk_data walk_data;
+ struct mark_def_sites_global_data mark_def_sites_global_data;
+ referenced_var_iterator rvi;
+ tree var;
+
+ /* Allocate memory for the DEF_BLOCKS hash table. */
+ def_blocks = htab_create (num_referenced_vars,
+ def_blocks_hash, def_blocks_eq, def_blocks_free);
+ FOR_EACH_REFERENCED_VAR(var, rvi)
+ set_current_def (var, NULL_TREE);
+
+ /* Setup callbacks for the generic dominator tree walker to find and
+ mark definition sites. */
+ walk_data.walk_stmts_backward = false;
+ walk_data.dom_direction = CDI_DOMINATORS;
+ walk_data.initialize_block_local_data = NULL;
+ walk_data.before_dom_children_before_stmts = mark_def_sites_initialize_block;
+ walk_data.before_dom_children_walk_stmts = mark_def_sites;
+ walk_data.before_dom_children_after_stmts = NULL;
+ walk_data.after_dom_children_before_stmts = NULL;
+ walk_data.after_dom_children_walk_stmts = NULL;
+ walk_data.after_dom_children_after_stmts = NULL;
+ walk_data.interesting_blocks = NULL;
+
+ /* Notice that this bitmap is indexed using variable UIDs, so it must be
+ large enough to accommodate all the variables referenced in the
+ function, not just the ones we are renaming. */
+ mark_def_sites_global_data.kills = BITMAP_ALLOC (NULL);
+
+ /* Create the set of interesting blocks that will be filled by
+ mark_def_sites. */
+ mark_def_sites_global_data.interesting_blocks = interesting_blocks;
+ walk_data.global_data = &mark_def_sites_global_data;
+
+ /* We do not have any local data. */
+ walk_data.block_local_data_size = 0;
+
+ /* Initialize the dominator walker. */
+ init_walk_dominator_tree (&walk_data);
+
+ /* Recursively walk the dominator tree. */
+ walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR);
+
+ /* Finalize the dominator walker. */
+ fini_walk_dominator_tree (&walk_data);
+
+ /* We no longer need this bitmap, clear and free it. */
+ BITMAP_FREE (mark_def_sites_global_data.kills);
+}
+
+
+/* Main entry point into the SSA builder. The renaming process
+ proceeds in four main phases:
+
+ 1- Compute dominance frontier and immediate dominators, needed to
+ insert PHI nodes and rename the function in dominator tree
+ order.
+
+ 2- Find and mark all the blocks that define variables
+ (mark_def_site_blocks).
+
+ 3- Insert PHI nodes at dominance frontiers (insert_phi_nodes).
+
+ 4- Rename all the blocks (rewrite_blocks) and statements in the program.
+
+ Steps 3 and 4 are done using the dominator tree walker
+ (walk_dominator_tree). */
+
+static void
+rewrite_into_ssa (void)
+{
+ bitmap *dfs;
+ basic_block bb;
+ sbitmap interesting_blocks;
+
+ timevar_push (TV_TREE_SSA_OTHER);
+
+ /* Initialize operand data structures. */
+ init_ssa_operands ();
+
+ /* Initialize the set of interesting blocks. The callback
+ mark_def_sites will add to this set those blocks that the renamer
+ should process. */
+ interesting_blocks = sbitmap_alloc (last_basic_block);
+ sbitmap_zero (interesting_blocks);
+
+ /* Initialize dominance frontier. */
+ dfs = (bitmap *) xmalloc (last_basic_block * sizeof (bitmap));
+ FOR_EACH_BB (bb)
+ dfs[bb->index] = BITMAP_ALLOC (NULL);
+
+ /* 1- Compute dominance frontiers. */
+ calculate_dominance_info (CDI_DOMINATORS);
+ compute_dominance_frontiers (dfs);
+
+ /* 2- Find and mark definition sites. */
+ mark_def_site_blocks (interesting_blocks);
+
+ /* 3- Insert PHI nodes at dominance frontiers of definition blocks. */
+ insert_phi_nodes (dfs);
+
+ /* 4- Rename all the blocks. */
+ rewrite_blocks (ENTRY_BLOCK_PTR, REWRITE_ALL, interesting_blocks);
+
+ /* Free allocated memory. */
+ FOR_EACH_BB (bb)
+ BITMAP_FREE (dfs[bb->index]);
+ free (dfs);
+ sbitmap_free (interesting_blocks);
+
+ timevar_pop (TV_TREE_SSA_OTHER);
+ in_ssa_p = true;
+}
+
+
+struct tree_opt_pass pass_build_ssa =
+{
+ "ssa", /* name */
+ NULL, /* gate */
+ rewrite_into_ssa, /* execute */
+ NULL, /* sub */
+ NULL, /* next */
+ 0, /* static_pass_number */
+ 0, /* tv_id */
+ PROP_cfg | PROP_referenced_vars, /* properties_required */
+ PROP_ssa, /* properties_provided */
+ 0, /* properties_destroyed */
+ 0, /* todo_flags_start */
+ TODO_dump_func
+ | TODO_verify_ssa
+ | TODO_remove_unused_locals, /* todo_flags_finish */
+ 0 /* letter */
+};
+
+
+/* Mark the definition of VAR at STMT and BB as interesting for the
+ renamer. BLOCKS is the set of blocks that need updating. */
+
+static void
+mark_def_interesting (tree var, tree stmt, basic_block bb, bitmap blocks,
+ bool insert_phi_p)
+{
+ REGISTER_DEFS_IN_THIS_STMT (stmt) = 1;
+ bitmap_set_bit (blocks, bb->index);
+
+ if (insert_phi_p)
+ {
+ bool is_phi_p = TREE_CODE (stmt) == PHI_NODE;
+
+ set_def_block (var, bb, is_phi_p);
+
+ /* If VAR is an SSA name in NEW_SSA_NAMES, this is a definition
+ site for both itself and all the old names replaced by it. */
+ if (TREE_CODE (var) == SSA_NAME && is_new_name (var))
+ {
+ bitmap_iterator bi;
+ unsigned i;
+ bitmap set = names_replaced_by (var);
+ if (set)
+ EXECUTE_IF_SET_IN_BITMAP (set, 0, i, bi)
+ set_def_block (ssa_name (i), bb, is_phi_p);
+ }
+ }
+}
+
+
+/* Mark the use of VAR at STMT and BB as interesting for the
+ renamer. INSERT_PHI_P is true if we are going to insert new PHI
+ nodes. BLOCKS is the set of blocks that need updating. */
+
+static inline void
+mark_use_interesting (tree var, tree stmt, basic_block bb, bitmap blocks,
+ bool insert_phi_p)
+{
+ REWRITE_THIS_STMT (stmt) = 1;
+ bitmap_set_bit (blocks, bb->index);
+
+ /* If VAR has not been defined in BB, then it is live-on-entry
+ to BB. Note that we cannot just use the block holding VAR's
+ definition because if VAR is one of the names in OLD_SSA_NAMES,
+ it will have several definitions (itself and all the names that
+ replace it). */
+ if (insert_phi_p)
+ {
+ struct def_blocks_d *db_p = get_def_blocks_for (var);
+ if (!bitmap_bit_p (db_p->def_blocks, bb->index))
+ set_livein_block (var, bb);
+ }
+}
+
+
+/* Do a dominator walk starting at BB processing statements that
+ reference symbols in SYMS_TO_RENAME. This is very similar to
+ mark_def_sites, but the scan handles statements whose operands may
+ already be SSA names. Blocks that contain defs or uses of symbols
+ in SYMS_TO_RENAME are added to BLOCKS.
+
+ If INSERT_PHI_P is true, mark those uses as live in the
+ corresponding block. This is later used by the PHI placement
+ algorithm to make PHI pruning decisions. */
+
+static void
+prepare_block_for_update (basic_block bb, bitmap blocks, bool insert_phi_p)
+{
+ basic_block son;
+ block_stmt_iterator si;
+ tree phi;
+
+ /* Process PHI nodes marking interesting those that define or use
+ the symbols that we are interested in. */
+ for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
+ {
+ tree lhs_sym, lhs = PHI_RESULT (phi);
+
+ lhs_sym = DECL_P (lhs) ? lhs : SSA_NAME_VAR (lhs);
+
+ if (symbol_marked_for_renaming (lhs_sym))
+ {
+ mark_use_interesting (lhs_sym, phi, bb, blocks, insert_phi_p);
+ mark_def_interesting (lhs_sym, phi, bb, blocks, insert_phi_p);
+ }
+ }
+
+ /* Process the statements. */
+ for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
+ {
+ tree stmt;
+ ssa_op_iter i;
+ use_operand_p use_p;
+ def_operand_p def_p;
+
+ stmt = bsi_stmt (si);
+
+ FOR_EACH_SSA_USE_OPERAND (use_p, stmt, i, SSA_OP_USE)
+ {
+ tree use = USE_FROM_PTR (use_p);
+ tree sym = DECL_P (use) ? use : SSA_NAME_VAR (use);
+ if (symbol_marked_for_renaming (sym))
+ mark_use_interesting (use, stmt, bb, blocks, insert_phi_p);
+ }
+
+ FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, i, SSA_OP_DEF)
+ {
+ tree def = DEF_FROM_PTR (def_p);
+ tree sym = DECL_P (def) ? def : SSA_NAME_VAR (def);
+
+ if (symbol_marked_for_renaming (sym))
+ mark_def_interesting (def, stmt, bb, blocks, insert_phi_p);
+ }
+
+ FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, i, SSA_OP_VIRTUAL_DEFS)
+ {
+ tree def = DEF_FROM_PTR (def_p);
+ tree sym = DECL_P (def) ? def : SSA_NAME_VAR (def);
+
+ if (symbol_marked_for_renaming (sym))
+ {
+ mark_use_interesting (sym, stmt, bb, blocks, insert_phi_p);
+ mark_def_interesting (sym, stmt, bb, blocks, insert_phi_p);
+ }
+ }
+
+ FOR_EACH_SSA_USE_OPERAND (use_p, stmt, i, SSA_OP_VUSE)
+ {
+ tree use = USE_FROM_PTR (use_p);
+ tree sym = DECL_P (use) ? use : SSA_NAME_VAR (use);
+
+ if (symbol_marked_for_renaming (sym))
+ mark_use_interesting (sym, stmt, bb, blocks, insert_phi_p);
+ }
+ }
+
+ /* Now visit all the blocks dominated by BB. */
+ for (son = first_dom_son (CDI_DOMINATORS, bb);
+ son;
+ son = next_dom_son (CDI_DOMINATORS, son))
+ prepare_block_for_update (son, blocks, insert_phi_p);
+}
+
+
+/* Helper for prepare_names_to_update. Mark all the use sites for
+ NAME as interesting. BLOCKS and INSERT_PHI_P are as in
+ prepare_names_to_update. */
+
+static void
+prepare_use_sites_for (tree name, bitmap blocks, bool insert_phi_p)
+{
+ use_operand_p use_p;
+ imm_use_iterator iter;
+
+ FOR_EACH_IMM_USE_FAST (use_p, iter, name)
+ {
+ tree stmt = USE_STMT (use_p);
+ basic_block bb = bb_for_stmt (stmt);
+
+ if (TREE_CODE (stmt) == PHI_NODE)
+ {
+ /* Mark this use of NAME interesting for the renamer.
+ Notice that we explicitly call mark_use_interesting with
+ INSERT_PHI_P == false.
+
+ This is to avoid marking NAME as live-in in this block
+ BB. If we were to mark NAME live-in to BB, then NAME
+ would be considered live-in through ALL incoming edges to
+ BB which is not what we want. Since we are updating the
+ SSA form for NAME, we don't really know what other names
+ of NAME are coming in through other edges into BB.
+
+ If we considered NAME live-in at BB, then the PHI
+ placement algorithm may try to insert PHI nodes in blocks
+ that are not only unnecessary but also the renamer would
+ not know how to fill in. */
+ mark_use_interesting (name, stmt, bb, blocks, false);
+
+ /* As discussed above, we only want to mark NAME live-in
+ through the edge corresponding to its slot inside the PHI
+ argument list. So, we look for the block BB1 where NAME
+ is flowing through. If BB1 does not contain a definition
+ of NAME, then consider NAME live-in at BB1. */
+ if (insert_phi_p)
+ {
+ int ix = PHI_ARG_INDEX_FROM_USE (use_p);
+ edge e = PHI_ARG_EDGE (stmt, ix);
+ basic_block bb1 = e->src;
+ struct def_blocks_d *db = get_def_blocks_for (name);
+
+ if (!bitmap_bit_p (db->def_blocks, bb1->index))
+ set_livein_block (name, bb1);
+ }
+ }
+ else
+ {
+ /* For regular statements, mark this as an interesting use
+ for NAME. */
+ mark_use_interesting (name, stmt, bb, blocks, insert_phi_p);
+ }
+ }
+}
+
+
+/* Helper for prepare_names_to_update. Mark the definition site for
+ NAME as interesting. BLOCKS and INSERT_PHI_P are as in
+ prepare_names_to_update. */
+
+static void
+prepare_def_site_for (tree name, bitmap blocks, bool insert_phi_p)
+{
+ tree stmt;
+ basic_block bb;
+
+ gcc_assert (names_to_release == NULL
+ || !bitmap_bit_p (names_to_release, SSA_NAME_VERSION (name)));
+
+ stmt = SSA_NAME_DEF_STMT (name);
+ bb = bb_for_stmt (stmt);
+ if (bb)
+ {
+ gcc_assert (bb->index < last_basic_block);
+ mark_def_interesting (name, stmt, bb, blocks, insert_phi_p);
+ }
+}
+
+
+/* Mark definition and use sites of names in NEW_SSA_NAMES and
+ OLD_SSA_NAMES. Add each definition block to BLOCKS. INSERT_PHI_P
+ is true if the caller wants to insert PHI nodes for newly created
+ names. */
+
+static void
+prepare_names_to_update (bitmap blocks, bool insert_phi_p)
+{
+ unsigned i = 0;
+ bitmap_iterator bi;
+ sbitmap_iterator sbi;
+
+ /* If a name N from NEW_SSA_NAMES is also marked to be released,
+ remove it from NEW_SSA_NAMES so that we don't try to visit its
+ defining basic block (which most likely doesn't exist). Notice
+ that we cannot do the same with names in OLD_SSA_NAMES because we
+ want to replace existing instances. */
+ if (names_to_release)
+ EXECUTE_IF_SET_IN_BITMAP (names_to_release, 0, i, bi)
+ RESET_BIT (new_ssa_names, i);
+
+ /* First process names in NEW_SSA_NAMES. Otherwise, uses of old
+ names may be considered to be live-in on blocks that contain
+ definitions for their replacements. */
+ EXECUTE_IF_SET_IN_SBITMAP (new_ssa_names, 0, i, sbi)
+ prepare_def_site_for (ssa_name (i), blocks, insert_phi_p);
+
+ /* If an old name is in NAMES_TO_RELEASE, we cannot remove it from
+ OLD_SSA_NAMES, but we have to ignore its definition site. */
+ EXECUTE_IF_SET_IN_SBITMAP (old_ssa_names, 0, i, sbi)
+ {
+ if (names_to_release == NULL || !bitmap_bit_p (names_to_release, i))
+ prepare_def_site_for (ssa_name (i), blocks, insert_phi_p);
+ prepare_use_sites_for (ssa_name (i), blocks, insert_phi_p);
+ }
+}
+
+
+/* Dump all the names replaced by NAME to FILE. */
+
+void
+dump_names_replaced_by (FILE *file, tree name)
+{
+ unsigned i;
+ bitmap old_set;
+ bitmap_iterator bi;
+
+ print_generic_expr (file, name, 0);
+ fprintf (file, " -> { ");
+
+ old_set = names_replaced_by (name);
+ EXECUTE_IF_SET_IN_BITMAP (old_set, 0, i, bi)
+ {
+ print_generic_expr (file, ssa_name (i), 0);
+ fprintf (file, " ");
+ }
+
+ fprintf (file, "}\n");
+}
+
+
+/* Dump all the names replaced by NAME to stderr. */
+
+void
+debug_names_replaced_by (tree name)
+{
+ dump_names_replaced_by (stderr, name);
+}
+
+
+/* Dump SSA update information to FILE. */
+
+void
+dump_update_ssa (FILE *file)
+{
+ unsigned i = 0;
+ bitmap_iterator bi;
+
+ if (!need_ssa_update_p ())
+ return;
+
+ if (new_ssa_names && sbitmap_first_set_bit (new_ssa_names) >= 0)
+ {
+ sbitmap_iterator sbi;
+
+ fprintf (file, "\nSSA replacement table\n");
+ fprintf (file, "N_i -> { O_1 ... O_j } means that N_i replaces "
+ "O_1, ..., O_j\n\n");
+
+ EXECUTE_IF_SET_IN_SBITMAP (new_ssa_names, 0, i, sbi)
+ dump_names_replaced_by (file, ssa_name (i));
+
+ fprintf (file, "\n");
+ fprintf (file, "Number of virtual NEW -> OLD mappings: %7u\n",
+ update_ssa_stats.num_virtual_mappings);
+ fprintf (file, "Number of real NEW -> OLD mappings: %7u\n",
+ update_ssa_stats.num_total_mappings
+ - update_ssa_stats.num_virtual_mappings);
+ fprintf (file, "Number of total NEW -> OLD mappings: %7u\n",
+ update_ssa_stats.num_total_mappings);
+
+ fprintf (file, "\nNumber of virtual symbols: %u\n",
+ update_ssa_stats.num_virtual_symbols);
+ }
+
+ if (syms_to_rename && !bitmap_empty_p (syms_to_rename))
+ {
+ fprintf (file, "\n\nSymbols to be put in SSA form\n\n");
+ EXECUTE_IF_SET_IN_BITMAP (syms_to_rename, 0, i, bi)
+ {
+ print_generic_expr (file, referenced_var (i), 0);
+ fprintf (file, " ");
+ }
+ }
+
+ if (names_to_release && !bitmap_empty_p (names_to_release))
+ {
+ fprintf (file, "\n\nSSA names to release after updating the SSA web\n\n");
+ EXECUTE_IF_SET_IN_BITMAP (names_to_release, 0, i, bi)
+ {
+ print_generic_expr (file, ssa_name (i), 0);
+ fprintf (file, " ");
+ }
+ }
+
+ fprintf (file, "\n\n");
+}
+
+
+/* Dump SSA update information to stderr. */
+
+void
+debug_update_ssa (void)
+{
+ dump_update_ssa (stderr);
+}
+
+
+/* Initialize data structures used for incremental SSA updates. */
+
+static void
+init_update_ssa (void)
+{
+ /* Reserve more space than the current number of names. The calls to
+ add_new_name_mapping are typically done after creating new SSA
+ names, so we'll need to reallocate these arrays. */
+ old_ssa_names = sbitmap_alloc (num_ssa_names + NAME_SETS_GROWTH_FACTOR);
+ sbitmap_zero (old_ssa_names);
+
+ new_ssa_names = sbitmap_alloc (num_ssa_names + NAME_SETS_GROWTH_FACTOR);
+ sbitmap_zero (new_ssa_names);
+
+ repl_tbl = htab_create (20, repl_map_hash, repl_map_eq, repl_map_free);
+ need_to_initialize_update_ssa_p = false;
+ need_to_update_vops_p = false;
+ syms_to_rename = BITMAP_ALLOC (NULL);
+ names_to_release = NULL;
+ memset (&update_ssa_stats, 0, sizeof (update_ssa_stats));
+ update_ssa_stats.virtual_symbols = BITMAP_ALLOC (NULL);
}
-/* Return the set of blocks where variable VAR is defined and the blocks
- where VAR is live on entry (livein). If no entry is found in
- DEF_BLOCKS, a new one is created and returned. */
+/* Deallocate data structures used for incremental SSA updates. */
-static inline struct def_blocks_d *
-get_def_blocks_for (tree var)
+void
+delete_update_ssa (void)
{
- struct def_blocks_d db, *db_p;
- void **slot;
+ unsigned i;
+ bitmap_iterator bi;
- db.var = var;
- slot = htab_find_slot (def_blocks, (void *) &db, INSERT);
- if (*slot == NULL)
+ sbitmap_free (old_ssa_names);
+ old_ssa_names = NULL;
+
+ sbitmap_free (new_ssa_names);
+ new_ssa_names = NULL;
+
+ htab_delete (repl_tbl);
+ repl_tbl = NULL;
+
+ need_to_initialize_update_ssa_p = true;
+ need_to_update_vops_p = false;
+ BITMAP_FREE (syms_to_rename);
+ BITMAP_FREE (update_ssa_stats.virtual_symbols);
+
+ if (names_to_release)
{
- db_p = xmalloc (sizeof (*db_p));
- db_p->var = var;
- db_p->def_blocks = BITMAP_XMALLOC ();
- db_p->livein_blocks = BITMAP_XMALLOC ();
- *slot = (void *) db_p;
+ EXECUTE_IF_SET_IN_BITMAP (names_to_release, 0, i, bi)
+ release_ssa_name (ssa_name (i));
+ BITMAP_FREE (names_to_release);
}
- else
- db_p = (struct def_blocks_d *) *slot;
- return db_p;
-}
+ for (i = 1; i < num_ssa_names; i++)
+ {
+ tree n = ssa_name (i);
-/* If a variable V in VARS_TO_RENAME is a pointer, the renaming
- process will cause us to lose the name memory tags that may have
- been associated with the various SSA_NAMEs of V. This means that
- the variables aliased to those name tags also need to be renamed
- again.
+ if (n)
+ {
+ free (SSA_NAME_AUX (n));
+ SSA_NAME_AUX (n) = NULL;
+ }
+ }
+}
- FIXME 1- We should either have a better scheme for renaming
- pointers that doesn't lose name tags or re-run alias
- analysis to recover points-to information.
- 2- Currently we just invalidate *all* the name tags. This
- should be more selective. */
+/* Create a new name for OLD_NAME in statement STMT and replace the
+ operand pointed to by DEF_P with the newly created name. Return
+ the new name and register the replacement mapping <NEW, OLD> in
+ update_ssa's tables. */
-static void
-invalidate_name_tags (bitmap vars_to_rename)
+tree
+create_new_def_for (tree old_name, tree stmt, def_operand_p def)
{
- size_t i;
- bool rename_name_tags_p;
+ tree new_name = duplicate_ssa_name (old_name, stmt);
- rename_name_tags_p = false;
- EXECUTE_IF_SET_IN_BITMAP (vars_to_rename, 0, i,
- if (POINTER_TYPE_P (TREE_TYPE (referenced_var (i))))
- {
- rename_name_tags_p = true;
- break;
- });
+ SET_DEF (def, new_name);
- if (rename_name_tags_p)
- for (i = 0; i < num_referenced_vars; i++)
- {
- var_ann_t ann = var_ann (referenced_var (i));
+ if (TREE_CODE (stmt) == PHI_NODE)
+ {
+ edge e;
+ edge_iterator ei;
+ basic_block bb = bb_for_stmt (stmt);
- if (ann->mem_tag_kind == NAME_TAG)
+ /* If needed, mark NEW_NAME as occurring in an abnormal PHI node. */
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ if (e->flags & EDGE_ABNORMAL)
{
- size_t j;
- varray_type may_aliases = ann->may_aliases;
-
- bitmap_set_bit (vars_to_rename, ann->uid);
- if (ann->may_aliases)
- for (j = 0; j < VARRAY_ACTIVE_SIZE (may_aliases); j++)
- {
- tree var = VARRAY_TREE (may_aliases, j);
- bitmap_set_bit (vars_to_rename, var_ann (var)->uid);
- }
+ SSA_NAME_OCCURS_IN_ABNORMAL_PHI (new_name) = 1;
+ break;
}
- }
+ }
+
+ register_new_name_mapping (new_name, old_name);
+
+ /* For the benefit of passes that will be updating the SSA form on
+ their own, set the current reaching definition of OLD_NAME to be
+ NEW_NAME. */
+ set_current_def (old_name, new_name);
+
+ return new_name;
}
-/* Main entry point into the SSA builder. The renaming process
- proceeds in five main phases:
+/* Register name NEW to be a replacement for name OLD. This function
+ must be called for every replacement that should be performed by
+ update_ssa. */
+
+void
+register_new_name_mapping (tree new, tree old)
+{
+ if (need_to_initialize_update_ssa_p)
+ init_update_ssa ();
- 1- If VARS_TO_RENAME has any entries, any existing PHI nodes for
- those variables are removed from the flow graph so that they can
- be computed again.
+ add_new_name_mapping (new, old);
+}
- 2- Compute dominance frontier and immediate dominators, needed to
- insert PHI nodes and rename the function in dominator tree
- order.
- 3- Find and mark all the blocks that define variables
- (mark_def_sites).
+/* Register symbol SYM to be renamed by update_ssa. */
- 4- Insert PHI nodes at dominance frontiers (insert_phi_nodes).
+void
+mark_sym_for_renaming (tree sym)
+{
+ if (need_to_initialize_update_ssa_p)
+ init_update_ssa ();
- 5- Rename all the blocks (rewrite_initialize_block,
- rewrite_add_phi_arguments) and statements in the program
- (rewrite_stmt).
+ bitmap_set_bit (syms_to_rename, DECL_UID (sym));
+
+ if (!is_gimple_reg (sym))
+ need_to_update_vops_p = true;
+}
- Steps 3 and 5 are done using the dominator tree walker
- (walk_dominator_tree). */
+
+/* Register all the symbols in SET to be renamed by update_ssa. */
void
-rewrite_into_ssa (void)
+mark_set_for_renaming (bitmap set)
{
- bitmap *dfs;
- basic_block bb;
- struct dom_walk_data walk_data;
- struct mark_def_sites_global_data mark_def_sites_global_data;
- unsigned int i;
+ bitmap_iterator bi;
+ unsigned i;
+
+ if (bitmap_empty_p (set))
+ return;
+
+ if (need_to_initialize_update_ssa_p)
+ init_update_ssa ();
+
+ bitmap_ior_into (syms_to_rename, set);
+
+ EXECUTE_IF_SET_IN_BITMAP (set, 0, i, bi)
+ if (!is_gimple_reg (referenced_var (i)))
+ {
+ need_to_update_vops_p = true;
+ break;
+ }
+}
+
+
+/* Return true if there is any work to be done by update_ssa. */
+
+bool
+need_ssa_update_p (void)
+{
+ return syms_to_rename || old_ssa_names || new_ssa_names;
+}
+
+
+/* Return true if name N has been registered in the replacement table. */
+
+bool
+name_registered_for_update_p (tree n)
+{
+ if (!need_ssa_update_p ())
+ return false;
+
+ return is_new_name (n)
+ || is_old_name (n)
+ || symbol_marked_for_renaming (SSA_NAME_VAR (n));
+}
+
+
+/* Return the set of all the SSA names marked to be replaced. */
+
+bitmap
+ssa_names_to_replace (void)
+{
+ unsigned i = 0;
+ bitmap ret;
+ sbitmap_iterator sbi;
- timevar_push (TV_TREE_SSA_OTHER);
+ ret = BITMAP_ALLOC (NULL);
+ EXECUTE_IF_SET_IN_SBITMAP (old_ssa_names, 0, i, sbi)
+ bitmap_set_bit (ret, i);
+
+ return ret;
+}
+
+
+/* Mark NAME to be released after update_ssa has finished. */
+
+void
+release_ssa_name_after_update_ssa (tree name)
+{
+ gcc_assert (!need_to_initialize_update_ssa_p);
+
+ if (names_to_release == NULL)
+ names_to_release = BITMAP_ALLOC (NULL);
+
+ bitmap_set_bit (names_to_release, SSA_NAME_VERSION (name));
+}
+
+
+/* Insert new PHI nodes to replace VAR. DFS contains dominance
+ frontier information. BLOCKS is the set of blocks to be updated.
+
+ This is slightly different than the regular PHI insertion
+ algorithm. The value of UPDATE_FLAGS controls how PHI nodes for
+ real names (i.e., GIMPLE registers) are inserted:
+
+ - If UPDATE_FLAGS == TODO_update_ssa, we are only interested in PHI
+ nodes inside the region affected by the block that defines VAR
+ and the blocks that define all its replacements. All these
+ definition blocks are stored in DEF_BLOCKS[VAR]->DEF_BLOCKS.
+
+ First, we compute the entry point to the region (ENTRY). This is
+ given by the nearest common dominator to all the definition
+ blocks. When computing the iterated dominance frontier (IDF), any
+ block not strictly dominated by ENTRY is ignored.
+
+ We then call the standard PHI insertion algorithm with the pruned
+ IDF.
- /* Initialize the array of variables to rename. */
- if (vars_to_rename != NULL)
+ - If UPDATE_FLAGS == TODO_update_ssa_full_phi, the IDF for real
+ names is not pruned. PHI nodes are inserted at every IDF block. */
+
+static void
+insert_updated_phi_nodes_for (tree var, bitmap *dfs, bitmap blocks,
+ unsigned update_flags)
+{
+ basic_block entry;
+ struct def_blocks_d *db;
+ bitmap idf, pruned_idf;
+ bitmap_iterator bi;
+ unsigned i;
+
+#if defined ENABLE_CHECKING
+ if (TREE_CODE (var) == SSA_NAME)
+ gcc_assert (is_old_name (var));
+ else
+ gcc_assert (symbol_marked_for_renaming (var));
+#endif
+
+ /* Get all the definition sites for VAR. */
+ db = find_def_blocks_for (var);
+
+ /* No need to do anything if there were no definitions to VAR. */
+ if (db == NULL || bitmap_empty_p (db->def_blocks))
+ return;
+
+ /* Compute the initial iterated dominance frontier. */
+ idf = find_idf (db->def_blocks, dfs);
+ pruned_idf = BITMAP_ALLOC (NULL);
+
+ if (TREE_CODE (var) == SSA_NAME)
+ {
+ if (update_flags == TODO_update_ssa)
+ {
+ /* If doing regular SSA updates for GIMPLE registers, we are
+ only interested in IDF blocks dominated by the nearest
+ common dominator of all the definition blocks. */
+ entry = nearest_common_dominator_for_set (CDI_DOMINATORS,
+ db->def_blocks);
+
+ if (entry != ENTRY_BLOCK_PTR)
+ EXECUTE_IF_SET_IN_BITMAP (idf, 0, i, bi)
+ if (BASIC_BLOCK (i) != entry
+ && dominated_by_p (CDI_DOMINATORS, BASIC_BLOCK (i), entry))
+ bitmap_set_bit (pruned_idf, i);
+ }
+ else
+ {
+ /* Otherwise, do not prune the IDF for VAR. */
+ gcc_assert (update_flags == TODO_update_ssa_full_phi);
+ bitmap_copy (pruned_idf, idf);
+ }
+ }
+ else
{
- invalidate_name_tags (vars_to_rename);
+ /* Otherwise, VAR is a symbol that needs to be put into SSA form
+ for the first time, so we need to compute the full IDF for
+ it. */
+ bitmap_copy (pruned_idf, idf);
+ }
+
+ if (!bitmap_empty_p (pruned_idf))
+ {
+ /* Make sure that PRUNED_IDF blocks and all their feeding blocks
+ are included in the region to be updated. The feeding blocks
+ are important to guarantee that the PHI arguments are renamed
+ properly. */
+ bitmap_ior_into (blocks, pruned_idf);
+ EXECUTE_IF_SET_IN_BITMAP (pruned_idf, 0, i, bi)
+ {
+ edge e;
+ edge_iterator ei;
+ basic_block bb = BASIC_BLOCK (i);
- /* Now remove all the existing PHI nodes (if any) for the variables
- that we are about to rename into SSA. */
- remove_all_phi_nodes_for (vars_to_rename);
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ if (e->src->index >= 0)
+ bitmap_set_bit (blocks, e->src->index);
+ }
+
+ insert_phi_nodes_for (var, pruned_idf, true);
}
- /* Allocate memory for the DEF_BLOCKS hash table. */
- def_blocks = htab_create (VARRAY_ACTIVE_SIZE (referenced_vars),
- def_blocks_hash, def_blocks_eq, def_blocks_free);
+ BITMAP_FREE (pruned_idf);
+ BITMAP_FREE (idf);
+}
- /* Initialize dominance frontier and immediate dominator bitmaps.
- Also count the number of predecessors for each block. Doing so
- can save significant time during PHI insertion for large graphs. */
- dfs = (bitmap *) xmalloc (last_basic_block * sizeof (bitmap *));
- FOR_EACH_BB (bb)
- {
- edge e;
- int count = 0;
- for (e = bb->pred; e; e = e->pred_next)
- count++;
+/* Heuristic to determine whether SSA name mappings for virtual names
+ should be discarded and their symbols rewritten from scratch. When
+ there is a large number of mappings for virtual names, the
+ insertion of PHI nodes for the old names in the mappings takes
+ considerable more time than if we inserted PHI nodes for the
+ symbols instead.
- bb_ann (bb)->num_preds = count;
- dfs[bb->index] = BITMAP_XMALLOC ();
+ Currently the heuristic takes these stats into account:
+
+ - Number of mappings for virtual SSA names.
+ - Number of distinct virtual symbols involved in those mappings.
+
+ If the number of virtual mappings is much larger than the number of
+ virtual symbols, then it will be faster to compute PHI insertion
+ spots for the symbols. Even if this involves traversing the whole
+ CFG, which is what happens when symbols are renamed from scratch. */
+
+static bool
+switch_virtuals_to_full_rewrite_p (void)
+{
+ if (update_ssa_stats.num_virtual_mappings < (unsigned) MIN_VIRTUAL_MAPPINGS)
+ return false;
+
+ if (update_ssa_stats.num_virtual_mappings
+ > (unsigned) VIRTUAL_MAPPINGS_TO_SYMS_RATIO
+ * update_ssa_stats.num_virtual_symbols)
+ return true;
+
+ return false;
+}
+
+
+/* Remove every virtual mapping and mark all the affected virtual
+ symbols for renaming. */
+
+static void
+switch_virtuals_to_full_rewrite (void)
+{
+ unsigned i = 0;
+ sbitmap_iterator sbi;
+
+ if (dump_file)
+ {
+ fprintf (dump_file, "\nEnabled virtual name mapping heuristic.\n");
+ fprintf (dump_file, "\tNumber of virtual mappings: %7u\n",
+ update_ssa_stats.num_virtual_mappings);
+ fprintf (dump_file, "\tNumber of unique virtual symbols: %7u\n",
+ update_ssa_stats.num_virtual_symbols);
+ fprintf (dump_file, "Updating FUD-chains from top of CFG will be "
+ "faster than processing\nthe name mappings.\n\n");
}
- for (i = 0; i < num_referenced_vars; i++)
- var_ann (referenced_var (i))->current_def = NULL;
+ /* Remove all virtual names from NEW_SSA_NAMES and OLD_SSA_NAMES.
+ Note that it is not really necessary to remove the mappings from
+ REPL_TBL, that would only waste time. */
+ EXECUTE_IF_SET_IN_SBITMAP (new_ssa_names, 0, i, sbi)
+ if (!is_gimple_reg (ssa_name (i)))
+ RESET_BIT (new_ssa_names, i);
- /* Ensure that the dominance information is OK. */
+ EXECUTE_IF_SET_IN_SBITMAP (old_ssa_names, 0, i, sbi)
+ if (!is_gimple_reg (ssa_name (i)))
+ RESET_BIT (old_ssa_names, i);
+
+ bitmap_ior_into (syms_to_rename, update_ssa_stats.virtual_symbols);
+}
+
+
+/* Given a set of newly created SSA names (NEW_SSA_NAMES) and a set of
+ existing SSA names (OLD_SSA_NAMES), update the SSA form so that:
+
+ 1- The names in OLD_SSA_NAMES dominated by the definitions of
+ NEW_SSA_NAMES are all re-written to be reached by the
+ appropriate definition from NEW_SSA_NAMES.
+
+ 2- If needed, new PHI nodes are added to the iterated dominance
+ frontier of the blocks where each of NEW_SSA_NAMES are defined.
+
+ The mapping between OLD_SSA_NAMES and NEW_SSA_NAMES is setup by
+ calling register_new_name_mapping for every pair of names that the
+ caller wants to replace.
+
+ The caller identifies the new names that have been inserted and the
+ names that need to be replaced by calling register_new_name_mapping
+ for every pair <NEW, OLD>. Note that the function assumes that the
+ new names have already been inserted in the IL.
+
+ For instance, given the following code:
+
+ 1 L0:
+ 2 x_1 = PHI (0, x_5)
+ 3 if (x_1 < 10)
+ 4 if (x_1 > 7)
+ 5 y_2 = 0
+ 6 else
+ 7 y_3 = x_1 + x_7
+ 8 endif
+ 9 x_5 = x_1 + 1
+ 10 goto L0;
+ 11 endif
+
+ Suppose that we insert new names x_10 and x_11 (lines 4 and 8).
+
+ 1 L0:
+ 2 x_1 = PHI (0, x_5)
+ 3 if (x_1 < 10)
+ 4 x_10 = ...
+ 5 if (x_1 > 7)
+ 6 y_2 = 0
+ 7 else
+ 8 x_11 = ...
+ 9 y_3 = x_1 + x_7
+ 10 endif
+ 11 x_5 = x_1 + 1
+ 12 goto L0;
+ 13 endif
+
+ We want to replace all the uses of x_1 with the new definitions of
+ x_10 and x_11. Note that the only uses that should be replaced are
+ those at lines 5, 9 and 11. Also, the use of x_7 at line 9 should
+ *not* be replaced (this is why we cannot just mark symbol 'x' for
+ renaming).
+
+ Additionally, we may need to insert a PHI node at line 11 because
+ that is a merge point for x_10 and x_11. So the use of x_1 at line
+ 11 will be replaced with the new PHI node. The insertion of PHI
+ nodes is optional. They are not strictly necessary to preserve the
+ SSA form, and depending on what the caller inserted, they may not
+ even be useful for the optimizers. UPDATE_FLAGS controls various
+ aspects of how update_ssa operates, see the documentation for
+ TODO_update_ssa*. */
+
+void
+update_ssa (unsigned update_flags)
+{
+ bitmap blocks;
+ basic_block bb, start_bb;
+ bitmap_iterator bi;
+ unsigned i = 0;
+ sbitmap tmp;
+ bool insert_phi_p;
+ sbitmap_iterator sbi;
+
+ if (!need_ssa_update_p ())
+ return;
+
+ timevar_push (TV_TREE_SSA_INCREMENTAL);
+
+ /* Ensure that the dominance information is up-to-date. */
calculate_dominance_info (CDI_DOMINATORS);
- /* Compute dominance frontiers. */
- compute_dominance_frontiers (dfs);
+ /* Only one update flag should be set. */
+ gcc_assert (update_flags == TODO_update_ssa
+ || update_flags == TODO_update_ssa_no_phi
+ || update_flags == TODO_update_ssa_full_phi
+ || update_flags == TODO_update_ssa_only_virtuals);
- /* Setup callbacks for the generic dominator tree walker to find and
- mark definition sites. */
- walk_data.walk_stmts_backward = false;
- walk_data.dom_direction = CDI_DOMINATORS;
- walk_data.initialize_block_local_data = NULL;
- walk_data.before_dom_children_before_stmts = mark_def_sites_initialize_block;
- walk_data.before_dom_children_walk_stmts = mark_def_sites;
- walk_data.before_dom_children_after_stmts = NULL;
- walk_data.after_dom_children_before_stmts = NULL;
- walk_data.after_dom_children_walk_stmts = NULL;
- walk_data.after_dom_children_after_stmts = NULL;
+ /* If we only need to update virtuals, remove all the mappings for
+ real names before proceeding. The caller is responsible for
+ having dealt with the name mappings before calling update_ssa. */
+ if (update_flags == TODO_update_ssa_only_virtuals)
+ {
+ sbitmap_zero (old_ssa_names);
+ sbitmap_zero (new_ssa_names);
+ htab_empty (repl_tbl);
+ }
- /* Notice that this bitmap is indexed using variable UIDs, so it must be
- large enough to accommodate all the variables referenced in the
- function, not just the ones we are renaming. */
- mark_def_sites_global_data.kills = sbitmap_alloc (num_referenced_vars);
- walk_data.global_data = &mark_def_sites_global_data;
+ insert_phi_p = (update_flags != TODO_update_ssa_no_phi);
- /* We do not have any local data. */
- walk_data.block_local_data_size = 0;
+ if (insert_phi_p)
+ {
+ /* If the caller requested PHI nodes to be added, initialize
+ live-in information data structures (DEF_BLOCKS). */
+
+ /* For each SSA name N, the DEF_BLOCKS table describes where the
+ name is defined, which blocks have PHI nodes for N, and which
+ blocks have uses of N (i.e., N is live-on-entry in those
+ blocks). */
+ def_blocks = htab_create (num_ssa_names, def_blocks_hash,
+ def_blocks_eq, def_blocks_free);
+ }
+ else
+ {
+ def_blocks = NULL;
+ }
- /* Initialize the dominator walker. */
- init_walk_dominator_tree (&walk_data);
+ blocks = BITMAP_ALLOC (NULL);
- /* Recursively walk the dominator tree. */
- walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR);
+ /* Clear the REWRITE_THIS_STMT and REGISTER_DEFS_IN_THIS_STMT flags
+ for every statement and PHI node. */
+ FOR_EACH_BB (bb)
+ {
+ block_stmt_iterator si;
+ tree phi;
- /* Finalize the dominator walker. */
- fini_walk_dominator_tree (&walk_data);
+ for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
+ {
+ REWRITE_THIS_STMT (phi) = 0;
+ REGISTER_DEFS_IN_THIS_STMT (phi) = 0;
+ }
- /* We no longer need this bitmap, clear and free it. */
- sbitmap_free (mark_def_sites_global_data.kills);
+ for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
+ {
+ tree stmt = bsi_stmt (si);
+ /* We are going to use the operand cache API, such as
+ SET_USE, SET_DEF, and FOR_EACH_IMM_USE_FAST. The operand
+ cache for each statement should be up-to-date. */
+ gcc_assert (!stmt_modified_p (stmt));
+ REWRITE_THIS_STMT (stmt) = 0;
+ REGISTER_DEFS_IN_THIS_STMT (stmt) = 0;
+ }
+ }
- /* Insert PHI nodes at dominance frontiers of definition blocks. */
- insert_phi_nodes (dfs);
+ /* Heuristic to avoid massive slow downs when the replacement
+ mappings include lots of virtual names. */
+ if (insert_phi_p && switch_virtuals_to_full_rewrite_p ())
+ switch_virtuals_to_full_rewrite ();
- /* Rewrite all the basic blocks in the program. */
- timevar_push (TV_TREE_SSA_REWRITE_BLOCKS);
+ /* If there are names defined in the replacement table, prepare
+ definition and use sites for all the names in NEW_SSA_NAMES and
+ OLD_SSA_NAMES. */
+ if (sbitmap_first_set_bit (new_ssa_names) >= 0)
+ {
+ prepare_names_to_update (blocks, insert_phi_p);
+
+ /* If all the names in NEW_SSA_NAMES had been marked for
+ removal, and there are no symbols to rename, then there's
+ nothing else to do. */
+ if (sbitmap_first_set_bit (new_ssa_names) < 0
+ && bitmap_empty_p (syms_to_rename))
+ goto done;
+ }
- /* Setup callbacks for the generic dominator tree walker. */
- walk_data.walk_stmts_backward = false;
- walk_data.dom_direction = CDI_DOMINATORS;
- walk_data.initialize_block_local_data = rewrite_initialize_block_local_data;
- walk_data.before_dom_children_before_stmts = rewrite_initialize_block;
- walk_data.before_dom_children_walk_stmts = rewrite_stmt;
- walk_data.before_dom_children_after_stmts = rewrite_add_phi_arguments;
- walk_data.after_dom_children_before_stmts = NULL;
- walk_data.after_dom_children_walk_stmts = NULL;
- walk_data.after_dom_children_after_stmts = rewrite_finalize_block;
- walk_data.global_data = NULL;
- walk_data.block_local_data_size = sizeof (struct rewrite_block_data);
+ /* Next, determine the block at which to start the renaming process. */
+ if (!bitmap_empty_p (syms_to_rename))
+ {
+ /* If we have to rename some symbols from scratch, we need to
+ start the process at the root of the CFG. FIXME, it should
+ be possible to determine the nearest block that had a
+ definition for each of the symbols that are marked for
+ updating. For now this seems more work than it's worth. */
+ start_bb = ENTRY_BLOCK_PTR;
+
+ /* Traverse the CFG looking for definitions and uses of symbols
+ in SYMS_TO_RENAME. Mark interesting blocks and statements
+ and set local live-in information for the PHI placement
+ heuristics. */
+ prepare_block_for_update (start_bb, blocks, insert_phi_p);
+ }
+ else
+ {
+ /* Otherwise, the entry block to the region is the nearest
+ common dominator for the blocks in BLOCKS. */
+ start_bb = nearest_common_dominator_for_set (CDI_DOMINATORS, blocks);
+ }
- /* Initialize the dominator walker. */
- init_walk_dominator_tree (&walk_data);
+ /* If requested, insert PHI nodes at the iterated dominance frontier
+ of every block, creating new definitions for names in OLD_SSA_NAMES
+ and for symbols in SYMS_TO_RENAME. */
+ if (insert_phi_p)
+ {
+ bitmap *dfs;
- /* Recursively walk the dominator tree rewriting each statement in
- each basic block. */
- walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR);
+ /* If the caller requested PHI nodes to be added, compute
+ dominance frontiers. */
+ dfs = XNEWVEC (bitmap, last_basic_block);
+ FOR_EACH_BB (bb)
+ dfs[bb->index] = BITMAP_ALLOC (NULL);
+ compute_dominance_frontiers (dfs);
- /* Finalize the dominator walker. */
- fini_walk_dominator_tree (&walk_data);
+ if (sbitmap_first_set_bit (old_ssa_names) >= 0)
+ {
+ sbitmap_iterator sbi;
+
+ /* insert_update_phi_nodes_for will call add_new_name_mapping
+ when inserting new PHI nodes, so the set OLD_SSA_NAMES
+ will grow while we are traversing it (but it will not
+ gain any new members). Copy OLD_SSA_NAMES to a temporary
+ for traversal. */
+ sbitmap tmp = sbitmap_alloc (old_ssa_names->n_bits);
+ sbitmap_copy (tmp, old_ssa_names);
+ EXECUTE_IF_SET_IN_SBITMAP (tmp, 0, i, sbi)
+ insert_updated_phi_nodes_for (ssa_name (i), dfs, blocks,
+ update_flags);
+ sbitmap_free (tmp);
+ }
- timevar_pop (TV_TREE_SSA_REWRITE_BLOCKS);
+ EXECUTE_IF_SET_IN_BITMAP (syms_to_rename, 0, i, bi)
+ insert_updated_phi_nodes_for (referenced_var (i), dfs, blocks,
+ update_flags);
+
+ FOR_EACH_BB (bb)
+ BITMAP_FREE (dfs[bb->index]);
+ free (dfs);
+
+ /* Insertion of PHI nodes may have added blocks to the region.
+ We need to re-compute START_BB to include the newly added
+ blocks. */
+ if (start_bb != ENTRY_BLOCK_PTR)
+ start_bb = nearest_common_dominator_for_set (CDI_DOMINATORS, blocks);
+ }
+
+ /* Reset the current definition for name and symbol before renaming
+ the sub-graph. */
+ EXECUTE_IF_SET_IN_SBITMAP (old_ssa_names, 0, i, sbi)
+ set_current_def (ssa_name (i), NULL_TREE);
+
+ EXECUTE_IF_SET_IN_BITMAP (syms_to_rename, 0, i, bi)
+ set_current_def (referenced_var (i), NULL_TREE);
+
+ /* Now start the renaming process at START_BB. */
+ tmp = sbitmap_alloc (last_basic_block);
+ sbitmap_zero (tmp);
+ EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
+ SET_BIT (tmp, i);
+
+ rewrite_blocks (start_bb, REWRITE_UPDATE, tmp);
+
+ sbitmap_free (tmp);
/* Debugging dumps. */
- if (dump_file && (dump_flags & TDF_STATS))
+ if (dump_file)
{
- dump_dfa_stats (dump_file);
- dump_tree_ssa_stats (dump_file);
+ int c;
+ unsigned i;
+
+ dump_update_ssa (dump_file);
+
+ fprintf (dump_file, "Incremental SSA update started at block: %d\n\n",
+ start_bb->index);
+
+ c = 0;
+ EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
+ c++;
+ fprintf (dump_file, "Number of blocks in CFG: %d\n", last_basic_block);
+ fprintf (dump_file, "Number of blocks to update: %d (%3.0f%%)\n\n",
+ c, PERCENT (c, last_basic_block));
+
+ if (dump_flags & TDF_DETAILS)
+ {
+ fprintf (dump_file, "Affected blocks: ");
+ EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
+ fprintf (dump_file, "%u ", i);
+ fprintf (dump_file, "\n");
+ }
+
+ fprintf (dump_file, "\n\n");
}
/* Free allocated memory. */
- FOR_EACH_BB (bb)
- BITMAP_XFREE (dfs[bb->index]);
- free (dfs);
-
- htab_delete (def_blocks);
+done:
+ BITMAP_FREE (blocks);
+ delete_update_ssa ();
- timevar_pop (TV_TREE_SSA_OTHER);
+ timevar_pop (TV_TREE_SSA_INCREMENTAL);
}
-
-struct tree_opt_pass pass_build_ssa =
-{
- "ssa", /* name */
- NULL, /* gate */
- rewrite_into_ssa, /* execute */
- NULL, /* sub */
- NULL, /* next */
- 0, /* static_pass_number */
- 0, /* tv_id */
- PROP_cfg | PROP_referenced_vars, /* properties_required */
- PROP_ssa, /* properties_provided */
- 0, /* properties_destroyed */
- 0, /* todo_flags_start */
- TODO_dump_func | TODO_verify_ssa /* todo_flags_finish */
-};
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