/* Rewrite a program in Normal form into SSA.
- Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
+ Copyright (C) 2001, 2002, 2003, 2004, 2005, 2007, 2008, 2009
+ Free Software Foundation, Inc.
Contributed by Diego Novillo <dnovillo@redhat.com>
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2, or (at your option)
+the Free Software Foundation; either version 3, or (at your option)
any later version.
GCC is distributed in the hope that it will be useful,
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
-along with GCC; see the file COPYING. If not, write to
-the Free Software Foundation, 59 Temple Place - Suite 330,
-Boston, MA 02111-1307, USA. */
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
#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-gimple.h"
+#include "gimple.h"
#include "tree-inline.h"
#include "varray.h"
#include "timevar.h"
#include "domwalk.h"
#include "ggc.h"
#include "params.h"
+#include "vecprim.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. */
struct def_blocks_d
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.
+ - An SSA_NAME (N) indicates that the current definition of the
+ underlying variable should be set to the given SSA_NAME. If the
+ symbol associated with the SSA_NAME is not a GIMPLE register, the
+ next slot in the stack must be a _DECL node (SYM). In this case,
+ the name N in the previous slot is the current reaching
+ definition for SYM.
- 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
+ - A NULL node at the top entry is used to mark the last slot
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_P(int);
-DEF_VEC_ALLOC_P(int,heap);
/* Set of existing SSA names being replaced by update_ssa. */
static sbitmap old_ssa_names;
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;
+sbitmap interesting_blocks;
/* 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;
+static VEC(gimple_vec, heap) *phis_to_rewrite;
+
+/* The bitmap of non-NULL elements of PHIS_TO_REWRITE. */
+static bitmap blocks_with_phis_to_rewrite;
+
/* 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
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;
+/* The function the SSA updating data structures have been initialized for.
+ NULL if they need to be initialized by register_new_name_mapping. */
+static struct function *update_ssa_initialized_fn = NULL;
/* Statistics kept by update_ssa to use in the virtual mapping
heuristic. If the number of virtual mappings is beyond certain
/* 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;
};
/* Information stored for SSA names. */
struct ssa_name_info
{
+ /* The current reaching definition replacing this SSA name. */
+ tree current_def;
+
/* 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;
+ /* Age of this record (so that info_for_ssa_name table can be cleared
+ quickly); if AGE < CURRENT_INFO_FOR_SSA_NAME_AGE, then the fields
+ are assumed to be null. */
+ unsigned age;
};
+/* The information associated with names. */
+typedef struct ssa_name_info *ssa_name_info_p;
+DEF_VEC_P (ssa_name_info_p);
+DEF_VEC_ALLOC_P (ssa_name_info_p, heap);
+
+static VEC(ssa_name_info_p, heap) *info_for_ssa_name;
+static unsigned current_info_for_ssa_name_age;
+
+/* The set of blocks affected by update_ssa. */
+static bitmap blocks_to_update;
/* The main entry point to the SSA renamer (rewrite_blocks) may be
called several times to do different, but related, tasks.
};
-/* 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 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);
+extern void dump_update_ssa (FILE *);
+extern void debug_update_ssa (void);
+extern void dump_names_replaced_by (FILE *, tree);
+extern void debug_names_replaced_by (tree);
+extern void dump_def_blocks (FILE *);
+extern void debug_def_blocks (void);
+extern void dump_defs_stack (FILE *, int);
+extern void debug_defs_stack (int);
+extern void dump_currdefs (FILE *);
+extern void debug_currdefs (void);
+
+/* Return true if STMT needs to be rewritten. When renaming a subset
+ of the variables, not all statements will be processed. This is
+ decided in mark_def_sites. */
+
+static inline bool
+rewrite_uses_p (gimple stmt)
+{
+ return gimple_visited_p (stmt);
+}
+
+
+/* Set the rewrite marker on STMT to the value given by REWRITE_P. */
+
+static inline void
+set_rewrite_uses (gimple stmt, bool rewrite_p)
+{
+ gimple_set_visited (stmt, rewrite_p);
+}
+
+
+/* Return true if the DEFs created by statement STMT should be
+ registered when marking new definition sites. This is slightly
+ different than rewrite_uses_p: 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. */
+
+static inline bool
+register_defs_p (gimple stmt)
+{
+ return gimple_plf (stmt, GF_PLF_1) != 0;
+}
+
+
+/* If REGISTER_DEFS_P is true, mark STMT to have its DEFs registered. */
+
+static inline void
+set_register_defs (gimple stmt, bool register_defs_p)
+{
+ gimple_set_plf (stmt, GF_PLF_1, register_defs_p);
+}
+
/* Get the information associated with NAME. */
-static inline struct ssa_name_info *
+static inline ssa_name_info_p
get_ssa_name_ann (tree name)
{
- if (!SSA_NAME_AUX (name))
- SSA_NAME_AUX (name) = xcalloc (1, sizeof (struct ssa_name_info));
+ unsigned ver = SSA_NAME_VERSION (name);
+ unsigned len = VEC_length (ssa_name_info_p, info_for_ssa_name);
+ struct ssa_name_info *info;
+
+ if (ver >= len)
+ {
+ unsigned new_len = num_ssa_names;
+
+ VEC_reserve (ssa_name_info_p, heap, info_for_ssa_name, new_len);
+ while (len++ < new_len)
+ {
+ struct ssa_name_info *info = XCNEW (struct ssa_name_info);
+ info->age = current_info_for_ssa_name_age;
+ VEC_quick_push (ssa_name_info_p, info_for_ssa_name, info);
+ }
+ }
+
+ info = VEC_index (ssa_name_info_p, info_for_ssa_name, ver);
+ if (info->age < current_info_for_ssa_name_age)
+ {
+ info->need_phi_state = NEED_PHI_STATE_UNKNOWN;
+ info->current_def = NULL_TREE;
+ info->age = current_info_for_ssa_name_age;
+ }
+
+ return info;
+}
- return SSA_NAME_AUX (name);
+
+/* Clears info for SSA names. */
+
+static void
+clear_ssa_name_info (void)
+{
+ current_info_for_ssa_name_age++;
}
-/* Gets phi_state field for VAR. */
+/* Get phi_state field for VAR. */
static inline enum need_phi_state
get_phi_state (tree var)
}
-/* Compute global livein information given the set of blockx where
+/* Compute global livein information given the set of blocks where
an object is locally live at the start of the block (LIVEIN)
and the set of blocks where the object is defined (DEF_BLOCKS).
for LIVEIN). */
void
-compute_global_livein (bitmap livein, bitmap def_blocks)
+compute_global_livein (bitmap livein ATTRIBUTE_UNUSED, bitmap def_blocks ATTRIBUTE_UNUSED)
{
basic_block bb, *worklist, *tos;
unsigned i;
= (basic_block *) xmalloc (sizeof (basic_block) * (last_basic_block + 1));
EXECUTE_IF_SET_IN_BITMAP (livein, 0, i, bi)
- {
- *tos++ = BASIC_BLOCK (i);
- }
+ *tos++ = BASIC_BLOCK (i);
/* Iterate until the worklist is empty. */
while (tos != worklist)
}
+/* Cleans up the REWRITE_THIS_STMT and REGISTER_DEFS_IN_THIS_STMT flags for
+ all statements in basic block BB. */
+
+static void
+initialize_flags_in_bb (basic_block bb)
+{
+ gimple stmt;
+ gimple_stmt_iterator gsi;
+
+ for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ {
+ gimple phi = gsi_stmt (gsi);
+ set_rewrite_uses (phi, false);
+ set_register_defs (phi, false);
+ }
+
+ for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ {
+ stmt = gsi_stmt (gsi);
+
+ /* 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 (!gimple_modified_p (stmt));
+ set_rewrite_uses (stmt, false);
+ set_register_defs (stmt, false);
+ }
+}
+
+/* Mark block BB as interesting for update_ssa. */
+
+static void
+mark_block_for_update (basic_block bb)
+{
+ gcc_assert (blocks_to_update != NULL);
+ if (bitmap_bit_p (blocks_to_update, bb->index))
+ return;
+ bitmap_set_bit (blocks_to_update, bb->index);
+ initialize_flags_in_bb (bb);
+}
+
/* 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. */
slot = htab_find_slot (def_blocks, (void *) &db, INSERT);
if (*slot == NULL)
{
- db_p = xmalloc (sizeof (*db_p));
+ 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);
static inline bool
symbol_marked_for_renaming (tree sym)
{
- gcc_assert (DECL_P (sym));
- return bitmap_bit_p (syms_to_rename, var_ann (sym)->uid);
+ return bitmap_bit_p (SYMS_TO_RENAME (cfun), DECL_UID (sym));
}
is_old_name (tree name)
{
unsigned ver = SSA_NAME_VERSION (name);
+ if (!new_ssa_names)
+ return false;
return ver < new_ssa_names->n_bits && TEST_BIT (old_ssa_names, ver);
}
is_new_name (tree name)
{
unsigned ver = SSA_NAME_VERSION (name);
+ if (!new_ssa_names)
+ return false;
return ver < new_ssa_names->n_bits && TEST_BIT (new_ssa_names, ver);
}
}
-/* Return the names replaced by NEW (i.e., REPL_TBL[NEW].SET). */
+/* Return the names replaced by NEW_TREE (i.e., REPL_TBL[NEW_TREE].SET). */
static inline bitmap
-names_replaced_by (tree new)
+names_replaced_by (tree new_tree)
{
struct repl_map_d m;
void **slot;
- m.name = new;
+ m.name = new_tree;
slot = htab_find_slot (repl_tbl, (void *) &m, NO_INSERT);
/* If N was not registered in the replacement table, return NULL. */
}
-/* Add OLD to REPL_TBL[NEW].SET. */
+/* Add OLD to REPL_TBL[NEW_TREE].SET. */
static inline void
-add_to_repl_tbl (tree new, tree old)
+add_to_repl_tbl (tree new_tree, tree old)
{
struct repl_map_d m, *mp;
void **slot;
- m.name = new;
+ m.name = new_tree;
slot = htab_find_slot (repl_tbl, (void *) &m, INSERT);
if (*slot == NULL)
{
- mp = xmalloc (sizeof (*mp));
- mp->name = new;
+ mp = XNEW (struct repl_map_d);
+ mp->name = new_tree;
mp->set = BITMAP_ALLOC (NULL);
*slot = (void *) mp;
}
}
-/* Add a new mapping NEW -> OLD REPL_TBL. Every entry N_i in REPL_TBL
+/* Add a new mapping NEW_TREE -> 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
-add_new_name_mapping (tree new, tree old)
+add_new_name_mapping (tree new_tree, tree old)
{
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));
-
- /* 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)
- {
- 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);
- }
+ /* OLD and NEW_TREE must be different SSA names for the same symbol. */
+ gcc_assert (new_tree != old && SSA_NAME_VAR (new_tree) == SSA_NAME_VAR (old));
/* If this mapping is for virtual names, we will need to update
- virtual operands. */
- if (!is_gimple_reg (new))
+ virtual operands. If this is a mapping for .MEM, then we gather
+ the symbols associated with each name. */
+ if (!is_gimple_reg (new_tree))
{
tree sym;
- size_t uid;
- need_to_update_vops_p = true;
+ update_ssa_stats.num_virtual_mappings++;
+ update_ssa_stats.num_virtual_symbols++;
/* Keep counts of virtual mappings and symbols to use in the
virtual mapping heuristic. If we have large numbers of
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 = var_ann (sym)->uid;
- update_ssa_stats.num_virtual_mappings++;
- if (!bitmap_bit_p (update_ssa_stats.virtual_symbols, uid))
- {
- bitmap_set_bit (update_ssa_stats.virtual_symbols, uid);
- update_ssa_stats.num_virtual_symbols++;
- }
+ sym = SSA_NAME_VAR (new_tree);
+ bitmap_set_bit (update_ssa_stats.virtual_symbols, DECL_UID (sym));
+ }
+
+ /* 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)
+ {
+ 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);
}
/* Update the REPL_TBL table. */
- add_to_repl_tbl (new, old);
+ add_to_repl_tbl (new_tree, old);
/* If OLD had already been registered as a new name, then all the
- names that OLD replaces should also be replaced by NEW. */
+ names that OLD replaces should also be replaced by NEW_TREE. */
if (is_new_name (old))
- bitmap_ior_into (names_replaced_by (new), names_replaced_by (old));
+ bitmap_ior_into (names_replaced_by (new_tree), names_replaced_by (old));
- /* Register NEW and OLD in NEW_SSA_NAMES and OLD_SSA_NAMES,
+ /* Register NEW_TREE and OLD in NEW_SSA_NAMES and OLD_SSA_NAMES,
respectively. */
- SET_BIT (new_ssa_names, SSA_NAME_VERSION (new));
+ SET_BIT (new_ssa_names, SSA_NAME_VERSION (new_tree));
SET_BIT (old_ssa_names, SSA_NAME_VERSION (old));
/* Update mapping counter to use in the virtual mapping heuristic. */
BB:
1- Variables defined by S in the DEFS of S are marked in the bitmap
- WALK_DATA->GLOBAL_DATA->KILLS.
+ 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.
+ then it is 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. */
static void
-mark_def_sites (struct dom_walk_data *walk_data,
- basic_block bb,
- block_stmt_iterator bsi)
+mark_def_sites (basic_block bb, gimple stmt, bitmap kills)
{
- struct mark_def_sites_global_data *gd = walk_data->global_data;
- bitmap kills = gd->kills;
- tree stmt, def;
+ tree def;
use_operand_p use_p;
- def_operand_p def_p;
ssa_op_iter iter;
- stmt = bsi_stmt (bsi);
- update_stmt_if_modified (stmt);
+ /* Since this is the first time that we rewrite the program into SSA
+ form, force an operand scan on every statement. */
+ update_stmt (stmt);
- REGISTER_DEFS_IN_THIS_STMT (stmt) = 0;
- REWRITE_THIS_STMT (stmt) = 0;
+ gcc_assert (blocks_to_update == NULL);
+ set_register_defs (stmt, false);
+ set_rewrite_uses (stmt, false);
+
+ if (is_gimple_debug (stmt))
+ return;
/* 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)
+ FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE)
{
tree sym = USE_FROM_PTR (use_p);
gcc_assert (DECL_P (sym));
- if (!bitmap_bit_p (kills, var_ann (sym)->uid))
+ 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;
+ set_rewrite_uses (stmt, true);
}
- /* 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)
+ /* Now process the defs. Mark BB as the definition block and add
+ each def to the set of killed symbols. */
+ FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
{
gcc_assert (DECL_P (def));
set_def_block (def, bb, false);
- bitmap_set_bit (kills, var_ann (def)->uid);
- REGISTER_DEFS_IN_THIS_STMT (stmt) = 1;
+ bitmap_set_bit (kills, DECL_UID (def));
+ set_register_defs (stmt, true);
}
/* 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);
+ if (rewrite_uses_p (stmt) || register_defs_p (stmt))
+ SET_BIT (interesting_blocks, bb->index);
+}
+
+/* Structure used by prune_unused_phi_nodes to record bounds of the intervals
+ in the dfs numbering of the dominance tree. */
+
+struct dom_dfsnum
+{
+ /* Basic block whose index this entry corresponds to. */
+ unsigned bb_index;
+
+ /* The dfs number of this node. */
+ unsigned dfs_num;
+};
+
+/* Compares two entries of type struct dom_dfsnum by dfs_num field. Callback
+ for qsort. */
+
+static int
+cmp_dfsnum (const void *a, const void *b)
+{
+ const struct dom_dfsnum *const da = (const struct dom_dfsnum *) a;
+ const struct dom_dfsnum *const db = (const struct dom_dfsnum *) b;
+
+ return (int) da->dfs_num - (int) db->dfs_num;
}
+/* Among the intervals starting at the N points specified in DEFS, find
+ the one that contains S, and return its bb_index. */
+
+static unsigned
+find_dfsnum_interval (struct dom_dfsnum *defs, unsigned n, unsigned s)
+{
+ unsigned f = 0, t = n, m;
+
+ while (t > f + 1)
+ {
+ m = (f + t) / 2;
+ if (defs[m].dfs_num <= s)
+ f = m;
+ else
+ t = m;
+ }
+
+ return defs[f].bb_index;
+}
-/* 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. */
+/* Clean bits from PHIS for phi nodes whose value cannot be used in USES.
+ KILLS is a bitmap of blocks where the value is defined before any use. */
-static bitmap
-find_idf (bitmap def_blocks, bitmap *dfs)
+static void
+prune_unused_phi_nodes (bitmap phis, bitmap kills, bitmap uses)
{
+ VEC(int, heap) *worklist;
bitmap_iterator bi;
- unsigned bb_index;
- VEC(int,heap) *work_stack;
- bitmap phi_insertion_points;
-
- work_stack = VEC_alloc (int, heap, n_basic_blocks);
- phi_insertion_points = BITMAP_ALLOC (NULL);
-
- /* 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 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. */
- while (VEC_length (int, work_stack) > 0)
- {
- bb_index = VEC_pop (int, work_stack);
-
- /* 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);
-
- EXECUTE_IF_AND_COMPL_IN_BITMAP (dfs[bb_index], phi_insertion_points,
- 0, bb_index, bi)
+ unsigned i, b, p, u, top;
+ bitmap live_phis;
+ basic_block def_bb, use_bb;
+ edge e;
+ edge_iterator ei;
+ bitmap to_remove;
+ struct dom_dfsnum *defs;
+ unsigned n_defs, adef;
+
+ if (bitmap_empty_p (uses))
+ {
+ bitmap_clear (phis);
+ return;
+ }
+
+ /* The phi must dominate a use, or an argument of a live phi. Also, we
+ do not create any phi nodes in def blocks, unless they are also livein. */
+ to_remove = BITMAP_ALLOC (NULL);
+ bitmap_and_compl (to_remove, kills, uses);
+ bitmap_and_compl_into (phis, to_remove);
+ if (bitmap_empty_p (phis))
+ {
+ BITMAP_FREE (to_remove);
+ return;
+ }
+
+ /* We want to remove the unnecessary phi nodes, but we do not want to compute
+ liveness information, as that may be linear in the size of CFG, and if
+ there are lot of different variables to rewrite, this may lead to quadratic
+ behavior.
+
+ Instead, we basically emulate standard dce. We put all uses to worklist,
+ then for each of them find the nearest def that dominates them. If this
+ def is a phi node, we mark it live, and if it was not live before, we
+ add the predecessors of its basic block to the worklist.
+
+ To quickly locate the nearest def that dominates use, we use dfs numbering
+ of the dominance tree (that is already available in order to speed up
+ queries). For each def, we have the interval given by the dfs number on
+ entry to and on exit from the corresponding subtree in the dominance tree.
+ The nearest dominator for a given use is the smallest of these intervals
+ that contains entry and exit dfs numbers for the basic block with the use.
+ If we store the bounds for all the uses to an array and sort it, we can
+ locate the nearest dominating def in logarithmic time by binary search.*/
+ bitmap_ior (to_remove, kills, phis);
+ n_defs = bitmap_count_bits (to_remove);
+ defs = XNEWVEC (struct dom_dfsnum, 2 * n_defs + 1);
+ defs[0].bb_index = 1;
+ defs[0].dfs_num = 0;
+ adef = 1;
+ EXECUTE_IF_SET_IN_BITMAP (to_remove, 0, i, bi)
+ {
+ def_bb = BASIC_BLOCK (i);
+ defs[adef].bb_index = i;
+ defs[adef].dfs_num = bb_dom_dfs_in (CDI_DOMINATORS, def_bb);
+ defs[adef + 1].bb_index = i;
+ defs[adef + 1].dfs_num = bb_dom_dfs_out (CDI_DOMINATORS, def_bb);
+ adef += 2;
+ }
+ BITMAP_FREE (to_remove);
+ gcc_assert (adef == 2 * n_defs + 1);
+ qsort (defs, adef, sizeof (struct dom_dfsnum), cmp_dfsnum);
+ gcc_assert (defs[0].bb_index == 1);
+
+ /* Now each DEFS entry contains the number of the basic block to that the
+ dfs number corresponds. Change them to the number of basic block that
+ corresponds to the interval following the dfs number. Also, for the
+ dfs_out numbers, increase the dfs number by one (so that it corresponds
+ to the start of the following interval, not to the end of the current
+ one). We use WORKLIST as a stack. */
+ worklist = VEC_alloc (int, heap, n_defs + 1);
+ VEC_quick_push (int, worklist, 1);
+ top = 1;
+ n_defs = 1;
+ for (i = 1; i < adef; i++)
+ {
+ b = defs[i].bb_index;
+ if (b == top)
+ {
+ /* This is a closing element. Interval corresponding to the top
+ of the stack after removing it follows. */
+ VEC_pop (int, worklist);
+ top = VEC_index (int, worklist, VEC_length (int, worklist) - 1);
+ defs[n_defs].bb_index = top;
+ defs[n_defs].dfs_num = defs[i].dfs_num + 1;
+ }
+ else
{
- /* 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);
+ /* Opening element. Nothing to do, just push it to the stack and move
+ it to the correct position. */
+ defs[n_defs].bb_index = defs[i].bb_index;
+ defs[n_defs].dfs_num = defs[i].dfs_num;
+ VEC_quick_push (int, worklist, b);
+ top = b;
}
+
+ /* If this interval starts at the same point as the previous one, cancel
+ the previous one. */
+ if (defs[n_defs].dfs_num == defs[n_defs - 1].dfs_num)
+ defs[n_defs - 1].bb_index = defs[n_defs].bb_index;
+ else
+ n_defs++;
}
+ VEC_pop (int, worklist);
+ gcc_assert (VEC_empty (int, worklist));
- VEC_free (int, heap, work_stack);
+ /* Now process the uses. */
+ live_phis = BITMAP_ALLOC (NULL);
+ EXECUTE_IF_SET_IN_BITMAP (uses, 0, i, bi)
+ {
+ VEC_safe_push (int, heap, worklist, i);
+ }
- return phi_insertion_points;
-}
+ while (!VEC_empty (int, worklist))
+ {
+ b = VEC_pop (int, worklist);
+ if (b == ENTRY_BLOCK)
+ continue;
+ /* If there is a phi node in USE_BB, it is made live. Otherwise,
+ find the def that dominates the immediate dominator of USE_BB
+ (the kill in USE_BB does not dominate the use). */
+ if (bitmap_bit_p (phis, b))
+ p = b;
+ else
+ {
+ use_bb = get_immediate_dominator (CDI_DOMINATORS, BASIC_BLOCK (b));
+ p = find_dfsnum_interval (defs, n_defs,
+ bb_dom_dfs_in (CDI_DOMINATORS, use_bb));
+ if (!bitmap_bit_p (phis, p))
+ continue;
+ }
+
+ /* If the phi node is already live, there is nothing to do. */
+ if (bitmap_bit_p (live_phis, p))
+ continue;
+
+ /* Mark the phi as live, and add the new uses to the worklist. */
+ bitmap_set_bit (live_phis, p);
+ def_bb = BASIC_BLOCK (p);
+ FOR_EACH_EDGE (e, ei, def_bb->preds)
+ {
+ u = e->src->index;
+ if (bitmap_bit_p (uses, u))
+ continue;
+
+ /* In case there is a kill directly in the use block, do not record
+ the use (this is also necessary for correctness, as we assume that
+ uses dominated by a def directly in their block have been filtered
+ out before). */
+ if (bitmap_bit_p (kills, u))
+ continue;
+
+ bitmap_set_bit (uses, u);
+ VEC_safe_push (int, heap, worklist, u);
+ }
+ }
+
+ VEC_free (int, heap, worklist);
+ bitmap_copy (phis, live_phis);
+ BITMAP_FREE (live_phis);
+ free (defs);
+}
/* 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
static inline tree
get_default_def_for (tree sym)
{
- tree ddef = default_def (sym);
+ tree ddef = gimple_default_def (cfun, sym);
if (ddef == NULL_TREE)
{
- ddef = make_ssa_name (sym, build_empty_stmt ());
+ ddef = make_ssa_name (sym, gimple_build_nop ());
set_default_def (sym, ddef);
}
}
+/* Marks phi node PHI in basic block BB for rewrite. */
+
+static void
+mark_phi_for_rewrite (basic_block bb, gimple phi)
+{
+ gimple_vec phis;
+ unsigned i, idx = bb->index;
+
+ if (rewrite_uses_p (phi))
+ return;
+
+ set_rewrite_uses (phi, true);
+
+ if (!blocks_with_phis_to_rewrite)
+ return;
+
+ bitmap_set_bit (blocks_with_phis_to_rewrite, idx);
+ VEC_reserve (gimple_vec, heap, phis_to_rewrite, last_basic_block + 1);
+ for (i = VEC_length (gimple_vec, phis_to_rewrite); i <= idx; i++)
+ VEC_quick_push (gimple_vec, phis_to_rewrite, NULL);
+
+ phis = VEC_index (gimple_vec, phis_to_rewrite, idx);
+ if (!phis)
+ phis = VEC_alloc (gimple, heap, 10);
+
+ VEC_safe_push (gimple, heap, phis, phi);
+ VEC_replace (gimple_vec, phis_to_rewrite, idx, phis);
+}
+
/* 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.
+ function assumes that the caller is incrementally updating the
+ existing SSA form, in which case VAR may be an SSA name instead of
+ a symbol.
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
{
unsigned bb_index;
edge e;
- tree phi;
+ gimple phi;
basic_block bb;
bitmap_iterator bi;
struct def_blocks_d *def_map;
/* 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);
+ /* Remove obviously useless phi nodes. */
+ prune_unused_phi_nodes (phi_insertion_points, def_map->def_blocks,
+ def_map->livein_blocks);
/* And insert the PHI nodes. */
- EXECUTE_IF_AND_IN_BITMAP (phi_insertion_points, def_map->livein_blocks,
- 0, bb_index, bi)
+ EXECUTE_IF_SET_IN_BITMAP (phi_insertion_points, 0, bb_index, bi)
{
bb = BASIC_BLOCK (bb_index);
+ if (update_p)
+ mark_block_for_update (bb);
+
+ phi = NULL;
- if (update_p && TREE_CODE (var) == SSA_NAME)
+ if (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
edge_iterator ei;
tree new_lhs;
+ gcc_assert (update_p);
phi = create_phi_node (var, bb);
+
new_lhs = duplicate_ssa_name (var, phi);
- SET_PHI_RESULT (phi, new_lhs);
+ gimple_phi_set_result (phi, new_lhs);
add_new_name_mapping (new_lhs, var);
/* Add VAR to every argument slot of PHI. We need VAR in
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);
+ add_phi_arg (phi, var, e, UNKNOWN_LOCATION);
}
else
{
- tree sym = DECL_P (var) ? var : SSA_NAME_VAR (var);
- phi = create_phi_node (sym, bb);
+ tree tracked_var;
+
+ gcc_assert (DECL_P (var));
+ phi = create_phi_node (var, bb);
+
+ tracked_var = target_for_debug_bind (var);
+ if (tracked_var)
+ {
+ gimple note = gimple_build_debug_bind (tracked_var,
+ PHI_RESULT (phi),
+ phi);
+ gimple_stmt_iterator si = gsi_after_labels (bb);
+ gsi_insert_before (&si, note, GSI_SAME_STMT);
+ }
}
/* Mark this PHI node as interesting for update_ssa. */
- REGISTER_DEFS_IN_THIS_STMT (phi) = 1;
- REWRITE_THIS_STMT (phi) = 1;
+ set_register_defs (phi, true);
+ mark_phi_for_rewrite (bb, phi);
}
}
/* 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). */
+ the flowgraph. */
static void
insert_phi_nodes (bitmap *dfs)
{
- unsigned i;
+ referenced_var_iterator rvi;
+ bitmap_iterator bi;
+ tree var;
+ bitmap vars;
+ unsigned uid;
timevar_push (TV_TREE_INSERT_PHI_NODES);
- for (i = 0; i < num_referenced_vars; i++)
+ /* Do two stages to avoid code generation differences for UID
+ differences but no UID ordering differences. */
+
+ vars = BITMAP_ALLOC (NULL);
+ FOR_EACH_REFERENCED_VAR (var, rvi)
{
struct def_blocks_d *def_map;
- bitmap idf;
- tree var = referenced_var (i);
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);
- }
+ bitmap_set_bit (vars, DECL_UID (var));
+ }
+
+ EXECUTE_IF_SET_IN_BITMAP (vars, 0, uid, bi)
+ {
+ tree var = referenced_var (uid);
+ struct def_blocks_d *def_map;
+ bitmap idf;
+
+ def_map = find_def_blocks_for (var);
+ idf = compute_idf (def_map->def_blocks, dfs);
+ insert_phi_nodes_for (var, idf, false);
+ BITMAP_FREE (idf);
}
+ BITMAP_FREE (vars);
+
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. */
+/* Push SYM's current reaching definition into BLOCK_DEFS_STACK and
+ register DEF (an SSA_NAME) to be a new definition for SYM. */
-void
-register_new_def (tree def, VEC(tree,heap) **block_defs_p)
+static void
+register_new_def (tree def, tree sym)
{
- tree var = SSA_NAME_VAR (def);
tree currdef;
-
+
/* If this variable is set in a single basic block and all uses are
dominated by the set(s) in that single basic block, then there is
no reason to record anything for this variable in the block local
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 (get_phi_state (var) == NEED_PHI_STATE_NO)
+ if (get_phi_state (sym) == NEED_PHI_STATE_NO)
{
- set_current_def (var, def);
+ set_current_def (sym, def);
return;
}
- currdef = get_current_def (var);
+ currdef = get_current_def (sym);
+
+ /* If SYM is not a GIMPLE register, then CURRDEF may be a name whose
+ SSA_NAME_VAR is not necessarily SYM. In this case, also push SYM
+ in the stack so that we know which symbol is being defined by
+ this SSA name when we unwind the stack. */
+ if (currdef && !is_gimple_reg (sym))
+ VEC_safe_push (tree, heap, block_defs_stack, sym);
- /* 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. */
- VEC_safe_push (tree, heap, *block_defs_p, currdef ? currdef : var);
+ /* Push the current reaching definition into BLOCK_DEFS_STACK. 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. */
+ VEC_safe_push (tree, heap, block_defs_stack, currdef ? currdef : sym);
- /* Set the current reaching definition for VAR to be DEF. */
- set_current_def (var, def);
+ /* Set the current reaching definition for SYM to be DEF. */
+ set_current_def (sym, def);
}
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.
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);
- }
-}
-
-
/* Return the current definition for variable VAR. If none is found,
- create a new SSA name to act as the zeroth definition for VAR. If VAR
- is call clobbered and there exists a more recent definition of
- GLOBAL_VAR, return the definition for GLOBAL_VAR. This means that VAR
- has been clobbered by a function call since its last assignment. */
+ create a new SSA name to act as the zeroth definition for VAR. */
static tree
get_reaching_def (tree var)
{
- tree currdef_var, avar;
-
+ tree currdef;
+
/* Lookup the current reaching definition for VAR. */
- currdef_var = get_current_def (var);
+ currdef = 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)
+ if (currdef == NULL_TREE)
{
- avar = DECL_P (var) ? var : SSA_NAME_VAR (var);
- currdef_var = get_default_def_for (avar);
- set_current_def (var, currdef_var);
+ tree sym = DECL_P (var) ? var : SSA_NAME_VAR (var);
+ currdef = get_default_def_for (sym);
+ set_current_def (var, currdef);
}
/* Return the current reaching definition for VAR, or the default
definition, if we had to create one. */
- return currdef_var;
+ return currdef;
}
definition of a variable when a new real or virtual definition is found. */
static void
-rewrite_stmt (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
- basic_block bb ATTRIBUTE_UNUSED,
- block_stmt_iterator si)
+rewrite_stmt (gimple_stmt_iterator si)
{
- tree stmt;
use_operand_p use_p;
def_operand_p def_p;
ssa_op_iter iter;
-
- stmt = bsi_stmt (si);
+ gimple stmt = gsi_stmt (si);
/* 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))
+ gcc_assert (blocks_to_update == NULL);
+ if (!rewrite_uses_p (stmt) && !register_defs_p (stmt))
return;
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "Renaming statement ");
- print_generic_stmt (dump_file, stmt, TDF_SLIM);
+ print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
fprintf (dump_file, "\n");
}
- /* 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)
+ /* Step 1. Rewrite USES in the statement. */
+ if (rewrite_uses_p (stmt))
+ FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE)
{
tree var = USE_FROM_PTR (use_p);
gcc_assert (DECL_P (var));
SET_USE (use_p, get_reaching_def (var));
}
- /* 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)
+ /* Step 2. Register the statement's DEF operands. */
+ if (register_defs_p (stmt))
+ FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, iter, SSA_OP_DEF)
{
tree var = DEF_FROM_PTR (def_p);
+ tree name = make_ssa_name (var, stmt);
+ tree tracked_var;
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);
+ SET_DEF (def_p, name);
+ register_new_def (DEF_FROM_PTR (def_p), var);
+
+ tracked_var = target_for_debug_bind (var);
+ if (tracked_var)
+ {
+ gimple note = gimple_build_debug_bind (tracked_var, name, stmt);
+ gsi_insert_after (&si, note, GSI_SAME_STMT);
+ }
}
}
that definition is reaching the PHI node. */
static void
-rewrite_add_phi_arguments (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
- basic_block bb)
+rewrite_add_phi_arguments (basic_block bb)
{
edge e;
edge_iterator ei;
FOR_EACH_EDGE (e, ei, bb->succs)
{
- tree phi;
+ gimple phi;
+ gimple_stmt_iterator gsi;
- for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi))
+ for (gsi = gsi_start_phis (e->dest); !gsi_end_p (gsi);
+ gsi_next (&gsi))
{
tree currdef;
- currdef = get_reaching_def (SSA_NAME_VAR (PHI_RESULT (phi)));
- add_phi_arg (phi, currdef, e);
+ gimple stmt;
+
+ phi = gsi_stmt (gsi);
+ currdef = get_reaching_def (SSA_NAME_VAR (gimple_phi_result (phi)));
+ stmt = SSA_NAME_DEF_STMT (currdef);
+ add_phi_arg (phi, currdef, e, gimple_location (stmt));
}
}
}
-
-/* Called after visiting basic block BB. Restore CURRDEFS to its
- original value. */
+/* 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_finalize_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
- basic_block bb ATTRIBUTE_UNUSED)
+rewrite_enter_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
+ basic_block bb)
{
- /* Restore CURRDEFS to its original state. */
- while (VEC_length (tree, block_defs_stack) > 0)
- {
+ gimple phi;
+ gimple_stmt_iterator gsi;
+
+ 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 (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ {
+ tree result;
+
+ phi = gsi_stmt (gsi);
+ result = gimple_phi_result (phi);
+ gcc_assert (is_gimple_reg (result));
+ register_new_def (result, SSA_NAME_VAR (result));
+ }
+
+ /* 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. */
+ if (TEST_BIT (interesting_blocks, bb->index))
+ for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ rewrite_stmt (gsi);
+
+ /* 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. */
+ rewrite_add_phi_arguments (bb);
+}
+
+
+
+/* Called after visiting all the statements in basic block BB and all
+ of its dominator children. Restore CURRDEFS to its original value. */
+
+static void
+rewrite_leave_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)
{
+ /* If we recorded an SSA_NAME, then make the SSA_NAME the
+ current definition of its underlying variable. Note that
+ if the SSA_NAME is not for a GIMPLE register, the symbol
+ being defined is stored in the next slot in the stack.
+ This mechanism is needed because an SSA name for a
+ non-register symbol may be the definition for more than
+ one symbol (e.g., SFTs, aliased variables, etc). */
saved_def = tmp;
var = SSA_NAME_VAR (saved_def);
+ if (!is_gimple_reg (var))
+ var = VEC_pop (tree, block_defs_stack);
}
else
{
+ /* If we recorded anything else, it must have been a _DECL
+ node and its current reaching definition must have been
+ NULL. */
saved_def = NULL;
var = tmp;
}
-
+
set_current_def (var, saved_def);
}
}
+/* Dump bitmap SET (assumed to contain VAR_DECLs) to FILE. */
+
+void
+dump_decl_set (FILE *file, bitmap set)
+{
+ if (set)
+ {
+ bitmap_iterator bi;
+ unsigned i;
+
+ fprintf (file, "{ ");
+
+ EXECUTE_IF_SET_IN_BITMAP (set, 0, i, bi)
+ {
+ print_generic_expr (file, referenced_var (i), 0);
+ fprintf (file, " ");
+ }
+
+ fprintf (file, "}");
+ }
+ else
+ fprintf (file, "NIL");
+}
+
+
+/* Dump bitmap SET (assumed to contain VAR_DECLs) to FILE. */
+
+void
+debug_decl_set (bitmap set)
+{
+ dump_decl_set (stderr, set);
+ fprintf (stderr, "\n");
+}
+
+
+/* Dump the renaming stack (block_defs_stack) to FILE. Traverse the
+ stack up to a maximum of N levels. If N is -1, the whole stack is
+ dumped. New levels are created when the dominator tree traversal
+ used for renaming enters a new sub-tree. */
+
+void
+dump_defs_stack (FILE *file, int n)
+{
+ int i, j;
+
+ fprintf (file, "\n\nRenaming stack");
+ if (n > 0)
+ fprintf (file, " (up to %d levels)", n);
+ fprintf (file, "\n\n");
+
+ i = 1;
+ fprintf (file, "Level %d (current level)\n", i);
+ for (j = (int) VEC_length (tree, block_defs_stack) - 1; j >= 0; j--)
+ {
+ tree name, var;
+
+ name = VEC_index (tree, block_defs_stack, j);
+ if (name == NULL_TREE)
+ {
+ i++;
+ if (n > 0 && i > n)
+ break;
+ fprintf (file, "\nLevel %d\n", i);
+ continue;
+ }
+
+ if (DECL_P (name))
+ {
+ var = name;
+ name = NULL_TREE;
+ }
+ else
+ {
+ var = SSA_NAME_VAR (name);
+ if (!is_gimple_reg (var))
+ {
+ j--;
+ var = VEC_index (tree, block_defs_stack, j);
+ }
+ }
+
+ fprintf (file, " Previous CURRDEF (");
+ print_generic_expr (file, var, 0);
+ fprintf (file, ") = ");
+ if (name)
+ print_generic_expr (file, name, 0);
+ else
+ fprintf (file, "<NIL>");
+ fprintf (file, "\n");
+ }
+}
+
+
+/* Dump the renaming stack (block_defs_stack) to stderr. Traverse the
+ stack up to a maximum of N levels. If N is -1, the whole stack is
+ dumped. New levels are created when the dominator tree traversal
+ used for renaming enters a new sub-tree. */
+
+void
+debug_defs_stack (int n)
+{
+ dump_defs_stack (stderr, n);
+}
+
+
+/* Dump the current reaching definition of every symbol to FILE. */
+
+void
+dump_currdefs (FILE *file)
+{
+ referenced_var_iterator i;
+ tree var;
+
+ fprintf (file, "\n\nCurrent reaching definitions\n\n");
+ FOR_EACH_REFERENCED_VAR (var, i)
+ if (SYMS_TO_RENAME (cfun) == NULL
+ || bitmap_bit_p (SYMS_TO_RENAME (cfun), DECL_UID (var)))
+ {
+ fprintf (file, "CURRDEF (");
+ print_generic_expr (file, var, 0);
+ fprintf (file, ") = ");
+ if (get_current_def (var))
+ print_generic_expr (file, get_current_def (var), 0);
+ else
+ fprintf (file, "<NIL>");
+ fprintf (file, "\n");
+ }
+}
+
+
+/* Dump the current reaching definition of every symbol to stderr. */
+
+void
+debug_currdefs (void)
+{
+ dump_currdefs (stderr);
+}
+
+
/* 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);
+ fprintf (file, "SSA renaming 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_def_blocks (file);
+ dump_defs_stack (file, -1);
+ dump_currdefs (file);
+ dump_tree_ssa_stats (file);
}
void
dump_tree_ssa_stats (FILE *file)
{
- fprintf (file, "\nHash table statistics:\n");
+ if (def_blocks || repl_tbl)
+ fprintf (file, "\nHash table statistics:\n");
- fprintf (file, " def_blocks: ");
- htab_statistics (file, def_blocks);
+ if (def_blocks)
+ {
+ fprintf (file, " def_blocks: ");
+ htab_statistics (file, def_blocks);
+ }
- fprintf (file, "\n");
+ if (repl_tbl)
+ {
+ fprintf (file, " repl_tbl: ");
+ htab_statistics (file, repl_tbl);
+ }
+
+ if (def_blocks || repl_tbl)
+ fprintf (file, "\n");
}
static void
def_blocks_free (void *p)
{
- struct def_blocks_d *entry = 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);
/* Callback for htab_traverse to dump the DEF_BLOCKS hash table. */
static int
-debug_def_blocks_r (void **slot, void *data ATTRIBUTE_UNUSED)
+debug_def_blocks_r (void **slot, void *data)
{
+ FILE *file = (FILE *) data;
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");
+
+ fprintf (file, "VAR: ");
+ print_generic_expr (file, db_p->var, dump_flags);
+ bitmap_print (file, db_p->def_blocks, ", DEF_BLOCKS: { ", "}");
+ bitmap_print (file, db_p->livein_blocks, ", LIVEIN_BLOCKS: { ", "}");
+ bitmap_print (file, db_p->phi_blocks, ", PHI_BLOCKS: { ", "}\n");
return 1;
}
+/* Dump the DEF_BLOCKS hash table on FILE. */
+
+void
+dump_def_blocks (FILE *file)
+{
+ fprintf (file, "\n\nDefinition and live-in blocks:\n\n");
+ if (def_blocks)
+ htab_traverse (def_blocks, debug_def_blocks_r, file);
+}
+
+
/* Dump the DEF_BLOCKS hash table on stderr. */
void
debug_def_blocks (void)
{
- htab_traverse (def_blocks, debug_def_blocks_r, NULL);
+ dump_def_blocks (stderr);
}
{
tree currdef = get_current_def (old_name);
- /* Push the current reaching definition into *BLOCK_DEFS_P.
+ /* Push the current reaching definition into BLOCK_DEFS_STACK.
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
}
-/* 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
}
+/* Same as maybe_replace_use, but without introducing default stmts,
+ returning false to indicate a need to do so. */
+
+static inline bool
+maybe_replace_use_in_debug_stmt (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_current_def (sym);
+ else if (is_old_name (use))
+ {
+ rdef = get_current_def (use);
+ /* We can't assume that, if there's no current definition, the
+ default one should be used. It could be the case that we've
+ rearranged blocks so that the earlier definition no longer
+ dominates the use. */
+ if (!rdef && SSA_NAME_IS_DEFAULT_DEF (use))
+ rdef = use;
+ }
+ else
+ rdef = use;
+
+ if (rdef && rdef != use)
+ SET_USE (use_p, rdef);
+
+ return rdef != NULL_TREE;
+}
+
+
/* 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)
+maybe_register_def (def_operand_p def_p, gimple stmt,
+ gimple_stmt_iterator gsi)
{
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 DEF is a naked symbol that needs renaming, create a new
+ name for it. */
if (symbol_marked_for_renaming (sym))
{
if (DECL_P (def))
{
+ tree tracked_var;
+
def = make_ssa_name (def, stmt);
SET_DEF (def_p, def);
+
+ tracked_var = target_for_debug_bind (sym);
+ if (tracked_var)
+ {
+ gimple note = gimple_build_debug_bind (tracked_var, def, stmt);
+ gsi_insert_after (&gsi, note, GSI_SAME_STMT);
+ }
}
register_new_update_single (def, sym);
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)
+rewrite_update_stmt (gimple stmt, gimple_stmt_iterator gsi)
{
- 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))
+ if (!rewrite_uses_p (stmt) && !register_defs_p (stmt))
+ return;
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, "Updating SSA information for statement ");
+ print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
+ fprintf (dump_file, "\n");
+ }
+
+ /* Rewrite USES included in OLD_SSA_NAMES and USES whose underlying
+ symbol is marked for renaming. */
+ if (rewrite_uses_p (stmt))
+ {
+ if (is_gimple_debug (stmt))
+ {
+ bool failed = false;
+
+ FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE)
+ if (!maybe_replace_use_in_debug_stmt (use_p))
+ {
+ failed = true;
+ break;
+ }
+
+ if (failed)
+ {
+ /* DOM sometimes threads jumps in such a way that a
+ debug stmt ends up referencing a SSA variable that no
+ longer dominates the debug stmt, but such that all
+ incoming definitions refer to the same definition in
+ an earlier dominator. We could try to recover that
+ definition somehow, but this will have to do for now.
+
+ Introducing a default definition, which is what
+ maybe_replace_use() would do in such cases, may
+ modify code generation, for the otherwise-unused
+ default definition would never go away, modifying SSA
+ version numbers all over. */
+ gimple_debug_bind_reset_value (stmt);
+ update_stmt (stmt);
+ }
+ }
+ else
+ {
+ FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_ALL_USES)
+ 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_p (stmt))
+ FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, iter, SSA_OP_ALL_DEFS)
+ maybe_register_def (def_p, stmt, gsi);
+}
+
+
+/* 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 (basic_block bb)
+{
+ edge e;
+ edge_iterator ei;
+ unsigned i;
+
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ {
+ gimple phi;
+ gimple_vec phis;
+
+ if (!bitmap_bit_p (blocks_with_phis_to_rewrite, e->dest->index))
+ continue;
+
+ phis = VEC_index (gimple_vec, phis_to_rewrite, e->dest->index);
+ for (i = 0; VEC_iterate (gimple, phis, i, phi); i++)
+ {
+ tree arg, lhs_sym, reaching_def = NULL;
+ use_operand_p arg_p;
+
+ gcc_assert (rewrite_uses_p (phi));
+
+ 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;
+
+ lhs_sym = SSA_NAME_VAR (gimple_phi_result (phi));
+
+ 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. */
+ reaching_def = get_reaching_def (lhs_sym);
+
+ }
+ else
+ {
+ tree sym = DECL_P (arg) ? arg : SSA_NAME_VAR (arg);
+
+ if (symbol_marked_for_renaming (sym))
+ reaching_def = get_reaching_def (sym);
+ else if (is_old_name (arg))
+ reaching_def = get_reaching_def (arg);
+ }
+
+ /* Update the argument if there is a reaching def. */
+ if (reaching_def)
+ {
+ gimple stmt;
+ source_location locus;
+ int arg_i = PHI_ARG_INDEX_FROM_USE (arg_p);
+
+ SET_USE (arg_p, reaching_def);
+ stmt = SSA_NAME_DEF_STMT (reaching_def);
+
+ /* Single element PHI nodes behave like copies, so get the
+ location from the phi argument. */
+ if (gimple_code (stmt) == GIMPLE_PHI &&
+ gimple_phi_num_args (stmt) == 1)
+ locus = gimple_phi_arg_location (stmt, 0);
+ else
+ locus = gimple_location (stmt);
+
+ gimple_phi_arg_set_location (phi, arg_i, locus);
+ }
+
+
+ if (e->flags & EDGE_ABNORMAL)
+ SSA_NAME_OCCURS_IN_ABNORMAL_PHI (USE_FROM_PTR (arg_p)) = 1;
+ }
+ }
+}
+
+
+/* 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_enter_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
+ basic_block bb)
+{
+ edge e;
+ edge_iterator ei;
+ bool is_abnormal_phi;
+ gimple_stmt_iterator gsi;
+
+ 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);
+
+ if (!bitmap_bit_p (blocks_to_update, bb->index))
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");
- }
+ /* 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 (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ {
+ tree lhs, lhs_sym;
+ gimple phi = gsi_stmt (gsi);
+
+ if (!register_defs_p (phi))
+ continue;
+
+ lhs = gimple_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));
- /* 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 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 (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);
+ if (is_abnormal_phi)
+ SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs) = 1;
}
- /* 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))
+ /* Step 2. Rewrite every variable used in each statement in the block. */
+ if (TEST_BIT (interesting_blocks, bb->index))
{
- 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);
+ gcc_assert (bitmap_bit_p (blocks_to_update, bb->index));
+ for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ rewrite_update_stmt (gsi_stmt (gsi), gsi);
}
-}
-
-
-/* Replace the operand pointed 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);
+ /* Step 3. Update PHI nodes. */
+ rewrite_update_phi_arguments (bb);
}
-
-/* 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. */
+/* 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_phi_arguments (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
- basic_block bb)
+rewrite_update_leave_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
+ basic_block bb ATTRIBUTE_UNUSED)
{
- edge e;
- edge_iterator ei;
-
- FOR_EACH_EDGE (e, ei, bb->succs)
+ while (VEC_length (tree, block_defs_stack) > 0)
{
- 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);
+ tree var = VEC_pop (tree, block_defs_stack);
+ tree saved_def;
- if (symbol_marked_for_renaming (sym))
- replace_use (arg_p, sym);
- else if (is_old_name (arg))
- replace_use (arg_p, arg);
- }
+ /* NULL indicates the unwind stop point for this block (see
+ rewrite_update_enter_block). */
+ if (var == NULL)
+ return;
- if (e->flags & EDGE_ABNORMAL)
- SSA_NAME_OCCURS_IN_ABNORMAL_PHI (USE_FROM_PTR (arg_p)) = 1;
- }
+ saved_def = VEC_pop (tree, block_defs_stack);
+ set_current_def (var, saved_def);
}
}
/* Rewrite the actual blocks, statements, and PHI arguments, to be in SSA
- form.
+ form.
ENTRY indicates the block where to start. Every block dominated by
ENTRY will be rewritten.
are not present in BLOCKS are ignored. */
static void
-rewrite_blocks (basic_block entry, enum rewrite_mode what, sbitmap blocks)
+rewrite_blocks (basic_block entry, enum rewrite_mode what)
{
struct dom_walk_data walk_data;
-
+
/* Rewrite all the basic blocks in the program. */
timevar_push (TV_TREE_SSA_REWRITE_BLOCKS);
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;
+ {
+ walk_data.before_dom_children = rewrite_enter_block;
+ walk_data.after_dom_children = rewrite_leave_block;
+ }
else if (what == REWRITE_UPDATE)
- walk_data.after_dom_children_after_stmts = rewrite_update_fini_block;
+ {
+ walk_data.before_dom_children = rewrite_update_enter_block;
+ walk_data.after_dom_children = rewrite_update_leave_block;
+ }
else
gcc_unreachable ();
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);
}
-/* Block initialization routine for mark_def_sites. Clear the
- KILLS bitmap at the start of each block. */
+/* Block processing routine for mark_def_sites. Clear the KILLS bitmap
+ at the start of each block, and call mark_def_sites for each statement. */
static void
-mark_def_sites_initialize_block (struct dom_walk_data *walk_data,
- basic_block bb ATTRIBUTE_UNUSED)
+mark_def_sites_block (struct dom_walk_data *walk_data, basic_block bb)
{
- struct mark_def_sites_global_data *gd = walk_data->global_data;
- bitmap kills = gd->kills;
+ struct mark_def_sites_global_data *gd;
+ bitmap kills;
+ gimple_stmt_iterator gsi;
+
+ gd = (struct mark_def_sites_global_data *) walk_data->global_data;
+ kills = gd->kills;
+
bitmap_clear (kills);
+ for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ mark_def_sites (bb, gsi_stmt (gsi), 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. */
+ The INTERESTING_BLOCKS global will be filled in with all the blocks
+ that should be processed by the renamer. It is assumed that the
+ caller has already initialized and zeroed it. */
static void
-mark_def_site_blocks (sbitmap interesting_blocks)
+mark_def_site_blocks (void)
{
- size_t i;
struct dom_walk_data walk_data;
struct mark_def_sites_global_data mark_def_sites_global_data;
- /* Allocate memory for the DEF_BLOCKS hash table. */
- def_blocks = htab_create (VEC_length (tree, referenced_vars),
- def_blocks_hash, def_blocks_eq, def_blocks_free);
-
- for (i = 0; i < num_referenced_vars; i++)
- set_current_def (referenced_var (i), 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;
+ walk_data.before_dom_children = mark_def_sites_block;
+ walk_data.after_dom_children = 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. */
}
+/* Initialize internal data needed during renaming. */
+
+static void
+init_ssa_renamer (void)
+{
+ tree var;
+ referenced_var_iterator rvi;
+
+ cfun->gimple_df->in_ssa_p = false;
+
+ /* Allocate memory for the DEF_BLOCKS hash table. */
+ gcc_assert (def_blocks == NULL);
+ 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);
+}
+
+
+/* Deallocate internal data structures used by the renamer. */
+
+static void
+fini_ssa_renamer (void)
+{
+ if (def_blocks)
+ {
+ htab_delete (def_blocks);
+ def_blocks = NULL;
+ }
+
+ cfun->gimple_df->in_ssa_p = true;
+}
+
/* Main entry point into the SSA builder. The renaming process
proceeds in four main phases:
4- Rename all the blocks (rewrite_blocks) and statements in the program.
- Steps 3 and 5 are done using the dominator tree walker
+ Steps 3 and 4 are done using the dominator tree walker
(walk_dominator_tree). */
-static void
+static unsigned int
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 internal data needed by the renamer. */
+ init_ssa_renamer ();
+
/* Initialize the set of interesting blocks. The callback
mark_def_sites will add to this set those blocks that the renamer
should process. */
sbitmap_zero (interesting_blocks);
/* Initialize dominance frontier. */
- dfs = (bitmap *) xmalloc (last_basic_block * sizeof (bitmap *));
+ dfs = XNEWVEC (bitmap, last_basic_block);
FOR_EACH_BB (bb)
dfs[bb->index] = BITMAP_ALLOC (NULL);
compute_dominance_frontiers (dfs);
/* 2- Find and mark definition sites. */
- mark_def_site_blocks (interesting_blocks);
+ mark_def_site_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);
+ rewrite_blocks (ENTRY_BLOCK_PTR, REWRITE_ALL);
/* Free allocated memory. */
FOR_EACH_BB (bb)
BITMAP_FREE (dfs[bb->index]);
free (dfs);
+
sbitmap_free (interesting_blocks);
+ fini_ssa_renamer ();
+
timevar_pop (TV_TREE_SSA_OTHER);
- in_ssa_p = true;
+ return 0;
}
-struct tree_opt_pass pass_build_ssa =
+struct gimple_opt_pass pass_build_ssa =
{
+ {
+ GIMPLE_PASS,
"ssa", /* name */
NULL, /* gate */
rewrite_into_ssa, /* execute */
NULL, /* sub */
NULL, /* next */
0, /* static_pass_number */
- 0, /* tv_id */
+ TV_NONE, /* 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 */
- 0 /* letter */
+ TODO_dump_func
+ | TODO_update_ssa_only_virtuals
+ | TODO_verify_ssa
+ | TODO_remove_unused_locals /* todo_flags_finish */
+ }
};
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)
+mark_def_interesting (tree var, gimple stmt, basic_block bb, bool insert_phi_p)
{
- REGISTER_DEFS_IN_THIS_STMT (stmt) = 1;
- bitmap_set_bit (blocks, bb->index);
+ gcc_assert (bitmap_bit_p (blocks_to_update, bb->index));
+ set_register_defs (stmt, true);
if (insert_phi_p)
{
- bool is_phi_p = TREE_CODE (stmt) == PHI_NODE;
+ bool is_phi_p = gimple_code (stmt) == GIMPLE_PHI;
set_def_block (var, 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. */
+ nodes. */
static inline void
-mark_use_interesting (tree var, tree stmt, basic_block bb, bitmap blocks,
- bool insert_phi_p)
+mark_use_interesting (tree var, gimple stmt, basic_block bb, bool insert_phi_p)
{
- REWRITE_THIS_STMT (stmt) = 1;
- bitmap_set_bit (blocks, bb->index);
+ basic_block def_bb = gimple_bb (stmt);
+
+ mark_block_for_update (def_bb);
+ mark_block_for_update (bb);
+
+ if (gimple_code (stmt) == GIMPLE_PHI)
+ mark_phi_for_rewrite (def_bb, stmt);
+ else
+ {
+ set_rewrite_uses (stmt, true);
+
+ if (is_gimple_debug (stmt))
+ return;
+ }
/* 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
/* 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.
+ already be SSA names.
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. */
+ algorithm to make PHI pruning decisions.
+
+ FIXME. Most of this would be unnecessary if we could associate a
+ symbol to all the SSA names that reference it. But that
+ sounds like it would be expensive to maintain. Still, it
+ would be interesting to see if it makes better sense to do
+ that. */
static void
-prepare_block_for_update (basic_block bb, bitmap blocks, bool insert_phi_p)
+prepare_block_for_update (basic_block bb, bool insert_phi_p)
{
basic_block son;
- block_stmt_iterator si;
- tree phi;
+ gimple_stmt_iterator si;
+ edge e;
+ edge_iterator ei;
+
+ mark_block_for_update (bb);
/* 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))
+ for (si = gsi_start_phis (bb); !gsi_end_p (si); gsi_next (&si))
{
- tree lhs_sym, lhs = PHI_RESULT (phi);
+ gimple phi = gsi_stmt (si);
+ tree lhs_sym, lhs = gimple_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);
- }
+ if (!symbol_marked_for_renaming (lhs_sym))
+ continue;
+
+ mark_def_interesting (lhs_sym, phi, bb, insert_phi_p);
+
+ /* Mark the uses in phi nodes as interesting. It would be more correct
+ to process the arguments of the phi nodes of the successor edges of
+ BB at the end of prepare_block_for_update, however, that turns out
+ to be significantly more expensive. Doing it here is conservatively
+ correct -- it may only cause us to believe a value to be live in a
+ block that also contains its definition, and thus insert a few more
+ phi nodes for it. */
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ mark_use_interesting (lhs_sym, phi, e->src, insert_phi_p);
}
/* Process the statements. */
- for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
+ for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si))
{
- tree stmt;
+ gimple 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)
+ stmt = gsi_stmt (si);
+
+ FOR_EACH_SSA_USE_OPERAND (use_p, stmt, i, SSA_OP_ALL_USES)
{
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);
+ mark_use_interesting (sym, stmt, bb, insert_phi_p);
}
- FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, i, SSA_OP_VIRTUAL_DEFS)
+ FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, i, SSA_OP_ALL_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);
+ mark_def_interesting (sym, stmt, bb, 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);
+ son;
+ son = next_dom_son (CDI_DOMINATORS, son))
+ prepare_block_for_update (son, insert_phi_p);
}
prepare_names_to_update. */
static void
-prepare_use_sites_for (tree name, bitmap blocks, bool insert_phi_p)
+prepare_use_sites_for (tree name, 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);
+ gimple stmt = USE_STMT (use_p);
+ basic_block bb = gimple_bb (stmt);
- if (TREE_CODE (stmt) == PHI_NODE)
+ if (gimple_code (stmt) == GIMPLE_PHI)
{
- /* 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);
- }
+ int ix = PHI_ARG_INDEX_FROM_USE (use_p);
+ edge e = gimple_phi_arg_edge (stmt, ix);
+ mark_use_interesting (name, stmt, e->src, insert_phi_p);
}
else
{
/* For regular statements, mark this as an interesting use
for NAME. */
- mark_use_interesting (name, stmt, bb, blocks, insert_phi_p);
+ mark_use_interesting (name, stmt, bb, insert_phi_p);
}
}
}
prepare_names_to_update. */
static void
-prepare_def_site_for (tree name, bitmap blocks, bool insert_phi_p)
+prepare_def_site_for (tree name, bool insert_phi_p)
{
- tree stmt;
+ gimple 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);
+ bb = gimple_bb (stmt);
if (bb)
{
gcc_assert (bb->index < last_basic_block);
- mark_def_interesting (name, stmt, bb, blocks, insert_phi_p);
+ mark_block_for_update (bb);
+ mark_def_interesting (name, stmt, bb, 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. */
+ OLD_SSA_NAMES. 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)
+prepare_names_to_update (bool insert_phi_p)
{
- unsigned i;
+ 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
/* 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,
- prepare_def_site_for (ssa_name (i), blocks, insert_phi_p));
+ EXECUTE_IF_SET_IN_SBITMAP (new_ssa_names, 0, i, sbi)
+ prepare_def_site_for (ssa_name (i), 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,
+ 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);
- });
+ prepare_def_site_for (ssa_name (i), insert_phi_p);
+ prepare_use_sites_for (ssa_name (i), insert_phi_p);
+ }
}
void
dump_update_ssa (FILE *file)
{
- unsigned i;
+ unsigned i = 0;
bitmap_iterator bi;
- if (!need_ssa_update_p ())
+ if (!need_ssa_update_p (cfun))
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,
- dump_names_replaced_by (file, ssa_name (i)));
+ 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_symbols);
}
- if (syms_to_rename && !bitmap_empty_p (syms_to_rename))
+ if (!bitmap_empty_p (SYMS_TO_RENAME (cfun)))
{
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, " ");
- }
+ dump_decl_set (file, SYMS_TO_RENAME (cfun));
+ fprintf (file, "\n");
}
if (names_to_release && !bitmap_empty_p (names_to_release))
/* Initialize data structures used for incremental SSA updates. */
static void
-init_update_ssa (void)
+init_update_ssa (struct function *fn)
{
/* Reserve more space than the current number of names. The calls to
add_new_name_mapping are typically done after creating new SSA
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);
+ update_ssa_initialized_fn = fn;
}
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_clear (SYMS_TO_RENAME (update_ssa_initialized_fn));
BITMAP_FREE (update_ssa_stats.virtual_symbols);
if (names_to_release)
BITMAP_FREE (names_to_release);
}
- for (i = 1; i < num_ssa_names; i++)
- {
- tree n = ssa_name (i);
+ clear_ssa_name_info ();
- if (n)
- {
- free (SSA_NAME_AUX (n));
- SSA_NAME_AUX (n) = NULL;
- }
- }
+ fini_ssa_renamer ();
+
+ if (blocks_with_phis_to_rewrite)
+ EXECUTE_IF_SET_IN_BITMAP (blocks_with_phis_to_rewrite, 0, i, bi)
+ {
+ gimple_vec phis = VEC_index (gimple_vec, phis_to_rewrite, i);
+
+ VEC_free (gimple, heap, phis);
+ VEC_replace (gimple_vec, phis_to_rewrite, i, NULL);
+ }
+
+ BITMAP_FREE (blocks_with_phis_to_rewrite);
+ BITMAP_FREE (blocks_to_update);
+ update_ssa_initialized_fn = NULL;
}
update_ssa's tables. */
tree
-create_new_def_for (tree old_name, tree stmt, def_operand_p def)
+create_new_def_for (tree old_name, gimple stmt, def_operand_p def)
{
tree new_name = duplicate_ssa_name (old_name, stmt);
SET_DEF (def, new_name);
- if (TREE_CODE (stmt) == PHI_NODE)
+ if (gimple_code (stmt) == GIMPLE_PHI)
{
edge e;
edge_iterator ei;
- basic_block bb = bb_for_stmt (stmt);
+ basic_block bb = gimple_bb (stmt);
/* If needed, mark NEW_NAME as occurring in an abnormal PHI node. */
FOR_EACH_EDGE (e, ei, bb->preds)
update_ssa. */
void
-register_new_name_mapping (tree new, tree old)
+register_new_name_mapping (tree new_tree, tree old)
{
- if (need_to_initialize_update_ssa_p)
- init_update_ssa ();
+ if (!update_ssa_initialized_fn)
+ init_update_ssa (cfun);
+
+ gcc_assert (update_ssa_initialized_fn == cfun);
- add_new_name_mapping (new, old);
+ add_new_name_mapping (new_tree, old);
}
void
mark_sym_for_renaming (tree sym)
{
- if (need_to_initialize_update_ssa_p)
- init_update_ssa ();
-
- bitmap_set_bit (syms_to_rename, var_ann (sym)->uid);
-
- if (!is_gimple_reg (sym))
- need_to_update_vops_p = true;
+ bitmap_set_bit (SYMS_TO_RENAME (cfun), DECL_UID (sym));
}
bitmap_iterator bi;
unsigned i;
- if (bitmap_empty_p (set))
+ if (set == NULL || 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;
- }
+ mark_sym_for_renaming (referenced_var (i));
}
-/* Return true if there is any work to be done by update_ssa. */
+/* Return true if there is any work to be done by update_ssa
+ for function FN. */
bool
-need_ssa_update_p (void)
+need_ssa_update_p (struct function *fn)
{
- return syms_to_rename || old_ssa_names || new_ssa_names;
+ gcc_assert (fn != NULL);
+ return (update_ssa_initialized_fn == fn
+ || (fn->gimple_df
+ && !bitmap_empty_p (SYMS_TO_RENAME (fn))));
}
+/* Return true if SSA name mappings have been registered for SSA updating. */
+
+bool
+name_mappings_registered_p (void)
+{
+ if (!update_ssa_initialized_fn)
+ return false;
+
+ gcc_assert (update_ssa_initialized_fn == cfun);
+
+ return repl_tbl && htab_elements (repl_tbl) > 0;
+}
/* Return true if name N has been registered in the replacement table. */
bool
-name_registered_for_update_p (tree n)
+name_registered_for_update_p (tree n ATTRIBUTE_UNUSED)
{
- if (!need_ssa_update_p ())
+ if (!update_ssa_initialized_fn)
return false;
- return is_new_name (n)
- || is_old_name (n)
- || symbol_marked_for_renaming (SSA_NAME_VAR (n));
+ gcc_assert (update_ssa_initialized_fn == cfun);
+
+ return is_new_name (n) || is_old_name (n);
}
bitmap
ssa_names_to_replace (void)
{
- unsigned i;
+ unsigned i = 0;
bitmap ret;
-
+ sbitmap_iterator sbi;
+
+ gcc_assert (update_ssa_initialized_fn == NULL
+ || update_ssa_initialized_fn == cfun);
+
ret = BITMAP_ALLOC (NULL);
- EXECUTE_IF_SET_IN_SBITMAP (old_ssa_names, 0, i,
- bitmap_set_bit (ret, i));
+ EXECUTE_IF_SET_IN_SBITMAP (old_ssa_names, 0, i, sbi)
+ bitmap_set_bit (ret, i);
return ret;
}
void
release_ssa_name_after_update_ssa (tree name)
{
- gcc_assert (!need_to_initialize_update_ssa_p);
+ gcc_assert (cfun && update_ssa_initialized_fn == cfun);
if (names_to_release == NULL)
names_to_release = BITMAP_ALLOC (NULL);
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
return;
/* Compute the initial iterated dominance frontier. */
- idf = find_idf (db->def_blocks, dfs);
+ idf = compute_idf (db->def_blocks, dfs);
pruned_idf = BITMAP_ALLOC (NULL);
if (TREE_CODE (var) == SSA_NAME)
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
are included in the region to be updated. The feeding blocks
are important to guarantee that the PHI arguments are renamed
properly. */
+
+ /* FIXME, this is not needed if we are updating symbols. We are
+ already starting at the ENTRY block anyway. */
bitmap_ior_into (blocks, pruned_idf);
EXECUTE_IF_SET_IN_BITMAP (pruned_idf, 0, i, bi)
{
static void
switch_virtuals_to_full_rewrite (void)
{
- unsigned i;
+ unsigned i = 0;
+ sbitmap_iterator sbi;
if (dump_file)
{
/* 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,
+ EXECUTE_IF_SET_IN_SBITMAP (new_ssa_names, 0, i, sbi)
if (!is_gimple_reg (ssa_name (i)))
- RESET_BIT (new_ssa_names, i));
+ RESET_BIT (new_ssa_names, i);
- EXECUTE_IF_SET_IN_SBITMAP (old_ssa_names, 0, i,
+ EXECUTE_IF_SET_IN_SBITMAP (old_ssa_names, 0, i, sbi)
if (!is_gimple_reg (ssa_name (i)))
- RESET_BIT (old_ssa_names, i));
+ RESET_BIT (old_ssa_names, i);
- bitmap_ior_into (syms_to_rename, update_ssa_stats.virtual_symbols);
+ mark_set_for_renaming (update_ssa_stats.virtual_symbols);
}
void
update_ssa (unsigned update_flags)
{
- bitmap *dfs, blocks;
basic_block bb, start_bb;
bitmap_iterator bi;
- unsigned i;
- sbitmap tmp;
+ unsigned i = 0;
bool insert_phi_p;
+ sbitmap_iterator sbi;
- if (!need_ssa_update_p ())
+ if (!need_ssa_update_p (cfun))
return;
timevar_push (TV_TREE_SSA_INCREMENTAL);
+ if (!update_ssa_initialized_fn)
+ init_update_ssa (cfun);
+ gcc_assert (update_ssa_initialized_fn == cfun);
+
+ blocks_with_phis_to_rewrite = BITMAP_ALLOC (NULL);
+ if (!phis_to_rewrite)
+ phis_to_rewrite = VEC_alloc (gimple_vec, heap, last_basic_block);
+ blocks_to_update = BITMAP_ALLOC (NULL);
+
/* Ensure that the dominance information is up-to-date. */
calculate_dominance_info (CDI_DOMINATORS);
if (insert_phi_p)
{
- /* If the caller requested PHI nodes to be added, compute
- dominance frontiers and initialize live-in information data
- structures (DEF_BLOCKS). */
- dfs = (bitmap *) xmalloc (last_basic_block * sizeof (bitmap *));
- FOR_EACH_BB (bb)
- dfs[bb->index] = BITMAP_ALLOC (NULL);
- compute_dominance_frontiers (dfs);
+ /* 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
}
else
{
- dfs = NULL;
def_blocks = NULL;
}
- blocks = BITMAP_ALLOC (NULL);
-
- /* 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;
-
- for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
- {
- REWRITE_THIS_STMT (phi) = 0;
- REGISTER_DEFS_IN_THIS_STMT (phi) = 0;
- }
-
- for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
- {
- tree stmt = bsi_stmt (si);
- REWRITE_THIS_STMT (stmt) = 0;
- REGISTER_DEFS_IN_THIS_STMT (stmt) = 0;
- }
- }
-
/* 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 ())
OLD_SSA_NAMES. */
if (sbitmap_first_set_bit (new_ssa_names) >= 0)
{
- prepare_names_to_update (blocks, insert_phi_p);
+ prepare_names_to_update (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))
+ && bitmap_empty_p (SYMS_TO_RENAME (cfun)))
goto done;
}
/* Next, determine the block at which to start the renaming process. */
- if (!bitmap_empty_p (syms_to_rename))
+ if (!bitmap_empty_p (SYMS_TO_RENAME (cfun)))
{
/* If we have to rename some symbols from scratch, we need to
start the process at the root of the CFG. FIXME, it should
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);
+ /* Traverse the CFG looking for existing 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, 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);
+ start_bb = nearest_common_dominator_for_set (CDI_DOMINATORS,
+ blocks_to_update);
}
/* If requested, insert PHI nodes at the iterated dominance frontier
and for symbols in SYMS_TO_RENAME. */
if (insert_phi_p)
{
+ bitmap *dfs;
+
+ /* 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);
+
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
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,
- insert_updated_phi_nodes_for (ssa_name (i), dfs, blocks,
- update_flags));
+ EXECUTE_IF_SET_IN_SBITMAP (tmp, 0, i, sbi)
+ insert_updated_phi_nodes_for (ssa_name (i), dfs, blocks_to_update,
+ update_flags);
sbitmap_free (tmp);
}
- EXECUTE_IF_SET_IN_BITMAP (syms_to_rename, 0, i, bi)
- insert_updated_phi_nodes_for (referenced_var (i), dfs, blocks,
+ EXECUTE_IF_SET_IN_BITMAP (SYMS_TO_RENAME (cfun), 0, i, bi)
+ insert_updated_phi_nodes_for (referenced_var (i), dfs, blocks_to_update,
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);
+ start_bb = nearest_common_dominator_for_set (CDI_DOMINATORS,
+ blocks_to_update);
}
/* Reset the current definition for name and symbol before renaming
the sub-graph. */
- EXECUTE_IF_SET_IN_SBITMAP (old_ssa_names, 0, i,
- set_current_def (ssa_name (i), NULL_TREE));
+ 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)
+ EXECUTE_IF_SET_IN_BITMAP (SYMS_TO_RENAME (cfun), 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);
+ interesting_blocks = sbitmap_alloc (last_basic_block);
+ sbitmap_zero (interesting_blocks);
+ EXECUTE_IF_SET_IN_BITMAP (blocks_to_update, 0, i, bi)
+ SET_BIT (interesting_blocks, i);
- rewrite_blocks (start_bb, REWRITE_UPDATE, tmp);
+ rewrite_blocks (start_bb, REWRITE_UPDATE);
- sbitmap_free (tmp);
+ sbitmap_free (interesting_blocks);
/* Debugging dumps. */
if (dump_file)
start_bb->index);
c = 0;
- EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
+ EXECUTE_IF_SET_IN_BITMAP (blocks_to_update, 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",
if (dump_flags & TDF_DETAILS)
{
fprintf (dump_file, "Affected blocks: ");
- EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
+ EXECUTE_IF_SET_IN_BITMAP (blocks_to_update, 0, i, bi)
fprintf (dump_file, "%u ", i);
fprintf (dump_file, "\n");
}
/* Free allocated memory. */
done:
- if (insert_phi_p)
- {
- FOR_EACH_BB (bb)
- BITMAP_FREE (dfs[bb->index]);
- free (dfs);
- }
-
- BITMAP_FREE (blocks);
delete_update_ssa ();
timevar_pop (TV_TREE_SSA_INCREMENTAL);