/* Routines for performing Temporary Expression Replacement (TER) in SSA trees.
- Copyright (C) 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
+ Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008 Free Software Foundation,
+ Inc.
Contributed by Andrew MacLeod <amacleod@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, 51 Franklin Street, Fifth Floor,
-Boston, MA 02110-1301, USA. */
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
#include "config.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
-#include "flags.h"
-#include "rtl.h"
-#include "tm_p.h"
-#include "ggc.h"
-#include "langhooks.h"
-#include "hard-reg-set.h"
-#include "basic-block.h"
-#include "output.h"
-#include "expr.h"
-#include "function.h"
#include "diagnostic.h"
#include "bitmap.h"
#include "tree-flow.h"
-#include "tree-gimple.h"
-#include "tree-inline.h"
-#include "varray.h"
-#include "timevar.h"
-#include "hashtab.h"
#include "tree-dump.h"
#include "tree-ssa-live.h"
-#include "tree-pass.h"
-#include "toplev.h"
-#include "vecprim.h"
+#include "flags.h"
/* Temporary Expression Replacement (TER)
Replace SSA version variables during out-of-ssa with their defining
- expression if there is only one use of the variable.
+ expression if there is only one use of the variable.
This pass is required in order for the RTL expansion pass to see larger
chunks of code. This allows it to make better choices on RTL pattern
selection. When expand is rewritten and merged with out-of-ssa, and
- understands SSA, this should be eliminated.
+ understands SSA, this should be eliminated.
A pass is made through the function, one block at a time. No cross block
information is tracked.
Variables which only have one use, and whose defining stmt is considered
a replaceable expression (see is_replaceable_p) are tracked to see whether
- they can be replaced at their use location.
-
+ they can be replaced at their use location.
+
n_12 = C * 10
a_2 = b_5 + 6
v_9 = a_2 * n_12
v_9 = (b_5 + 6) * (C * 10)
which will then have the ssa_name assigned to regular variables, and the
- resulting code which will be passed ot the expander looks something like:
+ resulting code which will be passed to the expander looks something like:
v = (b + 6) * (C * 10)
-
- This requires ensuring that none of the variables used by the expression
- change between the def point and where it is used. Furthermore, if any
- of the ssa_names used in this expression are themselves replaceable, we
- have to ensure none of that expressions' arguments change either.
- Although SSA_NAMES themselves don't change, this pass is performed after
- coalescing has coalesced different SSA_NAMES together, so there could be a
+
+ This requires ensuring that none of the variables used by the expression
+ change between the def point and where it is used. Furthermore, if any
+ of the ssa_names used in this expression are themselves replaceable, we
+ have to ensure none of that expressions' arguments change either.
+ Although SSA_NAMES themselves don't change, this pass is performed after
+ coalescing has coalesced different SSA_NAMES together, so there could be a
definition of an SSA_NAME which is coalesced with a use that causes a
- problem. ie
-
+ problem, i.e.,
+
PHI b_5 = <b_8(2), b_14(1)>
<...>
a_2 = b_5 + 6
v_9 = a_2 * n_12
<...>
- If b_5, b_8 and b_14 are all colaesced together...
+ If b_5, b_8 and b_14 are all coalesced together...
The expression b_5 + 6 CANNOT replace the use in the statement defining v_9
because b_8 is in fact killing the value of b_5 since they share a partition
- and will be assigned the same memory or regster location.
-
+ and will be assigned the same memory or register location.
+
TER implements this but stepping through the instructions in a block and
- tracking potential expressions for replacement, and the paritions they are
+ tracking potential expressions for replacement, and the partitions they are
dependent on. Expressions are represented by the SSA_NAME_VERSION of the
- DEF on the LHS of a GIMPLE_MODIFY_STMT and the expression is the RHS.
+ DEF on the LHS of a GIMPLE_ASSIGN and the expression is the RHS.
When a stmt is determined to be a possible replacement expression, the
following steps are taken:
- EXPR_DECL_UID bitmap is allocated and set to the base variable UID of the
- def and any uses in the expression. non-NULL means the expression is being
+ EXPR_DECL_UID bitmap is allocated and set to the base variable UID of the
+ def and any uses in the expression. non-NULL means the expression is being
tracked. The UID's themselves are used to prevent TER substitution into
- accumulating sequences.
- ie
+ accumulating sequences, i.e.,
+
x = x + y
x = x + z
x = x + w
etc.
this can result in very large expressions which don't accomplish anything
- see PR tree-optimization/17549.
+ see PR tree-optimization/17549.
- PARTITION_DEPENDENCIES is another bitmap array, and it has a bit set for any
+ PARTITION_DEPENDENCIES is another bitmap array, and it has a bit set for any
partition which is used in the expression. This is primarily used to remove
an expression from the partition kill lists when a decision is made whether
to replace it or not. This is indexed by ssa version number as well, and
indicates a partition number. virtual operands are not tracked individually,
- but they are summarized by an artifical partition called VIRTUAL_PARTITION.
- This means a MAY or MUST def will kill *ALL* expressions that are dependant
+ but they are summarized by an artificial partition called VIRTUAL_PARTITION.
+ This means a MAY or MUST def will kill *ALL* expressions that are dependent
on a virtual operand.
- Note that the EXPR_DECL_UID and this bitmap represent very similar
+ Note that the EXPR_DECL_UID and this bitmap represent very similar
information, but the info in one is not easy to obtain from the other.
KILL_LIST is yet another bitmap array, this time it is indexed by partition
- number, and represents a list of active expressions which will will no
+ number, and represents a list of active expressions which will will no
longer be valid if a definition into this partition takes place.
PARTITION_IN_USE is simply a bitmap which is used to track which partitions
- currently have sokmething in their kill list. This is used at the end of
+ currently have something in their kill list. This is used at the end of
a block to clear out the KILL_LIST bitmaps at the end of each block.
- NEW_REPLACEABLE_DEPENDENCIES is used as a temporary place to store
- dependencies which will be reused by the current defintion. ALl the uses
+ NEW_REPLACEABLE_DEPENDENCIES is used as a temporary place to store
+ dependencies which will be reused by the current definition. All the uses
on an expression are processed before anything else is done. If a use is
determined to be a replaceable expression AND the current stmt is also going
to be replaceable, all the dependencies of this replaceable use will be
a_2 = b_5 + 6
v_8 = a_2 + c_4
- a_2's expression 'b_5 + 6' is determined to be replaceable at the use
+ a_2's expression 'b_5 + 6' is determined to be replaceable at the use
location. It is dependent on the partition 'b_5' is in. This is cached into
- the NEW_REPLACEABLE_DEPENDENCIES bitmap. and when v_8 is examined for
- replaceablility, it is a candidate, and it is dependent on the partition
+ the NEW_REPLACEABLE_DEPENDENCIES bitmap, and when v_8 is examined for
+ replaceability, it is a candidate, and it is dependent on the partition
b_5 is in *NOT* a_2, as well as c_4's partition.
if v_8 is also replaceable:
x_9 = v_8 * 5
x_9 is dependent on partitions b_5, and c_4
-
- if a statement is found which has either of those partitions written to
+
+ if a statement is found which has either of those partitions written to
before x_9 is used, then x_9 itself is NOT replaceable. */
/* Temporary Expression Replacement (TER) table information. */
-typedef struct temp_expr_table_d
+typedef struct temp_expr_table_d
{
var_map map;
bitmap *partition_dependencies; /* Partitions expr is dependent on. */
- tree *replaceable_expressions; /* Replacement expression table. */
+ bitmap replaceable_expressions; /* Replacement expression table. */
bitmap *expr_decl_uids; /* Base uids of exprs. */
bitmap *kill_list; /* Expr's killed by a partition. */
- int virtual_partition; /* Psuedo partition for virtual ops. */
- bitmap partition_in_use; /* Partitions with kill entires. */
+ int virtual_partition; /* Pseudo partition for virtual ops. */
+ bitmap partition_in_use; /* Partitions with kill entries. */
bitmap new_replaceable_dependencies; /* Holding place for pending dep's. */
int *num_in_part; /* # of ssa_names in a partition. */
} *temp_expr_table_p;
-/* Used to indicate a dependency on V_MAY_DEFs. */
+/* Used to indicate a dependency on VDEFs. */
#define VIRTUAL_PARTITION(table) (table->virtual_partition)
#ifdef ENABLE_CHECKING
}
-/* Free TER table T. If there are valid replacements, return the expression
+/* Free TER table T. If there are valid replacements, return the expression
vector. */
-static tree *
+static bitmap
free_temp_expr_table (temp_expr_table_p t)
{
- tree *ret = NULL;
- unsigned i;
+ bitmap ret = NULL;
#ifdef ENABLE_CHECKING
unsigned x;
for (x = 0; x <= num_var_partitions (t->map); x++)
gcc_assert (!t->kill_list[x]);
+ for (x = 0; x < num_ssa_names; x++)
+ {
+ gcc_assert (t->expr_decl_uids[x] == NULL);
+ gcc_assert (t->partition_dependencies[x] == NULL);
+ }
#endif
BITMAP_FREE (t->partition_in_use);
+ BITMAP_FREE (t->new_replaceable_dependencies);
- for (i = 0; i <= num_ssa_names; i++)
- if (t->expr_decl_uids[i])
- BITMAP_FREE (t->expr_decl_uids[i]);
free (t->expr_decl_uids);
-
free (t->kill_list);
free (t->partition_dependencies);
+ free (t->num_in_part);
if (t->replaceable_expressions)
ret = t->replaceable_expressions;
{
if (!tab->replaceable_expressions)
return false;
- return tab->replaceable_expressions[version] != NULL_TREE;
+ return bitmap_bit_p (tab->replaceable_expressions, version);
}
-/* Add partition P to the list if partititons VERSION is dependent on. TAB is
+/* Add partition P to the list if partitions VERSION is dependent on. TAB is
the expression table */
static inline void
}
-/* Remove VER from the partition kill list for P. TAB is the expression
+/* Remove VER from the partition kill list for P. TAB is the expression
table. */
-static inline void
+static inline void
remove_from_partition_kill_list (temp_expr_table_p tab, int p, int version)
{
#ifdef ENABLE_CHECKING
}
-/* Add a dependency between the def of ssa VERSION and VAR. If VAR is
- replaceable by an expression, add a dependence each of the elements of the
+/* Add a dependency between the def of ssa VERSION and VAR. If VAR is
+ replaceable by an expression, add a dependence each of the elements of the
expression. These are contained in the new_replaceable list. TAB is the
expression table. */
{
if (!bitmap_empty_p (tab->new_replaceable_dependencies))
{
- /* Version will now be killed by a write to any partition the
+ /* Version will now be killed by a write to any partition the
substituted expression would have been killed by. */
EXECUTE_IF_SET_IN_BITMAP (tab->new_replaceable_dependencies, 0, x, bi)
add_to_partition_kill_list (tab, x, version);
- /* Rather than set partition_dependencies and in_use lists bit by
+ /* Rather than set partition_dependencies and in_use lists bit by
bit, simply OR in the new_replaceable_dependencies bits. */
if (!tab->partition_dependencies[version])
tab->partition_dependencies[version] = BITMAP_ALLOC (NULL);
- bitmap_ior_into (tab->partition_dependencies[version],
+ bitmap_ior_into (tab->partition_dependencies[version],
tab->new_replaceable_dependencies);
- bitmap_ior_into (tab->partition_in_use,
+ bitmap_ior_into (tab->partition_in_use,
tab->new_replaceable_dependencies);
/* It is only necessary to add these once. */
bitmap_clear (tab->new_replaceable_dependencies);
/* Return TRUE if expression STMT is suitable for replacement. */
static inline bool
-is_replaceable_p (tree stmt)
+is_replaceable_p (gimple stmt)
{
- tree call_expr;
use_operand_p use_p;
- tree def, use_stmt;
+ tree def;
+ gimple use_stmt;
+ location_t locus1, locus2;
+ tree block1, block2;
/* Only consider modify stmts. */
- if (TREE_CODE (stmt) != GIMPLE_MODIFY_STMT)
+ if (!is_gimple_assign (stmt))
+ return false;
+
+ /* If the statement may throw an exception, it cannot be replaced. */
+ if (stmt_could_throw_p (stmt))
return false;
/* Punt if there is more than 1 def. */
return false;
/* If the use isn't in this block, it wont be replaced either. */
- if (bb_for_stmt (use_stmt) != bb_for_stmt (stmt))
+ if (gimple_bb (use_stmt) != gimple_bb (stmt))
+ return false;
+
+ locus1 = gimple_location (stmt);
+ block1 = gimple_block (stmt);
+
+ if (gimple_code (use_stmt) == GIMPLE_PHI)
+ {
+ locus2 = 0;
+ block2 = NULL_TREE;
+ }
+ else
+ {
+ locus2 = gimple_location (use_stmt);
+ block2 = gimple_block (use_stmt);
+ }
+
+ if (!optimize
+ && ((locus1 && locus1 != locus2) || (block1 && block1 != block2)))
return false;
/* Used in this block, but at the TOP of the block, not the end. */
- if (TREE_CODE (use_stmt) == PHI_NODE)
+ if (gimple_code (use_stmt) == GIMPLE_PHI)
+ return false;
+
+ /* There must be no VDEFs. */
+ if (gimple_vdef (stmt))
return false;
- /* There must be no V_MAY_DEFS or V_MUST_DEFS. */
- if (!(ZERO_SSA_OPERANDS (stmt, (SSA_OP_VMAYDEF | SSA_OP_VMUSTDEF))))
+ /* Without alias info we can't move around loads. */
+ if (gimple_references_memory_p (stmt) && !optimize)
return false;
/* Float expressions must go through memory if float-store is on. */
- if (flag_float_store
- && FLOAT_TYPE_P (TREE_TYPE (GENERIC_TREE_OPERAND (stmt, 1))))
+ if (flag_float_store
+ && FLOAT_TYPE_P (gimple_expr_type (stmt)))
return false;
- /* Calls to functions with side-effects cannot be replaced. */
- if ((call_expr = get_call_expr_in (stmt)) != NULL_TREE)
- {
- int call_flags = call_expr_flags (call_expr);
- if (TREE_SIDE_EFFECTS (call_expr)
- && !(call_flags & (ECF_PURE | ECF_CONST | ECF_NORETURN)))
- return false;
- }
+ /* An assignment with a register variable on the RHS is not
+ replaceable. */
+ if (gimple_assign_rhs_code (stmt) == VAR_DECL
+ && DECL_HARD_REGISTER (gimple_assign_rhs1 (stmt)))
+ return false;
+
+ /* No function calls can be replaced. */
+ if (is_gimple_call (stmt))
+ return false;
- /* Leave any stmt with voltile operands alone as well. */
- if (stmt_ann (stmt)->has_volatile_ops)
+ /* Leave any stmt with volatile operands alone as well. */
+ if (gimple_has_volatile_ops (stmt))
return false;
-
return true;
}
-/* This function will remove the expression for VERSION from replacement
- consideration in table TAB. If FREE_EXPR is true, then remove the
+/* This function will remove the expression for VERSION from replacement
+ consideration in table TAB. If FREE_EXPR is true, then remove the
expression from consideration as well by freeing the decl uid bitmap. */
static void
}
-/* Create an expression entry fora replaceable expression. */
+/* Create an expression entry for a replaceable expression. */
-static void
-process_replaceable (temp_expr_table_p tab, tree stmt)
+static void
+process_replaceable (temp_expr_table_p tab, gimple stmt)
{
tree var, def, basevar;
int version;
tab->expr_decl_uids[version] = def_vars;
/* If there are VUSES, add a dependence on virtual defs. */
- if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_VUSE))
+ if (gimple_vuse (stmt))
{
make_dependent_on_partition (tab, version, VIRTUAL_PARTITION (tab));
add_to_partition_kill_list (tab, VIRTUAL_PARTITION (tab), version);
{
unsigned version;
- /* Mark every active expr dependent on this var as not replaceable.
+ /* Mark every active expr dependent on this var as not replaceable.
finished_with_expr can modify the bitmap, so we can't execute over it. */
while (tab->kill_list[partition])
{
}
-/* This function kills all expressions in TAB which are dependent on virtual
+/* This function kills all expressions in TAB which are dependent on virtual
partitions. */
static inline void
/* Mark the expression associated with VAR as replaceable, and enter
- the defining stmt into the partition_dependencies table TAB. if
+ the defining stmt into the partition_dependencies table TAB. If
MORE_REPLACING is true, accumulate the pending partition dependencies. */
static void
/* Move the dependence list to the pending listpending. */
if (more_replacing && tab->partition_dependencies[version])
- bitmap_ior_into (tab->new_replaceable_dependencies,
+ bitmap_ior_into (tab->new_replaceable_dependencies,
tab->partition_dependencies[version]);
finished_with_expr (tab, version, !more_replacing);
/* Set the replaceable expression. */
if (!tab->replaceable_expressions)
- tab->replaceable_expressions = XCNEWVEC (tree, num_ssa_names + 1);
- tab->replaceable_expressions[version] = SSA_NAME_DEF_STMT (var);
+ tab->replaceable_expressions = BITMAP_ALLOC (NULL);
+ bitmap_set_bit (tab->replaceable_expressions, version);
}
static void
find_replaceable_in_bb (temp_expr_table_p tab, basic_block bb)
{
- block_stmt_iterator bsi;
- tree stmt, def, use;
- stmt_ann_t ann;
+ gimple_stmt_iterator bsi;
+ gimple stmt;
+ tree def, use;
int partition;
var_map map = tab->map;
ssa_op_iter iter;
bool stmt_replaceable;
- for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
+ for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi))
{
- stmt = bsi_stmt (bsi);
- ann = stmt_ann (stmt);
+ stmt = gsi_stmt (bsi);
+
+ if (is_gimple_debug (stmt))
+ continue;
stmt_replaceable = is_replaceable_p (stmt);
+
/* Determine if this stmt finishes an existing expression. */
FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE)
{
}
}
- /* Mark expression as replaceable unless stmt is volatile or the
- def variable has the same root variable as something in the
+ /* Mark expression as replaceable unless stmt is volatile or the
+ def variable has the same root variable as something in the
substitution list. */
- if (ann->has_volatile_ops || same_root_var)
+ if (gimple_has_volatile_ops (stmt) || same_root_var)
finished_with_expr (tab, ver, true);
else
mark_replaceable (tab, use, stmt_replaceable);
}
}
-
+
/* Next, see if this stmt kills off an active expression. */
FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
{
/* A V_{MAY,MUST}_DEF kills any expression using a virtual operand,
including the current stmt. */
- if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_VIRTUAL_DEFS))
+ if (gimple_vdef (stmt))
kill_virtual_exprs (tab);
}
}
/* This function is the driver routine for replacement of temporary expressions
- in the SSA->normal phase, operating on MAP. If there are replaceable
- expressions, a table is returned which maps SSA versions to the
- expressions they should be replaced with. A NULL_TREE indicates no
- replacement should take place. If there are no replacements at all,
+ in the SSA->normal phase, operating on MAP. If there are replaceable
+ expressions, a table is returned which maps SSA versions to the
+ expressions they should be replaced with. A NULL_TREE indicates no
+ replacement should take place. If there are no replacements at all,
NULL is returned by the function, otherwise an expression vector indexed
by SSA_NAME version numbers. */
-extern tree *
+extern bitmap
find_replaceable_exprs (var_map map)
{
basic_block bb;
temp_expr_table_p table;
- tree *ret;
+ bitmap ret;
table = new_temp_expr_table (map);
FOR_EACH_BB (bb)
{
find_replaceable_in_bb (table, bb);
- gcc_assert (bitmap_empty_p (table->partition_in_use));
-
#ifdef ENABLE_CHECKING
- {
- unsigned i;
- /* Make sure all the tables have been cleared out. */
- for (i = 0; i < num_ssa_names + 1; i++)
- {
- gcc_assert (table->partition_dependencies[i] == NULL);
- gcc_assert (table->expr_decl_uids[i] == NULL);
- if (i < num_var_partitions (map))
- gcc_assert (table->kill_list[i] == NULL);
- }
- }
+ gcc_assert (bitmap_empty_p (table->partition_in_use));
#endif
}
return ret;
}
-
/* Dump TER expression table EXPR to file F. */
-extern void
-dump_replaceable_exprs (FILE *f, tree *expr)
+void
+dump_replaceable_exprs (FILE *f, bitmap expr)
{
- tree stmt, var;
- int x;
+ tree var;
+ unsigned x;
fprintf (f, "\nReplacing Expressions\n");
- for (x = 0; x < (int)num_ssa_names; x++)
- if (expr[x])
+ for (x = 0; x < num_ssa_names; x++)
+ if (bitmap_bit_p (expr, x))
{
- stmt = expr[x];
- var = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_DEF);
- gcc_assert (var != NULL_TREE);
+ var = ssa_name (x);
print_generic_expr (f, var, TDF_SLIM);
fprintf (f, " replace with --> ");
- print_generic_expr (f, TREE_OPERAND (stmt, 1), TDF_SLIM);
+ print_gimple_stmt (f, SSA_NAME_DEF_STMT (var), 0, TDF_SLIM);
fprintf (f, "\n");
}
fprintf (f, "\n");
exclusively to debug TER. F is the place to send debug info and T is the
table being debugged. */
-extern void
+void
debug_ter (FILE *f, temp_expr_table_p t)
{
unsigned x, y;
bitmap_iterator bi;
- fprintf (f, "\nDumping current state of TER\n virtual partition = %d\n",
+ fprintf (f, "\nDumping current state of TER\n virtual partition = %d\n",
VIRTUAL_PARTITION (t));
if (t->replaceable_expressions)
dump_replaceable_exprs (f, t->replaceable_expressions);
{
print_generic_expr (stderr, ssa_name (x), TDF_SLIM);
fprintf (f, " dep-parts : ");
- if (t->partition_dependencies[x]
+ if (t->partition_dependencies[x]
&& !bitmap_empty_p (t->partition_dependencies[x]))
{
EXECUTE_IF_SET_IN_BITMAP (t->partition_dependencies[x], 0, y, bi)
fprintf (stderr, "\n");
}
- bitmap_print (f, t->partition_in_use, "Partitions in use ",
+ bitmap_print (f, t->partition_in_use, "Partitions in use ",
"\npartition KILL lists:\n");
for (x = 0; x <= num_var_partitions (t->map); x++)