/* Rename SSA copies.
- Copyright (C) 2004, 2006, 2007, 2008 Free Software Foundation, Inc.
+ Copyright (C) 2004, 2006, 2007, 2008, 2009, 2010, 2011
+ Free Software Foundation, Inc.
Contributed by Andrew MacLeod <amacleod@redhat.com>
This file is part of GCC.
#include "flags.h"
#include "basic-block.h"
#include "function.h"
-#include "diagnostic.h"
+#include "tree-pretty-print.h"
#include "bitmap.h"
#include "tree-flow.h"
#include "gimple.h"
#include "tree-pass.h"
#include "langhooks.h"
+static struct
+{
+ /* Number of copies coalesced. */
+ int coalesced;
+} stats;
+
/* The following routines implement the SSA copy renaming phase.
This optimization looks for copies between 2 SSA_NAMES, either through a
T.3_5 = <blah>
a_1 = T.3_5
- If this copy couldn't be copy propagated, it could possibly remain in the
- program throughout the optimization phases. After SSA->normal, it would
+ If this copy couldn't be copy propagated, it could possibly remain in the
+ program throughout the optimization phases. After SSA->normal, it would
become:
T.3 = <blah>
a = T.3
-
- Since T.3_5 is distinct from all other SSA versions of T.3, there is no
- fundamental reason why the base variable needs to be T.3, subject to
- certain restrictions. This optimization attempts to determine if we can
+
+ Since T.3_5 is distinct from all other SSA versions of T.3, there is no
+ fundamental reason why the base variable needs to be T.3, subject to
+ certain restrictions. This optimization attempts to determine if we can
change the base variable on copies like this, and result in code such as:
a_5 = <blah>
a_1 = a_5
- This gives the SSA->normal pass a shot at coalescing a_1 and a_5. If it is
+ This gives the SSA->normal pass a shot at coalescing a_1 and a_5. If it is
possible, the copy goes away completely. If it isn't possible, a new temp
will be created for a_5, and you will end up with the exact same code:
a_1 = <blah>
<blah2> = a_1
- get turned into
-
+ get turned into
+
T.3_5 = <blah>
a_1 = T.3_5
<blah2> = a_1
<blah2> = a_1
which copy propagation would then turn into:
-
+
a_5 = <blah>
<blah2> = a_5
return false;
}
- /* Never attempt to coalesce 2 difference parameters. */
+ /* Never attempt to coalesce 2 different parameters. */
if (TREE_CODE (root1) == PARM_DECL && TREE_CODE (root2) == PARM_DECL)
{
if (debug)
ign1 = TREE_CODE (root1) == VAR_DECL && DECL_IGNORED_P (root1);
ign2 = TREE_CODE (root2) == VAR_DECL && DECL_IGNORED_P (root2);
- /* Never attempt to coalesce 2 user variables unless one is an inline
+ /* Never attempt to coalesce 2 user variables unless one is an inline
variable. */
if (!ign1 && !ign2)
{
ign2 = true;
else if (DECL_FROM_INLINE (root1))
ign1 = true;
- else
+ else
{
if (debug)
fprintf (debug, " : 2 different USER vars. No coalesce.\n");
}
}
- /* If both values have default defs, we can't coalesce. If only one has a
+ /* If both values have default defs, we can't coalesce. If only one has a
tag, make sure that variable is the new root partition. */
if (gimple_default_def (cfun, root1))
{
ign2 = false;
}
- /* Don't coalesce if the two variables aren't type compatible. */
- if (!types_compatible_p (TREE_TYPE (root1), TREE_TYPE (root2)))
+ /* Don't coalesce if the new chosen root variable would be read-only.
+ If both ign1 && ign2, then the root var of the larger partition
+ wins, so reject in that case if any of the root vars is TREE_READONLY.
+ Otherwise reject only if the root var, on which replace_ssa_name_symbol
+ will be called below, is readonly. */
+ if ((TREE_READONLY (root1) && ign2) || (TREE_READONLY (root2) && ign1))
{
if (debug)
- fprintf (debug, " : Incompatible types. No coalesce.\n");
+ fprintf (debug, " : Readonly variable. No coalesce.\n");
return false;
}
- /* Don't coalesce if the aliasing sets of the types are different. */
- if (POINTER_TYPE_P (TREE_TYPE (root1))
- && POINTER_TYPE_P (TREE_TYPE (root2))
- && ((get_alias_set (TREE_TYPE (TREE_TYPE (root1)))
- != get_alias_set (TREE_TYPE (TREE_TYPE (root2))))
- || (DECL_P (root1) && DECL_P (root2)
- && DECL_NO_TBAA_P (root1) != DECL_NO_TBAA_P (root2))))
+ /* Don't coalesce if the two variables aren't type compatible . */
+ if (!types_compatible_p (TREE_TYPE (root1), TREE_TYPE (root2))
+ /* There is a disconnect between the middle-end type-system and
+ VRP, avoid coalescing enum types with different bounds. */
+ || ((TREE_CODE (TREE_TYPE (root1)) == ENUMERAL_TYPE
+ || TREE_CODE (TREE_TYPE (root2)) == ENUMERAL_TYPE)
+ && TREE_TYPE (root1) != TREE_TYPE (root2)))
{
if (debug)
- fprintf (debug, " : 2 different aliasing sets. No coalesce.\n");
+ fprintf (debug, " : Incompatible types. No coalesce.\n");
return false;
}
-
/* Merge the two partitions. */
p3 = partition_union (map->var_partition, p1, p2);
- /* Set the root variable of the partition to the better choice, if there is
+ /* Set the root variable of the partition to the better choice, if there is
one. */
if (!ign2)
replace_ssa_name_symbol (partition_to_var (map, p3), root2);
if (debug)
{
fprintf (debug, " --> P%d ", p3);
- print_generic_expr (debug, SSA_NAME_VAR (partition_to_var (map, p3)),
+ print_generic_expr (debug, SSA_NAME_VAR (partition_to_var (map, p3)),
TDF_SLIM);
fprintf (debug, "\n");
}
/* This function will make a pass through the IL, and attempt to coalesce any
SSA versions which occur in PHI's or copies. Coalescing is accomplished by
- changing the underlying root variable of all coalesced version. This will
- then cause the SSA->normal pass to attempt to coalesce them all to the same
+ changing the underlying root variable of all coalesced version. This will
+ then cause the SSA->normal pass to attempt to coalesce them all to the same
variable. */
static unsigned int
else
debug = NULL;
- map = init_var_map (num_ssa_names + 1);
+ map = init_var_map (num_ssa_names);
FOR_EACH_BB (bb)
{
/* Now one more pass to make all elements of a partition share the same
root variable. */
-
- for (x = 1; x <= num_ssa_names; x++)
+
+ for (x = 1; x < num_ssa_names; x++)
{
part_var = partition_to_var (map, x);
if (!part_var)
continue;
- var = map->partition_to_var[x];
+ var = ssa_name (x);
if (debug)
{
if (SSA_NAME_VAR (var) != SSA_NAME_VAR (part_var))
fprintf (debug, "\n");
}
}
+ stats.coalesced++;
replace_ssa_name_symbol (var, SSA_NAME_VAR (part_var));
}
+ statistics_counter_event (cfun, "copies coalesced",
+ stats.coalesced);
delete_var_map (map);
return updated ? TODO_remove_unused_locals : 0;
}
return flag_tree_copyrename != 0;
}
-struct gimple_opt_pass pass_rename_ssa_copies =
+struct gimple_opt_pass pass_rename_ssa_copies =
{
{
GIMPLE_PASS,
PROP_cfg | PROP_ssa, /* properties_required */
0, /* properties_provided */
0, /* properties_destroyed */
- 0, /* todo_flags_start */
+ 0, /* todo_flags_start */
TODO_dump_func | TODO_verify_ssa /* todo_flags_finish */
}
-};
+};