bd52d17906
too large to list, but see: http://gcc.gnu.org/gcc-3.4/changes.html http://gcc.gnu.org/gcc-4.0/changes.html http://gcc.gnu.org/gcc-4.1/changes.html for the details.
366 lines
10 KiB
C
366 lines
10 KiB
C
/* Register conflict graph computation routines.
|
||
Copyright (C) 2000, 2003, 2004, 2005 Free Software Foundation, Inc.
|
||
Contributed by CodeSourcery, LLC
|
||
|
||
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) any later
|
||
version.
|
||
|
||
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
|
||
WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
||
FITNESS FOR A PARTICULAR PURPOSE. See the 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. */
|
||
|
||
/* References:
|
||
|
||
Building an Optimizing Compiler
|
||
Robert Morgan
|
||
Butterworth-Heinemann, 1998 */
|
||
|
||
#include "config.h"
|
||
#include "system.h"
|
||
#include "coretypes.h"
|
||
#include "tm.h"
|
||
#include "obstack.h"
|
||
#include "hashtab.h"
|
||
#include "rtl.h"
|
||
#include "hard-reg-set.h"
|
||
#include "basic-block.h"
|
||
|
||
/* A register conflict graph is an undirected graph containing nodes
|
||
for some or all of the regs used in a function. Arcs represent
|
||
conflicts, i.e. two nodes are connected by an arc if there is a
|
||
point in the function at which the regs corresponding to the two
|
||
nodes are both live.
|
||
|
||
The conflict graph is represented by the data structures described
|
||
in Morgan section 11.3.1. Nodes are not stored explicitly; only
|
||
arcs are. An arc stores the numbers of the regs it connects.
|
||
|
||
Arcs can be located by two methods:
|
||
|
||
- The two reg numbers for each arc are hashed into a single
|
||
value, and the arc is placed in a hash table according to this
|
||
value. This permits quick determination of whether a specific
|
||
conflict is present in the graph.
|
||
|
||
- Additionally, the arc data structures are threaded by a set of
|
||
linked lists by single reg number. Since each arc references
|
||
two regs, there are two next pointers, one for the
|
||
smaller-numbered reg and one for the larger-numbered reg. This
|
||
permits the quick enumeration of conflicts for a single
|
||
register.
|
||
|
||
Arcs are allocated from an obstack. */
|
||
|
||
/* An arc in a conflict graph. */
|
||
|
||
struct conflict_graph_arc_def
|
||
{
|
||
/* The next element of the list of conflicts involving the
|
||
smaller-numbered reg, as an index in the table of arcs of this
|
||
graph. Contains NULL if this is the tail. */
|
||
struct conflict_graph_arc_def *smaller_next;
|
||
|
||
/* The next element of the list of conflicts involving the
|
||
larger-numbered reg, as an index in the table of arcs of this
|
||
graph. Contains NULL if this is the tail. */
|
||
struct conflict_graph_arc_def *larger_next;
|
||
|
||
/* The smaller-numbered reg involved in this conflict. */
|
||
int smaller;
|
||
|
||
/* The larger-numbered reg involved in this conflict. */
|
||
int larger;
|
||
};
|
||
|
||
typedef struct conflict_graph_arc_def *conflict_graph_arc;
|
||
typedef const struct conflict_graph_arc_def *const_conflict_graph_arc;
|
||
|
||
|
||
/* A conflict graph. */
|
||
|
||
struct conflict_graph_def
|
||
{
|
||
/* A hash table of arcs. Used to search for a specific conflict. */
|
||
htab_t arc_hash_table;
|
||
|
||
/* The number of regs this conflict graph handles. */
|
||
int num_regs;
|
||
|
||
/* For each reg, the arc at the head of a list that threads through
|
||
all the arcs involving that reg. An entry is NULL if no
|
||
conflicts exist involving that reg. */
|
||
conflict_graph_arc *neighbor_heads;
|
||
|
||
/* Arcs are allocated from here. */
|
||
struct obstack arc_obstack;
|
||
};
|
||
|
||
/* The initial capacity (number of conflict arcs) for newly-created
|
||
conflict graphs. */
|
||
#define INITIAL_ARC_CAPACITY 64
|
||
|
||
|
||
/* Computes the hash value of the conflict graph arc connecting regs
|
||
R1 and R2. R1 is assumed to be smaller or equal to R2. */
|
||
#define CONFLICT_HASH_FN(R1, R2) ((R2) * ((R2) - 1) / 2 + (R1))
|
||
|
||
static hashval_t arc_hash (const void *);
|
||
static int arc_eq (const void *, const void *);
|
||
static int print_conflict (int, int, void *);
|
||
|
||
/* Callback function to compute the hash value of an arc. Uses
|
||
current_graph to locate the graph to which the arc belongs. */
|
||
|
||
static hashval_t
|
||
arc_hash (const void *arcp)
|
||
{
|
||
const_conflict_graph_arc arc = (const_conflict_graph_arc) arcp;
|
||
|
||
return CONFLICT_HASH_FN (arc->smaller, arc->larger);
|
||
}
|
||
|
||
/* Callback function to determine the equality of two arcs in the hash
|
||
table. */
|
||
|
||
static int
|
||
arc_eq (const void *arcp1, const void *arcp2)
|
||
{
|
||
const_conflict_graph_arc arc1 = (const_conflict_graph_arc) arcp1;
|
||
const_conflict_graph_arc arc2 = (const_conflict_graph_arc) arcp2;
|
||
|
||
return arc1->smaller == arc2->smaller && arc1->larger == arc2->larger;
|
||
}
|
||
|
||
/* Creates an empty conflict graph to hold conflicts among NUM_REGS
|
||
registers. */
|
||
|
||
conflict_graph
|
||
conflict_graph_new (int num_regs)
|
||
{
|
||
conflict_graph graph = xmalloc (sizeof (struct conflict_graph_def));
|
||
graph->num_regs = num_regs;
|
||
|
||
/* Set up the hash table. No delete action is specified; memory
|
||
management of arcs is through the obstack. */
|
||
graph->arc_hash_table
|
||
= htab_create (INITIAL_ARC_CAPACITY, &arc_hash, &arc_eq, NULL);
|
||
|
||
/* Create an obstack for allocating arcs. */
|
||
obstack_init (&graph->arc_obstack);
|
||
|
||
/* Create and zero the lookup table by register number. */
|
||
graph->neighbor_heads = xcalloc (num_regs, sizeof (conflict_graph_arc));
|
||
|
||
return graph;
|
||
}
|
||
|
||
/* Deletes a conflict graph. */
|
||
|
||
void
|
||
conflict_graph_delete (conflict_graph graph)
|
||
{
|
||
obstack_free (&graph->arc_obstack, NULL);
|
||
htab_delete (graph->arc_hash_table);
|
||
free (graph->neighbor_heads);
|
||
free (graph);
|
||
}
|
||
|
||
/* Adds a conflict to GRAPH between regs REG1 and REG2, which must be
|
||
distinct. Returns nonzero, unless the conflict is already present
|
||
in GRAPH, in which case it does nothing and returns zero. */
|
||
|
||
int
|
||
conflict_graph_add (conflict_graph graph, int reg1, int reg2)
|
||
{
|
||
int smaller = MIN (reg1, reg2);
|
||
int larger = MAX (reg1, reg2);
|
||
struct conflict_graph_arc_def dummy;
|
||
conflict_graph_arc arc;
|
||
void **slot;
|
||
|
||
/* A reg cannot conflict with itself. */
|
||
gcc_assert (reg1 != reg2);
|
||
|
||
dummy.smaller = smaller;
|
||
dummy.larger = larger;
|
||
slot = htab_find_slot (graph->arc_hash_table, (void *) &dummy, INSERT);
|
||
|
||
/* If the conflict is already there, do nothing. */
|
||
if (*slot != NULL)
|
||
return 0;
|
||
|
||
/* Allocate an arc. */
|
||
arc
|
||
= obstack_alloc (&graph->arc_obstack,
|
||
sizeof (struct conflict_graph_arc_def));
|
||
|
||
/* Record the reg numbers. */
|
||
arc->smaller = smaller;
|
||
arc->larger = larger;
|
||
|
||
/* Link the conflict into two lists, one for each reg. */
|
||
arc->smaller_next = graph->neighbor_heads[smaller];
|
||
graph->neighbor_heads[smaller] = arc;
|
||
arc->larger_next = graph->neighbor_heads[larger];
|
||
graph->neighbor_heads[larger] = arc;
|
||
|
||
/* Put it in the hash table. */
|
||
*slot = (void *) arc;
|
||
|
||
return 1;
|
||
}
|
||
|
||
/* Returns nonzero if a conflict exists in GRAPH between regs REG1
|
||
and REG2. */
|
||
|
||
int
|
||
conflict_graph_conflict_p (conflict_graph graph, int reg1, int reg2)
|
||
{
|
||
/* Build an arc to search for. */
|
||
struct conflict_graph_arc_def arc;
|
||
arc.smaller = MIN (reg1, reg2);
|
||
arc.larger = MAX (reg1, reg2);
|
||
|
||
return htab_find (graph->arc_hash_table, (void *) &arc) != NULL;
|
||
}
|
||
|
||
/* Calls ENUM_FN for each conflict in GRAPH involving REG. EXTRA is
|
||
passed back to ENUM_FN. */
|
||
|
||
void
|
||
conflict_graph_enum (conflict_graph graph, int reg,
|
||
conflict_graph_enum_fn enum_fn, void *extra)
|
||
{
|
||
conflict_graph_arc arc = graph->neighbor_heads[reg];
|
||
while (arc != NULL)
|
||
{
|
||
/* Invoke the callback. */
|
||
if ((*enum_fn) (arc->smaller, arc->larger, extra))
|
||
/* Stop if requested. */
|
||
break;
|
||
|
||
/* Which next pointer to follow depends on whether REG is the
|
||
smaller or larger reg in this conflict. */
|
||
if (reg < arc->larger)
|
||
arc = arc->smaller_next;
|
||
else
|
||
arc = arc->larger_next;
|
||
}
|
||
}
|
||
|
||
/* For each conflict between a register x and SRC in GRAPH, adds a
|
||
conflict to GRAPH between x and TARGET. */
|
||
|
||
void
|
||
conflict_graph_merge_regs (conflict_graph graph, int target, int src)
|
||
{
|
||
conflict_graph_arc arc = graph->neighbor_heads[src];
|
||
|
||
if (target == src)
|
||
return;
|
||
|
||
while (arc != NULL)
|
||
{
|
||
int other = arc->smaller;
|
||
|
||
if (other == src)
|
||
other = arc->larger;
|
||
|
||
conflict_graph_add (graph, target, other);
|
||
|
||
/* Which next pointer to follow depends on whether REG is the
|
||
smaller or larger reg in this conflict. */
|
||
if (src < arc->larger)
|
||
arc = arc->smaller_next;
|
||
else
|
||
arc = arc->larger_next;
|
||
}
|
||
}
|
||
|
||
/* Holds context information while a conflict graph is being traversed
|
||
for printing. */
|
||
|
||
struct print_context
|
||
{
|
||
/* The file pointer to which we're printing. */
|
||
FILE *fp;
|
||
|
||
/* The reg whose conflicts we're printing. */
|
||
int reg;
|
||
|
||
/* Whether a conflict has already been printed for this reg. */
|
||
int started;
|
||
};
|
||
|
||
/* Callback function when enumerating conflicts during printing. */
|
||
|
||
static int
|
||
print_conflict (int reg1, int reg2, void *contextp)
|
||
{
|
||
struct print_context *context = (struct print_context *) contextp;
|
||
int reg;
|
||
|
||
/* If this is the first conflict printed for this reg, start a new
|
||
line. */
|
||
if (! context->started)
|
||
{
|
||
fprintf (context->fp, " %d:", context->reg);
|
||
context->started = 1;
|
||
}
|
||
|
||
/* Figure out the reg whose conflicts we're printing. The other reg
|
||
is the interesting one. */
|
||
if (reg1 == context->reg)
|
||
reg = reg2;
|
||
else
|
||
{
|
||
gcc_assert (reg2 == context->reg);
|
||
reg = reg1;
|
||
}
|
||
|
||
/* Print the conflict. */
|
||
fprintf (context->fp, " %d", reg);
|
||
|
||
/* Continue enumerating. */
|
||
return 0;
|
||
}
|
||
|
||
/* Prints the conflicts in GRAPH to FP. */
|
||
|
||
void
|
||
conflict_graph_print (conflict_graph graph, FILE *fp)
|
||
{
|
||
int reg;
|
||
struct print_context context;
|
||
|
||
context.fp = fp;
|
||
fprintf (fp, "Conflicts:\n");
|
||
|
||
/* Loop over registers supported in this graph. */
|
||
for (reg = 0; reg < graph->num_regs; ++reg)
|
||
{
|
||
context.reg = reg;
|
||
context.started = 0;
|
||
|
||
/* Scan the conflicts for reg, printing as we go. A label for
|
||
this line will be printed the first time a conflict is
|
||
printed for the reg; we won't start a new line if this reg
|
||
has no conflicts. */
|
||
conflict_graph_enum (graph, reg, &print_conflict, &context);
|
||
|
||
/* If this reg does have conflicts, end the line. */
|
||
if (context.started)
|
||
fputc ('\n', fp);
|
||
}
|
||
}
|