/* Register conflict graph computation routines.
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/* Register conflict graph computation routines.
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Copyright (C) 2000, 2003, 2004, 2005, 2007 Free Software Foundation, Inc.
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Copyright (C) 2000, 2003, 2004, 2005, 2007 Free Software Foundation, Inc.
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Contributed by CodeSourcery, LLC
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Contributed by CodeSourcery, LLC
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This file is part of GCC.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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Software Foundation; either version 3, or (at your option) any later
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version.
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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for more details.
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|
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You should have received a copy of the GNU General Public License
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING3. If not see
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along with GCC; see the file COPYING3. If not see
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<http://www.gnu.org/licenses/>. */
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<http://www.gnu.org/licenses/>. */
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/* References:
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/* References:
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Building an Optimizing Compiler
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Building an Optimizing Compiler
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Robert Morgan
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Robert Morgan
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Butterworth-Heinemann, 1998 */
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Butterworth-Heinemann, 1998 */
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#include "config.h"
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#include "config.h"
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#include "system.h"
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#include "system.h"
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#include "coretypes.h"
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#include "coretypes.h"
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#include "tm.h"
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#include "tm.h"
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#include "obstack.h"
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#include "obstack.h"
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#include "hashtab.h"
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#include "hashtab.h"
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#include "rtl.h"
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#include "rtl.h"
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#include "hard-reg-set.h"
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#include "hard-reg-set.h"
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#include "basic-block.h"
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#include "basic-block.h"
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/* A register conflict graph is an undirected graph containing nodes
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/* A register conflict graph is an undirected graph containing nodes
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for some or all of the regs used in a function. Arcs represent
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for some or all of the regs used in a function. Arcs represent
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conflicts, i.e. two nodes are connected by an arc if there is a
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conflicts, i.e. two nodes are connected by an arc if there is a
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point in the function at which the regs corresponding to the two
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point in the function at which the regs corresponding to the two
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nodes are both live.
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nodes are both live.
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The conflict graph is represented by the data structures described
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The conflict graph is represented by the data structures described
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in Morgan section 11.3.1. Nodes are not stored explicitly; only
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in Morgan section 11.3.1. Nodes are not stored explicitly; only
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arcs are. An arc stores the numbers of the regs it connects.
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arcs are. An arc stores the numbers of the regs it connects.
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Arcs can be located by two methods:
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Arcs can be located by two methods:
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|
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- The two reg numbers for each arc are hashed into a single
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- The two reg numbers for each arc are hashed into a single
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value, and the arc is placed in a hash table according to this
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value, and the arc is placed in a hash table according to this
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value. This permits quick determination of whether a specific
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value. This permits quick determination of whether a specific
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conflict is present in the graph.
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conflict is present in the graph.
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- Additionally, the arc data structures are threaded by a set of
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- Additionally, the arc data structures are threaded by a set of
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linked lists by single reg number. Since each arc references
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linked lists by single reg number. Since each arc references
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two regs, there are two next pointers, one for the
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two regs, there are two next pointers, one for the
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smaller-numbered reg and one for the larger-numbered reg. This
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smaller-numbered reg and one for the larger-numbered reg. This
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permits the quick enumeration of conflicts for a single
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permits the quick enumeration of conflicts for a single
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register.
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register.
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Arcs are allocated from an obstack. */
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Arcs are allocated from an obstack. */
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/* An arc in a conflict graph. */
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/* An arc in a conflict graph. */
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struct conflict_graph_arc_def
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struct conflict_graph_arc_def
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{
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{
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/* The next element of the list of conflicts involving the
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/* The next element of the list of conflicts involving the
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smaller-numbered reg, as an index in the table of arcs of this
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smaller-numbered reg, as an index in the table of arcs of this
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graph. Contains NULL if this is the tail. */
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graph. Contains NULL if this is the tail. */
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struct conflict_graph_arc_def *smaller_next;
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struct conflict_graph_arc_def *smaller_next;
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/* The next element of the list of conflicts involving the
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/* The next element of the list of conflicts involving the
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larger-numbered reg, as an index in the table of arcs of this
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larger-numbered reg, as an index in the table of arcs of this
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graph. Contains NULL if this is the tail. */
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graph. Contains NULL if this is the tail. */
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struct conflict_graph_arc_def *larger_next;
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struct conflict_graph_arc_def *larger_next;
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/* The smaller-numbered reg involved in this conflict. */
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/* The smaller-numbered reg involved in this conflict. */
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int smaller;
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int smaller;
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/* The larger-numbered reg involved in this conflict. */
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/* The larger-numbered reg involved in this conflict. */
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int larger;
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int larger;
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};
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};
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typedef struct conflict_graph_arc_def *conflict_graph_arc;
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typedef struct conflict_graph_arc_def *conflict_graph_arc;
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typedef const struct conflict_graph_arc_def *const_conflict_graph_arc;
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typedef const struct conflict_graph_arc_def *const_conflict_graph_arc;
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/* A conflict graph. */
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/* A conflict graph. */
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struct conflict_graph_def
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struct conflict_graph_def
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{
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{
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/* A hash table of arcs. Used to search for a specific conflict. */
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/* A hash table of arcs. Used to search for a specific conflict. */
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htab_t arc_hash_table;
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htab_t arc_hash_table;
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/* The number of regs this conflict graph handles. */
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/* The number of regs this conflict graph handles. */
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int num_regs;
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int num_regs;
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/* For each reg, the arc at the head of a list that threads through
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/* For each reg, the arc at the head of a list that threads through
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all the arcs involving that reg. An entry is NULL if no
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all the arcs involving that reg. An entry is NULL if no
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conflicts exist involving that reg. */
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conflicts exist involving that reg. */
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conflict_graph_arc *neighbor_heads;
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conflict_graph_arc *neighbor_heads;
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/* Arcs are allocated from here. */
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/* Arcs are allocated from here. */
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struct obstack arc_obstack;
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struct obstack arc_obstack;
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};
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};
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/* The initial capacity (number of conflict arcs) for newly-created
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/* The initial capacity (number of conflict arcs) for newly-created
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conflict graphs. */
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conflict graphs. */
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#define INITIAL_ARC_CAPACITY 64
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#define INITIAL_ARC_CAPACITY 64
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/* Computes the hash value of the conflict graph arc connecting regs
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/* Computes the hash value of the conflict graph arc connecting regs
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R1 and R2. R1 is assumed to be smaller or equal to R2. */
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R1 and R2. R1 is assumed to be smaller or equal to R2. */
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#define CONFLICT_HASH_FN(R1, R2) ((R2) * ((R2) - 1) / 2 + (R1))
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#define CONFLICT_HASH_FN(R1, R2) ((R2) * ((R2) - 1) / 2 + (R1))
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static hashval_t arc_hash (const void *);
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static hashval_t arc_hash (const void *);
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static int arc_eq (const void *, const void *);
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static int arc_eq (const void *, const void *);
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static int print_conflict (int, int, void *);
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static int print_conflict (int, int, void *);
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/* Callback function to compute the hash value of an arc. Uses
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/* Callback function to compute the hash value of an arc. Uses
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current_graph to locate the graph to which the arc belongs. */
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current_graph to locate the graph to which the arc belongs. */
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static hashval_t
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static hashval_t
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arc_hash (const void *arcp)
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arc_hash (const void *arcp)
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{
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{
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const_conflict_graph_arc arc = (const_conflict_graph_arc) arcp;
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const_conflict_graph_arc arc = (const_conflict_graph_arc) arcp;
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return CONFLICT_HASH_FN (arc->smaller, arc->larger);
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return CONFLICT_HASH_FN (arc->smaller, arc->larger);
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}
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}
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/* Callback function to determine the equality of two arcs in the hash
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/* Callback function to determine the equality of two arcs in the hash
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table. */
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table. */
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static int
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static int
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arc_eq (const void *arcp1, const void *arcp2)
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arc_eq (const void *arcp1, const void *arcp2)
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{
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{
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const_conflict_graph_arc arc1 = (const_conflict_graph_arc) arcp1;
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const_conflict_graph_arc arc1 = (const_conflict_graph_arc) arcp1;
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const_conflict_graph_arc arc2 = (const_conflict_graph_arc) arcp2;
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const_conflict_graph_arc arc2 = (const_conflict_graph_arc) arcp2;
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return arc1->smaller == arc2->smaller && arc1->larger == arc2->larger;
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return arc1->smaller == arc2->smaller && arc1->larger == arc2->larger;
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}
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}
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/* Creates an empty conflict graph to hold conflicts among NUM_REGS
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/* Creates an empty conflict graph to hold conflicts among NUM_REGS
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registers. */
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registers. */
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conflict_graph
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conflict_graph
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conflict_graph_new (int num_regs)
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conflict_graph_new (int num_regs)
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{
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{
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conflict_graph graph = XNEW (struct conflict_graph_def);
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conflict_graph graph = XNEW (struct conflict_graph_def);
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graph->num_regs = num_regs;
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graph->num_regs = num_regs;
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/* Set up the hash table. No delete action is specified; memory
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/* Set up the hash table. No delete action is specified; memory
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management of arcs is through the obstack. */
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management of arcs is through the obstack. */
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graph->arc_hash_table
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graph->arc_hash_table
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= htab_create (INITIAL_ARC_CAPACITY, &arc_hash, &arc_eq, NULL);
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= htab_create (INITIAL_ARC_CAPACITY, &arc_hash, &arc_eq, NULL);
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/* Create an obstack for allocating arcs. */
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/* Create an obstack for allocating arcs. */
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obstack_init (&graph->arc_obstack);
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obstack_init (&graph->arc_obstack);
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/* Create and zero the lookup table by register number. */
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/* Create and zero the lookup table by register number. */
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graph->neighbor_heads = XCNEWVEC (conflict_graph_arc, num_regs);
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graph->neighbor_heads = XCNEWVEC (conflict_graph_arc, num_regs);
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return graph;
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return graph;
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}
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}
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/* Deletes a conflict graph. */
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/* Deletes a conflict graph. */
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void
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void
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conflict_graph_delete (conflict_graph graph)
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conflict_graph_delete (conflict_graph graph)
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{
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{
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obstack_free (&graph->arc_obstack, NULL);
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obstack_free (&graph->arc_obstack, NULL);
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htab_delete (graph->arc_hash_table);
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htab_delete (graph->arc_hash_table);
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free (graph->neighbor_heads);
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free (graph->neighbor_heads);
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free (graph);
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free (graph);
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}
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}
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/* Adds a conflict to GRAPH between regs REG1 and REG2, which must be
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/* Adds a conflict to GRAPH between regs REG1 and REG2, which must be
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distinct. Returns nonzero, unless the conflict is already present
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distinct. Returns nonzero, unless the conflict is already present
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in GRAPH, in which case it does nothing and returns zero. */
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in GRAPH, in which case it does nothing and returns zero. */
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int
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int
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conflict_graph_add (conflict_graph graph, int reg1, int reg2)
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conflict_graph_add (conflict_graph graph, int reg1, int reg2)
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{
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{
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int smaller = MIN (reg1, reg2);
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int smaller = MIN (reg1, reg2);
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int larger = MAX (reg1, reg2);
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int larger = MAX (reg1, reg2);
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struct conflict_graph_arc_def dummy;
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struct conflict_graph_arc_def dummy;
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conflict_graph_arc arc;
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conflict_graph_arc arc;
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void **slot;
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void **slot;
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/* A reg cannot conflict with itself. */
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/* A reg cannot conflict with itself. */
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gcc_assert (reg1 != reg2);
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gcc_assert (reg1 != reg2);
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dummy.smaller = smaller;
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dummy.smaller = smaller;
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dummy.larger = larger;
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dummy.larger = larger;
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slot = htab_find_slot (graph->arc_hash_table, (void *) &dummy, INSERT);
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slot = htab_find_slot (graph->arc_hash_table, (void *) &dummy, INSERT);
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/* If the conflict is already there, do nothing. */
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/* If the conflict is already there, do nothing. */
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if (*slot != NULL)
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if (*slot != NULL)
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return 0;
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return 0;
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/* Allocate an arc. */
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/* Allocate an arc. */
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arc
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arc
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= obstack_alloc (&graph->arc_obstack,
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= obstack_alloc (&graph->arc_obstack,
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sizeof (struct conflict_graph_arc_def));
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sizeof (struct conflict_graph_arc_def));
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/* Record the reg numbers. */
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/* Record the reg numbers. */
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arc->smaller = smaller;
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arc->smaller = smaller;
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arc->larger = larger;
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arc->larger = larger;
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/* Link the conflict into two lists, one for each reg. */
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/* Link the conflict into two lists, one for each reg. */
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arc->smaller_next = graph->neighbor_heads[smaller];
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arc->smaller_next = graph->neighbor_heads[smaller];
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graph->neighbor_heads[smaller] = arc;
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graph->neighbor_heads[smaller] = arc;
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arc->larger_next = graph->neighbor_heads[larger];
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arc->larger_next = graph->neighbor_heads[larger];
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graph->neighbor_heads[larger] = arc;
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graph->neighbor_heads[larger] = arc;
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/* Put it in the hash table. */
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/* Put it in the hash table. */
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*slot = (void *) arc;
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*slot = (void *) arc;
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return 1;
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return 1;
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}
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}
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/* Returns nonzero if a conflict exists in GRAPH between regs REG1
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/* Returns nonzero if a conflict exists in GRAPH between regs REG1
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and REG2. */
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and REG2. */
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int
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int
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conflict_graph_conflict_p (conflict_graph graph, int reg1, int reg2)
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conflict_graph_conflict_p (conflict_graph graph, int reg1, int reg2)
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{
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{
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/* Build an arc to search for. */
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/* Build an arc to search for. */
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struct conflict_graph_arc_def arc;
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struct conflict_graph_arc_def arc;
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arc.smaller = MIN (reg1, reg2);
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arc.smaller = MIN (reg1, reg2);
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arc.larger = MAX (reg1, reg2);
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arc.larger = MAX (reg1, reg2);
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return htab_find (graph->arc_hash_table, (void *) &arc) != NULL;
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return htab_find (graph->arc_hash_table, (void *) &arc) != NULL;
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}
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}
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/* Calls ENUM_FN for each conflict in GRAPH involving REG. EXTRA is
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/* Calls ENUM_FN for each conflict in GRAPH involving REG. EXTRA is
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passed back to ENUM_FN. */
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passed back to ENUM_FN. */
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void
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void
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conflict_graph_enum (conflict_graph graph, int reg,
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conflict_graph_enum (conflict_graph graph, int reg,
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conflict_graph_enum_fn enum_fn, void *extra)
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conflict_graph_enum_fn enum_fn, void *extra)
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{
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{
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conflict_graph_arc arc = graph->neighbor_heads[reg];
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conflict_graph_arc arc = graph->neighbor_heads[reg];
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while (arc != NULL)
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while (arc != NULL)
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{
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{
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/* Invoke the callback. */
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/* Invoke the callback. */
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if ((*enum_fn) (arc->smaller, arc->larger, extra))
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if ((*enum_fn) (arc->smaller, arc->larger, extra))
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/* Stop if requested. */
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/* Stop if requested. */
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break;
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break;
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|
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/* Which next pointer to follow depends on whether REG is the
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/* Which next pointer to follow depends on whether REG is the
|
smaller or larger reg in this conflict. */
|
smaller or larger reg in this conflict. */
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if (reg < arc->larger)
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if (reg < arc->larger)
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arc = arc->smaller_next;
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arc = arc->smaller_next;
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else
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else
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arc = arc->larger_next;
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arc = arc->larger_next;
|
}
|
}
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}
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}
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/* For each conflict between a register x and SRC in GRAPH, adds a
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/* For each conflict between a register x and SRC in GRAPH, adds a
|
conflict to GRAPH between x and TARGET. */
|
conflict to GRAPH between x and TARGET. */
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|
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void
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void
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conflict_graph_merge_regs (conflict_graph graph, int target, int src)
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conflict_graph_merge_regs (conflict_graph graph, int target, int src)
|
{
|
{
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conflict_graph_arc arc = graph->neighbor_heads[src];
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conflict_graph_arc arc = graph->neighbor_heads[src];
|
|
|
if (target == src)
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if (target == src)
|
return;
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return;
|
|
|
while (arc != NULL)
|
while (arc != NULL)
|
{
|
{
|
int other = arc->smaller;
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int other = arc->smaller;
|
|
|
if (other == src)
|
if (other == src)
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other = arc->larger;
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other = arc->larger;
|
|
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conflict_graph_add (graph, target, other);
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conflict_graph_add (graph, target, other);
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|
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/* Which next pointer to follow depends on whether REG is the
|
/* Which next pointer to follow depends on whether REG is the
|
smaller or larger reg in this conflict. */
|
smaller or larger reg in this conflict. */
|
if (src < arc->larger)
|
if (src < arc->larger)
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arc = arc->smaller_next;
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arc = arc->smaller_next;
|
else
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else
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arc = arc->larger_next;
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arc = arc->larger_next;
|
}
|
}
|
}
|
}
|
|
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/* Holds context information while a conflict graph is being traversed
|
/* Holds context information while a conflict graph is being traversed
|
for printing. */
|
for printing. */
|
|
|
struct print_context
|
struct print_context
|
{
|
{
|
/* The file pointer to which we're printing. */
|
/* The file pointer to which we're printing. */
|
FILE *fp;
|
FILE *fp;
|
|
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/* The reg whose conflicts we're printing. */
|
/* The reg whose conflicts we're printing. */
|
int reg;
|
int reg;
|
|
|
/* Whether a conflict has already been printed for this reg. */
|
/* Whether a conflict has already been printed for this reg. */
|
int started;
|
int started;
|
};
|
};
|
|
|
/* Callback function when enumerating conflicts during printing. */
|
/* Callback function when enumerating conflicts during printing. */
|
|
|
static int
|
static int
|
print_conflict (int reg1, int reg2, void *contextp)
|
print_conflict (int reg1, int reg2, void *contextp)
|
{
|
{
|
struct print_context *context = (struct print_context *) contextp;
|
struct print_context *context = (struct print_context *) contextp;
|
int reg;
|
int reg;
|
|
|
/* If this is the first conflict printed for this reg, start a new
|
/* If this is the first conflict printed for this reg, start a new
|
line. */
|
line. */
|
if (! context->started)
|
if (! context->started)
|
{
|
{
|
fprintf (context->fp, " %d:", context->reg);
|
fprintf (context->fp, " %d:", context->reg);
|
context->started = 1;
|
context->started = 1;
|
}
|
}
|
|
|
/* Figure out the reg whose conflicts we're printing. The other reg
|
/* Figure out the reg whose conflicts we're printing. The other reg
|
is the interesting one. */
|
is the interesting one. */
|
if (reg1 == context->reg)
|
if (reg1 == context->reg)
|
reg = reg2;
|
reg = reg2;
|
else
|
else
|
{
|
{
|
gcc_assert (reg2 == context->reg);
|
gcc_assert (reg2 == context->reg);
|
reg = reg1;
|
reg = reg1;
|
}
|
}
|
|
|
/* Print the conflict. */
|
/* Print the conflict. */
|
fprintf (context->fp, " %d", reg);
|
fprintf (context->fp, " %d", reg);
|
|
|
/* Continue enumerating. */
|
/* Continue enumerating. */
|
return 0;
|
return 0;
|
}
|
}
|
|
|
/* Prints the conflicts in GRAPH to FP. */
|
/* Prints the conflicts in GRAPH to FP. */
|
|
|
void
|
void
|
conflict_graph_print (conflict_graph graph, FILE *fp)
|
conflict_graph_print (conflict_graph graph, FILE *fp)
|
{
|
{
|
int reg;
|
int reg;
|
struct print_context context;
|
struct print_context context;
|
|
|
context.fp = fp;
|
context.fp = fp;
|
fprintf (fp, "Conflicts:\n");
|
fprintf (fp, "Conflicts:\n");
|
|
|
/* Loop over registers supported in this graph. */
|
/* Loop over registers supported in this graph. */
|
for (reg = 0; reg < graph->num_regs; ++reg)
|
for (reg = 0; reg < graph->num_regs; ++reg)
|
{
|
{
|
context.reg = reg;
|
context.reg = reg;
|
context.started = 0;
|
context.started = 0;
|
|
|
/* Scan the conflicts for reg, printing as we go. A label for
|
/* Scan the conflicts for reg, printing as we go. A label for
|
this line will be printed the first time a conflict is
|
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
|
printed for the reg; we won't start a new line if this reg
|
has no conflicts. */
|
has no conflicts. */
|
conflict_graph_enum (graph, reg, &print_conflict, &context);
|
conflict_graph_enum (graph, reg, &print_conflict, &context);
|
|
|
/* If this reg does have conflicts, end the line. */
|
/* If this reg does have conflicts, end the line. */
|
if (context.started)
|
if (context.started)
|
fputc ('\n', fp);
|
fputc ('\n', fp);
|
}
|
}
|
}
|
}
|
|
|
