1 /*
2 * Copyright (C) 1995-2008 University of Karlsruhe. All right reserved.
3 *
4 * This file is part of libFirm.
5 *
6 * This file may be distributed and/or modified under the terms of the
7 * GNU General Public License version 2 as published by the Free Software
8 * Foundation and appearing in the file LICENSE.GPL included in the
9 * packaging of this file.
10 *
11 * Licensees holding valid libFirm Professional Edition licenses may use
12 * this file in accordance with the libFirm Commercial License.
13 * Agreement provided with the Software.
14 *
15 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
16 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
17 * PURPOSE.
18 */
19
20 /**
21 * @file
22 * @brief Remove critical edges.
23 * @author Christian Schaefer, Goetz Lindenmaier, Sebastian Felis,
24 * Michael Beck
25 */
26 #include "config.h"
27
28 #include "irop_t.h"
29 #include "irnode_t.h"
30 #include "ircons.h"
31 #include "irgwalk.h"
32 #include "irgopt.h"
33
34 typedef struct cf_env {
35 char ignore_exc_edges; /**< set if exception edges should be ignored. */
36 char changed; /**< flag indicates that the cf graphs has changed. */
37 } cf_env;
38
39 /**
40 * Called by walker of remove_critical_cf_edges().
41 *
42 * Place an empty block to an edge between a blocks of multiple
43 * predecessors and a block of multiple successors.
44 *
45 * @param n IR node
46 * @param env Environment of walker.
47 */
walk_critical_cf_edges(ir_node * n,void * env)48 static void walk_critical_cf_edges(ir_node *n, void *env)
49 {
50 int arity, i;
51 ir_node *pre, *block, *jmp;
52 cf_env *cenv = (cf_env*)env;
53 ir_graph *irg = get_irn_irg(n);
54
55 /* Block has multiple predecessors */
56 arity = get_irn_arity(n);
57 if (arity > 1) {
58 if (n == get_irg_end_block(irg))
59 return; /* No use to add a block here. */
60
61 for (i = 0; i < arity; ++i) {
62 const ir_op *cfop;
63
64 pre = get_irn_n(n, i);
65 /* don't count Bad's */
66 if (is_Bad(pre))
67 continue;
68
69 cfop = get_irn_op(skip_Proj(pre));
70 if (is_op_fragile(cfop)) {
71 if (cenv->ignore_exc_edges && is_x_except_Proj(pre))
72 continue;
73 goto insert;
74 }
75 if (is_unknown_jump(pre)) {
76 /* we can't add blocks in between ijmp and its destinations
77 * TODO: What now, we can't split all critical edges because of this... */
78 fprintf(stderr, "libfirm warning: Couldn't split all critical edges (compiler will probably fail now)\n");
79 continue;
80 }
81 /* we don't want place nodes in the start block, so handle it like forking */
82 if (is_op_forking(cfop) || cfop == op_Start) {
83 /* Predecessor has multiple successors. Insert new control flow edge edges. */
84 insert:
85 /* set predecessor of new block */
86 block = new_r_Block(irg, 1, &pre);
87 /* insert new jmp node to new block */
88 jmp = new_r_Jmp(block);
89 /* set successor of new block */
90 set_irn_n(n, i, jmp);
91 cenv->changed = 1;
92 }
93 }
94 }
95 }
96
remove_critical_cf_edges_ex(ir_graph * irg,int ignore_exception_edges)97 void remove_critical_cf_edges_ex(ir_graph *irg, int ignore_exception_edges)
98 {
99 cf_env env;
100
101 env.ignore_exc_edges = (char)ignore_exception_edges;
102 env.changed = 0;
103
104 irg_block_walk_graph(irg, NULL, walk_critical_cf_edges, &env);
105 if (env.changed) {
106 /* control flow changed */
107 clear_irg_properties(irg, IR_GRAPH_PROPERTY_CONSISTENT_DOMINANCE);
108 }
109 add_irg_properties(irg, IR_GRAPH_PROPERTY_NO_CRITICAL_EDGES);
110 }
111
remove_critical_cf_edges(ir_graph * irg)112 void remove_critical_cf_edges(ir_graph *irg)
113 {
114 remove_critical_cf_edges_ex(irg, 1);
115 }
116