1/*
2 * Copyright © 2010 Intel Corporation
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
21 * DEALINGS IN THE SOFTWARE.
22 */
23
24/**
25 * \file ir_basic_block.cpp
26 *
27 * Basic block analysis of instruction streams.
28 */
29
30#include "ir.h"
31#include "ir_visitor.h"
32#include "ir_basic_block.h"
33#include "glsl_types.h"
34
35/**
36 * Calls a user function for every basic block in the instruction stream.
37 *
38 * Basic block analysis is pretty easy in our IR thanks to the lack of
39 * unstructured control flow.  We've got:
40 *
41 * ir_loop (for () {}, while () {}, do {} while ())
42 * ir_loop_jump (
43 * ir_if () {}
44 * ir_return
45 * ir_call()
46 *
47 * Note that the basic blocks returned by this don't encompass all
48 * operations performed by the program -- for example, if conditions
49 * don't get returned, nor do the assignments that will be generated
50 * for ir_call parameters.
51 */
52void call_for_basic_blocks(exec_list *instructions,
53			   void (*callback)(ir_instruction *first,
54					    ir_instruction *last,
55					    void *data),
56			   void *data)
57{
58   ir_instruction *leader = NULL;
59   ir_instruction *last = NULL;
60
61   foreach_iter(exec_list_iterator, iter, *instructions) {
62      ir_instruction *ir = (ir_instruction *)iter.get();
63      ir_if *ir_if;
64      ir_loop *ir_loop;
65      ir_function *ir_function;
66
67      if (!leader)
68	 leader = ir;
69
70      if ((ir_if = ir->as_if())) {
71	 callback(leader, ir, data);
72	 leader = NULL;
73
74	 call_for_basic_blocks(&ir_if->then_instructions, callback, data);
75	 call_for_basic_blocks(&ir_if->else_instructions, callback, data);
76      } else if ((ir_loop = ir->as_loop())) {
77	 callback(leader, ir, data);
78	 leader = NULL;
79	 call_for_basic_blocks(&ir_loop->body_instructions, callback, data);
80      } else if (ir->as_return() || ir->as_call()) {
81	 callback(leader, ir, data);
82	 leader = NULL;
83      } else if ((ir_function = ir->as_function())) {
84	 /* A function definition doesn't interrupt our basic block
85	  * since execution doesn't go into it.  We should process the
86	  * bodies of its signatures for BBs, though.
87	  *
88	  * Note that we miss an opportunity for producing more
89	  * maximal BBs between the instructions that precede main()
90	  * and the body of main().  Perhaps those instructions ought
91	  * to live inside of main().
92	  */
93	 foreach_iter(exec_list_iterator, fun_iter, *ir_function) {
94	    ir_function_signature *ir_sig;
95
96	    ir_sig = (ir_function_signature *)fun_iter.get();
97
98	    call_for_basic_blocks(&ir_sig->body, callback, data);
99	 }
100      }
101      last = ir;
102   }
103   if (leader) {
104      callback(leader, last, data);
105   }
106}
107