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25 * \file ir_basic_block.cpp
27 * Basic block analysis of instruction streams.
32 #include "ir_visitor.h"
33 #include "ir_basic_block.h"
34 #include "glsl_types.h"
36 class ir_has_call_visitor
: public ir_hierarchical_visitor
{
43 virtual ir_visitor_status
visit_enter(ir_call
*ir
)
54 * Calls a user function for every basic block in the instruction stream.
56 * Basic block analysis is pretty easy in our IR thanks to the lack of
57 * unstructured control flow. We've got:
59 * ir_loop (for () {}, while () {}, do {} while ())
65 * Note that the basic blocks returned by this don't encompass all
66 * operations performed by the program -- for example, if conditions
67 * don't get returned, nor do the assignments that will be generated
68 * for ir_call parameters.
70 void call_for_basic_blocks(exec_list
*instructions
,
71 void (*callback
)(ir_instruction
*first
,
76 ir_instruction
*leader
= NULL
;
77 ir_instruction
*last
= NULL
;
79 foreach_iter(exec_list_iterator
, iter
, *instructions
) {
80 ir_instruction
*ir
= (ir_instruction
*)iter
.get();
83 ir_function
*ir_function
;
88 if ((ir_if
= ir
->as_if())) {
89 callback(leader
, ir
, data
);
92 call_for_basic_blocks(&ir_if
->then_instructions
, callback
, data
);
93 call_for_basic_blocks(&ir_if
->else_instructions
, callback
, data
);
94 } else if ((ir_loop
= ir
->as_loop())) {
95 callback(leader
, ir
, data
);
97 call_for_basic_blocks(&ir_loop
->body_instructions
, callback
, data
);
98 } else if (ir
->as_return() || ir
->as_call()) {
99 callback(leader
, ir
, data
);
101 } else if ((ir_function
= ir
->as_function())) {
102 /* A function definition doesn't interrupt our basic block
103 * since execution doesn't go into it. We should process the
104 * bodies of its signatures for BBs, though.
106 * Note that we miss an opportunity for producing more
107 * maximal BBs between the instructions that precede main()
108 * and the body of main(). Perhaps those instructions ought
109 * to live inside of main().
111 foreach_iter(exec_list_iterator
, fun_iter
, *ir_function
) {
112 ir_function_signature
*ir_sig
;
114 ir_sig
= (ir_function_signature
*)fun_iter
.get();
116 call_for_basic_blocks(&ir_sig
->body
, callback
, data
);
118 } else if (ir
->as_assignment()) {
119 ir_has_call_visitor v
;
121 /* If there's a call in the expression tree being assigned,
122 * then that ends the BB too.
124 * The assumption is that any consumer of the basic block
125 * walker is fine with the fact that the call is somewhere in
126 * the tree even if portions of the tree may be evaluated
129 * A consumer that has an issue with this could not process
130 * the last instruction of the basic block. If doing so,
131 * expression flattener may be useful before using the basic
132 * block finder to get more maximal basic blocks out.
136 callback(leader
, ir
, data
);
143 callback(leader
, last
, data
);