src/glsl/ir_basic_block.cpp

   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  */
  52 void 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_list(n, instructions) {
  62       ir_instruction *ir = (ir_instruction *) n;
  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_jump() || 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_list(func_node, &ir_function->signatures) {
  94             ir_function_signature *ir_sig = (ir_function_signature *) func_node;
  95
  96             call_for_basic_blocks(&ir_sig->body, callback, data);
  97          }
  98       }
  99       last = ir;
 100    }
 101    if (leader) {
 102       callback(leader, last, data);
 103    }
 104 }