Go to most recent revision | Details | Last modification | View Log | RSS feed
| Rev | Author | Line No. | Line |
|---|---|---|---|
| 1901 | serge | 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 opt_dead_code.cpp |
||
| 26 | * |
||
| 27 | * Eliminates dead assignments and variable declarations from the code. |
||
| 28 | */ |
||
| 29 | |||
| 30 | #include "ir.h" |
||
| 31 | #include "ir_visitor.h" |
||
| 32 | #include "ir_variable_refcount.h" |
||
| 33 | #include "glsl_types.h" |
||
| 34 | |||
| 35 | static bool debug = false; |
||
| 36 | |||
| 37 | /** |
||
| 38 | * Do a dead code pass over instructions and everything that instructions |
||
| 39 | * references. |
||
| 40 | * |
||
| 41 | * Note that this will remove assignments to globals, so it is not suitable |
||
| 42 | * for usage on an unlinked instruction stream. |
||
| 43 | */ |
||
| 44 | bool |
||
| 45 | do_dead_code(exec_list *instructions) |
||
| 46 | { |
||
| 47 | ir_variable_refcount_visitor v; |
||
| 48 | bool progress = false; |
||
| 49 | |||
| 50 | v.run(instructions); |
||
| 51 | |||
| 52 | foreach_iter(exec_list_iterator, iter, v.variable_list) { |
||
| 53 | variable_entry *entry = (variable_entry *)iter.get(); |
||
| 54 | |||
| 55 | /* Since each assignment is a reference, the refereneced count must be |
||
| 56 | * greater than or equal to the assignment count. If they are equal, |
||
| 57 | * then all of the references are assignments, and the variable is |
||
| 58 | * dead. |
||
| 59 | * |
||
| 60 | * Note that if the variable is neither assigned nor referenced, both |
||
| 61 | * counts will be zero and will be caught by the equality test. |
||
| 62 | */ |
||
| 63 | assert(entry->referenced_count >= entry->assigned_count); |
||
| 64 | |||
| 65 | if (debug) { |
||
| 66 | printf("%s@%p: %d refs, %d assigns, %sdeclared in our scope\n", |
||
| 67 | entry->var->name, (void *) entry->var, |
||
| 68 | entry->referenced_count, entry->assigned_count, |
||
| 69 | entry->declaration ? "" : "not "); |
||
| 70 | } |
||
| 71 | |||
| 72 | if ((entry->referenced_count > entry->assigned_count) |
||
| 73 | || !entry->declaration) |
||
| 74 | continue; |
||
| 75 | |||
| 76 | if (entry->assign) { |
||
| 77 | /* Remove a single dead assignment to the variable we found. |
||
| 78 | * Don't do so if it's a shader output, though. |
||
| 79 | */ |
||
| 80 | if (entry->var->mode != ir_var_out && |
||
| 81 | entry->var->mode != ir_var_inout && |
||
| 82 | !ir_has_call(entry->assign)) { |
||
| 83 | entry->assign->remove(); |
||
| 84 | progress = true; |
||
| 85 | |||
| 86 | if (debug) { |
||
| 87 | printf("Removed assignment to %s@%p\n", |
||
| 88 | entry->var->name, (void *) entry->var); |
||
| 89 | } |
||
| 90 | } |
||
| 91 | } else { |
||
| 92 | /* If there are no assignments or references to the variable left, |
||
| 93 | * then we can remove its declaration. |
||
| 94 | */ |
||
| 95 | |||
| 96 | /* uniform initializers are precious, and could get used by another |
||
| 97 | * stage. |
||
| 98 | */ |
||
| 99 | if (entry->var->mode == ir_var_uniform && |
||
| 100 | entry->var->constant_value) |
||
| 101 | continue; |
||
| 102 | |||
| 103 | entry->var->remove(); |
||
| 104 | progress = true; |
||
| 105 | |||
| 106 | if (debug) { |
||
| 107 | printf("Removed declaration of %s@%p\n", |
||
| 108 | entry->var->name, (void *) entry->var); |
||
| 109 | } |
||
| 110 | } |
||
| 111 | } |
||
| 112 | |||
| 113 | return progress; |
||
| 114 | } |
||
| 115 | |||
| 116 | /** |
||
| 117 | * Does a dead code pass on the functions present in the instruction stream. |
||
| 118 | * |
||
| 119 | * This is suitable for use while the program is not linked, as it will |
||
| 120 | * ignore variable declarations (and the assignments to them) for variables |
||
| 121 | * with global scope. |
||
| 122 | */ |
||
| 123 | bool |
||
| 124 | do_dead_code_unlinked(exec_list *instructions) |
||
| 125 | { |
||
| 126 | bool progress = false; |
||
| 127 | |||
| 128 | foreach_iter(exec_list_iterator, iter, *instructions) { |
||
| 129 | ir_instruction *ir = (ir_instruction *)iter.get(); |
||
| 130 | ir_function *f = ir->as_function(); |
||
| 131 | if (f) { |
||
| 132 | foreach_iter(exec_list_iterator, sigiter, *f) { |
||
| 133 | ir_function_signature *sig = |
||
| 134 | (ir_function_signature *) sigiter.get(); |
||
| 135 | if (do_dead_code(&sig->body)) |
||
| 136 | progress = true; |
||
| 137 | } |
||
| 138 | } |
||
| 139 | } |
||
| 140 | |||
| 141 | return progress; |
||
| 142 | } |