src/compiler/nir/nir_sweep.c

   1 /*
   2  * Copyright © 2015 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 DEALINGS
  21  * IN THE SOFTWARE.
  22  */
  23
  24 #include "nir.h"
  25
  26 /**
  27  * \file nir_sweep.c
  28  *
  29  * The nir_sweep() pass performs a mark and sweep pass over a nir_shader's associated
  30  * memory - anything still connected to the program will be kept, and any dead memory
  31  * we dropped on the floor will be freed.
  32  *
  33  * The expectation is that drivers should call this when finished compiling the shader
  34  * (after any optimization, lowering, and so on).  However, it's also fine to call it
  35  * earlier, and even many times, trading CPU cycles for memory savings.
  36  */
  37
  38 #define steal_list(mem_ctx, type, list) \
  39    foreach_list_typed(type, obj, node, list) { ralloc_steal(mem_ctx, obj); }
  40
  41 static void sweep_cf_node(nir_shader *nir, nir_cf_node *cf_node);
  42
  43 static bool
  44 sweep_src_indirect(nir_src *src, void *nir)
  45 {
  46    if (!src->is_ssa && src->reg.indirect)
  47       ralloc_steal(nir, src->reg.indirect);
  48
  49    return true;
  50 }
  51
  52 static bool
  53 sweep_dest_indirect(nir_dest *dest, void *nir)
  54 {
  55    if (!dest->is_ssa && dest->reg.indirect)
  56       ralloc_steal(nir, dest->reg.indirect);
  57
  58    return true;
  59 }
  60
  61 static void
  62 sweep_block(nir_shader *nir, nir_block *block)
  63 {
  64    ralloc_steal(nir, block);
  65
  66    /* sweep_impl will mark all metadata invalid.  We can safely release all of
  67     * this here.
  68     */
  69    ralloc_free(block->live_in);
  70    block->live_in = NULL;
  71
  72    ralloc_free(block->live_out);
  73    block->live_out = NULL;
  74
  75    nir_foreach_instr(instr, block) {
  76       ralloc_steal(nir, instr);
  77
  78       nir_foreach_src(instr, sweep_src_indirect, nir);
  79       nir_foreach_dest(instr, sweep_dest_indirect, nir);
  80    }
  81 }
  82
  83 static void
  84 sweep_if(nir_shader *nir, nir_if *iff)
  85 {
  86    ralloc_steal(nir, iff);
  87
  88    foreach_list_typed(nir_cf_node, cf_node, node, &iff->then_list) {
  89       sweep_cf_node(nir, cf_node);
  90    }
  91
  92    foreach_list_typed(nir_cf_node, cf_node, node, &iff->else_list) {
  93       sweep_cf_node(nir, cf_node);
  94    }
  95 }
  96
  97 static void
  98 sweep_loop(nir_shader *nir, nir_loop *loop)
  99 {
 100    ralloc_steal(nir, loop);
 101
 102    foreach_list_typed(nir_cf_node, cf_node, node, &loop->body) {
 103       sweep_cf_node(nir, cf_node);
 104    }
 105 }
 106
 107 static void
 108 sweep_cf_node(nir_shader *nir, nir_cf_node *cf_node)
 109 {
 110    switch (cf_node->type) {
 111    case nir_cf_node_block:
 112       sweep_block(nir, nir_cf_node_as_block(cf_node));
 113       break;
 114    case nir_cf_node_if:
 115       sweep_if(nir, nir_cf_node_as_if(cf_node));
 116       break;
 117    case nir_cf_node_loop:
 118       sweep_loop(nir, nir_cf_node_as_loop(cf_node));
 119       break;
 120    default:
 121       unreachable("Invalid CF node type");
 122    }
 123 }
 124
 125 static void
 126 sweep_impl(nir_shader *nir, nir_function_impl *impl)
 127 {
 128    ralloc_steal(nir, impl);
 129
 130    steal_list(nir, nir_variable, &impl->locals);
 131    steal_list(nir, nir_register, &impl->registers);
 132
 133    foreach_list_typed(nir_cf_node, cf_node, node, &impl->body) {
 134       sweep_cf_node(nir, cf_node);
 135    }
 136
 137    sweep_block(nir, impl->end_block);
 138
 139    /* Wipe out all the metadata, if any. */
 140    nir_metadata_preserve(impl, nir_metadata_none);
 141 }
 142
 143 static void
 144 sweep_function(nir_shader *nir, nir_function *f)
 145 {
 146    ralloc_steal(nir, f);
 147    ralloc_steal(nir, f->params);
 148
 149    if (f->impl)
 150       sweep_impl(nir, f->impl);
 151 }
 152
 153 void
 154 nir_sweep(nir_shader *nir)
 155 {
 156    void *rubbish = ralloc_context(NULL);
 157
 158    /* First, move ownership of all the memory to a temporary context; assume dead. */
 159    ralloc_adopt(rubbish, nir);
 160
 161    ralloc_steal(nir, (char *)nir->info.name);
 162    if (nir->info.label)
 163       ralloc_steal(nir, (char *)nir->info.label);
 164
 165    /* Variables and registers are not dead.  Steal them back. */
 166    steal_list(nir, nir_variable, &nir->variables);
 167
 168    /* Recurse into functions, stealing their contents back. */
 169    foreach_list_typed(nir_function, func, node, &nir->functions) {
 170       sweep_function(nir, func);
 171    }
 172
 173    ralloc_steal(nir, nir->constant_data);
 174
 175    /* Free everything we didn't steal back. */
 176    ralloc_free(rubbish);
 177 }