1 files changed, 531 insertions, 0 deletions

diff --git a/src/intel/compiler/brw_cfg.cpp b/src/intel/compiler/brw_cfg.cpp
new file mode 100644
index 00000000000..fad12eec588
--- /dev/null
+++ b/src/intel/compiler/brw_cfg.cpp
@@ -0,0 +1,531 @@
+/*
+ * Copyright © 2012 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ * Authors:
+ *    Eric Anholt <[email protected]>
+ *
+ */
+
+#include "brw_cfg.h"
+
+/** @file brw_cfg.cpp
+ *
+ * Walks the shader instructions generated and creates a set of basic
+ * blocks with successor/predecessor edges connecting them.
+ */
+
+static bblock_t *
+pop_stack(exec_list *list)
+{
+   bblock_link *link = (bblock_link *)list->get_tail();
+   bblock_t *block = link->block;
+   link->link.remove();
+
+   return block;
+}
+
+static exec_node *
+link(void *mem_ctx, bblock_t *block)
+{
+   bblock_link *l = new(mem_ctx) bblock_link(block);
+   return &l->link;
+}
+
+bblock_t::bblock_t(cfg_t *cfg) :
+   cfg(cfg), idom(NULL), start_ip(0), end_ip(0), num(0), cycle_count(0)
+{
+   instructions.make_empty();
+   parents.make_empty();
+   children.make_empty();
+}
+
+void
+bblock_t::add_successor(void *mem_ctx, bblock_t *successor)
+{
+   successor->parents.push_tail(::link(mem_ctx, this));
+   children.push_tail(::link(mem_ctx, successor));
+}
+
+bool
+bblock_t::is_predecessor_of(const bblock_t *block) const
+{
+   foreach_list_typed_safe (bblock_link, parent, link, &block->parents) {
+      if (parent->block == this) {
+         return true;
+      }
+   }
+
+   return false;
+}
+
+bool
+bblock_t::is_successor_of(const bblock_t *block) const
+{
+   foreach_list_typed_safe (bblock_link, child, link, &block->children) {
+      if (child->block == this) {
+         return true;
+      }
+   }
+
+   return false;
+}
+
+static bool
+ends_block(const backend_instruction *inst)
+{
+   enum opcode op = inst->opcode;
+
+   return op == BRW_OPCODE_IF ||
+          op == BRW_OPCODE_ELSE ||
+          op == BRW_OPCODE_CONTINUE ||
+          op == BRW_OPCODE_BREAK ||
+          op == BRW_OPCODE_WHILE;
+}
+
+static bool
+starts_block(const backend_instruction *inst)
+{
+   enum opcode op = inst->opcode;
+
+   return op == BRW_OPCODE_DO ||
+          op == BRW_OPCODE_ENDIF;
+}
+
+bool
+bblock_t::can_combine_with(const bblock_t *that) const
+{
+   if ((const bblock_t *)this->link.next != that)
+      return false;
+
+   if (ends_block(this->end()) ||
+       starts_block(that->start()))
+      return false;
+
+   return true;
+}
+
+void
+bblock_t::combine_with(bblock_t *that)
+{
+   assert(this->can_combine_with(that));
+   foreach_list_typed (bblock_link, link, link, &this->children) {
+      assert(link->block == that);
+   }
+   foreach_list_typed (bblock_link, link, link, &that->parents) {
+      assert(link->block == this);
+   }
+
+   this->end_ip = that->end_ip;
+   this->instructions.append_list(&that->instructions);
+
+   this->cfg->remove_block(that);
+}
+
+void
+bblock_t::dump(backend_shader *s) const
+{
+   int ip = this->start_ip;
+   foreach_inst_in_block(backend_instruction, inst, this) {
+      fprintf(stderr, "%5d: ", ip);
+      s->dump_instruction(inst);
+      ip++;
+   }
+}
+
+cfg_t::cfg_t(exec_list *instructions)
+{
+   mem_ctx = ralloc_context(NULL);
+   block_list.make_empty();
+   blocks = NULL;
+   num_blocks = 0;
+   idom_dirty = true;
+   cycle_count = 0;
+
+   bblock_t *cur = NULL;
+   int ip = 0;
+
+   bblock_t *entry = new_block();
+   bblock_t *cur_if = NULL;    /**< BB ending with IF. */
+   bblock_t *cur_else = NULL;  /**< BB ending with ELSE. */
+   bblock_t *cur_endif = NULL; /**< BB starting with ENDIF. */
+   bblock_t *cur_do = NULL;    /**< BB starting with DO. */
+   bblock_t *cur_while = NULL; /**< BB immediately following WHILE. */
+   exec_list if_stack, else_stack, do_stack, while_stack;
+   bblock_t *next;
+
+   set_next_block(&cur, entry, ip);
+
+   foreach_in_list_safe(backend_instruction, inst, instructions) {
+      /* set_next_block wants the post-incremented ip */
+      ip++;
+
+      inst->exec_node::remove();
+
+      switch (inst->opcode) {
+      case BRW_OPCODE_IF:
+         cur->instructions.push_tail(inst);
+
+	 /* Push our information onto a stack so we can recover from
+	  * nested ifs.
+	  */
+	 if_stack.push_tail(link(mem_ctx, cur_if));
+	 else_stack.push_tail(link(mem_ctx, cur_else));
+
+	 cur_if = cur;
+	 cur_else = NULL;
+         cur_endif = NULL;
+
+	 /* Set up our immediately following block, full of "then"
+	  * instructions.
+	  */
+	 next = new_block();
+	 cur_if->add_successor(mem_ctx, next);
+
+	 set_next_block(&cur, next, ip);
+	 break;
+
+      case BRW_OPCODE_ELSE:
+         cur->instructions.push_tail(inst);
+
+         cur_else = cur;
+
+	 next = new_block();
+         assert(cur_if != NULL);
+	 cur_if->add_successor(mem_ctx, next);
+
+	 set_next_block(&cur, next, ip);
+	 break;
+
+      case BRW_OPCODE_ENDIF: {
+         if (cur->instructions.is_empty()) {
+            /* New block was just created; use it. */
+            cur_endif = cur;
+         } else {
+            cur_endif = new_block();
+
+            cur->add_successor(mem_ctx, cur_endif);
+
+            set_next_block(&cur, cur_endif, ip - 1);
+         }
+
+         cur->instructions.push_tail(inst);
+
+         if (cur_else) {
+            cur_else->add_successor(mem_ctx, cur_endif);
+         } else {
+            assert(cur_if != NULL);
+            cur_if->add_successor(mem_ctx, cur_endif);
+         }
+
+         assert(cur_if->end()->opcode == BRW_OPCODE_IF);
+         assert(!cur_else || cur_else->end()->opcode == BRW_OPCODE_ELSE);
+
+	 /* Pop the stack so we're in the previous if/else/endif */
+	 cur_if = pop_stack(&if_stack);
+	 cur_else = pop_stack(&else_stack);
+	 break;
+      }
+      case BRW_OPCODE_DO:
+	 /* Push our information onto a stack so we can recover from
+	  * nested loops.
+	  */
+	 do_stack.push_tail(link(mem_ctx, cur_do));
+	 while_stack.push_tail(link(mem_ctx, cur_while));
+
+	 /* Set up the block just after the while.  Don't know when exactly
+	  * it will start, yet.
+	  */
+	 cur_while = new_block();
+
+         if (cur->instructions.is_empty()) {
+            /* New block was just created; use it. */
+            cur_do = cur;
+         } else {
+            cur_do = new_block();
+
+            cur->add_successor(mem_ctx, cur_do);
+
+            set_next_block(&cur, cur_do, ip - 1);
+         }
+
+         cur->instructions.push_tail(inst);
+	 break;
+
+      case BRW_OPCODE_CONTINUE:
+         cur->instructions.push_tail(inst);
+
+         assert(cur_do != NULL);
+	 cur->add_successor(mem_ctx, cur_do);
+
+	 next = new_block();
+	 if (inst->predicate)
+	    cur->add_successor(mem_ctx, next);
+
+	 set_next_block(&cur, next, ip);
+	 break;
+
+      case BRW_OPCODE_BREAK:
+         cur->instructions.push_tail(inst);
+
+         assert(cur_while != NULL);
+	 cur->add_successor(mem_ctx, cur_while);
+
+	 next = new_block();
+	 if (inst->predicate)
+	    cur->add_successor(mem_ctx, next);
+
+	 set_next_block(&cur, next, ip);
+	 break;
+
+      case BRW_OPCODE_WHILE:
+         cur->instructions.push_tail(inst);
+
+         assert(cur_do != NULL && cur_while != NULL);
+	 cur->add_successor(mem_ctx, cur_do);
+
+         if (inst->predicate)
+            cur->add_successor(mem_ctx, cur_while);
+
+	 set_next_block(&cur, cur_while, ip);
+
+	 /* Pop the stack so we're in the previous loop */
+	 cur_do = pop_stack(&do_stack);
+	 cur_while = pop_stack(&while_stack);
+	 break;
+
+      default:
+         cur->instructions.push_tail(inst);
+	 break;
+      }
+   }
+
+   cur->end_ip = ip - 1;
+
+   make_block_array();
+}
+
+cfg_t::~cfg_t()
+{
+   ralloc_free(mem_ctx);
+}
+
+void
+cfg_t::remove_block(bblock_t *block)
+{
+   foreach_list_typed_safe (bblock_link, predecessor, link, &block->parents) {
+      /* Remove block from all of its predecessors' successor lists. */
+      foreach_list_typed_safe (bblock_link, successor, link,
+                               &predecessor->block->children) {
+         if (block == successor->block) {
+            successor->link.remove();
+            ralloc_free(successor);
+         }
+      }
+
+      /* Add removed-block's successors to its predecessors' successor lists. */
+      foreach_list_typed (bblock_link, successor, link, &block->children) {
+         if (!successor->block->is_successor_of(predecessor->block)) {
+            predecessor->block->children.push_tail(link(mem_ctx,
+                                                        successor->block));
+         }
+      }
+   }
+
+   foreach_list_typed_safe (bblock_link, successor, link, &block->children) {
+      /* Remove block from all of its childrens' parents lists. */
+      foreach_list_typed_safe (bblock_link, predecessor, link,
+                               &successor->block->parents) {
+         if (block == predecessor->block) {
+            predecessor->link.remove();
+            ralloc_free(predecessor);
+         }
+      }
+
+      /* Add removed-block's predecessors to its successors' predecessor lists. */
+      foreach_list_typed (bblock_link, predecessor, link, &block->parents) {
+         if (!predecessor->block->is_predecessor_of(successor->block)) {
+            successor->block->parents.push_tail(link(mem_ctx,
+                                                     predecessor->block));
+         }
+      }
+   }
+
+   block->link.remove();
+
+   for (int b = block->num; b < this->num_blocks - 1; b++) {
+      this->blocks[b] = this->blocks[b + 1];
+      this->blocks[b]->num = b;
+   }
+
+   this->blocks[this->num_blocks - 1]->num = this->num_blocks - 2;
+   this->num_blocks--;
+   idom_dirty = true;
+}
+
+bblock_t *
+cfg_t::new_block()
+{
+   bblock_t *block = new(mem_ctx) bblock_t(this);
+
+   return block;
+}
+
+void
+cfg_t::set_next_block(bblock_t **cur, bblock_t *block, int ip)
+{
+   if (*cur) {
+      (*cur)->end_ip = ip - 1;
+   }
+
+   block->start_ip = ip;
+   block->num = num_blocks++;
+   block_list.push_tail(&block->link);
+   *cur = block;
+}
+
+void
+cfg_t::make_block_array()
+{
+   blocks = ralloc_array(mem_ctx, bblock_t *, num_blocks);
+
+   int i = 0;
+   foreach_block (block, this) {
+      blocks[i++] = block;
+   }
+   assert(i == num_blocks);
+}
+
+void
+cfg_t::dump(backend_shader *s)
+{
+   if (idom_dirty)
+      calculate_idom();
+
+   foreach_block (block, this) {
+      if (block->idom)
+         fprintf(stderr, "START B%d IDOM(B%d)", block->num, block->idom->num);
+      else
+         fprintf(stderr, "START B%d IDOM(none)", block->num);
+
+      foreach_list_typed(bblock_link, link, link, &block->parents) {
+         fprintf(stderr, " <-B%d",
+                 link->block->num);
+      }
+      fprintf(stderr, "\n");
+      if (s != NULL)
+         block->dump(s);
+      fprintf(stderr, "END B%d", block->num);
+      foreach_list_typed(bblock_link, link, link, &block->children) {
+         fprintf(stderr, " ->B%d",
+                 link->block->num);
+      }
+      fprintf(stderr, "\n");
+   }
+}
+
+/* Calculates the immediate dominator of each block, according to "A Simple,
+ * Fast Dominance Algorithm" by Keith D. Cooper, Timothy J. Harvey, and Ken
+ * Kennedy.
+ *
+ * The authors claim that for control flow graphs of sizes normally encountered
+ * (less than 1000 nodes) that this algorithm is significantly faster than
+ * others like Lengauer-Tarjan.
+ */
+void
+cfg_t::calculate_idom()
+{
+   foreach_block(block, this) {
+      block->idom = NULL;
+   }
+   blocks[0]->idom = blocks[0];
+
+   bool changed;
+   do {
+      changed = false;
+
+      foreach_block(block, this) {
+         if (block->num == 0)
+            continue;
+
+         bblock_t *new_idom = NULL;
+         foreach_list_typed(bblock_link, parent, link, &block->parents) {
+            if (parent->block->idom) {
+               if (new_idom == NULL) {
+                  new_idom = parent->block;
+               } else if (parent->block->idom != NULL) {
+                  new_idom = intersect(parent->block, new_idom);
+               }
+            }
+         }
+
+         if (block->idom != new_idom) {
+            block->idom = new_idom;
+            changed = true;
+         }
+      }
+   } while (changed);
+
+   idom_dirty = false;
+}
+
+bblock_t *
+cfg_t::intersect(bblock_t *b1, bblock_t *b2)
+{
+   /* Note, the comparisons here are the opposite of what the paper says
+    * because we index blocks from beginning -> end (i.e. reverse post-order)
+    * instead of post-order like they assume.
+    */
+   while (b1->num != b2->num) {
+      while (b1->num > b2->num)
+         b1 = b1->idom;
+      while (b2->num > b1->num)
+         b2 = b2->idom;
+   }
+   assert(b1);
+   return b1;
+}
+
+void
+cfg_t::dump_cfg()
+{
+   printf("digraph CFG {\n");
+   for (int b = 0; b < num_blocks; b++) {
+      bblock_t *block = this->blocks[b];
+
+      foreach_list_typed_safe (bblock_link, child, link, &block->children) {
+         printf("\t%d -> %d\n", b, child->block->num);
+      }
+   }
+   printf("}\n");
+}
+
+void
+cfg_t::dump_domtree()
+{
+   printf("digraph DominanceTree {\n");
+   foreach_block(block, this) {
+      if (block->idom) {
+         printf("\t%d -> %d\n", block->idom->num, block->num);
+      }
+   }
+   printf("}\n");
+}