android: generate files by $(call es-gen)

[mesa.git] / src / glsl / lower_jumps.cpp

diff --git a/src/glsl/lower_jumps.cpp b/src/glsl/lower_jumps.cpp
index cbdd8eaa8be34fe4f2cb43354f4a5d2298b88ba2..ec7a0c537ff11044b3bcaf5b378dd3361b87687d 100644 (file)
--- a/src/glsl/lower_jumps.cpp
+++ b/src/glsl/lower_jumps.cpp
@@ -133,6 +133,8 @@ enum jump_strength
    strength_return
 };
 
+namespace {
+
 struct block_record
 {
    /* minimum jump strength (of lowered IR, not pre-lowering IR)
@@ -279,8 +281,13 @@ struct ir_lower_jumps_visitor : public ir_control_flow_visitor {
    bool lower_main_return;
 
    ir_lower_jumps_visitor()
+      : progress(false),
+        pull_out_jumps(false),
+        lower_continue(false),
+        lower_break(false),
+        lower_sub_return(false),
+        lower_main_return(false)
    {
-      this->progress = false;
    }
 
    void truncate_after_instruction(exec_node *ir)
@@ -341,6 +348,50 @@ struct ir_lower_jumps_visitor : public ir_control_flow_visitor {
       ir->replace_with(new(ir) ir_loop_jump(ir_loop_jump::jump_break));
    }
 
+   /**
+    * Create the necessary instruction to replace a break instruction.
+    */
+   ir_instruction *create_lowered_break()
+   {
+      void *ctx = this->function.signature;
+      return new(ctx) ir_assignment(
+          new(ctx) ir_dereference_variable(this->loop.get_break_flag()),
+          new(ctx) ir_constant(true),
+          0);
+   }
+
+   /**
+    * If the given instruction is a break, lower it to an instruction
+    * that sets the break flag, without consulting
+    * should_lower_jump().
+    *
+    * It is safe to pass NULL to this function.
+    */
+   void lower_break_unconditionally(ir_instruction *ir)
+   {
+      if (get_jump_strength(ir) != strength_break) {
+         return;
+      }
+      ir->replace_with(create_lowered_break());
+   }
+
+   /**
+    * If the block ends in a conditional or unconditional break, lower
+    * it, even though should_lower_jump() says it needn't be lowered.
+    */
+   void lower_final_breaks(exec_list *block)
+   {
+      ir_instruction *ir = (ir_instruction *) block->get_tail();
+      lower_break_unconditionally(ir);
+      ir_if *ir_if = ir->as_if();
+      if (ir_if) {
+          lower_break_unconditionally(
+              (ir_instruction *) ir_if->then_instructions.get_tail());
+          lower_break_unconditionally(
+              (ir_instruction *) ir_if->else_instructions.get_tail());
+      }
+   }
+
    virtual void visit(class ir_loop_jump * ir)
    {
       /* Eliminate all instructions after each one, since they are
@@ -394,6 +445,7 @@ struct ir_lower_jumps_visitor : public ir_control_flow_visitor {
        * satisfied, because discard statements can't contain other
        * statements.
        */
+      (void) ir;
    }
 
    enum jump_strength get_jump_strength(ir_instruction* ir)
@@ -445,9 +497,20 @@ struct ir_lower_jumps_visitor : public ir_control_flow_visitor {
 
    block_record visit_block(exec_list* list)
    {
+      /* Note: since visiting a node may change that node's next
+       * pointer, we can't use visit_exec_list(), because
+       * visit_exec_list() caches the node's next pointer before
+       * visiting it.  So we use foreach_in_list() instead.
+       *
+       * foreach_in_list() isn't safe if the node being visited gets
+       * removed, but fortunately this visitor doesn't do that.
+       */
+
       block_record saved_block = this->block;
       this->block = block_record();
-      visit_exec_list(list, this);
+      foreach_in_list(ir_instruction, node, list) {
+         node->accept(this);
+      }
       block_record ret = this->block;
       this->block = saved_block;
       return ret;
@@ -605,7 +668,7 @@ retry: /* we get here if we put code after the if inside a branch */
              * The visit() function for the loop will ensure that the
              * break flag is checked after executing the loop body.
              */
-            jumps[lower]->insert_before(new(ir) ir_assignment(new (ir) ir_dereference_variable(this->loop.get_break_flag()), new (ir) ir_constant(true), 0));
+            jumps[lower]->insert_before(create_lowered_break());
             goto lower_continue;
          } else if(jump_strengths[lower] == strength_continue) {
 lower_continue:
@@ -627,7 +690,10 @@ lower_continue:
             block_records[lower].min_strength = strength_always_clears_execute_flag;
             block_records[lower].may_clear_execute_flag = true;
             this->progress = true;
-            break;
+
+            /* Let the loop run again, in case the other branch of the
+             * if needs to be lowered too.
+             */
          }
       }
 
@@ -822,6 +888,9 @@ lower_continue:
       }
 
       if(this->loop.break_flag) {
+         /* We only get here if we are lowering breaks */
+         assert (lower_break);
+
          /* If a break flag was generated while visiting the body of
           * the loop, then at least one break was lowered, so we need
           * to generate an if statement at the end of the loop that
@@ -829,7 +898,13 @@ lower_continue:
           * generate won't violate the CONTAINED_JUMPS_LOWERED
           * postcondition, because should_lower_jump() always returns
           * false for a break that happens at the end of a loop.
+          *
+          * However, if the loop already ends in a conditional or
+          * unconditional break, then we need to lower that break,
+          * because it won't be at the end of the loop anymore.
           */
+         lower_final_breaks(&ir->body_instructions);
+
          ir_if* break_if = new(ir) ir_if(new(ir) ir_dereference_variable(this->loop.break_flag));
          break_if->then_instructions.push_tail(new(ir) ir_loop_jump(ir_loop_jump::jump_break));
          ir->body_instructions.push_tail(break_if);
@@ -924,6 +999,8 @@ lower_continue:
    }
 };
 
+} /* anonymous namespace */
+
 bool
 do_lower_jumps(exec_list *instructions, bool pull_out_jumps, bool lower_sub_return, bool lower_main_return, bool lower_continue, bool lower_break)
 {
@@ -934,10 +1011,12 @@ do_lower_jumps(exec_list *instructions, bool pull_out_jumps, bool lower_sub_retu
    v.lower_sub_return = lower_sub_return;
    v.lower_main_return = lower_main_return;
 
+   bool progress_ever = false;
    do {
       v.progress = false;
       visit_exec_list(instructions, &v);
+      progress_ever = v.progress || progress_ever;
    } while (v.progress);
 
-   return v.progress;
+   return progress_ever;
 }