glsl: move to compiler/

Signed-off-by: Emil Velikov <[email protected]>
Acked-by: Matt Turner <[email protected]>
Acked-by: Jose Fonseca <[email protected]>

1 files changed, 246 insertions, 0 deletions

diff --git a/src/compiler/glsl/loop_controls.cpp b/src/compiler/glsl/loop_controls.cpp
new file mode 100644
index 00000000000..c717605ec74
--- /dev/null
+++ b/src/compiler/glsl/loop_controls.cpp
@@ -0,0 +1,246 @@
+/*
+ * Copyright © 2010 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.
+ */
+
+#include <limits.h>
+#include "main/compiler.h"
+#include "compiler/glsl_types.h"
+#include "loop_analysis.h"
+#include "ir_hierarchical_visitor.h"
+
+/**
+ * Find an initializer of a variable outside a loop
+ *
+ * Works backwards from the loop to find the pre-loop value of the variable.
+ * This is used, for example, to find the initial value of loop induction
+ * variables.
+ *
+ * \param loop  Loop where \c var is an induction variable
+ * \param var   Variable whose initializer is to be found
+ *
+ * \return
+ * The \c ir_rvalue assigned to the variable outside the loop.  May return
+ * \c NULL if no initializer can be found.
+ */
+ir_rvalue *
+find_initial_value(ir_loop *loop, ir_variable *var)
+{
+   for (exec_node *node = loop->prev;
+	!node->is_head_sentinel();
+	node = node->prev) {
+      ir_instruction *ir = (ir_instruction *) node;
+
+      switch (ir->ir_type) {
+      case ir_type_call:
+      case ir_type_loop:
+      case ir_type_loop_jump:
+      case ir_type_return:
+      case ir_type_if:
+	 return NULL;
+
+      case ir_type_function:
+      case ir_type_function_signature:
+	 assert(!"Should not get here.");
+	 return NULL;
+
+      case ir_type_assignment: {
+	 ir_assignment *assign = ir->as_assignment();
+	 ir_variable *assignee = assign->lhs->whole_variable_referenced();
+
+	 if (assignee == var)
+	    return (assign->condition != NULL) ? NULL : assign->rhs;
+
+	 break;
+      }
+
+      default:
+	 break;
+      }
+   }
+
+   return NULL;
+}
+
+
+int
+calculate_iterations(ir_rvalue *from, ir_rvalue *to, ir_rvalue *increment,
+		     enum ir_expression_operation op)
+{
+   if (from == NULL || to == NULL || increment == NULL)
+      return -1;
+
+   void *mem_ctx = ralloc_context(NULL);
+
+   ir_expression *const sub =
+      new(mem_ctx) ir_expression(ir_binop_sub, from->type, to, from);
+
+   ir_expression *const div =
+      new(mem_ctx) ir_expression(ir_binop_div, sub->type, sub, increment);
+
+   ir_constant *iter = div->constant_expression_value();
+
+   if (iter == NULL)
+      return -1;
+
+   if (!iter->type->is_integer()) {
+      const ir_expression_operation op = iter->type->is_double()
+         ? ir_unop_d2i : ir_unop_f2i;
+      ir_rvalue *cast =
+         new(mem_ctx) ir_expression(op, glsl_type::int_type, iter, NULL);
+
+      iter = cast->constant_expression_value();
+   }
+
+   int iter_value = iter->get_int_component(0);
+
+   /* Make sure that the calculated number of iterations satisfies the exit
+    * condition.  This is needed to catch off-by-one errors and some types of
+    * ill-formed loops.  For example, we need to detect that the following
+    * loop does not have a maximum iteration count.
+    *
+    *    for (float x = 0.0; x != 0.9; x += 0.2)
+    *        ;
+    */
+   const int bias[] = { -1, 0, 1 };
+   bool valid_loop = false;
+
+   for (unsigned i = 0; i < ARRAY_SIZE(bias); i++) {
+      /* Increment may be of type int, uint or float. */
+      switch (increment->type->base_type) {
+      case GLSL_TYPE_INT:
+         iter = new(mem_ctx) ir_constant(iter_value + bias[i]);
+         break;
+      case GLSL_TYPE_UINT:
+         iter = new(mem_ctx) ir_constant(unsigned(iter_value + bias[i]));
+         break;
+      case GLSL_TYPE_FLOAT:
+         iter = new(mem_ctx) ir_constant(float(iter_value + bias[i]));
+         break;
+      case GLSL_TYPE_DOUBLE:
+         iter = new(mem_ctx) ir_constant(double(iter_value + bias[i]));
+         break;
+      default:
+          unreachable("Unsupported type for loop iterator.");
+      }
+
+      ir_expression *const mul =
+	 new(mem_ctx) ir_expression(ir_binop_mul, increment->type, iter,
+				    increment);
+
+      ir_expression *const add =
+	 new(mem_ctx) ir_expression(ir_binop_add, mul->type, mul, from);
+
+      ir_expression *const cmp =
+	 new(mem_ctx) ir_expression(op, glsl_type::bool_type, add, to);
+
+      ir_constant *const cmp_result = cmp->constant_expression_value();
+
+      assert(cmp_result != NULL);
+      if (cmp_result->get_bool_component(0)) {
+	 iter_value += bias[i];
+	 valid_loop = true;
+	 break;
+      }
+   }
+
+   ralloc_free(mem_ctx);
+   return (valid_loop) ? iter_value : -1;
+}
+
+namespace {
+
+class loop_control_visitor : public ir_hierarchical_visitor {
+public:
+   loop_control_visitor(loop_state *state)
+   {
+      this->state = state;
+      this->progress = false;
+   }
+
+   virtual ir_visitor_status visit_leave(ir_loop *ir);
+
+   loop_state *state;
+
+   bool progress;
+};
+
+} /* anonymous namespace */
+
+ir_visitor_status
+loop_control_visitor::visit_leave(ir_loop *ir)
+{
+   loop_variable_state *const ls = this->state->get(ir);
+
+   /* If we've entered a loop that hasn't been analyzed, something really,
+    * really bad has happened.
+    */
+   if (ls == NULL) {
+      assert(ls != NULL);
+      return visit_continue;
+   }
+
+   if (ls->limiting_terminator != NULL) {
+      /* If the limiting terminator has an iteration count of zero, then we've
+       * proven that the loop cannot run, so delete it.
+       */
+      int iterations = ls->limiting_terminator->iterations;
+      if (iterations == 0) {
+         ir->remove();
+         this->progress = true;
+         return visit_continue;
+      }
+   }
+
+   /* Remove the conditional break statements associated with all terminators
+    * that are associated with a fixed iteration count, except for the one
+    * associated with the limiting terminator--that one needs to stay, since
+    * it terminates the loop.  Exception: if the loop still has a normative
+    * bound, then that terminates the loop, so we don't even need the limiting
+    * terminator.
+    */
+   foreach_in_list(loop_terminator, t, &ls->terminators) {
+      if (t->iterations < 0)
+         continue;
+
+      if (t != ls->limiting_terminator) {
+         t->ir->remove();
+
+         assert(ls->num_loop_jumps > 0);
+         ls->num_loop_jumps--;
+
+         this->progress = true;
+      }
+   }
+
+   return visit_continue;
+}
+
+
+bool
+set_loop_controls(exec_list *instructions, loop_state *ls)
+{
+   loop_control_visitor v(ls);
+
+   v.run(instructions);
+
+   return v.progress;
+}