Nouveau - Aug 2015 - [PATCH] glsl: Extend lowering pass for gl_ClipDistance to support other arrays

This will come in handy when we want to lower gl_CullDistance into
gl_CullDistanceMESA.

Signed-off-by: Tobias Klausmann <tobias.johannes.klausmann at mni.thm.de>
---
 src/glsl/Makefile.sources        |   2 +-
 src/glsl/ir_optimization.h       |   1 +
 src/glsl/lower_clip_distance.cpp | 574 ------------------------------------
 src/glsl/lower_distance.cpp      | 606 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 608 insertions(+), 575 deletions(-)
 delete mode 100644 src/glsl/lower_clip_distance.cpp
 create mode 100644 src/glsl/lower_distance.cpp

diff --git a/src/glsl/Makefile.sources b/src/glsl/Makefile.sources
index 0b77244..00ba480 100644
--- a/src/glsl/Makefile.sources
+++ b/src/glsl/Makefile.sources
@@ -143,7 +143,7 @@ LIBGLSL_FILES = \
 	loop_analysis.h \
 	loop_controls.cpp \
 	loop_unroll.cpp \
-	lower_clip_distance.cpp \
+	lower_distance.cpp \
 	lower_const_arrays_to_uniforms.cpp \
 	lower_discard.cpp \
 	lower_discard_flow.cpp \
diff --git a/src/glsl/ir_optimization.h b/src/glsl/ir_optimization.h
index eef107e..fe62e74 100644
--- a/src/glsl/ir_optimization.h
+++ b/src/glsl/ir_optimization.h
@@ -120,6 +120,7 @@ bool lower_variable_index_to_cond_assign(gl_shader_stage
stage,
 bool lower_quadop_vector(exec_list *instructions, bool dont_lower_swz);
 bool lower_const_arrays_to_uniforms(exec_list *instructions);
 bool lower_clip_distance(gl_shader *shader);
+bool lower_cull_distance(gl_shader *shader);
 void lower_output_reads(unsigned stage, exec_list *instructions);
 bool lower_packing_builtins(exec_list *instructions, int op_mask);
 void lower_ubo_reference(struct gl_shader *shader, exec_list *instructions);
diff --git a/src/glsl/lower_clip_distance.cpp b/src/glsl/lower_clip_distance.cpp
deleted file mode 100644
index 1ada215..0000000
--- a/src/glsl/lower_clip_distance.cpp
+++ /dev/null
@@ -1,574 +0,0 @@
-/*
- * Copyright © 2011 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.
- */
-
-/**
- * \file lower_clip_distance.cpp
- *
- * This pass accounts for the difference between the way
- * gl_ClipDistance is declared in standard GLSL (as an array of
- * floats), and the way it is frequently implemented in hardware (as
- * a pair of vec4s, with four clip distances packed into each).
- *
- * The declaration of gl_ClipDistance is replaced with a declaration
- * of gl_ClipDistanceMESA, and any references to gl_ClipDistance are
- * translated to refer to gl_ClipDistanceMESA with the appropriate
- * swizzling of array indices.  For instance:
- *
- *   gl_ClipDistance[i]
- *
- * is translated into:
- *
- *   gl_ClipDistanceMESA[i>>2][i&3]
- *
- * Since some hardware may not internally represent gl_ClipDistance as a pair
- * of vec4's, this lowering pass is optional.  To enable it, set the
- * LowerClipDistance flag in gl_shader_compiler_options to true.
- */
-
-#include "glsl_symbol_table.h"
-#include "ir_rvalue_visitor.h"
-#include "ir.h"
-#include "program/prog_instruction.h" /* For WRITEMASK_* */
-
-namespace {
-
-class lower_clip_distance_visitor : public ir_rvalue_visitor {
-public:
-   explicit lower_clip_distance_visitor(gl_shader_stage shader_stage)
-      : progress(false), old_clip_distance_out_var(NULL),
-        old_clip_distance_in_var(NULL), new_clip_distance_out_var(NULL),
-        new_clip_distance_in_var(NULL), shader_stage(shader_stage)
-   {
-   }
-
-   virtual ir_visitor_status visit(ir_variable *);
-   void create_indices(ir_rvalue*, ir_rvalue *&, ir_rvalue *&);
-   bool is_clip_distance_vec8(ir_rvalue *ir);
-   ir_rvalue *lower_clip_distance_vec8(ir_rvalue *ir);
-   virtual ir_visitor_status visit_leave(ir_assignment *);
-   void visit_new_assignment(ir_assignment *ir);
-   virtual ir_visitor_status visit_leave(ir_call *);
-
-   virtual void handle_rvalue(ir_rvalue **rvalue);
-
-   void fix_lhs(ir_assignment *);
-
-   bool progress;
-
-   /**
-    * Pointer to the declaration of gl_ClipDistance, if found.
-    *
-    * Note:
-    *
-    * - the in_var is for geometry and both tessellation shader inputs only.
-    *
-    * - since gl_ClipDistance is available in tessellation control,
-    *   tessellation evaluation and geometry shaders as both an input
-    *   and an output, it's possible for both old_clip_distance_out_var
-    *   and old_clip_distance_in_var to be non-null.
-    */
-   ir_variable *old_clip_distance_out_var;
-   ir_variable *old_clip_distance_in_var;
-
-   /**
-    * Pointer to the newly-created gl_ClipDistanceMESA variable.
-    */
-   ir_variable *new_clip_distance_out_var;
-   ir_variable *new_clip_distance_in_var;
-
-   /**
-    * Type of shader we are compiling (e.g. MESA_SHADER_VERTEX)
-    */
-   const gl_shader_stage shader_stage;
-};
-
-} /* anonymous namespace */
-
-/**
- * Replace any declaration of gl_ClipDistance as an array of floats with a
- * declaration of gl_ClipDistanceMESA as an array of vec4's.
- */
-ir_visitor_status
-lower_clip_distance_visitor::visit(ir_variable *ir)
-{
-   ir_variable **old_var;
-   ir_variable **new_var;
-
-   if (!ir->name || strcmp(ir->name, "gl_ClipDistance") != 0)
-      return visit_continue;
-   assert (ir->type->is_array());
-
-   if (ir->data.mode == ir_var_shader_out) {
-      if (this->old_clip_distance_out_var)
-         return visit_continue;
-      old_var = &old_clip_distance_out_var;
-      new_var = &new_clip_distance_out_var;
-   } else if (ir->data.mode == ir_var_shader_in) {
-      if (this->old_clip_distance_in_var)
-         return visit_continue;
-      old_var = &old_clip_distance_in_var;
-      new_var = &new_clip_distance_in_var;
-   } else {
-      unreachable("not reached");
-   }
-
-   this->progress = true;
-
-   if (!ir->type->fields.array->is_array()) {
-      /* gl_ClipDistance (used for vertex, tessellation evaluation and
-       * geometry output, and fragment input).
-       */
-      assert((ir->data.mode == ir_var_shader_in &&
-              this->shader_stage == MESA_SHADER_FRAGMENT) ||
-             (ir->data.mode == ir_var_shader_out &&
-              (this->shader_stage == MESA_SHADER_VERTEX ||
-               this->shader_stage == MESA_SHADER_TESS_EVAL ||
-               this->shader_stage == MESA_SHADER_GEOMETRY)));
-
-      *old_var = ir;
-      assert (ir->type->fields.array == glsl_type::float_type);
-      unsigned new_size = (ir->type->array_size() + 3) / 4;
-
-      /* Clone the old var so that we inherit all of its properties */
-      *new_var = ir->clone(ralloc_parent(ir), NULL);
-
-      /* And change the properties that we need to change */
-      (*new_var)->name = ralloc_strdup(*new_var,
"gl_ClipDistanceMESA");
-      (*new_var)->type = glsl_type::get_array_instance(glsl_type::vec4_type,
-                                                       new_size);
-      (*new_var)->data.max_array_access = ir->data.max_array_access / 4;
-
-      ir->replace_with(*new_var);
-   } else {
-      /* 2D gl_ClipDistance (used for tessellation control, tessellation
-       * evaluation and geometry input, and tessellation control output).
-       */
-      assert((ir->data.mode == ir_var_shader_in &&
-              (this->shader_stage == MESA_SHADER_GEOMETRY ||
-               this->shader_stage == MESA_SHADER_TESS_EVAL)) ||
-             this->shader_stage == MESA_SHADER_TESS_CTRL);
-
-      *old_var = ir;
-      assert (ir->type->fields.array->fields.array ==
glsl_type::float_type);
-      unsigned new_size = (ir->type->fields.array->array_size() + 3) /
4;
-
-      /* Clone the old var so that we inherit all of its properties */
-      *new_var = ir->clone(ralloc_parent(ir), NULL);
-
-      /* And change the properties that we need to change */
-      (*new_var)->name = ralloc_strdup(*new_var,
"gl_ClipDistanceMESA");
-      (*new_var)->type = glsl_type::get_array_instance(
-         glsl_type::get_array_instance(glsl_type::vec4_type,
-            new_size),
-         ir->type->array_size());
-      (*new_var)->data.max_array_access = ir->data.max_array_access / 4;
-
-      ir->replace_with(*new_var);
-   }
-
-   return visit_continue;
-}
-
-
-/**
- * Create the necessary GLSL rvalues to index into gl_ClipDistanceMESA based
- * on the rvalue previously used to index into gl_ClipDistance.
- *
- * \param array_index Selects one of the vec4's in gl_ClipDistanceMESA
- * \param swizzle_index Selects a component within the vec4 selected by
- *        array_index.
- */
-void
-lower_clip_distance_visitor::create_indices(ir_rvalue *old_index,
-                                            ir_rvalue *&array_index,
-                                            ir_rvalue *&swizzle_index)
-{
-   void *ctx = ralloc_parent(old_index);
-
-   /* Make sure old_index is a signed int so that the bitwise "shift"
and
-    * "and" operations below type check properly.
-    */
-   if (old_index->type != glsl_type::int_type) {
-      assert (old_index->type == glsl_type::uint_type);
-      old_index = new(ctx) ir_expression(ir_unop_u2i, old_index);
-   }
-
-   ir_constant *old_index_constant = old_index->constant_expression_value();
-   if (old_index_constant) {
-      /* gl_ClipDistance is being accessed via a constant index.  Don't
bother
-       * creating expressions to calculate the lowered indices.  Just create
-       * constants.
-       */
-      int const_val = old_index_constant->get_int_component(0);
-      array_index = new(ctx) ir_constant(const_val / 4);
-      swizzle_index = new(ctx) ir_constant(const_val % 4);
-   } else {
-      /* Create a variable to hold the value of old_index (so that we
-       * don't compute it twice).
-       */
-      ir_variable *old_index_var = new(ctx) ir_variable(
-         glsl_type::int_type, "clip_distance_index",
ir_var_temporary);
-      this->base_ir->insert_before(old_index_var);
-      this->base_ir->insert_before(new(ctx) ir_assignment(
-         new(ctx) ir_dereference_variable(old_index_var), old_index));
-
-      /* Create the expression clip_distance_index / 4.  Do this as a bit
-       * shift because that's likely to be more efficient.
-       */
-      array_index = new(ctx) ir_expression(
-         ir_binop_rshift, new(ctx) ir_dereference_variable(old_index_var),
-         new(ctx) ir_constant(2));
-
-      /* Create the expression clip_distance_index % 4.  Do this as a bitwise
-       * AND because that's likely to be more efficient.
-       */
-      swizzle_index = new(ctx) ir_expression(
-         ir_binop_bit_and, new(ctx) ir_dereference_variable(old_index_var),
-         new(ctx) ir_constant(3));
-   }
-}
-
-
-/**
- * Determine whether the given rvalue describes an array of 8 floats that
- * needs to be lowered to an array of 2 vec4's; that is, determine whether
it
- * matches one of the following patterns:
- *
- * - gl_ClipDistance (if gl_ClipDistance is 1D)
- * - gl_ClipDistance[i] (if gl_ClipDistance is 2D)
- */
-bool
-lower_clip_distance_visitor::is_clip_distance_vec8(ir_rvalue *ir)
-{
-   /* Note that geometry shaders contain gl_ClipDistance both as an input
-    * (which is a 2D array) and an output (which is a 1D array), so it's
-    * possible for both this->old_clip_distance_out_var and
-    * this->old_clip_distance_in_var to be non-NULL in the same shader.
-    */
-
-   if (!ir->type->is_array())
-      return false;
-   if (ir->type->fields.array != glsl_type::float_type)
-      return false;
-
-   if (this->old_clip_distance_out_var) {
-      if (ir->variable_referenced() == this->old_clip_distance_out_var)
-         return true;
-   }
-   if (this->old_clip_distance_in_var) {
-      assert(this->shader_stage == MESA_SHADER_TESS_CTRL ||
-             this->shader_stage == MESA_SHADER_TESS_EVAL ||
-             this->shader_stage == MESA_SHADER_GEOMETRY ||
-             this->shader_stage == MESA_SHADER_FRAGMENT);
-
-      if (ir->variable_referenced() == this->old_clip_distance_in_var)
-         return true;
-   }
-   return false;
-}
-
-
-/**
- * If the given ir satisfies is_clip_distance_vec8(), return new ir
- * representing its lowered equivalent.  That is, map:
- *
- * - gl_ClipDistance    => gl_ClipDistanceMESA    (if gl_ClipDistance is 1D)
- * - gl_ClipDistance[i] => gl_ClipDistanceMESA[i] (if gl_ClipDistance is 2D)
- *
- * Otherwise return NULL.
- */
-ir_rvalue *
-lower_clip_distance_visitor::lower_clip_distance_vec8(ir_rvalue *ir)
-{
-   if (!ir->type->is_array())
-      return NULL;
-   if (ir->type->fields.array != glsl_type::float_type)
-      return NULL;
-
-   ir_variable **new_var = NULL;
-   if (this->old_clip_distance_out_var) {
-      if (ir->variable_referenced() == this->old_clip_distance_out_var)
-         new_var = &this->new_clip_distance_out_var;
-   }
-   if (this->old_clip_distance_in_var) {
-      if (ir->variable_referenced() == this->old_clip_distance_in_var)
-         new_var = &this->new_clip_distance_in_var;
-   }
-   if (new_var == NULL)
-      return NULL;
-
-   if (ir->as_dereference_variable()) {
-      return new(ralloc_parent(ir)) ir_dereference_variable(*new_var);
-   } else {
-      ir_dereference_array *array_ref = ir->as_dereference_array();
-      assert(array_ref);
-      assert(array_ref->array->as_dereference_variable());
-
-      return new(ralloc_parent(ir))
-         ir_dereference_array(*new_var, array_ref->array_index);
-   }
-}
-
-
-void
-lower_clip_distance_visitor::handle_rvalue(ir_rvalue **rv)
-{
-   if (*rv == NULL)
-      return;
-
-   ir_dereference_array *const array_deref = (*rv)->as_dereference_array();
-   if (array_deref == NULL)
-      return;
-
-   /* Replace any expression that indexes one of the floats in gl_ClipDistance
-    * with an expression that indexes into one of the vec4's in
-    * gl_ClipDistanceMESA and accesses the appropriate component.
-    */
-   ir_rvalue *lowered_vec8 -     
this->lower_clip_distance_vec8(array_deref->array);
-   if (lowered_vec8 != NULL) {
-      this->progress = true;
-      ir_rvalue *array_index;
-      ir_rvalue *swizzle_index;
-      this->create_indices(array_deref->array_index, array_index,
swizzle_index);
-      void *mem_ctx = ralloc_parent(array_deref);
-
-      ir_dereference_array *const new_array_deref -         new(mem_ctx)
ir_dereference_array(lowered_vec8, array_index);
-
-      ir_expression *const expr -         new(mem_ctx)
ir_expression(ir_binop_vector_extract,
-                                    new_array_deref,
-                                    swizzle_index);
-
-      *rv = expr;
-   }
-}
-
-void
-lower_clip_distance_visitor::fix_lhs(ir_assignment *ir)
-{
-   if (ir->lhs->ir_type == ir_type_expression) {
-      void *mem_ctx = ralloc_parent(ir);
-      ir_expression *const expr = (ir_expression *) ir->lhs;
-
-      /* The expression must be of the form:
-       *
-       *     (vector_extract gl_ClipDistanceMESA[i], j).
-       */
-      assert(expr->operation == ir_binop_vector_extract);
-      assert(expr->operands[0]->ir_type == ir_type_dereference_array);
-      assert(expr->operands[0]->type == glsl_type::vec4_type);
-
-      ir_dereference *const new_lhs = (ir_dereference *) expr->operands[0];
-      ir->rhs = new(mem_ctx) ir_expression(ir_triop_vector_insert,
-					   glsl_type::vec4_type,
-					   new_lhs->clone(mem_ctx, NULL),
-					   ir->rhs,
-					   expr->operands[1]);
-      ir->set_lhs(new_lhs);
-      ir->write_mask = WRITEMASK_XYZW;
-   }
-}
-
-/**
- * Replace any assignment having the 1D gl_ClipDistance (undereferenced) as
- * its LHS or RHS with a sequence of assignments, one for each component of
- * the array.  Each of these assignments is lowered to refer to
- * gl_ClipDistanceMESA as appropriate.
- *
- * We need to do a similar replacement for 2D gl_ClipDistance, however since
- * it's an input, the only case we need to address is where a 1D slice of
it
- * is the entire RHS of an assignment, e.g.:
- *
- *     foo = gl_in[i].gl_ClipDistance
- */
-ir_visitor_status
-lower_clip_distance_visitor::visit_leave(ir_assignment *ir)
-{
-   /* First invoke the base class visitor.  This causes handle_rvalue() to be
-    * called on ir->rhs and ir->condition.
-    */
-   ir_rvalue_visitor::visit_leave(ir);
-
-   if (this->is_clip_distance_vec8(ir->lhs) ||
-       this->is_clip_distance_vec8(ir->rhs)) {
-      /* LHS or RHS of the assignment is the entire 1D gl_ClipDistance array
-       * (or a 1D slice of a 2D gl_ClipDistance input array).  Since we are
-       * reshaping gl_ClipDistance from an array of floats to an array of
-       * vec4's, this isn't going to work as a bulk assignment anymore,
so
-       * unroll it to element-by-element assignments and lower each of them.
-       *
-       * Note: to unroll into element-by-element assignments, we need to make
-       * clones of the LHS and RHS.  This is safe because expressions and
-       * l-values are side-effect free.
-       */
-      void *ctx = ralloc_parent(ir);
-      int array_size = ir->lhs->type->array_size();
-      for (int i = 0; i < array_size; ++i) {
-         ir_dereference_array *new_lhs = new(ctx) ir_dereference_array(
-            ir->lhs->clone(ctx, NULL), new(ctx) ir_constant(i));
-         ir_dereference_array *new_rhs = new(ctx) ir_dereference_array(
-            ir->rhs->clone(ctx, NULL), new(ctx) ir_constant(i));
-         this->handle_rvalue((ir_rvalue **) &new_rhs);
-
-         /* Handle the LHS after creating the new assignment.  This must
-          * happen in this order because handle_rvalue may replace the old LHS
-          * with an ir_expression of ir_binop_vector_extract.  Since this is
-          * not a valide l-value, this will cause an assertion in the
-          * ir_assignment constructor to fail.
-          *
-          * If this occurs, replace the mangled LHS with a dereference of the
-          * vector, and replace the RHS with an ir_triop_vector_insert.
-          */
-         ir_assignment *const assign = new(ctx) ir_assignment(new_lhs,
new_rhs);
-         this->handle_rvalue((ir_rvalue **) &assign->lhs);
-         this->fix_lhs(assign);
-
-         this->base_ir->insert_before(assign);
-      }
-      ir->remove();
-
-      return visit_continue;
-   }
-
-   /* Handle the LHS as if it were an r-value.  Normally
-    * rvalue_visit(ir_assignment *) only visits the RHS, but we need to lower
-    * expressions in the LHS as well.
-    *
-    * This may cause the LHS to get replaced with an ir_expression of
-    * ir_binop_vector_extract.  If this occurs, replace it with a dereference
-    * of the vector, and replace the RHS with an ir_triop_vector_insert.
-    */
-   handle_rvalue((ir_rvalue **)&ir->lhs);
-   this->fix_lhs(ir);
-
-   return rvalue_visit(ir);
-}
-
-
-/**
- * Set up base_ir properly and call visit_leave() on a newly created
- * ir_assignment node.  This is used in cases where we have to insert an
- * ir_assignment in a place where we know the hierarchical visitor won't
see
- * it.
- */
-void
-lower_clip_distance_visitor::visit_new_assignment(ir_assignment *ir)
-{
-   ir_instruction *old_base_ir = this->base_ir;
-   this->base_ir = ir;
-   ir->accept(this);
-   this->base_ir = old_base_ir;
-}
-
-
-/**
- * If a 1D gl_ClipDistance variable appears as an argument in an ir_call
- * expression, replace it with a temporary variable, and make sure the ir_call
- * is preceded and/or followed by assignments that copy the contents of the
- * temporary variable to and/or from gl_ClipDistance.  Each of these
- * assignments is then lowered to refer to gl_ClipDistanceMESA.
- *
- * We need to do a similar replacement for 2D gl_ClipDistance, however since
- * it's an input, the only case we need to address is where a 1D slice of
it
- * is passed as an "in" parameter to an ir_call, e.g.:
- *
- *     foo(gl_in[i].gl_ClipDistance)
- */
-ir_visitor_status
-lower_clip_distance_visitor::visit_leave(ir_call *ir)
-{
-   void *ctx = ralloc_parent(ir);
-
-   const exec_node *formal_param_node = ir->callee->parameters.head;
-   const exec_node *actual_param_node = ir->actual_parameters.head;
-   while (!actual_param_node->is_tail_sentinel()) {
-      ir_variable *formal_param = (ir_variable *) formal_param_node;
-      ir_rvalue *actual_param = (ir_rvalue *) actual_param_node;
-
-      /* Advance formal_param_node and actual_param_node now so that we can
-       * safely replace actual_param with another node, if necessary, below.
-       */
-      formal_param_node = formal_param_node->next;
-      actual_param_node = actual_param_node->next;
-
-      if (this->is_clip_distance_vec8(actual_param)) {
-         /* User is trying to pass the whole 1D gl_ClipDistance array (or a 1D
-          * slice of a 2D gl_ClipDistance array) to a function call.  Since we
-          * are reshaping gl_ClipDistance from an array of floats to an array
-          * of vec4's, this isn't going to work anymore, so use a
temporary
-          * array instead.
-          */
-         ir_variable *temp_clip_distance = new(ctx) ir_variable(
-            actual_param->type, "temp_clip_distance",
ir_var_temporary);
-         this->base_ir->insert_before(temp_clip_distance);
-         actual_param->replace_with(
-            new(ctx) ir_dereference_variable(temp_clip_distance));
-         if (formal_param->data.mode == ir_var_function_in
-             || formal_param->data.mode == ir_var_function_inout) {
-            /* Copy from gl_ClipDistance to the temporary before the call.
-             * Since we are going to insert this copy before the current
-             * instruction, we need to visit it afterwards to make sure it
-             * gets lowered.
-             */
-            ir_assignment *new_assignment = new(ctx) ir_assignment(
-               new(ctx) ir_dereference_variable(temp_clip_distance),
-               actual_param->clone(ctx, NULL));
-            this->base_ir->insert_before(new_assignment);
-            this->visit_new_assignment(new_assignment);
-         }
-         if (formal_param->data.mode == ir_var_function_out
-             || formal_param->data.mode == ir_var_function_inout) {
-            /* Copy from the temporary to gl_ClipDistance after the call.
-             * Since visit_list_elements() has already decided which
-             * instruction it's going to visit next, we need to visit
-             * afterwards to make sure it gets lowered.
-             */
-            ir_assignment *new_assignment = new(ctx) ir_assignment(
-               actual_param->clone(ctx, NULL),
-               new(ctx) ir_dereference_variable(temp_clip_distance));
-            this->base_ir->insert_after(new_assignment);
-            this->visit_new_assignment(new_assignment);
-         }
-      }
-   }
-
-   return rvalue_visit(ir);
-}
-
-
-bool
-lower_clip_distance(gl_shader *shader)
-{
-   lower_clip_distance_visitor v(shader->Stage);
-
-   visit_list_elements(&v, shader->ir);
-
-   if (v.new_clip_distance_out_var)
-      shader->symbols->add_variable(v.new_clip_distance_out_var);
-   if (v.new_clip_distance_in_var)
-      shader->symbols->add_variable(v.new_clip_distance_in_var);
-
-   return v.progress;
-}
diff --git a/src/glsl/lower_distance.cpp b/src/glsl/lower_distance.cpp
new file mode 100644
index 0000000..172da3d
--- /dev/null
+++ b/src/glsl/lower_distance.cpp
@@ -0,0 +1,606 @@
+/*
+ * Copyright © 2011 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.
+ */
+
+/**
+ * \file lower_distance.cpp
+ *
+ * This pass accounts for the difference between the way
+ * gl_ClipDistance or gl_CullDistance is declared in standard GLSL
+ * (as an array of floats), and the way it is frequently implemented
+ * in hardware (as a pair of vec4s, with four clip or cull distances
+ * packed into each).
+ *
+ * The declaration of gl_ClipDistance or gl_CullDistance is replaced
+ * with a declaration of gl_ClipDistanceMESA or gl_CullDistanceMESA
+ * respectively, and any references to the original gl_ClipDistance
+ * or gl_CullDistance are translated to refer to gl_ClipDistanceMESA
+ * or gl_CullDistanceMESA with the appropriate swizzling of array
+ * indices.  For instance:
+ *
+ *   gl_ClipDistance[i]
+ *
+ * is translated into:
+ *
+ *   gl_ClipDistanceMESA[i>>2][i&3]
+ *
+ * Since some hardware may not internally represent these arrays as a
+ * pair of vec4's, this lowering pass is optional.  To enable it, set
+ * the LowerClipDistance flag in gl_shader_compiler_options to true.
+ */
+
+#include <string>
+#include "glsl_symbol_table.h"
+#include "ir_rvalue_visitor.h"
+#include "ir.h"
+#include "program/prog_instruction.h" /* For WRITEMASK_* */
+
+namespace {
+
+class lower_distance_visitor : public ir_rvalue_visitor {
+public:
+   explicit lower_distance_visitor(gl_shader_stage shader_stage,
+         std::string in_name, std::string out_name)
+      : progress(false), old_distance_out_var(NULL),
+        old_distance_in_var(NULL), new_distance_out_var(NULL),
+        new_distance_in_var(NULL), shader_stage(shader_stage),
+        in_name(in_name), out_name(out_name)
+   {
+   }
+
+   virtual ir_visitor_status visit(ir_variable *);
+   void create_indices(ir_rvalue*, ir_rvalue *&, ir_rvalue *&);
+   bool is_clip_distance_vec8(ir_rvalue *ir);
+   ir_rvalue *lower_clip_distance_vec8(ir_rvalue *ir);
+   virtual ir_visitor_status visit_leave(ir_assignment *);
+   void visit_new_assignment(ir_assignment *ir);
+   virtual ir_visitor_status visit_leave(ir_call *);
+
+   virtual void handle_rvalue(ir_rvalue **rvalue);
+
+   void fix_lhs(ir_assignment *);
+
+   bool progress;
+
+   /**
+    * Pointer to the declaration of ou arrays, if found.
+    *
+    * Note:
+    *
+    * - the in_var is for geometry and both tessellation shader inputs only.
+    *
+    * - since gl_ClipDistance is available in tessellation control,
+    *   tessellation evaluation and geometry shaders as both an input
+    *   and an output, it's possible for both old_distance_out_var
+    *   and old_distance_in_var to be non-null.
+    */
+   ir_variable *old_distance_out_var;
+   ir_variable *old_distance_in_var;
+
+   /**
+    * Pointer to the newly-created variable.
+    */
+   ir_variable *new_distance_out_var;
+   ir_variable *new_distance_in_var;
+
+   /**
+    * Type of shader we are compiling (e.g. MESA_SHADER_VERTEX)
+    */
+   const gl_shader_stage shader_stage;
+
+   /**
+    *  Identifier of the variables we manipulate
+    */
+
+   std::string in_name;
+   std::string out_name;
+};
+
+} /* anonymous namespace */
+
+/**
+ * Replace any declaration of in_name as an array of floats with a
+ * declaration of out_name as an array of vec4's.
+ */
+ir_visitor_status
+lower_distance_visitor::visit(ir_variable *ir)
+{
+   ir_variable **old_var;
+   ir_variable **new_var;
+
+   if (!ir->name || in_name.compare(ir->name) != 0)
+      return visit_continue;
+   assert (ir->type->is_array());
+
+   if (ir->data.mode == ir_var_shader_out) {
+      if (this->old_distance_out_var)
+         return visit_continue;
+      old_var = &old_distance_out_var;
+      new_var = &new_distance_out_var;
+   } else if (ir->data.mode == ir_var_shader_in) {
+      if (this->old_distance_in_var)
+         return visit_continue;
+      old_var = &old_distance_in_var;
+      new_var = &new_distance_in_var;
+   } else {
+      unreachable("not reached");
+   }
+
+   this->progress = true;
+
+   if (!ir->type->fields.array->is_array()) {
+      /* gl_ClipDistance / gl_CullDistance (used for vertex, tessellation
+       * evaluation and geometry output, and fragment input).
+       */
+      assert((ir->data.mode == ir_var_shader_in &&
+              this->shader_stage == MESA_SHADER_FRAGMENT) ||
+             (ir->data.mode == ir_var_shader_out &&
+              (this->shader_stage == MESA_SHADER_VERTEX ||
+               this->shader_stage == MESA_SHADER_TESS_EVAL ||
+               this->shader_stage == MESA_SHADER_GEOMETRY)));
+
+      *old_var = ir;
+      assert (ir->type->fields.array == glsl_type::float_type);
+      unsigned new_size = (ir->type->array_size() + 3) / 4;
+
+      /* Clone the old var so that we inherit all of its properties */
+      *new_var = ir->clone(ralloc_parent(ir), NULL);
+
+      /* And change the properties that we need to change */
+      (*new_var)->name = ralloc_strdup(*new_var, out_name.c_str());
+      (*new_var)->type = glsl_type::get_array_instance(glsl_type::vec4_type,
+                                                       new_size);
+      (*new_var)->data.max_array_access = ir->data.max_array_access / 4;
+
+      ir->replace_with(*new_var);
+   } else {
+      /* 2D gl_ClipDistance / gl_CullDistance (used for tessellation control,
+       * tessellation evaluation and geometry input, and tessellation control
+       * output).
+       */
+      assert((ir->data.mode == ir_var_shader_in &&
+              (this->shader_stage == MESA_SHADER_GEOMETRY ||
+               this->shader_stage == MESA_SHADER_TESS_EVAL)) ||
+             this->shader_stage == MESA_SHADER_TESS_CTRL);
+
+      *old_var = ir;
+      assert (ir->type->fields.array->fields.array ==
glsl_type::float_type);
+      unsigned new_size = (ir->type->fields.array->array_size() + 3) /
4;
+
+      /* Clone the old var so that we inherit all of its properties */
+      *new_var = ir->clone(ralloc_parent(ir), NULL);
+
+      /* And change the properties that we need to change */
+      (*new_var)->name = ralloc_strdup(*new_var, out_name.c_str());
+      (*new_var)->type = glsl_type::get_array_instance(
+         glsl_type::get_array_instance(glsl_type::vec4_type,
+            new_size),
+         ir->type->array_size());
+      (*new_var)->data.max_array_access = ir->data.max_array_access / 4;
+
+      ir->replace_with(*new_var);
+   }
+
+   return visit_continue;
+}
+
+
+/**
+ * Create the necessary GLSL rvalues to index into out_name based
+ * on the rvalue previously used to index into gl_ClipDistance.
+ *
+ * \param array_index Selects one of the vec4's in out_name
+ * \param swizzle_index Selects a component within the vec4 selected by
+ *        array_index.
+ */
+void
+lower_distance_visitor::create_indices(ir_rvalue *old_index,
+                                            ir_rvalue *&array_index,
+                                            ir_rvalue *&swizzle_index)
+{
+   void *ctx = ralloc_parent(old_index);
+
+   /* Make sure old_index is a signed int so that the bitwise "shift"
and
+    * "and" operations below type check properly.
+    */
+   if (old_index->type != glsl_type::int_type) {
+      assert (old_index->type == glsl_type::uint_type);
+      old_index = new(ctx) ir_expression(ir_unop_u2i, old_index);
+   }
+
+   ir_constant *old_index_constant = old_index->constant_expression_value();
+   if (old_index_constant) {
+      /* gl_ClipDistance / gl_CullDistance is being accessed via a constant
+       * index.  Don't bother creating expressions to calculate the lowered
+       * indices.  Just create constants.
+       */
+      int const_val = old_index_constant->get_int_component(0);
+      array_index = new(ctx) ir_constant(const_val / 4);
+      swizzle_index = new(ctx) ir_constant(const_val % 4);
+   } else {
+      /* Create a variable to hold the value of old_index (so that we
+       * don't compute it twice).
+       */
+      ir_variable *old_index_var = new(ctx) ir_variable(
+         glsl_type::int_type, "clip_distance_index",
ir_var_temporary);
+      this->base_ir->insert_before(old_index_var);
+      this->base_ir->insert_before(new(ctx) ir_assignment(
+         new(ctx) ir_dereference_variable(old_index_var), old_index));
+
+      /* Create the expression distance_index / 4.  Do this as a bit shift
+       * because that's likely to be more efficient.
+       */
+      array_index = new(ctx) ir_expression(
+         ir_binop_rshift, new(ctx) ir_dereference_variable(old_index_var),
+         new(ctx) ir_constant(2));
+
+      /* Create the expression distance_index % 4.  Do this as a bitwise AND
+       * because that's likely to be more efficient.
+       */
+      swizzle_index = new(ctx) ir_expression(
+         ir_binop_bit_and, new(ctx) ir_dereference_variable(old_index_var),
+         new(ctx) ir_constant(3));
+   }
+}
+
+
+/**
+ * Determine whether the given rvalue describes an array of 8 floats that
+ * needs to be lowered to an array of 2 vec4's; that is, determine whether
it
+ * matches one of the following patterns:
+ *
+ * - gl_ClipDistance (if gl_ClipDistance is 1D)
+ * - gl_ClipDistance[i] (if gl_ClipDistance is 2D)
+ */
+bool
+lower_distance_visitor::is_clip_distance_vec8(ir_rvalue *ir)
+{
+   /* Note that geometry shaders contain in_name
+    * both as an input (which is a 2D array) and an output (which is a 1D
+    * array), so it's possible for both this->old_distance_out_var and
+    * this->old_distance_in_var to be non-NULL in the same shader.
+    */
+
+   if (!ir->type->is_array())
+      return false;
+   if (ir->type->fields.array != glsl_type::float_type)
+      return false;
+
+   if (this->old_distance_out_var) {
+      if (ir->variable_referenced() == this->old_distance_out_var)
+         return true;
+   }
+   if (this->old_distance_in_var) {
+      assert(this->shader_stage == MESA_SHADER_TESS_CTRL ||
+             this->shader_stage == MESA_SHADER_TESS_EVAL ||
+             this->shader_stage == MESA_SHADER_GEOMETRY ||
+             this->shader_stage == MESA_SHADER_FRAGMENT);
+
+      if (ir->variable_referenced() == this->old_distance_in_var)
+         return true;
+   }
+   return false;
+}
+
+
+/**
+ * If the given ir satisfies is_distance_vec8(), return new ir
+ * representing its lowered equivalent.  That is, map:
+ *
+ * - gl_ClipDistance    => gl_ClipDistanceMESA    (if gl_ClipDistance is 1D)
+ * - gl_ClipDistance[i] => gl_ClipDistanceMESA[i] (if gl_ClipDistance is 2D)
+ *
+ * Otherwise return NULL.
+ */
+ir_rvalue *
+lower_distance_visitor::lower_clip_distance_vec8(ir_rvalue *ir)
+{
+   if (!ir->type->is_array())
+      return NULL;
+   if (ir->type->fields.array != glsl_type::float_type)
+      return NULL;
+
+   ir_variable **new_var = NULL;
+   if (this->old_distance_out_var) {
+      if (ir->variable_referenced() == this->old_distance_out_var)
+         new_var = &this->new_distance_out_var;
+   }
+   if (this->old_distance_in_var) {
+      if (ir->variable_referenced() == this->old_distance_in_var)
+         new_var = &this->new_distance_in_var;
+   }
+   if (new_var == NULL)
+      return NULL;
+
+   if (ir->as_dereference_variable()) {
+      return new(ralloc_parent(ir)) ir_dereference_variable(*new_var);
+   } else {
+      ir_dereference_array *array_ref = ir->as_dereference_array();
+      assert(array_ref);
+      assert(array_ref->array->as_dereference_variable());
+
+      return new(ralloc_parent(ir))
+         ir_dereference_array(*new_var, array_ref->array_index);
+   }
+}
+
+
+void
+lower_distance_visitor::handle_rvalue(ir_rvalue **rv)
+{
+   if (*rv == NULL)
+      return;
+
+   ir_dereference_array *const array_deref = (*rv)->as_dereference_array();
+   if (array_deref == NULL)
+      return;
+
+   /* Replace any expression that indexes one of the floats in in_name
+    * or in_name with an expression that indexes into one of the vec4's
+    * in out_name and accesses the appropriate component.
+    */
+   ir_rvalue *lowered_vec8 +     
this->lower_clip_distance_vec8(array_deref->array);
+   if (lowered_vec8 != NULL) {
+      this->progress = true;
+      ir_rvalue *array_index;
+      ir_rvalue *swizzle_index;
+      this->create_indices(array_deref->array_index, array_index,
swizzle_index);
+      void *mem_ctx = ralloc_parent(array_deref);
+
+      ir_dereference_array *const new_array_deref +         new(mem_ctx)
ir_dereference_array(lowered_vec8, array_index);
+
+      ir_expression *const expr +         new(mem_ctx)
ir_expression(ir_binop_vector_extract,
+                                    new_array_deref,
+                                    swizzle_index);
+
+      *rv = expr;
+   }
+}
+
+void
+lower_distance_visitor::fix_lhs(ir_assignment *ir)
+{
+   if (ir->lhs->ir_type == ir_type_expression) {
+      void *mem_ctx = ralloc_parent(ir);
+      ir_expression *const expr = (ir_expression *) ir->lhs;
+
+      /* The expression must be of the form:
+       *
+       *     (vector_extract gl_ClipDistanceMESA[i], j).
+       */
+      assert(expr->operation == ir_binop_vector_extract);
+      assert(expr->operands[0]->ir_type == ir_type_dereference_array);
+      assert(expr->operands[0]->type == glsl_type::vec4_type);
+
+      ir_dereference *const new_lhs = (ir_dereference *) expr->operands[0];
+      ir->rhs = new(mem_ctx) ir_expression(ir_triop_vector_insert,
+					   glsl_type::vec4_type,
+					   new_lhs->clone(mem_ctx, NULL),
+					   ir->rhs,
+					   expr->operands[1]);
+      ir->set_lhs(new_lhs);
+      ir->write_mask = WRITEMASK_XYZW;
+   }
+}
+
+/**
+ * Replace any assignment having the 1D in_name (undereferenced) as
+ * its LHS or RHS with a sequence of assignments, one for each component of
+ * the array.  Each of these assignments is lowered to refer to
+ * out_name as appropriate.
+ *
+ * We need to do a similar replacement for 2D in_name, however since
+ * it's an input, the only case we need to address is where a 1D slice of
it
+ * is the entire RHS of an assignment, e.g.:
+ *
+ *     foo = gl_in[i].gl_ClipDistance
+ */
+ir_visitor_status
+lower_distance_visitor::visit_leave(ir_assignment *ir)
+{
+   /* First invoke the base class visitor.  This causes handle_rvalue() to be
+    * called on ir->rhs and ir->condition.
+    */
+   ir_rvalue_visitor::visit_leave(ir);
+
+   if (this->is_clip_distance_vec8(ir->lhs) ||
+       this->is_clip_distance_vec8(ir->rhs)) {
+      /* LHS or RHS of the assignment is the entire 1D in_name array
+       * (or a 1D slice of a 2D in_name input array).  Since we are
+       * reshaping in_name from an array of floats to an array of
+       * vec4's, this isn't going to work as a bulk assignment anymore,
so
+       * unroll it to element-by-element assignments and lower each of them.
+       *
+       * Note: to unroll into element-by-element assignments, we need to make
+       * clones of the LHS and RHS.  This is safe because expressions and
+       * l-values are side-effect free.
+       */
+      void *ctx = ralloc_parent(ir);
+      int array_size = ir->lhs->type->array_size();
+      for (int i = 0; i < array_size; ++i) {
+         ir_dereference_array *new_lhs = new(ctx) ir_dereference_array(
+            ir->lhs->clone(ctx, NULL), new(ctx) ir_constant(i));
+         ir_dereference_array *new_rhs = new(ctx) ir_dereference_array(
+            ir->rhs->clone(ctx, NULL), new(ctx) ir_constant(i));
+         this->handle_rvalue((ir_rvalue **) &new_rhs);
+
+         /* Handle the LHS after creating the new assignment.  This must
+          * happen in this order because handle_rvalue may replace the old LHS
+          * with an ir_expression of ir_binop_vector_extract.  Since this is
+          * not a valide l-value, this will cause an assertion in the
+          * ir_assignment constructor to fail.
+          *
+          * If this occurs, replace the mangled LHS with a dereference of the
+          * vector, and replace the RHS with an ir_triop_vector_insert.
+          */
+         ir_assignment *const assign = new(ctx) ir_assignment(new_lhs,
new_rhs);
+         this->handle_rvalue((ir_rvalue **) &assign->lhs);
+         this->fix_lhs(assign);
+
+         this->base_ir->insert_before(assign);
+      }
+      ir->remove();
+
+      return visit_continue;
+   }
+
+   /* Handle the LHS as if it were an r-value.  Normally
+    * rvalue_visit(ir_assignment *) only visits the RHS, but we need to lower
+    * expressions in the LHS as well.
+    *
+    * This may cause the LHS to get replaced with an ir_expression of
+    * ir_binop_vector_extract.  If this occurs, replace it with a dereference
+    * of the vector, and replace the RHS with an ir_triop_vector_insert.
+    */
+   handle_rvalue((ir_rvalue **)&ir->lhs);
+   this->fix_lhs(ir);
+
+   return rvalue_visit(ir);
+}
+
+
+/**
+ * Set up base_ir properly and call visit_leave() on a newly created
+ * ir_assignment node.  This is used in cases where we have to insert an
+ * ir_assignment in a place where we know the hierarchical visitor won't
see
+ * it.
+ */
+void
+lower_distance_visitor::visit_new_assignment(ir_assignment *ir)
+{
+   ir_instruction *old_base_ir = this->base_ir;
+   this->base_ir = ir;
+   ir->accept(this);
+   this->base_ir = old_base_ir;
+}
+
+
+/**
+ * If a 1D in_name variable appears as an argument in an ir_call
+ * expression, replace it with a temporary variable, and make sure the ir_call
+ * is preceded and/or followed by assignments that copy the contents of the
+ * temporary variable to and/or from in_name.  Each of these
+ * assignments is then lowered to refer to out_name.
+ *
+ * We need to do a similar replacement for 2D in_name, however since
+ * it's an input, the only case we need to address is where a 1D slice of
it
+ * is passed as an "in" parameter to an ir_call, e.g.:
+ *
+ *     foo(gl_in[i].gl_ClipDistance)
+ */
+ir_visitor_status
+lower_distance_visitor::visit_leave(ir_call *ir)
+{
+   void *ctx = ralloc_parent(ir);
+
+   const exec_node *formal_param_node = ir->callee->parameters.head;
+   const exec_node *actual_param_node = ir->actual_parameters.head;
+   while (!actual_param_node->is_tail_sentinel()) {
+      ir_variable *formal_param = (ir_variable *) formal_param_node;
+      ir_rvalue *actual_param = (ir_rvalue *) actual_param_node;
+
+      /* Advance formal_param_node and actual_param_node now so that we can
+       * safely replace actual_param with another node, if necessary, below.
+       */
+      formal_param_node = formal_param_node->next;
+      actual_param_node = actual_param_node->next;
+
+      if (this->is_clip_distance_vec8(actual_param)) {
+         /* User is trying to pass the whole 1D in_name array (or a 1D
+          * slice of a 2D in_name array) to a function call.  Since we
+          * are reshaping in_name from an array of floats to an array
+          * of vec4's, this isn't going to work anymore, so use a
temporary
+          * array instead.
+          */
+         ir_variable *temp_clip_distance = new(ctx) ir_variable(
+            actual_param->type, "temp_clip_distance",
ir_var_temporary);
+         this->base_ir->insert_before(temp_clip_distance);
+         actual_param->replace_with(
+            new(ctx) ir_dereference_variable(temp_clip_distance));
+         if (formal_param->data.mode == ir_var_function_in
+             || formal_param->data.mode == ir_var_function_inout) {
+            /* Copy from in_name to the temporary before the call.
+             * Since we are going to insert this copy before the current
+             * instruction, we need to visit it afterwards to make sure it
+             * gets lowered.
+             */
+            ir_assignment *new_assignment = new(ctx) ir_assignment(
+               new(ctx) ir_dereference_variable(temp_clip_distance),
+               actual_param->clone(ctx, NULL));
+            this->base_ir->insert_before(new_assignment);
+            this->visit_new_assignment(new_assignment);
+         }
+         if (formal_param->data.mode == ir_var_function_out
+             || formal_param->data.mode == ir_var_function_inout) {
+            /* Copy from the temporary to in_name after the call.
+             * Since visit_list_elements() has already decided which
+             * instruction it's going to visit next, we need to visit
+             * afterwards to make sure it gets lowered.
+             */
+            ir_assignment *new_assignment = new(ctx) ir_assignment(
+               actual_param->clone(ctx, NULL),
+               new(ctx) ir_dereference_variable(temp_clip_distance));
+            this->base_ir->insert_after(new_assignment);
+            this->visit_new_assignment(new_assignment);
+         }
+      }
+   }
+
+   return rvalue_visit(ir);
+}
+
+
+bool
+lower_clip_distance(gl_shader *shader)
+{
+   lower_distance_visitor v(shader->Stage, "gl_ClipDistance",
+         "gl_ClipDistanceMESA");
+
+   visit_list_elements(&v, shader->ir);
+
+   if (v.new_distance_out_var)
+      shader->symbols->add_variable(v.new_distance_out_var);
+   if (v.new_distance_in_var)
+      shader->symbols->add_variable(v.new_distance_in_var);
+
+   return v.progress;
+}
+
+bool
+lower_cull_distance(gl_shader *shader)
+{
+   lower_distance_visitor v(shader->Stage, "gl_CullDistance",
+         "gl_CullDistanceMESA");
+
+   visit_list_elements(&v, shader->ir);
+
+   if (v.new_distance_out_var)
+      shader->symbols->add_variable(v.new_distance_out_var);
+   if (v.new_distance_in_var)
+      shader->symbols->add_variable(v.new_distance_in_var);
+
+   return v.progress;
+}
+
-- 
2.5.0

I said this on IRC, but I'll say it here too:

(a) please regenerate this with -M (not in the general case, but it
makes sense here)
(b) this seems odd as there's no support for cull distance elsewhere
yet. should be part of a series that adds cull distance support. right
now there is none, so this is out of place.

On Mon, Aug 17, 2015 at 10:50 PM, Tobias Klausmann
<tobias.johannes.klausmann at mni.thm.de> wrote:
> This will come in handy when we want to lower gl_CullDistance into
> gl_CullDistanceMESA.
>
> Signed-off-by: Tobias Klausmann <tobias.johannes.klausmann at
mni.thm.de>
> ---
>  src/glsl/Makefile.sources        |   2 +-
>  src/glsl/ir_optimization.h       |   1 +
>  src/glsl/lower_clip_distance.cpp | 574
------------------------------------
>  src/glsl/lower_distance.cpp      | 606
+++++++++++++++++++++++++++++++++++++++
>  4 files changed, 608 insertions(+), 575 deletions(-)
>  delete mode 100644 src/glsl/lower_clip_distance.cpp
>  create mode 100644 src/glsl/lower_distance.cpp
>
> diff --git a/src/glsl/Makefile.sources b/src/glsl/Makefile.sources
> index 0b77244..00ba480 100644
> --- a/src/glsl/Makefile.sources
> +++ b/src/glsl/Makefile.sources
> @@ -143,7 +143,7 @@ LIBGLSL_FILES = \
>         loop_analysis.h \
>         loop_controls.cpp \
>         loop_unroll.cpp \
> -       lower_clip_distance.cpp \
> +       lower_distance.cpp \
>         lower_const_arrays_to_uniforms.cpp \
>         lower_discard.cpp \
>         lower_discard_flow.cpp \
> diff --git a/src/glsl/ir_optimization.h b/src/glsl/ir_optimization.h
> index eef107e..fe62e74 100644
> --- a/src/glsl/ir_optimization.h
> +++ b/src/glsl/ir_optimization.h
> @@ -120,6 +120,7 @@ bool
lower_variable_index_to_cond_assign(gl_shader_stage stage,
>  bool lower_quadop_vector(exec_list *instructions, bool dont_lower_swz);
>  bool lower_const_arrays_to_uniforms(exec_list *instructions);
>  bool lower_clip_distance(gl_shader *shader);
> +bool lower_cull_distance(gl_shader *shader);
>  void lower_output_reads(unsigned stage, exec_list *instructions);
>  bool lower_packing_builtins(exec_list *instructions, int op_mask);
>  void lower_ubo_reference(struct gl_shader *shader, exec_list
*instructions);
> diff --git a/src/glsl/lower_clip_distance.cpp
b/src/glsl/lower_clip_distance.cpp
> deleted file mode 100644
> index 1ada215..0000000
> --- a/src/glsl/lower_clip_distance.cpp
> +++ /dev/null
> @@ -1,574 +0,0 @@
> -/*
> - * Copyright © 2011 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.
> - */
> -
> -/**
> - * \file lower_clip_distance.cpp
> - *
> - * This pass accounts for the difference between the way
> - * gl_ClipDistance is declared in standard GLSL (as an array of
> - * floats), and the way it is frequently implemented in hardware (as
> - * a pair of vec4s, with four clip distances packed into each).
> - *
> - * The declaration of gl_ClipDistance is replaced with a declaration
> - * of gl_ClipDistanceMESA, and any references to gl_ClipDistance are
> - * translated to refer to gl_ClipDistanceMESA with the appropriate
> - * swizzling of array indices.  For instance:
> - *
> - *   gl_ClipDistance[i]
> - *
> - * is translated into:
> - *
> - *   gl_ClipDistanceMESA[i>>2][i&3]
> - *
> - * Since some hardware may not internally represent gl_ClipDistance as a
pair
> - * of vec4's, this lowering pass is optional.  To enable it, set the
> - * LowerClipDistance flag in gl_shader_compiler_options to true.
> - */
> -
> -#include "glsl_symbol_table.h"
> -#include "ir_rvalue_visitor.h"
> -#include "ir.h"
> -#include "program/prog_instruction.h" /* For WRITEMASK_* */
> -
> -namespace {
> -
> -class lower_clip_distance_visitor : public ir_rvalue_visitor {
> -public:
> -   explicit lower_clip_distance_visitor(gl_shader_stage shader_stage)
> -      : progress(false), old_clip_distance_out_var(NULL),
> -        old_clip_distance_in_var(NULL), new_clip_distance_out_var(NULL),
> -        new_clip_distance_in_var(NULL), shader_stage(shader_stage)
> -   {
> -   }
> -
> -   virtual ir_visitor_status visit(ir_variable *);
> -   void create_indices(ir_rvalue*, ir_rvalue *&, ir_rvalue *&);
> -   bool is_clip_distance_vec8(ir_rvalue *ir);
> -   ir_rvalue *lower_clip_distance_vec8(ir_rvalue *ir);
> -   virtual ir_visitor_status visit_leave(ir_assignment *);
> -   void visit_new_assignment(ir_assignment *ir);
> -   virtual ir_visitor_status visit_leave(ir_call *);
> -
> -   virtual void handle_rvalue(ir_rvalue **rvalue);
> -
> -   void fix_lhs(ir_assignment *);
> -
> -   bool progress;
> -
> -   /**
> -    * Pointer to the declaration of gl_ClipDistance, if found.
> -    *
> -    * Note:
> -    *
> -    * - the in_var is for geometry and both tessellation shader inputs
only.
> -    *
> -    * - since gl_ClipDistance is available in tessellation control,
> -    *   tessellation evaluation and geometry shaders as both an input
> -    *   and an output, it's possible for both
old_clip_distance_out_var
> -    *   and old_clip_distance_in_var to be non-null.
> -    */
> -   ir_variable *old_clip_distance_out_var;
> -   ir_variable *old_clip_distance_in_var;
> -
> -   /**
> -    * Pointer to the newly-created gl_ClipDistanceMESA variable.
> -    */
> -   ir_variable *new_clip_distance_out_var;
> -   ir_variable *new_clip_distance_in_var;
> -
> -   /**
> -    * Type of shader we are compiling (e.g. MESA_SHADER_VERTEX)
> -    */
> -   const gl_shader_stage shader_stage;
> -};
> -
> -} /* anonymous namespace */
> -
> -/**
> - * Replace any declaration of gl_ClipDistance as an array of floats with a
> - * declaration of gl_ClipDistanceMESA as an array of vec4's.
> - */
> -ir_visitor_status
> -lower_clip_distance_visitor::visit(ir_variable *ir)
> -{
> -   ir_variable **old_var;
> -   ir_variable **new_var;
> -
> -   if (!ir->name || strcmp(ir->name, "gl_ClipDistance") !=
0)
> -      return visit_continue;
> -   assert (ir->type->is_array());
> -
> -   if (ir->data.mode == ir_var_shader_out) {
> -      if (this->old_clip_distance_out_var)
> -         return visit_continue;
> -      old_var = &old_clip_distance_out_var;
> -      new_var = &new_clip_distance_out_var;
> -   } else if (ir->data.mode == ir_var_shader_in) {
> -      if (this->old_clip_distance_in_var)
> -         return visit_continue;
> -      old_var = &old_clip_distance_in_var;
> -      new_var = &new_clip_distance_in_var;
> -   } else {
> -      unreachable("not reached");
> -   }
> -
> -   this->progress = true;
> -
> -   if (!ir->type->fields.array->is_array()) {
> -      /* gl_ClipDistance (used for vertex, tessellation evaluation and
> -       * geometry output, and fragment input).
> -       */
> -      assert((ir->data.mode == ir_var_shader_in &&
> -              this->shader_stage == MESA_SHADER_FRAGMENT) ||
> -             (ir->data.mode == ir_var_shader_out &&
> -              (this->shader_stage == MESA_SHADER_VERTEX ||
> -               this->shader_stage == MESA_SHADER_TESS_EVAL ||
> -               this->shader_stage == MESA_SHADER_GEOMETRY)));
> -
> -      *old_var = ir;
> -      assert (ir->type->fields.array == glsl_type::float_type);
> -      unsigned new_size = (ir->type->array_size() + 3) / 4;
> -
> -      /* Clone the old var so that we inherit all of its properties */
> -      *new_var = ir->clone(ralloc_parent(ir), NULL);
> -
> -      /* And change the properties that we need to change */
> -      (*new_var)->name = ralloc_strdup(*new_var,
"gl_ClipDistanceMESA");
> -      (*new_var)->type =
glsl_type::get_array_instance(glsl_type::vec4_type,
> -                                                       new_size);
> -      (*new_var)->data.max_array_access = ir->data.max_array_access
/ 4;
> -
> -      ir->replace_with(*new_var);
> -   } else {
> -      /* 2D gl_ClipDistance (used for tessellation control, tessellation
> -       * evaluation and geometry input, and tessellation control output).
> -       */
> -      assert((ir->data.mode == ir_var_shader_in &&
> -              (this->shader_stage == MESA_SHADER_GEOMETRY ||
> -               this->shader_stage == MESA_SHADER_TESS_EVAL)) ||
> -             this->shader_stage == MESA_SHADER_TESS_CTRL);
> -
> -      *old_var = ir;
> -      assert (ir->type->fields.array->fields.array ==
glsl_type::float_type);
> -      unsigned new_size = (ir->type->fields.array->array_size() +
3) / 4;
> -
> -      /* Clone the old var so that we inherit all of its properties */
> -      *new_var = ir->clone(ralloc_parent(ir), NULL);
> -
> -      /* And change the properties that we need to change */
> -      (*new_var)->name = ralloc_strdup(*new_var,
"gl_ClipDistanceMESA");
> -      (*new_var)->type = glsl_type::get_array_instance(
> -         glsl_type::get_array_instance(glsl_type::vec4_type,
> -            new_size),
> -         ir->type->array_size());
> -      (*new_var)->data.max_array_access = ir->data.max_array_access
/ 4;
> -
> -      ir->replace_with(*new_var);
> -   }
> -
> -   return visit_continue;
> -}
> -
> -
> -/**
> - * Create the necessary GLSL rvalues to index into gl_ClipDistanceMESA
based
> - * on the rvalue previously used to index into gl_ClipDistance.
> - *
> - * \param array_index Selects one of the vec4's in gl_ClipDistanceMESA
> - * \param swizzle_index Selects a component within the vec4 selected by
> - *        array_index.
> - */
> -void
> -lower_clip_distance_visitor::create_indices(ir_rvalue *old_index,
> -                                            ir_rvalue *&array_index,
> -                                            ir_rvalue *&swizzle_index)
> -{
> -   void *ctx = ralloc_parent(old_index);
> -
> -   /* Make sure old_index is a signed int so that the bitwise
"shift" and
> -    * "and" operations below type check properly.
> -    */
> -   if (old_index->type != glsl_type::int_type) {
> -      assert (old_index->type == glsl_type::uint_type);
> -      old_index = new(ctx) ir_expression(ir_unop_u2i, old_index);
> -   }
> -
> -   ir_constant *old_index_constant =
old_index->constant_expression_value();
> -   if (old_index_constant) {
> -      /* gl_ClipDistance is being accessed via a constant index. 
Don't bother
> -       * creating expressions to calculate the lowered indices.  Just
create
> -       * constants.
> -       */
> -      int const_val = old_index_constant->get_int_component(0);
> -      array_index = new(ctx) ir_constant(const_val / 4);
> -      swizzle_index = new(ctx) ir_constant(const_val % 4);
> -   } else {
> -      /* Create a variable to hold the value of old_index (so that we
> -       * don't compute it twice).
> -       */
> -      ir_variable *old_index_var = new(ctx) ir_variable(
> -         glsl_type::int_type, "clip_distance_index",
ir_var_temporary);
> -      this->base_ir->insert_before(old_index_var);
> -      this->base_ir->insert_before(new(ctx) ir_assignment(
> -         new(ctx) ir_dereference_variable(old_index_var), old_index));
> -
> -      /* Create the expression clip_distance_index / 4.  Do this as a bit
> -       * shift because that's likely to be more efficient.
> -       */
> -      array_index = new(ctx) ir_expression(
> -         ir_binop_rshift, new(ctx) ir_dereference_variable(old_index_var),
> -         new(ctx) ir_constant(2));
> -
> -      /* Create the expression clip_distance_index % 4.  Do this as a
bitwise
> -       * AND because that's likely to be more efficient.
> -       */
> -      swizzle_index = new(ctx) ir_expression(
> -         ir_binop_bit_and, new(ctx)
ir_dereference_variable(old_index_var),
> -         new(ctx) ir_constant(3));
> -   }
> -}
> -
> -
> -/**
> - * Determine whether the given rvalue describes an array of 8 floats that
> - * needs to be lowered to an array of 2 vec4's; that is, determine
whether it
> - * matches one of the following patterns:
> - *
> - * - gl_ClipDistance (if gl_ClipDistance is 1D)
> - * - gl_ClipDistance[i] (if gl_ClipDistance is 2D)
> - */
> -bool
> -lower_clip_distance_visitor::is_clip_distance_vec8(ir_rvalue *ir)
> -{
> -   /* Note that geometry shaders contain gl_ClipDistance both as an input
> -    * (which is a 2D array) and an output (which is a 1D array), so
it's
> -    * possible for both this->old_clip_distance_out_var and
> -    * this->old_clip_distance_in_var to be non-NULL in the same shader.
> -    */
> -
> -   if (!ir->type->is_array())
> -      return false;
> -   if (ir->type->fields.array != glsl_type::float_type)
> -      return false;
> -
> -   if (this->old_clip_distance_out_var) {
> -      if (ir->variable_referenced() ==
this->old_clip_distance_out_var)
> -         return true;
> -   }
> -   if (this->old_clip_distance_in_var) {
> -      assert(this->shader_stage == MESA_SHADER_TESS_CTRL ||
> -             this->shader_stage == MESA_SHADER_TESS_EVAL ||
> -             this->shader_stage == MESA_SHADER_GEOMETRY ||
> -             this->shader_stage == MESA_SHADER_FRAGMENT);
> -
> -      if (ir->variable_referenced() ==
this->old_clip_distance_in_var)
> -         return true;
> -   }
> -   return false;
> -}
> -
> -
> -/**
> - * If the given ir satisfies is_clip_distance_vec8(), return new ir
> - * representing its lowered equivalent.  That is, map:
> - *
> - * - gl_ClipDistance    => gl_ClipDistanceMESA    (if gl_ClipDistance
is 1D)
> - * - gl_ClipDistance[i] => gl_ClipDistanceMESA[i] (if gl_ClipDistance
is 2D)
> - *
> - * Otherwise return NULL.
> - */
> -ir_rvalue *
> -lower_clip_distance_visitor::lower_clip_distance_vec8(ir_rvalue *ir)
> -{
> -   if (!ir->type->is_array())
> -      return NULL;
> -   if (ir->type->fields.array != glsl_type::float_type)
> -      return NULL;
> -
> -   ir_variable **new_var = NULL;
> -   if (this->old_clip_distance_out_var) {
> -      if (ir->variable_referenced() ==
this->old_clip_distance_out_var)
> -         new_var = &this->new_clip_distance_out_var;
> -   }
> -   if (this->old_clip_distance_in_var) {
> -      if (ir->variable_referenced() ==
this->old_clip_distance_in_var)
> -         new_var = &this->new_clip_distance_in_var;
> -   }
> -   if (new_var == NULL)
> -      return NULL;
> -
> -   if (ir->as_dereference_variable()) {
> -      return new(ralloc_parent(ir)) ir_dereference_variable(*new_var);
> -   } else {
> -      ir_dereference_array *array_ref = ir->as_dereference_array();
> -      assert(array_ref);
> -      assert(array_ref->array->as_dereference_variable());
> -
> -      return new(ralloc_parent(ir))
> -         ir_dereference_array(*new_var, array_ref->array_index);
> -   }
> -}
> -
> -
> -void
> -lower_clip_distance_visitor::handle_rvalue(ir_rvalue **rv)
> -{
> -   if (*rv == NULL)
> -      return;
> -
> -   ir_dereference_array *const array_deref =
(*rv)->as_dereference_array();
> -   if (array_deref == NULL)
> -      return;
> -
> -   /* Replace any expression that indexes one of the floats in
gl_ClipDistance
> -    * with an expression that indexes into one of the vec4's in
> -    * gl_ClipDistanceMESA and accesses the appropriate component.
> -    */
> -   ir_rvalue *lowered_vec8 > -     
this->lower_clip_distance_vec8(array_deref->array);
> -   if (lowered_vec8 != NULL) {
> -      this->progress = true;
> -      ir_rvalue *array_index;
> -      ir_rvalue *swizzle_index;
> -      this->create_indices(array_deref->array_index, array_index,
swizzle_index);
> -      void *mem_ctx = ralloc_parent(array_deref);
> -
> -      ir_dereference_array *const new_array_deref > -        
new(mem_ctx) ir_dereference_array(lowered_vec8, array_index);
> -
> -      ir_expression *const expr > -         new(mem_ctx)
ir_expression(ir_binop_vector_extract,
> -                                    new_array_deref,
> -                                    swizzle_index);
> -
> -      *rv = expr;
> -   }
> -}
> -
> -void
> -lower_clip_distance_visitor::fix_lhs(ir_assignment *ir)
> -{
> -   if (ir->lhs->ir_type == ir_type_expression) {
> -      void *mem_ctx = ralloc_parent(ir);
> -      ir_expression *const expr = (ir_expression *) ir->lhs;
> -
> -      /* The expression must be of the form:
> -       *
> -       *     (vector_extract gl_ClipDistanceMESA[i], j).
> -       */
> -      assert(expr->operation == ir_binop_vector_extract);
> -      assert(expr->operands[0]->ir_type ==
ir_type_dereference_array);
> -      assert(expr->operands[0]->type == glsl_type::vec4_type);
> -
> -      ir_dereference *const new_lhs = (ir_dereference *)
expr->operands[0];
> -      ir->rhs = new(mem_ctx) ir_expression(ir_triop_vector_insert,
> -                                          glsl_type::vec4_type,
> -                                          new_lhs->clone(mem_ctx,
NULL),
> -                                          ir->rhs,
> -                                          expr->operands[1]);
> -      ir->set_lhs(new_lhs);
> -      ir->write_mask = WRITEMASK_XYZW;
> -   }
> -}
> -
> -/**
> - * Replace any assignment having the 1D gl_ClipDistance (undereferenced)
as
> - * its LHS or RHS with a sequence of assignments, one for each component
of
> - * the array.  Each of these assignments is lowered to refer to
> - * gl_ClipDistanceMESA as appropriate.
> - *
> - * We need to do a similar replacement for 2D gl_ClipDistance, however
since
> - * it's an input, the only case we need to address is where a 1D slice
of it
> - * is the entire RHS of an assignment, e.g.:
> - *
> - *     foo = gl_in[i].gl_ClipDistance
> - */
> -ir_visitor_status
> -lower_clip_distance_visitor::visit_leave(ir_assignment *ir)
> -{
> -   /* First invoke the base class visitor.  This causes handle_rvalue() to
be
> -    * called on ir->rhs and ir->condition.
> -    */
> -   ir_rvalue_visitor::visit_leave(ir);
> -
> -   if (this->is_clip_distance_vec8(ir->lhs) ||
> -       this->is_clip_distance_vec8(ir->rhs)) {
> -      /* LHS or RHS of the assignment is the entire 1D gl_ClipDistance
array
> -       * (or a 1D slice of a 2D gl_ClipDistance input array).  Since we
are
> -       * reshaping gl_ClipDistance from an array of floats to an array of
> -       * vec4's, this isn't going to work as a bulk assignment
anymore, so
> -       * unroll it to element-by-element assignments and lower each of
them.
> -       *
> -       * Note: to unroll into element-by-element assignments, we need to
make
> -       * clones of the LHS and RHS.  This is safe because expressions and
> -       * l-values are side-effect free.
> -       */
> -      void *ctx = ralloc_parent(ir);
> -      int array_size = ir->lhs->type->array_size();
> -      for (int i = 0; i < array_size; ++i) {
> -         ir_dereference_array *new_lhs = new(ctx) ir_dereference_array(
> -            ir->lhs->clone(ctx, NULL), new(ctx) ir_constant(i));
> -         ir_dereference_array *new_rhs = new(ctx) ir_dereference_array(
> -            ir->rhs->clone(ctx, NULL), new(ctx) ir_constant(i));
> -         this->handle_rvalue((ir_rvalue **) &new_rhs);
> -
> -         /* Handle the LHS after creating the new assignment.  This must
> -          * happen in this order because handle_rvalue may replace the old
LHS
> -          * with an ir_expression of ir_binop_vector_extract.  Since this
is
> -          * not a valide l-value, this will cause an assertion in the
> -          * ir_assignment constructor to fail.
> -          *
> -          * If this occurs, replace the mangled LHS with a dereference of
the
> -          * vector, and replace the RHS with an ir_triop_vector_insert.
> -          */
> -         ir_assignment *const assign = new(ctx) ir_assignment(new_lhs,
new_rhs);
> -         this->handle_rvalue((ir_rvalue **) &assign->lhs);
> -         this->fix_lhs(assign);
> -
> -         this->base_ir->insert_before(assign);
> -      }
> -      ir->remove();
> -
> -      return visit_continue;
> -   }
> -
> -   /* Handle the LHS as if it were an r-value.  Normally
> -    * rvalue_visit(ir_assignment *) only visits the RHS, but we need to
lower
> -    * expressions in the LHS as well.
> -    *
> -    * This may cause the LHS to get replaced with an ir_expression of
> -    * ir_binop_vector_extract.  If this occurs, replace it with a
dereference
> -    * of the vector, and replace the RHS with an ir_triop_vector_insert.
> -    */
> -   handle_rvalue((ir_rvalue **)&ir->lhs);
> -   this->fix_lhs(ir);
> -
> -   return rvalue_visit(ir);
> -}
> -
> -
> -/**
> - * Set up base_ir properly and call visit_leave() on a newly created
> - * ir_assignment node.  This is used in cases where we have to insert an
> - * ir_assignment in a place where we know the hierarchical visitor
won't see
> - * it.
> - */
> -void
> -lower_clip_distance_visitor::visit_new_assignment(ir_assignment *ir)
> -{
> -   ir_instruction *old_base_ir = this->base_ir;
> -   this->base_ir = ir;
> -   ir->accept(this);
> -   this->base_ir = old_base_ir;
> -}
> -
> -
> -/**
> - * If a 1D gl_ClipDistance variable appears as an argument in an ir_call
> - * expression, replace it with a temporary variable, and make sure the
ir_call
> - * is preceded and/or followed by assignments that copy the contents of
the
> - * temporary variable to and/or from gl_ClipDistance.  Each of these
> - * assignments is then lowered to refer to gl_ClipDistanceMESA.
> - *
> - * We need to do a similar replacement for 2D gl_ClipDistance, however
since
> - * it's an input, the only case we need to address is where a 1D slice
of it
> - * is passed as an "in" parameter to an ir_call, e.g.:
> - *
> - *     foo(gl_in[i].gl_ClipDistance)
> - */
> -ir_visitor_status
> -lower_clip_distance_visitor::visit_leave(ir_call *ir)
> -{
> -   void *ctx = ralloc_parent(ir);
> -
> -   const exec_node *formal_param_node = ir->callee->parameters.head;
> -   const exec_node *actual_param_node = ir->actual_parameters.head;
> -   while (!actual_param_node->is_tail_sentinel()) {
> -      ir_variable *formal_param = (ir_variable *) formal_param_node;
> -      ir_rvalue *actual_param = (ir_rvalue *) actual_param_node;
> -
> -      /* Advance formal_param_node and actual_param_node now so that we
can
> -       * safely replace actual_param with another node, if necessary,
below.
> -       */
> -      formal_param_node = formal_param_node->next;
> -      actual_param_node = actual_param_node->next;
> -
> -      if (this->is_clip_distance_vec8(actual_param)) {
> -         /* User is trying to pass the whole 1D gl_ClipDistance array (or
a 1D
> -          * slice of a 2D gl_ClipDistance array) to a function call. 
Since we
> -          * are reshaping gl_ClipDistance from an array of floats to an
array
> -          * of vec4's, this isn't going to work anymore, so use a
temporary
> -          * array instead.
> -          */
> -         ir_variable *temp_clip_distance = new(ctx) ir_variable(
> -            actual_param->type, "temp_clip_distance",
ir_var_temporary);
> -         this->base_ir->insert_before(temp_clip_distance);
> -         actual_param->replace_with(
> -            new(ctx) ir_dereference_variable(temp_clip_distance));
> -         if (formal_param->data.mode == ir_var_function_in
> -             || formal_param->data.mode == ir_var_function_inout) {
> -            /* Copy from gl_ClipDistance to the temporary before the call.
> -             * Since we are going to insert this copy before the current
> -             * instruction, we need to visit it afterwards to make sure it
> -             * gets lowered.
> -             */
> -            ir_assignment *new_assignment = new(ctx) ir_assignment(
> -               new(ctx) ir_dereference_variable(temp_clip_distance),
> -               actual_param->clone(ctx, NULL));
> -            this->base_ir->insert_before(new_assignment);
> -            this->visit_new_assignment(new_assignment);
> -         }
> -         if (formal_param->data.mode == ir_var_function_out
> -             || formal_param->data.mode == ir_var_function_inout) {
> -            /* Copy from the temporary to gl_ClipDistance after the call.
> -             * Since visit_list_elements() has already decided which
> -             * instruction it's going to visit next, we need to visit
> -             * afterwards to make sure it gets lowered.
> -             */
> -            ir_assignment *new_assignment = new(ctx) ir_assignment(
> -               actual_param->clone(ctx, NULL),
> -               new(ctx) ir_dereference_variable(temp_clip_distance));
> -            this->base_ir->insert_after(new_assignment);
> -            this->visit_new_assignment(new_assignment);
> -         }
> -      }
> -   }
> -
> -   return rvalue_visit(ir);
> -}
> -
> -
> -bool
> -lower_clip_distance(gl_shader *shader)
> -{
> -   lower_clip_distance_visitor v(shader->Stage);
> -
> -   visit_list_elements(&v, shader->ir);
> -
> -   if (v.new_clip_distance_out_var)
> -      shader->symbols->add_variable(v.new_clip_distance_out_var);
> -   if (v.new_clip_distance_in_var)
> -      shader->symbols->add_variable(v.new_clip_distance_in_var);
> -
> -   return v.progress;
> -}
> diff --git a/src/glsl/lower_distance.cpp b/src/glsl/lower_distance.cpp
> new file mode 100644
> index 0000000..172da3d
> --- /dev/null
> +++ b/src/glsl/lower_distance.cpp
> @@ -0,0 +1,606 @@
> +/*
> + * Copyright © 2011 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.
> + */
> +
> +/**
> + * \file lower_distance.cpp
> + *
> + * This pass accounts for the difference between the way
> + * gl_ClipDistance or gl_CullDistance is declared in standard GLSL
> + * (as an array of floats), and the way it is frequently implemented
> + * in hardware (as a pair of vec4s, with four clip or cull distances
> + * packed into each).
> + *
> + * The declaration of gl_ClipDistance or gl_CullDistance is replaced
> + * with a declaration of gl_ClipDistanceMESA or gl_CullDistanceMESA
> + * respectively, and any references to the original gl_ClipDistance
> + * or gl_CullDistance are translated to refer to gl_ClipDistanceMESA
> + * or gl_CullDistanceMESA with the appropriate swizzling of array
> + * indices.  For instance:
> + *
> + *   gl_ClipDistance[i]
> + *
> + * is translated into:
> + *
> + *   gl_ClipDistanceMESA[i>>2][i&3]
> + *
> + * Since some hardware may not internally represent these arrays as a
> + * pair of vec4's, this lowering pass is optional.  To enable it, set
> + * the LowerClipDistance flag in gl_shader_compiler_options to true.
> + */
> +
> +#include <string>
> +#include "glsl_symbol_table.h"
> +#include "ir_rvalue_visitor.h"
> +#include "ir.h"
> +#include "program/prog_instruction.h" /* For WRITEMASK_* */
> +
> +namespace {
> +
> +class lower_distance_visitor : public ir_rvalue_visitor {
> +public:
> +   explicit lower_distance_visitor(gl_shader_stage shader_stage,
> +         std::string in_name, std::string out_name)
> +      : progress(false), old_distance_out_var(NULL),
> +        old_distance_in_var(NULL), new_distance_out_var(NULL),
> +        new_distance_in_var(NULL), shader_stage(shader_stage),
> +        in_name(in_name), out_name(out_name)
> +   {
> +   }
> +
> +   virtual ir_visitor_status visit(ir_variable *);
> +   void create_indices(ir_rvalue*, ir_rvalue *&, ir_rvalue *&);
> +   bool is_clip_distance_vec8(ir_rvalue *ir);
> +   ir_rvalue *lower_clip_distance_vec8(ir_rvalue *ir);
> +   virtual ir_visitor_status visit_leave(ir_assignment *);
> +   void visit_new_assignment(ir_assignment *ir);
> +   virtual ir_visitor_status visit_leave(ir_call *);
> +
> +   virtual void handle_rvalue(ir_rvalue **rvalue);
> +
> +   void fix_lhs(ir_assignment *);
> +
> +   bool progress;
> +
> +   /**
> +    * Pointer to the declaration of ou arrays, if found.
> +    *
> +    * Note:
> +    *
> +    * - the in_var is for geometry and both tessellation shader inputs
only.
> +    *
> +    * - since gl_ClipDistance is available in tessellation control,
> +    *   tessellation evaluation and geometry shaders as both an input
> +    *   and an output, it's possible for both old_distance_out_var
> +    *   and old_distance_in_var to be non-null.
> +    */
> +   ir_variable *old_distance_out_var;
> +   ir_variable *old_distance_in_var;
> +
> +   /**
> +    * Pointer to the newly-created variable.
> +    */
> +   ir_variable *new_distance_out_var;
> +   ir_variable *new_distance_in_var;
> +
> +   /**
> +    * Type of shader we are compiling (e.g. MESA_SHADER_VERTEX)
> +    */
> +   const gl_shader_stage shader_stage;
> +
> +   /**
> +    *  Identifier of the variables we manipulate
> +    */
> +
> +   std::string in_name;
> +   std::string out_name;
> +};
> +
> +} /* anonymous namespace */
> +
> +/**
> + * Replace any declaration of in_name as an array of floats with a
> + * declaration of out_name as an array of vec4's.
> + */
> +ir_visitor_status
> +lower_distance_visitor::visit(ir_variable *ir)
> +{
> +   ir_variable **old_var;
> +   ir_variable **new_var;
> +
> +   if (!ir->name || in_name.compare(ir->name) != 0)
> +      return visit_continue;
> +   assert (ir->type->is_array());
> +
> +   if (ir->data.mode == ir_var_shader_out) {
> +      if (this->old_distance_out_var)
> +         return visit_continue;
> +      old_var = &old_distance_out_var;
> +      new_var = &new_distance_out_var;
> +   } else if (ir->data.mode == ir_var_shader_in) {
> +      if (this->old_distance_in_var)
> +         return visit_continue;
> +      old_var = &old_distance_in_var;
> +      new_var = &new_distance_in_var;
> +   } else {
> +      unreachable("not reached");
> +   }
> +
> +   this->progress = true;
> +
> +   if (!ir->type->fields.array->is_array()) {
> +      /* gl_ClipDistance / gl_CullDistance (used for vertex, tessellation
> +       * evaluation and geometry output, and fragment input).
> +       */
> +      assert((ir->data.mode == ir_var_shader_in &&
> +              this->shader_stage == MESA_SHADER_FRAGMENT) ||
> +             (ir->data.mode == ir_var_shader_out &&
> +              (this->shader_stage == MESA_SHADER_VERTEX ||
> +               this->shader_stage == MESA_SHADER_TESS_EVAL ||
> +               this->shader_stage == MESA_SHADER_GEOMETRY)));
> +
> +      *old_var = ir;
> +      assert (ir->type->fields.array == glsl_type::float_type);
> +      unsigned new_size = (ir->type->array_size() + 3) / 4;
> +
> +      /* Clone the old var so that we inherit all of its properties */
> +      *new_var = ir->clone(ralloc_parent(ir), NULL);
> +
> +      /* And change the properties that we need to change */
> +      (*new_var)->name = ralloc_strdup(*new_var, out_name.c_str());
> +      (*new_var)->type =
glsl_type::get_array_instance(glsl_type::vec4_type,
> +                                                       new_size);
> +      (*new_var)->data.max_array_access = ir->data.max_array_access
/ 4;
> +
> +      ir->replace_with(*new_var);
> +   } else {
> +      /* 2D gl_ClipDistance / gl_CullDistance (used for tessellation
control,
> +       * tessellation evaluation and geometry input, and tessellation
control
> +       * output).
> +       */
> +      assert((ir->data.mode == ir_var_shader_in &&
> +              (this->shader_stage == MESA_SHADER_GEOMETRY ||
> +               this->shader_stage == MESA_SHADER_TESS_EVAL)) ||
> +             this->shader_stage == MESA_SHADER_TESS_CTRL);
> +
> +      *old_var = ir;
> +      assert (ir->type->fields.array->fields.array ==
glsl_type::float_type);
> +      unsigned new_size = (ir->type->fields.array->array_size() +
3) / 4;
> +
> +      /* Clone the old var so that we inherit all of its properties */
> +      *new_var = ir->clone(ralloc_parent(ir), NULL);
> +
> +      /* And change the properties that we need to change */
> +      (*new_var)->name = ralloc_strdup(*new_var, out_name.c_str());
> +      (*new_var)->type = glsl_type::get_array_instance(
> +         glsl_type::get_array_instance(glsl_type::vec4_type,
> +            new_size),
> +         ir->type->array_size());
> +      (*new_var)->data.max_array_access = ir->data.max_array_access
/ 4;
> +
> +      ir->replace_with(*new_var);
> +   }
> +
> +   return visit_continue;
> +}
> +
> +
> +/**
> + * Create the necessary GLSL rvalues to index into out_name based
> + * on the rvalue previously used to index into gl_ClipDistance.
> + *
> + * \param array_index Selects one of the vec4's in out_name
> + * \param swizzle_index Selects a component within the vec4 selected by
> + *        array_index.
> + */
> +void
> +lower_distance_visitor::create_indices(ir_rvalue *old_index,
> +                                            ir_rvalue *&array_index,
> +                                            ir_rvalue *&swizzle_index)
> +{
> +   void *ctx = ralloc_parent(old_index);
> +
> +   /* Make sure old_index is a signed int so that the bitwise
"shift" and
> +    * "and" operations below type check properly.
> +    */
> +   if (old_index->type != glsl_type::int_type) {
> +      assert (old_index->type == glsl_type::uint_type);
> +      old_index = new(ctx) ir_expression(ir_unop_u2i, old_index);
> +   }
> +
> +   ir_constant *old_index_constant =
old_index->constant_expression_value();
> +   if (old_index_constant) {
> +      /* gl_ClipDistance / gl_CullDistance is being accessed via a
constant
> +       * index.  Don't bother creating expressions to calculate the
lowered
> +       * indices.  Just create constants.
> +       */
> +      int const_val = old_index_constant->get_int_component(0);
> +      array_index = new(ctx) ir_constant(const_val / 4);
> +      swizzle_index = new(ctx) ir_constant(const_val % 4);
> +   } else {
> +      /* Create a variable to hold the value of old_index (so that we
> +       * don't compute it twice).
> +       */
> +      ir_variable *old_index_var = new(ctx) ir_variable(
> +         glsl_type::int_type, "clip_distance_index",
ir_var_temporary);
> +      this->base_ir->insert_before(old_index_var);
> +      this->base_ir->insert_before(new(ctx) ir_assignment(
> +         new(ctx) ir_dereference_variable(old_index_var), old_index));
> +
> +      /* Create the expression distance_index / 4.  Do this as a bit shift
> +       * because that's likely to be more efficient.
> +       */
> +      array_index = new(ctx) ir_expression(
> +         ir_binop_rshift, new(ctx) ir_dereference_variable(old_index_var),
> +         new(ctx) ir_constant(2));
> +
> +      /* Create the expression distance_index % 4.  Do this as a bitwise
AND
> +       * because that's likely to be more efficient.
> +       */
> +      swizzle_index = new(ctx) ir_expression(
> +         ir_binop_bit_and, new(ctx)
ir_dereference_variable(old_index_var),
> +         new(ctx) ir_constant(3));
> +   }
> +}
> +
> +
> +/**
> + * Determine whether the given rvalue describes an array of 8 floats that
> + * needs to be lowered to an array of 2 vec4's; that is, determine
whether it
> + * matches one of the following patterns:
> + *
> + * - gl_ClipDistance (if gl_ClipDistance is 1D)
> + * - gl_ClipDistance[i] (if gl_ClipDistance is 2D)
> + */
> +bool
> +lower_distance_visitor::is_clip_distance_vec8(ir_rvalue *ir)
> +{
> +   /* Note that geometry shaders contain in_name
> +    * both as an input (which is a 2D array) and an output (which is a 1D
> +    * array), so it's possible for both this->old_distance_out_var
and
> +    * this->old_distance_in_var to be non-NULL in the same shader.
> +    */
> +
> +   if (!ir->type->is_array())
> +      return false;
> +   if (ir->type->fields.array != glsl_type::float_type)
> +      return false;
> +
> +   if (this->old_distance_out_var) {
> +      if (ir->variable_referenced() == this->old_distance_out_var)
> +         return true;
> +   }
> +   if (this->old_distance_in_var) {
> +      assert(this->shader_stage == MESA_SHADER_TESS_CTRL ||
> +             this->shader_stage == MESA_SHADER_TESS_EVAL ||
> +             this->shader_stage == MESA_SHADER_GEOMETRY ||
> +             this->shader_stage == MESA_SHADER_FRAGMENT);
> +
> +      if (ir->variable_referenced() == this->old_distance_in_var)
> +         return true;
> +   }
> +   return false;
> +}
> +
> +
> +/**
> + * If the given ir satisfies is_distance_vec8(), return new ir
> + * representing its lowered equivalent.  That is, map:
> + *
> + * - gl_ClipDistance    => gl_ClipDistanceMESA    (if gl_ClipDistance
is 1D)
> + * - gl_ClipDistance[i] => gl_ClipDistanceMESA[i] (if gl_ClipDistance
is 2D)
> + *
> + * Otherwise return NULL.
> + */
> +ir_rvalue *
> +lower_distance_visitor::lower_clip_distance_vec8(ir_rvalue *ir)
> +{
> +   if (!ir->type->is_array())
> +      return NULL;
> +   if (ir->type->fields.array != glsl_type::float_type)
> +      return NULL;
> +
> +   ir_variable **new_var = NULL;
> +   if (this->old_distance_out_var) {
> +      if (ir->variable_referenced() == this->old_distance_out_var)
> +         new_var = &this->new_distance_out_var;
> +   }
> +   if (this->old_distance_in_var) {
> +      if (ir->variable_referenced() == this->old_distance_in_var)
> +         new_var = &this->new_distance_in_var;
> +   }
> +   if (new_var == NULL)
> +      return NULL;
> +
> +   if (ir->as_dereference_variable()) {
> +      return new(ralloc_parent(ir)) ir_dereference_variable(*new_var);
> +   } else {
> +      ir_dereference_array *array_ref = ir->as_dereference_array();
> +      assert(array_ref);
> +      assert(array_ref->array->as_dereference_variable());
> +
> +      return new(ralloc_parent(ir))
> +         ir_dereference_array(*new_var, array_ref->array_index);
> +   }
> +}
> +
> +
> +void
> +lower_distance_visitor::handle_rvalue(ir_rvalue **rv)
> +{
> +   if (*rv == NULL)
> +      return;
> +
> +   ir_dereference_array *const array_deref =
(*rv)->as_dereference_array();
> +   if (array_deref == NULL)
> +      return;
> +
> +   /* Replace any expression that indexes one of the floats in in_name
> +    * or in_name with an expression that indexes into one of the
vec4's
> +    * in out_name and accesses the appropriate component.
> +    */
> +   ir_rvalue *lowered_vec8 > +     
this->lower_clip_distance_vec8(array_deref->array);
> +   if (lowered_vec8 != NULL) {
> +      this->progress = true;
> +      ir_rvalue *array_index;
> +      ir_rvalue *swizzle_index;
> +      this->create_indices(array_deref->array_index, array_index,
swizzle_index);
> +      void *mem_ctx = ralloc_parent(array_deref);
> +
> +      ir_dereference_array *const new_array_deref > +        
new(mem_ctx) ir_dereference_array(lowered_vec8, array_index);
> +
> +      ir_expression *const expr > +         new(mem_ctx)
ir_expression(ir_binop_vector_extract,
> +                                    new_array_deref,
> +                                    swizzle_index);
> +
> +      *rv = expr;
> +   }
> +}
> +
> +void
> +lower_distance_visitor::fix_lhs(ir_assignment *ir)
> +{
> +   if (ir->lhs->ir_type == ir_type_expression) {
> +      void *mem_ctx = ralloc_parent(ir);
> +      ir_expression *const expr = (ir_expression *) ir->lhs;
> +
> +      /* The expression must be of the form:
> +       *
> +       *     (vector_extract gl_ClipDistanceMESA[i], j).
> +       */
> +      assert(expr->operation == ir_binop_vector_extract);
> +      assert(expr->operands[0]->ir_type ==
ir_type_dereference_array);
> +      assert(expr->operands[0]->type == glsl_type::vec4_type);
> +
> +      ir_dereference *const new_lhs = (ir_dereference *)
expr->operands[0];
> +      ir->rhs = new(mem_ctx) ir_expression(ir_triop_vector_insert,
> +                                          glsl_type::vec4_type,
> +                                          new_lhs->clone(mem_ctx,
NULL),
> +                                          ir->rhs,
> +                                          expr->operands[1]);
> +      ir->set_lhs(new_lhs);
> +      ir->write_mask = WRITEMASK_XYZW;
> +   }
> +}
> +
> +/**
> + * Replace any assignment having the 1D in_name (undereferenced) as
> + * its LHS or RHS with a sequence of assignments, one for each component
of
> + * the array.  Each of these assignments is lowered to refer to
> + * out_name as appropriate.
> + *
> + * We need to do a similar replacement for 2D in_name, however since
> + * it's an input, the only case we need to address is where a 1D slice
of it
> + * is the entire RHS of an assignment, e.g.:
> + *
> + *     foo = gl_in[i].gl_ClipDistance
> + */
> +ir_visitor_status
> +lower_distance_visitor::visit_leave(ir_assignment *ir)
> +{
> +   /* First invoke the base class visitor.  This causes handle_rvalue() to
be
> +    * called on ir->rhs and ir->condition.
> +    */
> +   ir_rvalue_visitor::visit_leave(ir);
> +
> +   if (this->is_clip_distance_vec8(ir->lhs) ||
> +       this->is_clip_distance_vec8(ir->rhs)) {
> +      /* LHS or RHS of the assignment is the entire 1D in_name array
> +       * (or a 1D slice of a 2D in_name input array).  Since we are
> +       * reshaping in_name from an array of floats to an array of
> +       * vec4's, this isn't going to work as a bulk assignment
anymore, so
> +       * unroll it to element-by-element assignments and lower each of
them.
> +       *
> +       * Note: to unroll into element-by-element assignments, we need to
make
> +       * clones of the LHS and RHS.  This is safe because expressions and
> +       * l-values are side-effect free.
> +       */
> +      void *ctx = ralloc_parent(ir);
> +      int array_size = ir->lhs->type->array_size();
> +      for (int i = 0; i < array_size; ++i) {
> +         ir_dereference_array *new_lhs = new(ctx) ir_dereference_array(
> +            ir->lhs->clone(ctx, NULL), new(ctx) ir_constant(i));
> +         ir_dereference_array *new_rhs = new(ctx) ir_dereference_array(
> +            ir->rhs->clone(ctx, NULL), new(ctx) ir_constant(i));
> +         this->handle_rvalue((ir_rvalue **) &new_rhs);
> +
> +         /* Handle the LHS after creating the new assignment.  This must
> +          * happen in this order because handle_rvalue may replace the old
LHS
> +          * with an ir_expression of ir_binop_vector_extract.  Since this
is
> +          * not a valide l-value, this will cause an assertion in the
> +          * ir_assignment constructor to fail.
> +          *
> +          * If this occurs, replace the mangled LHS with a dereference of
the
> +          * vector, and replace the RHS with an ir_triop_vector_insert.
> +          */
> +         ir_assignment *const assign = new(ctx) ir_assignment(new_lhs,
new_rhs);
> +         this->handle_rvalue((ir_rvalue **) &assign->lhs);
> +         this->fix_lhs(assign);
> +
> +         this->base_ir->insert_before(assign);
> +      }
> +      ir->remove();
> +
> +      return visit_continue;
> +   }
> +
> +   /* Handle the LHS as if it were an r-value.  Normally
> +    * rvalue_visit(ir_assignment *) only visits the RHS, but we need to
lower
> +    * expressions in the LHS as well.
> +    *
> +    * This may cause the LHS to get replaced with an ir_expression of
> +    * ir_binop_vector_extract.  If this occurs, replace it with a
dereference
> +    * of the vector, and replace the RHS with an ir_triop_vector_insert.
> +    */
> +   handle_rvalue((ir_rvalue **)&ir->lhs);
> +   this->fix_lhs(ir);
> +
> +   return rvalue_visit(ir);
> +}
> +
> +
> +/**
> + * Set up base_ir properly and call visit_leave() on a newly created
> + * ir_assignment node.  This is used in cases where we have to insert an
> + * ir_assignment in a place where we know the hierarchical visitor
won't see
> + * it.
> + */
> +void
> +lower_distance_visitor::visit_new_assignment(ir_assignment *ir)
> +{
> +   ir_instruction *old_base_ir = this->base_ir;
> +   this->base_ir = ir;
> +   ir->accept(this);
> +   this->base_ir = old_base_ir;
> +}
> +
> +
> +/**
> + * If a 1D in_name variable appears as an argument in an ir_call
> + * expression, replace it with a temporary variable, and make sure the
ir_call
> + * is preceded and/or followed by assignments that copy the contents of
the
> + * temporary variable to and/or from in_name.  Each of these
> + * assignments is then lowered to refer to out_name.
> + *
> + * We need to do a similar replacement for 2D in_name, however since
> + * it's an input, the only case we need to address is where a 1D slice
of it
> + * is passed as an "in" parameter to an ir_call, e.g.:
> + *
> + *     foo(gl_in[i].gl_ClipDistance)
> + */
> +ir_visitor_status
> +lower_distance_visitor::visit_leave(ir_call *ir)
> +{
> +   void *ctx = ralloc_parent(ir);
> +
> +   const exec_node *formal_param_node = ir->callee->parameters.head;
> +   const exec_node *actual_param_node = ir->actual_parameters.head;
> +   while (!actual_param_node->is_tail_sentinel()) {
> +      ir_variable *formal_param = (ir_variable *) formal_param_node;
> +      ir_rvalue *actual_param = (ir_rvalue *) actual_param_node;
> +
> +      /* Advance formal_param_node and actual_param_node now so that we
can
> +       * safely replace actual_param with another node, if necessary,
below.
> +       */
> +      formal_param_node = formal_param_node->next;
> +      actual_param_node = actual_param_node->next;
> +
> +      if (this->is_clip_distance_vec8(actual_param)) {
> +         /* User is trying to pass the whole 1D in_name array (or a 1D
> +          * slice of a 2D in_name array) to a function call.  Since we
> +          * are reshaping in_name from an array of floats to an array
> +          * of vec4's, this isn't going to work anymore, so use a
temporary
> +          * array instead.
> +          */
> +         ir_variable *temp_clip_distance = new(ctx) ir_variable(
> +            actual_param->type, "temp_clip_distance",
ir_var_temporary);
> +         this->base_ir->insert_before(temp_clip_distance);
> +         actual_param->replace_with(
> +            new(ctx) ir_dereference_variable(temp_clip_distance));
> +         if (formal_param->data.mode == ir_var_function_in
> +             || formal_param->data.mode == ir_var_function_inout) {
> +            /* Copy from in_name to the temporary before the call.
> +             * Since we are going to insert this copy before the current
> +             * instruction, we need to visit it afterwards to make sure it
> +             * gets lowered.
> +             */
> +            ir_assignment *new_assignment = new(ctx) ir_assignment(
> +               new(ctx) ir_dereference_variable(temp_clip_distance),
> +               actual_param->clone(ctx, NULL));
> +            this->base_ir->insert_before(new_assignment);
> +            this->visit_new_assignment(new_assignment);
> +         }
> +         if (formal_param->data.mode == ir_var_function_out
> +             || formal_param->data.mode == ir_var_function_inout) {
> +            /* Copy from the temporary to in_name after the call.
> +             * Since visit_list_elements() has already decided which
> +             * instruction it's going to visit next, we need to visit
> +             * afterwards to make sure it gets lowered.
> +             */
> +            ir_assignment *new_assignment = new(ctx) ir_assignment(
> +               actual_param->clone(ctx, NULL),
> +               new(ctx) ir_dereference_variable(temp_clip_distance));
> +            this->base_ir->insert_after(new_assignment);
> +            this->visit_new_assignment(new_assignment);
> +         }
> +      }
> +   }
> +
> +   return rvalue_visit(ir);
> +}
> +
> +
> +bool
> +lower_clip_distance(gl_shader *shader)
> +{
> +   lower_distance_visitor v(shader->Stage, "gl_ClipDistance",
> +         "gl_ClipDistanceMESA");
> +
> +   visit_list_elements(&v, shader->ir);
> +
> +   if (v.new_distance_out_var)
> +      shader->symbols->add_variable(v.new_distance_out_var);
> +   if (v.new_distance_in_var)
> +      shader->symbols->add_variable(v.new_distance_in_var);
> +
> +   return v.progress;
> +}
> +
> +bool
> +lower_cull_distance(gl_shader *shader)
> +{
> +   lower_distance_visitor v(shader->Stage, "gl_CullDistance",
> +         "gl_CullDistanceMESA");
> +
> +   visit_list_elements(&v, shader->ir);
> +
> +   if (v.new_distance_out_var)
> +      shader->symbols->add_variable(v.new_distance_out_var);
> +   if (v.new_distance_in_var)
> +      shader->symbols->add_variable(v.new_distance_in_var);
> +
> +   return v.progress;
> +}
> +
> --
> 2.5.0
>
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