/*
* 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_1d_var(NULL),
old_clip_distance_2d_var(NULL), new_clip_distance_1d_var(NULL),
new_clip_distance_2d_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 2d_var is for geometry shader input only.
*
* - since gl_ClipDistance is available in geometry shaders as both an
* input and an output, it's possible for both old_clip_distance_1d_var
* and old_clip_distance_2d_var to be non-null.
*/
ir_variable *old_clip_distance_1d_var;
ir_variable *old_clip_distance_2d_var;
/**
* Pointer to the newly-created gl_ClipDistanceMESA variable.
*/
ir_variable *new_clip_distance_1d_var;
ir_variable *new_clip_distance_2d_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)
{
if (!ir->name || strcmp(ir->name, "gl_ClipDistance") != 0)
return visit_continue;
assert (ir->type->is_array());
if (!ir->type->element_type()->is_array()) {
/* 1D gl_ClipDistance (used for vertex and geometry output, and fragment
* input).
*/
if (this->old_clip_distance_1d_var)
return visit_continue;
this->progress = true;
this->old_clip_distance_1d_var = ir;
assert (ir->type->element_type() == 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 */
this->new_clip_distance_1d_var = ir->clone(ralloc_parent(ir), NULL);
/* And change the properties that we need to change */
this->new_clip_distance_1d_var->name
= ralloc_strdup(this->new_clip_distance_1d_var,
"gl_ClipDistanceMESA");
this->new_clip_distance_1d_var->type
= glsl_type::get_array_instance(glsl_type::vec4_type, new_size);
this->new_clip_distance_1d_var->data.max_array_access
= ir->data.max_array_access / 4;
ir->replace_with(this->new_clip_distance_1d_var);
} else {
/* 2D gl_ClipDistance (used for geometry input). */
assert(ir->data.mode == ir_var_shader_in &&
this->shader_stage == MESA_SHADER_GEOMETRY);
if (this->old_clip_distance_2d_var)
return visit_continue;
this->progress = true;
this->old_clip_distance_2d_var = ir;
assert (ir->type->element_type()->element_type() == glsl_type::float_type);
unsigned new_size = (ir->type->element_type()->array_size() + 3) / 4;
/* Clone the old var so that we inherit all of its properties */
this->new_clip_distance_2d_var = ir->clone(ralloc_parent(ir), NULL);
/* And change the properties that we need to change */
this->new_clip_distance_2d_var->name
= ralloc_strdup(this->new_clip_distance_2d_var, "gl_ClipDistanceMESA");
this->new_clip_distance_2d_var->type = glsl_type::get_array_instance(
glsl_type::get_array_instance(glsl_type::vec4_type,
new_size),
ir->type->array_size());
this->new_clip_distance_2d_var->data.max_array_access
= ir->data.max_array_access / 4;
ir->replace_with(this->new_clip_distance_2d_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_1d_var and
* this->old_clip_distance_2d_var to be non-NULL in the same shader.
*/
if (this->old_clip_distance_1d_var) {
ir_dereference_variable *var_ref = ir->as_dereference_variable();
if (var_ref && var_ref->var == this->old_clip_distance_1d_var)
return true;
}
if (this->old_clip_distance_2d_var) {
/* 2D clip distance is only possible as a geometry input */
assert(this->shader_stage == MESA_SHADER_GEOMETRY);
ir_dereference_array *array_ref = ir->as_dereference_array();
if (array_ref) {
ir_dereference_variable *var_ref =
array_ref->array->as_dereference_variable();
if (var_ref && var_ref->var == this->old_clip_distance_2d_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 (this->old_clip_distance_1d_var) {
ir_dereference_variable *var_ref = ir->as_dereference_variable();
if (var_ref && var_ref->var == this->old_clip_distance_1d_var) {
return new(ralloc_parent(ir))
ir_dereference_variable(this->new_clip_distance_1d_var);
}
}
if (this->old_clip_distance_2d_var) {
/* 2D clip distance is only possible as a geometry input */
assert(this->shader_stage == MESA_SHADER_GEOMETRY);
ir_dereference_array *array_ref = ir->as_dereference_array();
if (array_ref) {
ir_dereference_variable *var_ref =
array_ref->array->as_dereference_variable();
if (var_ref && var_ref->var == this->old_clip_distance_2d_var) {
return new(ralloc_parent(ir))
ir_dereference_array(this->new_clip_distance_2d_var,
array_ref->array_index);
}
}
}
return NULL;
}
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_1d_var)
shader->symbols->add_variable(v.new_clip_distance_1d_var);
if (v.new_clip_distance_2d_var)
shader->symbols->add_variable(v.new_clip_distance_2d_var);
return v.progress;
}