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/*
* Copyright © 2014 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
#include "ir.h"
#include "ir_visitor.h"
#include "ir_optimization.h"
/**
* Pre-linking, optimize unused built-in variables
*
* Uniforms, constants, system values, inputs (vertex shader only), and
* outputs (fragment shader only) that are not used can be removed.
*/
void
optimize_dead_builtin_variables(exec_list *instructions,
enum ir_variable_mode other)
{
foreach_in_list_safe(ir_variable, var, instructions) {
if (var->ir_type != ir_type_variable || var->data.used)
continue;
if (var->data.mode != ir_var_uniform
&& var->data.mode != ir_var_auto
&& var->data.mode != ir_var_system_value
&& var->data.mode != other)
continue;
/* So that linker rules can later be enforced, we cannot elimate
* variables that were redeclared in the shader code.
*/
if ((var->data.mode == other || var->data.mode == ir_var_system_value)
&& var->data.how_declared != ir_var_declared_implicitly)
continue;
if (!is_gl_identifier(var->name))
continue;
/* gl_ModelViewProjectionMatrix and gl_Vertex are special because they
* are used by ftransform. No other built-in variable is used by a
* built-in function. The forward declarations of these variables in
* the built-in function shader does not have the "state slot"
* information, so removing these variables from the user shader will
* cause problems later.
*
* For compute shaders, gl_GlobalInvocationID has some dependencies, so
* we avoid removing these dependencies.
*
* We also avoid removing gl_GlobalInvocationID at this stage because it
* might be used by a linked shader. In this case it still needs to be
* initialized by the main function.
*
* gl_GlobalInvocationID =
* gl_WorkGroupID * gl_WorkGroupSize + gl_LocalInvocationID
*
* Similarly, we initialize gl_LocalInvocationIndex in the main function:
*
* gl_LocalInvocationIndex =
* gl_LocalInvocationID.z * gl_WorkGroupSize.x * gl_WorkGroupSize.y +
* gl_LocalInvocationID.y * gl_WorkGroupSize.x +
* gl_LocalInvocationID.x;
*
* Matrix uniforms with "Transpose" are not eliminated because there's
* an optimization pass that can turn references to the regular matrix
* into references to the transpose matrix. Eliminating the transpose
* matrix would cause that pass to generate references to undeclareds
* variables (thank you, ir_validate).
*
* It doesn't seem worth the effort to track when the transpose could be
* eliminated (i.e., when the non-transpose was eliminated).
*/
if (strcmp(var->name, "gl_ModelViewProjectionMatrix") == 0
|| strcmp(var->name, "gl_Vertex") == 0
|| strcmp(var->name, "gl_WorkGroupID") == 0
|| strcmp(var->name, "gl_WorkGroupSize") == 0
|| strcmp(var->name, "gl_LocalInvocationID") == 0
|| strcmp(var->name, "gl_GlobalInvocationID") == 0
|| strcmp(var->name, "gl_LocalInvocationIndex") == 0
|| strstr(var->name, "Transpose") != NULL)
continue;
var->remove();
}
}
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