1012e95a40
After compilation (and before linking) we can eliminate quite a few
built-in variables. Basically, any uniform or constant (e.g.,
gl_MaxVertexTextureImageUnits) that isn't used (with one exception) can
be eliminated. System values, vertex shader inputs (with one
exception), and fragment shader outputs that are not used and not
re-declared in the shader text can also be removed.
gl_ModelViewProjectMatrix and gl_Vertex are used by the built-in
function ftransform. There are some complications with eliminating
these variables (see the comment in the patch), so they are not
eliminated.
Valgrind massif results for a trimmed apitrace of dota2:
n time(i) total(B) useful-heap(B) extra-heap(B) stacks(B)
Before (32-bit): 46 40,661,487,174 75,116,800 68,854,065 6,262,735 0
After (32-bit): 50 40,564,927,443 69,185,408 63,683,871 5,501,537 0
Before (64-bit): 64 37,200,329,700 104,872,672 96,514,546 8,358,126 0
After (64-bit): 59 36,822,048,449 96,526,888 89,113,000 7,413,888 0
A real savings of 4.9MiB on 32-bit and 7.0MiB on 64-bit.
v2: Don't remove any built-in with Transpose in the name.
v3: Fix comment typo noticed by Anuj.
Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Suggested-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Matt Turner <mattst88@gmail.com>
Acked-by: Anuj Phogat <anuj.phogat@gmail.com>
Cc: Eric Anholt <eric@anholt.net>
81 lines
3.3 KiB
C++
81 lines
3.3 KiB
C++
/*
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* Copyright © 2014 Intel Corporation
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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* DEALINGS IN THE SOFTWARE.
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*/
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#include "ir.h"
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#include "ir_visitor.h"
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#include "ir_optimization.h"
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/**
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* Pre-linking, optimize unused built-in variables
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*
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* Uniforms, constants, system values, inputs (vertex shader only), and
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* outputs (fragment shader only) that are not used can be removed.
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*/
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void
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optimize_dead_builtin_variables(exec_list *instructions,
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enum ir_variable_mode other)
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{
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foreach_in_list_safe(ir_variable, var, instructions) {
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if (var->ir_type != ir_type_variable || var->data.used)
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continue;
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if (var->data.mode != ir_var_uniform
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&& var->data.mode != ir_var_auto
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&& var->data.mode != ir_var_system_value
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&& var->data.mode != other)
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continue;
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/* So that linker rules can later be enforced, we cannot elimate
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* variables that were redeclared in the shader code.
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*/
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if ((var->data.mode == other || var->data.mode == ir_var_system_value)
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&& var->data.how_declared != ir_var_declared_implicitly)
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continue;
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if (strncmp(var->name, "gl_", 3) != 0)
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continue;
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/* gl_ModelViewProjectionMatrix and gl_Vertex are special because they
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* are used by ftransform. No other built-in variable is used by a
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* built-in function. The forward declarations of these variables in
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* the built-in function shader does not have the "state slot"
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* information, so removing these variables from the user shader will
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* cause problems later.
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*
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* Matrix uniforms with "Transpose" are not eliminated because there's
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* an optimization pass that can turn references to the regular matrix
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* into references to the transpose matrix. Eliminating the transpose
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* matrix would cause that pass to generate references to undeclareds
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* variables (thank you, ir_validate).
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*
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* It doesn't seem worth the effort to track when the transpose could be
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* eliminated (i.e., when the non-transpose was eliminated).
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*/
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if (strcmp(var->name, "gl_ModelViewProjectionMatrix") == 0
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|| strcmp(var->name, "gl_Vertex") == 0
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|| strstr(var->name, "Transpose") != NULL)
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continue;
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var->remove();
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}
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}
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