From: Ian Romanick Date: Thu, 29 May 2014 00:09:45 +0000 (-0700) Subject: glsl: Eliminate unused built-in variables after compilation X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=1012e95a40fe08f5d4f6219c1bc9812ad8f91423;p=mesa.git glsl: Eliminate unused built-in variables after compilation 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 Suggested-by: Eric Anholt Reviewed-by: Matt Turner Acked-by: Anuj Phogat Cc: Eric Anholt --- diff --git a/src/glsl/Makefile.sources b/src/glsl/Makefile.sources index cb8d5a6f7e8..bfb6993536e 100644 --- a/src/glsl/Makefile.sources +++ b/src/glsl/Makefile.sources @@ -87,6 +87,7 @@ LIBGLSL_FILES = \ $(GLSL_SRCDIR)/opt_copy_propagation.cpp \ $(GLSL_SRCDIR)/opt_copy_propagation_elements.cpp \ $(GLSL_SRCDIR)/opt_cse.cpp \ + $(GLSL_SRCDIR)/opt_dead_builtin_variables.cpp \ $(GLSL_SRCDIR)/opt_dead_builtin_varyings.cpp \ $(GLSL_SRCDIR)/opt_dead_code.cpp \ $(GLSL_SRCDIR)/opt_dead_code_local.cpp \ diff --git a/src/glsl/glsl_parser_extras.cpp b/src/glsl/glsl_parser_extras.cpp index 490c3c8eea3..2da6d5ab9d5 100644 --- a/src/glsl/glsl_parser_extras.cpp +++ b/src/glsl/glsl_parser_extras.cpp @@ -1483,6 +1483,26 @@ _mesa_glsl_compile_shader(struct gl_context *ctx, struct gl_shader *shader, ; validate_ir_tree(shader->ir); + + enum ir_variable_mode other; + switch (shader->Stage) { + case MESA_SHADER_VERTEX: + other = ir_var_shader_in; + break; + case MESA_SHADER_FRAGMENT: + other = ir_var_shader_out; + break; + default: + /* Something invalid to ensure optimize_dead_builtin_uniforms + * doesn't remove anything other than uniforms or constants. + */ + other = ir_var_mode_count; + break; + } + + optimize_dead_builtin_variables(shader->ir, other); + + validate_ir_tree(shader->ir); } if (shader->InfoLog) diff --git a/src/glsl/ir_optimization.h b/src/glsl/ir_optimization.h index 369dcd15b95..0c3a6383190 100644 --- a/src/glsl/ir_optimization.h +++ b/src/glsl/ir_optimization.h @@ -125,6 +125,8 @@ void lower_named_interface_blocks(void *mem_ctx, gl_shader *shader); bool optimize_redundant_jumps(exec_list *instructions); bool optimize_split_arrays(exec_list *instructions, bool linked); bool lower_offset_arrays(exec_list *instructions); +void optimize_dead_builtin_variables(exec_list *instructions, + enum ir_variable_mode other); bool lower_vertex_id(gl_shader *shader); diff --git a/src/glsl/opt_dead_builtin_variables.cpp b/src/glsl/opt_dead_builtin_variables.cpp new file mode 100644 index 00000000000..85c75d6f21f --- /dev/null +++ b/src/glsl/opt_dead_builtin_variables.cpp @@ -0,0 +1,81 @@ +/* + * 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 (strncmp(var->name, "gl_", 3) != 0) + 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. + * + * 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 + || strstr(var->name, "Transpose") != NULL) + continue; + + var->remove(); + } +}