From 719bf3016550a279cf0d399b946d0d0b77329927 Mon Sep 17 00:00:00 2001 From: Paul Berry Date: Tue, 15 Oct 2013 15:13:59 -0700 Subject: [PATCH] glsl: Remove unused gl_PerVertex interface blocks. The GLSL 4.10 rules for redeclaration of built-in interface blocks (which we've chosen to regard as clarifications of GLSL 1.50) only require gl_PerVertex blocks to match in shaders that actually use those blocks. The easiest way to implement this is to detect situations where a compiled shader doesn't refer to any elements of gl_PerVertex, and remove all the associated ir_variables from the shader at the end of ast-to-ir conversion. Fixes piglit tests linker/interstage-{pervertex,pervertex-in,pervertex-out}-redeclaration-unneeded. Reviewed-by: Ian Romanick Reviewed-by: Matt Turner --- src/glsl/ast_to_hir.cpp | 90 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 90 insertions(+) diff --git a/src/glsl/ast_to_hir.cpp b/src/glsl/ast_to_hir.cpp index d89b6486ea9..5b49efaf093 100644 --- a/src/glsl/ast_to_hir.cpp +++ b/src/glsl/ast_to_hir.cpp @@ -60,6 +60,10 @@ static void detect_conflicting_assignments(struct _mesa_glsl_parse_state *state, exec_list *instructions); +static void +remove_per_vertex_blocks(exec_list *instructions, + _mesa_glsl_parse_state *state, ir_variable_mode mode); + void _mesa_ast_to_hir(exec_list *instructions, struct _mesa_glsl_parse_state *state) @@ -114,6 +118,40 @@ _mesa_ast_to_hir(exec_list *instructions, struct _mesa_glsl_parse_state *state) var->remove(); instructions->push_head(var); } + + /* From section 7.1 (Built-In Language Variables) of the GLSL 4.10 spec: + * + * If multiple shaders using members of a built-in block belonging to + * the same interface are linked together in the same program, they + * must all redeclare the built-in block in the same way, as described + * in section 4.3.7 "Interface Blocks" for interface block matching, or + * a link error will result. + * + * The phrase "using members of a built-in block" implies that if two + * shaders are linked together and one of them *does not use* any members + * of the built-in block, then that shader does not need to have a matching + * redeclaration of the built-in block. + * + * This appears to be a clarification to the behaviour established for + * gl_PerVertex by GLSL 1.50, therefore implement it regardless of GLSL + * version. + * + * The definition of "interface" in section 4.3.7 that applies here is as + * follows: + * + * The boundary between adjacent programmable pipeline stages: This + * spans all the outputs in all compilation units of the first stage + * and all the inputs in all compilation units of the second stage. + * + * Therefore this rule applies to both inter- and intra-stage linking. + * + * The easiest way to implement this is to check whether the shader uses + * gl_PerVertex right after ast-to-ir conversion, and if it doesn't, simply + * remove all the relevant variable declaration from the IR, so that the + * linker won't see them and complain about mismatches. + */ + remove_per_vertex_blocks(instructions, state, ir_var_shader_in); + remove_per_vertex_blocks(instructions, state, ir_var_shader_out); } @@ -5141,3 +5179,55 @@ detect_conflicting_assignments(struct _mesa_glsl_parse_state *state, user_defined_fs_output->name); } } + + +static void +remove_per_vertex_blocks(exec_list *instructions, + _mesa_glsl_parse_state *state, ir_variable_mode mode) +{ + /* Find the gl_PerVertex interface block of the appropriate (in/out) mode, + * if it exists in this shader type. + */ + const glsl_type *per_vertex = NULL; + switch (mode) { + case ir_var_shader_in: + if (ir_variable *gl_in = state->symbols->get_variable("gl_in")) + per_vertex = gl_in->get_interface_type(); + break; + case ir_var_shader_out: + if (ir_variable *gl_Position = + state->symbols->get_variable("gl_Position")) { + per_vertex = gl_Position->get_interface_type(); + } + break; + default: + assert(!"Unexpected mode"); + break; + } + + /* If we didn't find a built-in gl_PerVertex interface block, then we don't + * need to do anything. + */ + if (per_vertex == NULL) + return; + + /* If the interface block is used by the shader, then we don't need to do + * anything. + */ + interface_block_usage_visitor v(mode, per_vertex); + v.run(instructions); + if (v.usage_found()) + return; + + /* Remove any ir_variable declarations that refer to the interface block + * we're removing. + */ + foreach_list_safe(node, instructions) { + ir_variable *const var = ((ir_instruction *) node)->as_variable(); + if (var != NULL && var->get_interface_type() == per_vertex && + var->mode == mode) { + state->symbols->disable_variable(var->name); + var->remove(); + } + } +} -- 2.30.2