From 02530c5dc5dc88078f41fb134c7e0e3833c9f772 Mon Sep 17 00:00:00 2001 From: Kenneth Graunke Date: Thu, 24 Sep 2015 17:01:23 -0700 Subject: [PATCH] nir: Add a function to count the number of vertices a GS emits. Some hardware (such as Broadwell) can run geometry shaders more efficiently when the number of vertices emitted is statically known. This pass provides a way to obtain the constant vertex count, or -1 indicating that the vertex count is unknown/non-constant. Signed-off-by: Kenneth Graunke Reviewed-by: Jordan Justen --- src/glsl/Makefile.sources | 1 + src/glsl/nir/nir.h | 2 + src/glsl/nir/nir_gs_count_vertices.c | 93 ++++++++++++++++++++++++++++ 3 files changed, 96 insertions(+) create mode 100644 src/glsl/nir/nir_gs_count_vertices.c diff --git a/src/glsl/Makefile.sources b/src/glsl/Makefile.sources index a8f4994cf34..32b6dba2e91 100644 --- a/src/glsl/Makefile.sources +++ b/src/glsl/Makefile.sources @@ -30,6 +30,7 @@ NIR_FILES = \ nir/nir_control_flow_private.h \ nir/nir_dominance.c \ nir/nir_from_ssa.c \ + nir/nir_gs_count_vertices.c \ nir/nir_intrinsics.c \ nir/nir_intrinsics.h \ nir/nir_live_variables.c \ diff --git a/src/glsl/nir/nir.h b/src/glsl/nir/nir.h index 4f45770e02d..d0c7b04a49f 100644 --- a/src/glsl/nir/nir.h +++ b/src/glsl/nir/nir.h @@ -1804,6 +1804,8 @@ void nir_dump_dom_frontier(nir_shader *shader, FILE *fp); void nir_dump_cfg_impl(nir_function_impl *impl, FILE *fp); void nir_dump_cfg(nir_shader *shader, FILE *fp); +int nir_gs_count_vertices(nir_shader *shader); + bool nir_split_var_copies(nir_shader *shader); void nir_lower_var_copy_instr(nir_intrinsic_instr *copy, void *mem_ctx); diff --git a/src/glsl/nir/nir_gs_count_vertices.c b/src/glsl/nir/nir_gs_count_vertices.c new file mode 100644 index 00000000000..e0bdf170d22 --- /dev/null +++ b/src/glsl/nir/nir_gs_count_vertices.c @@ -0,0 +1,93 @@ +/* + * Copyright © 2015 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 "nir.h" +#include "nir_builder.h" + +static nir_intrinsic_instr * +as_intrinsic(nir_instr *instr, nir_intrinsic_op op) +{ + if (instr->type != nir_instr_type_intrinsic) + return NULL; + + nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr); + if (intrin->intrinsic != op) + return NULL; + + return intrin; +} + +static nir_intrinsic_instr * +as_set_vertex_count(nir_instr *instr) +{ + return as_intrinsic(instr, nir_intrinsic_set_vertex_count); +} + +/** + * If a geometry shader emits a constant number of vertices, return the + * number of vertices. Otherwise, return -1 (unknown). + * + * This only works if you've used nir_lower_gs_intrinsics() to do vertex + * counting at the NIR level. + */ +int +nir_gs_count_vertices(nir_shader *shader) +{ + int count = -1; + + nir_foreach_overload(shader, overload) { + if (!overload->impl) + continue; + + /* set_vertex_count intrinsics only appear in predecessors of the + * end block. So we don't need to walk all of them. + */ + struct set_entry *entry; + set_foreach(overload->impl->end_block->predecessors, entry) { + nir_block *block = (nir_block *) entry->key; + + nir_foreach_instr_reverse(block, instr) { + nir_intrinsic_instr *intrin = as_set_vertex_count(instr); + if (!intrin) + continue; + + nir_const_value *val = nir_src_as_const_value(intrin->src[0]); + /* We've found a non-constant value. Bail. */ + if (!val) + return -1; + + if (count == -1) + count = val->i[0]; + + /* We've found contradictory set_vertex_count intrinsics. + * This can happen if there are early-returns in main() and + * different paths emit different numbers of vertices. + */ + if (count != val->i[0]) + return -1; + } + } + } + + return count; +} -- 2.30.2