From: Connor Abbott Date: Sun, 15 Nov 2015 01:26:47 +0000 (-0500) Subject: nir: add a vectorization pass X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=47e7c6961a36549118166a4f38072cb7711e8d52;p=mesa.git nir: add a vectorization pass This effectively does the opposite of nir_lower_alus_to_scalar, trying to combine per-component ALU operations with the same sources but different swizzles into one larger ALU operation. It uses a similar model as CSE, where we do a depth-first approach and keep around a hash set of instructions to be combined, but there are a few major differences: 1. For now, we only support entirely per-component ALU operations. 2. Since it's not always guaranteed that we'll be able to combine equivalent instructions, we keep a stack of equivalent instructions around, trying to combine new instructions with instructions on the stack. The pass isn't comprehensive by far; it can't handle operations where some of the sources are per-component and others aren't, and it can't handle phi nodes. But it should handle the more common cases, and it should be reasonably efficient. [Alyssa: Rebase on latest master, updating with respect to typeless moves] Acked-by: Alyssa Rosenzweig Acked-by: Jason Ekstrand --- diff --git a/src/compiler/Makefile.sources b/src/compiler/Makefile.sources index 0708b256feb..324e5a0e939 100644 --- a/src/compiler/Makefile.sources +++ b/src/compiler/Makefile.sources @@ -311,6 +311,7 @@ NIR_FILES = \ nir/nir_opt_shrink_load.c \ nir/nir_opt_trivial_continues.c \ nir/nir_opt_undef.c \ + nir/nir_opt_vectorize.c \ nir/nir_phi_builder.c \ nir/nir_phi_builder.h \ nir/nir_print.c \ diff --git a/src/compiler/nir/meson.build b/src/compiler/nir/meson.build index ad380e172f1..268acfeb2e6 100644 --- a/src/compiler/nir/meson.build +++ b/src/compiler/nir/meson.build @@ -192,6 +192,7 @@ files_libnir = files( 'nir_opt_shrink_load.c', 'nir_opt_trivial_continues.c', 'nir_opt_undef.c', + 'nir_opt_vectorize.c', 'nir_phi_builder.c', 'nir_phi_builder.h', 'nir_print.c', diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h index 8972b4af748..6b2ebcab6fb 100644 --- a/src/compiler/nir/nir.h +++ b/src/compiler/nir/nir.h @@ -3618,6 +3618,8 @@ bool nir_opt_trivial_continues(nir_shader *shader); bool nir_opt_undef(nir_shader *shader); +bool nir_opt_vectorize(nir_shader *shader); + bool nir_opt_conditional_discard(nir_shader *shader); void nir_strip(nir_shader *shader); diff --git a/src/compiler/nir/nir_opt_vectorize.c b/src/compiler/nir/nir_opt_vectorize.c new file mode 100644 index 00000000000..275202b0d85 --- /dev/null +++ b/src/compiler/nir/nir_opt_vectorize.c @@ -0,0 +1,453 @@ +/* + * Copyright © 2015 Connor Abbott + * + * 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_vla.h" +#include "nir_builder.h" +#include "util/u_dynarray.h" + +#define HASH(hash, data) _mesa_fnv32_1a_accumulate((hash), (data)) + +static uint32_t +hash_src(uint32_t hash, const nir_src *src) +{ + assert(src->is_ssa); + + return HASH(hash, src->ssa); +} + +static uint32_t +hash_alu_src(uint32_t hash, const nir_alu_src *src) +{ + assert(!src->abs && !src->negate); + + /* intentionally don't hash swizzle */ + + return hash_src(hash, &src->src); +} + +static uint32_t +hash_alu(uint32_t hash, const nir_alu_instr *instr) +{ + hash = HASH(hash, instr->op); + + hash = HASH(hash, instr->dest.dest.ssa.bit_size); + + for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) + hash = hash_alu_src(hash, &instr->src[i]); + + return hash; +} + +static uint32_t +hash_instr(const nir_instr *instr) +{ + uint32_t hash = _mesa_fnv32_1a_offset_bias; + + switch (instr->type) { + case nir_instr_type_alu: + return hash_alu(hash, nir_instr_as_alu(instr)); + default: + unreachable("bad instruction type"); + } +} + +static bool +srcs_equal(const nir_src *src1, const nir_src *src2) +{ + assert(src1->is_ssa); + assert(src2->is_ssa); + + return src1->ssa == src2->ssa; +} + +static bool +alu_srcs_equal(const nir_alu_src *src1, const nir_alu_src *src2) +{ + assert(!src1->abs); + assert(!src1->negate); + assert(!src2->abs); + assert(!src2->negate); + + return srcs_equal(&src1->src, &src2->src); +} + +static bool +instrs_equal(const nir_instr *instr1, const nir_instr *instr2) +{ + switch (instr1->type) { + case nir_instr_type_alu: { + nir_alu_instr *alu1 = nir_instr_as_alu(instr1); + nir_alu_instr *alu2 = nir_instr_as_alu(instr2); + + if (alu1->op != alu2->op) + return false; + + if (alu1->dest.dest.ssa.bit_size != alu2->dest.dest.ssa.bit_size) + return false; + + for (unsigned i = 0; i < nir_op_infos[alu1->op].num_inputs; i++) { + if (!alu_srcs_equal(&alu1->src[i], &alu2->src[i])) + return false; + } + + return true; + } + + default: + unreachable("bad instruction type"); + } +} + +static bool +instr_can_rewrite(nir_instr *instr) +{ + switch (instr->type) { + case nir_instr_type_alu: { + nir_alu_instr *alu = nir_instr_as_alu(instr); + + /* Don't try and vectorize mov's. Either they'll be handled by copy + * prop, or they're actually necessary and trying to vectorize them + * would result in fighting with copy prop. + */ + if (alu->op == nir_op_mov) + return false; + + if (nir_op_infos[alu->op].output_size != 0) + return false; + + for (unsigned i = 0; i < nir_op_infos[alu->op].num_inputs; i++) { + if (nir_op_infos[alu->op].input_sizes[i] != 0) + return false; + } + + return true; + } + + /* TODO support phi nodes */ + default: + break; + } + + return false; +} + +/* + * Tries to combine two instructions whose sources are different components of + * the same instructions into one vectorized instruction. Note that instr1 + * should dominate instr2. + */ + +static nir_instr * +instr_try_combine(nir_instr *instr1, nir_instr *instr2) +{ + assert(instr1->type == nir_instr_type_alu); + assert(instr2->type == nir_instr_type_alu); + nir_alu_instr *alu1 = nir_instr_as_alu(instr1); + nir_alu_instr *alu2 = nir_instr_as_alu(instr2); + + assert(alu1->dest.dest.ssa.bit_size == alu2->dest.dest.ssa.bit_size); + unsigned alu1_components = alu1->dest.dest.ssa.num_components; + unsigned alu2_components = alu2->dest.dest.ssa.num_components; + unsigned total_components = alu1_components + alu2_components; + + if (total_components > 4) + return NULL; + + nir_builder b; + nir_builder_init(&b, nir_cf_node_get_function(&instr1->block->cf_node)); + b.cursor = nir_after_instr(instr1); + + nir_alu_instr *new_alu = nir_alu_instr_create(b.shader, alu1->op); + nir_ssa_dest_init(&new_alu->instr, &new_alu->dest.dest, + total_components, alu1->dest.dest.ssa.bit_size, NULL); + new_alu->dest.write_mask = (1 << total_components) - 1; + + for (unsigned i = 0; i < nir_op_infos[alu1->op].num_inputs; i++) { + new_alu->src[i].src = alu1->src[i].src; + + for (unsigned j = 0; j < alu1_components; j++) + new_alu->src[i].swizzle[j] = alu1->src[i].swizzle[j]; + + for (unsigned j = 0; j < alu2_components; j++) { + new_alu->src[i].swizzle[j + alu1_components] = + alu2->src[i].swizzle[j]; + } + } + + nir_builder_instr_insert(&b, &new_alu->instr); + + unsigned swiz[4] = {0, 1, 2, 3}; + nir_ssa_def *new_alu1 = nir_swizzle(&b, &new_alu->dest.dest.ssa, swiz, + alu1_components); + + for (unsigned i = 0; i < alu2_components; i++) + swiz[i] += alu1_components; + nir_ssa_def *new_alu2 = nir_swizzle(&b, &new_alu->dest.dest.ssa, swiz, + alu2_components); + + nir_foreach_use_safe(src, &alu1->dest.dest.ssa) { + if (src->parent_instr->type == nir_instr_type_alu) { + /* For ALU instructions, rewrite the source directly to avoid a + * round-trip through copy propagation. + */ + + nir_instr_rewrite_src(src->parent_instr, src, + nir_src_for_ssa(&new_alu->dest.dest.ssa)); + } else { + nir_instr_rewrite_src(src->parent_instr, src, + nir_src_for_ssa(new_alu1)); + } + } + + nir_foreach_if_use_safe(src, &alu1->dest.dest.ssa) { + nir_if_rewrite_condition(src->parent_if, nir_src_for_ssa(new_alu1)); + } + + assert(list_empty(&alu1->dest.dest.ssa.uses)); + assert(list_empty(&alu1->dest.dest.ssa.if_uses)); + + nir_foreach_use_safe(src, &alu2->dest.dest.ssa) { + if (src->parent_instr->type == nir_instr_type_alu) { + /* For ALU instructions, rewrite the source directly to avoid a + * round-trip through copy propagation. + */ + + nir_alu_instr *use = nir_instr_as_alu(src->parent_instr); + + unsigned src_index = 5; + for (unsigned i = 0; i < nir_op_infos[use->op].num_inputs; i++) { + if (&use->src[i].src == src) { + src_index = i; + break; + } + } + assert(src_index != 5); + + nir_instr_rewrite_src(src->parent_instr, src, + nir_src_for_ssa(&new_alu->dest.dest.ssa)); + + for (unsigned i = 0; + i < nir_ssa_alu_instr_src_components(use, src_index); i++) { + use->src[src_index].swizzle[i] += alu1_components; + } + } else { + nir_instr_rewrite_src(src->parent_instr, src, + nir_src_for_ssa(new_alu2)); + } + } + + nir_foreach_if_use_safe(src, &alu2->dest.dest.ssa) { + nir_if_rewrite_condition(src->parent_if, nir_src_for_ssa(new_alu2)); + } + + assert(list_empty(&alu2->dest.dest.ssa.uses)); + assert(list_empty(&alu2->dest.dest.ssa.if_uses)); + + nir_instr_remove(instr1); + nir_instr_remove(instr2); + + return &new_alu->instr; +} + +/* + * Use an array to represent a stack of instructions that are equivalent. + * + * We push and pop instructions off the stack in dominance order. The first + * element dominates the second element which dominates the third, etc. When + * trying to add to the stack, first we try and combine the instruction with + * each of the instructions on the stack and, if successful, replace the + * instruction on the stack with the newly-combined instruction. + */ + +static struct util_dynarray * +vec_instr_stack_create(void *mem_ctx) +{ + struct util_dynarray *stack = ralloc(mem_ctx, struct util_dynarray); + util_dynarray_init(stack, mem_ctx); + return stack; +} + +/* returns true if we were able to successfully replace the instruction */ + +static bool +vec_instr_stack_push(struct util_dynarray *stack, nir_instr *instr) +{ + /* Walk the stack from child to parent to make live ranges shorter by + * matching the closest thing we can + */ + util_dynarray_foreach_reverse(stack, nir_instr *, stack_instr) { + nir_instr *new_instr = instr_try_combine(*stack_instr, instr); + if (new_instr) { + *stack_instr = new_instr; + return true; + } + } + + util_dynarray_append(stack, nir_instr *, instr); + return false; +} + +static void +vec_instr_stack_pop(struct util_dynarray *stack, nir_instr *instr) +{ + nir_instr *last = util_dynarray_pop(stack, nir_instr *); + assert(last == instr); +} + +static bool +cmp_func(const void *data1, const void *data2) +{ + const struct util_dynarray *arr1 = data1; + const struct util_dynarray *arr2 = data2; + + const nir_instr *instr1 = *(nir_instr **)util_dynarray_begin(arr1); + const nir_instr *instr2 = *(nir_instr **)util_dynarray_begin(arr2); + + return instrs_equal(instr1, instr2); +} + +static uint32_t +hash_stack(const void *data) +{ + const struct util_dynarray *stack = data; + const nir_instr *first = *(nir_instr **)util_dynarray_begin(stack); + return hash_instr(first); +} + +static struct set * +vec_instr_set_create(void) +{ + return _mesa_set_create(NULL, hash_stack, cmp_func); +} + +static void +vec_instr_set_destroy(struct set *instr_set) +{ + _mesa_set_destroy(instr_set, NULL); +} + +static bool +vec_instr_set_add_or_rewrite(struct set *instr_set, nir_instr *instr) +{ + if (!instr_can_rewrite(instr)) + return false; + + struct util_dynarray *new_stack = vec_instr_stack_create(instr_set); + vec_instr_stack_push(new_stack, instr); + + struct set_entry *entry = _mesa_set_search(instr_set, new_stack); + + if (entry) { + ralloc_free(new_stack); + struct util_dynarray *stack = (struct util_dynarray *) entry->key; + return vec_instr_stack_push(stack, instr); + } + + _mesa_set_add(instr_set, new_stack); + return false; +} + +static void +vec_instr_set_remove(struct set *instr_set, nir_instr *instr) +{ + if (!instr_can_rewrite(instr)) + return; + + /* + * It's pretty unfortunate that we have to do this, but it's a side effect + * of the hash set interfaces. The hash set assumes that we're only + * interested in storing one equivalent element at a time, and if we try to + * insert a duplicate element it will remove the original. We could hack up + * the comparison function to "know" which input is an instruction we + * passed in and which is an array that's part of the entry, but that + * wouldn't work because we need to pass an array to _mesa_set_add() in + * vec_instr_add_or_rewrite() above, and _mesa_set_add() will call our + * comparison function as well. + */ + struct util_dynarray *temp = vec_instr_stack_create(instr_set); + vec_instr_stack_push(temp, instr); + struct set_entry *entry = _mesa_set_search(instr_set, temp); + ralloc_free(temp); + + if (entry) { + struct util_dynarray *stack = (struct util_dynarray *) entry->key; + + if (util_dynarray_num_elements(stack, nir_instr *) > 1) + vec_instr_stack_pop(stack, instr); + else + _mesa_set_remove(instr_set, entry); + } +} + +static bool +vectorize_block(nir_block *block, struct set *instr_set) +{ + bool progress = false; + + nir_foreach_instr_safe(instr, block) { + if (vec_instr_set_add_or_rewrite(instr_set, instr)) + progress = true; + } + + for (unsigned i = 0; i < block->num_dom_children; i++) { + nir_block *child = block->dom_children[i]; + progress |= vectorize_block(child, instr_set); + } + + nir_foreach_instr_reverse(instr, block) + vec_instr_set_remove(instr_set, instr); + + return progress; +} + +static bool +nir_opt_vectorize_impl(nir_function_impl *impl) +{ + struct set *instr_set = vec_instr_set_create(); + + nir_metadata_require(impl, nir_metadata_dominance); + + bool progress = vectorize_block(nir_start_block(impl), instr_set); + + if (progress) + nir_metadata_preserve(impl, nir_metadata_block_index | + nir_metadata_dominance); + + vec_instr_set_destroy(instr_set); + return progress; +} + +bool +nir_opt_vectorize(nir_shader *shader) +{ + bool progress = false; + + nir_foreach_function(function, shader) { + if (function->impl) + progress |= nir_opt_vectorize_impl(function->impl); + } + + return progress; +}