diff --git a/src/compiler/nir/nir_inline_uniforms.c b/src/compiler/nir/nir_inline_uniforms.c index 1a732e20a23..652b9534691 100644 --- a/src/compiler/nir/nir_inline_uniforms.c +++ b/src/compiler/nir/nir_inline_uniforms.c @@ -25,9 +25,12 @@ * effectively inlining uniform values in the IR. The main benefit is register * usage decrease leading to better SMT (hyperthreading). It's accomplished * by targetting uniforms that determine whether a conditional branch is - * taken. + * taken or a loop can be unrolled. * - * Only uniforms used in if conditions are analyzed. + * Only uniforms used in these places are analyzed: + * 1. if condition + * 2. loop terminator + * 3. init and update value of induction variable used in loop terminator * * nir_find_inlinable_uniforms finds uniforms that can be inlined and stores * that information in shader_info. @@ -37,7 +40,8 @@ * (uniforms must be lowered to load_ubo before calling this) */ -#include "compiler/nir/nir_builder.h" +#include "nir_builder.h" +#include "nir_loop_analyze.h" /* Maximum value in shader_info::inlinable_uniform_dw_offsets[] */ #define MAX_OFFSET (UINT16_MAX * 4) @@ -131,14 +135,84 @@ src_only_uses_uniforms(const nir_src *src, int component, } } +static bool +is_induction_variable(const nir_src *src, int component, nir_loop_info *info, + uint32_t *uni_offsets, unsigned *num_offsets) +{ + if (!src->is_ssa) + return false; + + assert(component < src->ssa->num_components); + + /* Return true for induction variable (ie. i in for loop) */ + for (int i = 0; i < info->num_induction_vars; i++) { + nir_loop_induction_variable *var = info->induction_vars + i; + if (var->def == src->ssa) { + /* Induction variable should have constant initial value (ie. i = 0), + * constant update value (ie. i++) and constant end condition + * (ie. i < 10), so that we know the exact loop count for unrolling + * the loop. + * + * Add uniforms need to be inlined for this induction variable's + * initial and update value to be constant, for example: + * + * for (i = init; i < count; i += step) + * + * We collect uniform "init" and "step" here. + */ + if (var->init_src) { + if (!src_only_uses_uniforms(var->init_src, component, + uni_offsets, num_offsets)) + return false; + } + + if (var->update_src) { + nir_alu_src *alu_src = var->update_src; + if (!src_only_uses_uniforms(&alu_src->src, + alu_src->swizzle[component], + uni_offsets, num_offsets)) + return false; + } + + return true; + } + } + + return false; +} + static void -add_inlinable_uniforms(const nir_src *cond, uint32_t *uni_offsets, - unsigned *num_offsets) +add_inlinable_uniforms(const nir_src *cond, nir_loop_info *info, + uint32_t *uni_offsets, unsigned *num_offsets) { unsigned new_num = *num_offsets; /* If condition SSA is always scalar, so component is 0. */ unsigned component = 0; + /* Allow induction variable which means a loop terminator. */ + if (info) { + nir_ssa_scalar cond_scalar = {cond->ssa, 0}; + + /* Limit terminator condition to loop unroll support case which is a simple + * comparison (ie. "i < count" is supported, but "i + 1 < count" is not). + */ + if (nir_is_supported_terminator_condition(cond_scalar)) { + nir_alu_instr *alu = nir_instr_as_alu(cond->ssa->parent_instr); + + /* One side of comparison is induction variable, the other side is + * only uniform. + */ + for (int i = 0; i < 2; i++) { + if (is_induction_variable(&alu->src[i].src, alu->src[i].swizzle[0], + info, uni_offsets, &new_num)) { + cond = &alu->src[1 - i].src; + component = alu->src[1 - i].swizzle[0]; + break; + } + } + } + } + /* Only update uniform number when all uniforms in the expression * can be inlined. Partially inline uniforms can't lower if/loop. * @@ -163,6 +237,82 @@ add_inlinable_uniforms(const nir_src *cond, uint32_t *uni_offsets, *num_offsets = new_num; } +static void +process_node(nir_cf_node *node, nir_loop_info *info, + uint32_t *uni_offsets, unsigned *num_offsets) +{ + switch (node->type) { + case nir_cf_node_if: { + nir_if *if_node = nir_cf_node_as_if(node); + const nir_src *cond = &if_node->condition; + add_inlinable_uniforms(cond, info, uni_offsets, num_offsets); + + /* Do not pass loop info down so only alow induction variable + * in loop terminator "if": + * + * for (i = 0; true; i++) + * if (i == count) + * if (i == num) + * + * break + * + * so "num" won't be inlined due to the "if" is not a + * terminator. + */ + info = NULL; + + foreach_list_typed(nir_cf_node, nested_node, node, &if_node->then_list) + process_node(nested_node, info, uni_offsets, num_offsets); + foreach_list_typed(nir_cf_node, nested_node, node, &if_node->else_list) + process_node(nested_node, info, uni_offsets, num_offsets); + break; + } + + case nir_cf_node_loop: { + nir_loop *loop = nir_cf_node_as_loop(node); + + /* Replace loop info, no nested loop info currently: + * + * for (i = 0; i < count0; i++) + * for (j = 0; j < count1; j++) + * if (i == num) + * + * so "num" won't be inlined due to "i" is an induction + * variable of upper loop. + */ + info = loop->info; + + foreach_list_typed(nir_cf_node, nested_node, node, &loop->body) { + bool is_terminator = false; + list_for_each_entry(nir_loop_terminator, terminator, + &info->loop_terminator_list, + loop_terminator_link) { + if (nested_node == &terminator->nif->cf_node) { + is_terminator = true; + break; + } + } + + /* Allow induction variables for terminator "if" only: + * + * for (i = 0; i < count; i++) + * if (i == num) + * + * + * so "num" won't be inlined due to the "if" is not a + * terminator. + */ + nir_loop_info *use_info = is_terminator ? info : NULL; + process_node(nested_node, use_info, uni_offsets, num_offsets); + } + break; + } + + default: + break; + } +} + void nir_find_inlinable_uniforms(nir_shader *shader) { @@ -171,22 +321,10 @@ nir_find_inlinable_uniforms(nir_shader *shader) nir_foreach_function(function, shader) { if (function->impl) { - foreach_list_typed(nir_cf_node, node, node, &function->impl->body) { - switch (node->type) { - case nir_cf_node_if: { - const nir_src *cond = &nir_cf_node_as_if(node)->condition; - add_inlinable_uniforms(cond, uni_offsets, &num_offsets); - break; - } + nir_metadata_require(function->impl, nir_metadata_loop_analysis, nir_var_all); - case nir_cf_node_loop: - /* TODO: handle loops if we want to unroll them at draw time */ - break; - - default: - break; - } - } + foreach_list_typed(nir_cf_node, node, node, &function->impl->body) + process_node(node, NULL, uni_offsets, &num_offsets); } }