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Diffstat (limited to 'src/glsl/opt_cse.cpp')
| -rw-r--r-- | src/glsl/opt_cse.cpp | 599 |
1 files changed, 599 insertions, 0 deletions
diff --git a/src/glsl/opt_cse.cpp b/src/glsl/opt_cse.cpp new file mode 100644 index 00000000000..c0fdb23e64c --- /dev/null +++ b/src/glsl/opt_cse.cpp @@ -0,0 +1,599 @@ +/* + * Copyright © 2013 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. + */ + +/** + * \file opt_cse.cpp + * + * constant subexpression elimination at the GLSL IR level. + * + * Compare to brw_fs_cse.cpp for a more complete CSE implementation. This one + * is generic and handles texture operations, but it's rather simple currently + * and doesn't support modification of variables in the available expressions + * list, so it can't do variables other than uniforms or shader inputs. + */ + +#include "ir.h" +#include "ir_visitor.h" +#include "ir_rvalue_visitor.h" +#include "ir_basic_block.h" +#include "ir_optimization.h" +#include "ir_builder.h" +#include "glsl_types.h" + +using namespace ir_builder; + +static bool debug = false; + +namespace { + +/** + * This is the record of an available expression for common subexpression + * elimination. + */ +class ae_entry : public exec_node +{ +public: + ae_entry(ir_instruction *base_ir, ir_rvalue **val) + : val(val), base_ir(base_ir) + { + assert(val); + assert(*val); + assert(base_ir); + + var = NULL; + } + + /** + * The pointer to the expression that we might be able to reuse + * + * Note the double pointer -- this is the place in the base_ir expression + * tree that we would rewrite to move the expression out to a new variable + * assignment. + */ + ir_rvalue **val; + + /** + * Root instruction in the basic block where the expression appeared. + * + * This is used so that we can insert the new variable declaration into the + * instruction stream (since *val is just somewhere in base_ir's expression + * tree). + */ + ir_instruction *base_ir; + + /** + * The variable that the expression has been stored in, if it's been CSEd + * once already. + */ + ir_variable *var; +}; + +class cse_visitor : public ir_rvalue_visitor { +public: + cse_visitor(exec_list *validate_instructions) + : validate_instructions(validate_instructions) + { + progress = false; + mem_ctx = ralloc_context(NULL); + this->ae = new(mem_ctx) exec_list; + } + ~cse_visitor() + { + ralloc_free(mem_ctx); + } + + virtual ir_visitor_status visit_enter(ir_function_signature *ir); + virtual ir_visitor_status visit_enter(ir_loop *ir); + virtual ir_visitor_status visit_enter(ir_if *ir); + virtual ir_visitor_status visit_enter(ir_call *ir); + virtual void handle_rvalue(ir_rvalue **rvalue); + + bool progress; + +private: + void *mem_ctx; + + ir_rvalue *try_cse(ir_rvalue *rvalue); + void add_to_ae(ir_rvalue **rvalue); + + /** List of ae_entry: The available expressions to reuse */ + exec_list *ae; + + /** + * The whole shader, so that we can validate_ir_tree in debug mode. + * + * This proved quite useful when trying to get the tree manipulation + * right. + */ + exec_list *validate_instructions; +}; + +/** + * Visitor to walk an expression tree to check that all variables referenced + * are constants. + */ +class is_cse_candidate_visitor : public ir_hierarchical_visitor +{ +public: + + is_cse_candidate_visitor() + : ok(true) + { + } + + virtual ir_visitor_status visit(ir_dereference_variable *ir); + + bool ok; +}; + + +class contains_rvalue_visitor : public ir_rvalue_visitor +{ +public: + + contains_rvalue_visitor(ir_rvalue *val) + : val(val) + { + found = false; + } + + virtual void handle_rvalue(ir_rvalue **rvalue); + + bool found; + +private: + ir_rvalue *val; +}; + +} /* unnamed namespace */ + +static void +dump_ae(exec_list *ae) +{ + int i = 0; + + printf("CSE: AE contents:\n"); + foreach_list(node, ae) { + ae_entry *entry = (ae_entry *)node; + + printf("CSE: AE %2d (%p): ", i, entry); + (*entry->val)->print(); + printf("\n"); + + if (entry->var) + printf("CSE: in var %p:\n", entry->var); + + i++; + } +} + +ir_visitor_status +is_cse_candidate_visitor::visit(ir_dereference_variable *ir) +{ + /* Currently, since we don't handle kills of the ae based on variables + * getting assigned, we can only handle constant variables. + */ + if (ir->var->read_only) { + return visit_continue; + } else { + ok = false; + return visit_stop; + } +} + +void +contains_rvalue_visitor::handle_rvalue(ir_rvalue **rvalue) +{ + if (*rvalue == val) + found = true; +} + +static bool +contains_rvalue(ir_rvalue *haystack, ir_rvalue *needle) +{ + contains_rvalue_visitor v(needle); + haystack->accept(&v); + return v.found; +} + +static bool +is_cse_candidate(ir_rvalue *ir) +{ + /* Our temporary variable assignment generation isn't ready to handle + * anything bigger than a vector. + */ + if (!ir->type->is_vector() && !ir->type->is_scalar()) + return false; + + /* Only handle expressions and textures currently. We may want to extend + * to variable-index array dereferences at some point. + */ + switch (ir->ir_type) { + case ir_type_expression: + case ir_type_texture: + break; + default: + return false; + } + + is_cse_candidate_visitor v; + + ir->accept(&v); + + return v.ok; +} + +static bool +equals(ir_rvalue *a, ir_rvalue *b); + +static bool +equals(ir_constant *a, ir_constant *b) +{ + if (!a || !b) + return false; + + if (a->type != b->type) + return false; + + for (unsigned i = 0; i < a->type->components(); i++) { + if (a->value.u[i] != b->value.u[i]) + return false; + } + + return true; +} + +static bool +equals(ir_dereference_variable *a, ir_dereference_variable *b) +{ + if (!a || !b) + return false; + + return a->var == b->var; +} + +static bool +equals(ir_dereference_array *a, ir_dereference_array *b) +{ + if (!a || !b) + return false; + + if (!equals(a->array, b->array)) + return false; + + if (!equals(a->array_index, b->array_index)) + return false; + + return true; +} + +static bool +equals(ir_swizzle *a, ir_swizzle *b) +{ + if (!a || !b) + return false; + + if (a->type != b->type) + return false; + + if (a->mask.x != b->mask.x || + a->mask.y != b->mask.y || + a->mask.z != b->mask.z || + a->mask.w != b->mask.w) { + return false; + } + + return equals(a->val, b->val); +} + +static bool +equals(ir_texture *a, ir_texture *b) +{ + if (!a || !b) + return false; + + if (a->type != b->type) + return false; + + if (a->op != b->op) + return false; + + if (!equals(a->coordinate, b->coordinate)) + return false; + + if (!equals(a->projector, b->projector)) + return false; + + if (!equals(a->shadow_comparitor, b->shadow_comparitor)) + return false; + + if (!equals(a->offset, b->offset)) + return false; + + if (!equals(a->sampler, b->sampler)) + return false; + + switch (a->op) { + case ir_tex: + case ir_lod: + case ir_query_levels: + break; + case ir_txb: + if (!equals(a->lod_info.bias, b->lod_info.bias)) + return false; + break; + case ir_txl: + case ir_txf: + case ir_txs: + if (!equals(a->lod_info.lod, b->lod_info.lod)) + return false; + break; + case ir_txd: + if (!equals(a->lod_info.grad.dPdx, b->lod_info.grad.dPdx) || + !equals(a->lod_info.grad.dPdy, b->lod_info.grad.dPdy)) + return false; + case ir_txf_ms: + if (!equals(a->lod_info.sample_index, b->lod_info.sample_index)) + return false; + break; + case ir_tg4: + if (!equals(a->lod_info.component, b->lod_info.component)) + return false; + default: + assert(!"Unrecognized texture op"); + } + + return true; +} + +static bool +equals(ir_expression *a, ir_expression *b) +{ + if (!a || !b) + return false; + + if (a->type != b->type) + return false; + + if (a->operation != b->operation) + return false; + + for (unsigned i = 0; i < a->get_num_operands(); i++) { + if (!equals(a->operands[i], b->operands[i])) + return false; + } + + return true; +} + +static bool +equals(ir_rvalue *a, ir_rvalue *b) +{ + if (!a || !b) + return !a && !b; + + if (a->type != b->type) + return false; + + switch (a->ir_type) { + case ir_type_texture: + return equals(a->as_texture(), b->as_texture()); + + case ir_type_constant: + return equals(a->as_constant(), b->as_constant()); + + case ir_type_expression: + return equals(a->as_expression(), b->as_expression()); + + case ir_type_dereference_variable: + return equals(a->as_dereference_variable(), b->as_dereference_variable()); + + case ir_type_dereference_array: + return equals(a->as_dereference_array(), b->as_dereference_array()); + + case ir_type_swizzle: + return equals(a->as_swizzle(), b->as_swizzle()); + + default: + return false; + } +} + +/** + * Tries to find and return a reference to a previous computation of a given + * expression. + * + * Walk the list of available expressions checking if any of them match the + * rvalue, and if so, move the previous copy of the expression to a temporary + * and return a reference of the temporary. + */ +ir_rvalue * +cse_visitor::try_cse(ir_rvalue *rvalue) +{ + foreach_list(node, ae) { + ae_entry *entry = (ae_entry *)node; + + if (debug) { + printf("Comparing to AE %p: ", entry); + (*entry->val)->print(); + printf("\n"); + } + + if (!equals(rvalue, *entry->val)) + continue; + + if (debug) { + printf("CSE: Replacing: "); + (*entry->val)->print(); + printf("\n"); + printf("CSE: with: "); + rvalue->print(); + printf("\n"); + } + + if (!entry->var) { + ir_instruction *base_ir = entry->base_ir; + + ir_variable *var = new(rvalue) ir_variable(rvalue->type, + "cse", + ir_var_auto); + + /* Write the previous expression result into a new variable. */ + base_ir->insert_before(var); + ir_assignment *assignment = assign(var, *entry->val); + base_ir->insert_before(assignment); + + /* Replace the expression in the original tree with a deref of the + * variable, but keep tracking the expression for further reuse. + */ + *entry->val = new(rvalue) ir_dereference_variable(var); + entry->val = &assignment->rhs; + + entry->var = var; + + /* Update the base_irs in the AE list. We have to be sure that + * they're correct -- expressions from our base_ir that weren't moved + * need to stay in this base_ir (so that later consumption of them + * puts new variables between our new variable and our base_ir), but + * expressions from our base_ir that we *did* move need base_ir + * updated so that any further elimination from inside gets its new + * assignments put before our new assignment. + */ + foreach_list(fixup_node, ae) { + ae_entry *fixup_entry = (ae_entry *)fixup_node; + if (contains_rvalue(assignment->rhs, *fixup_entry->val)) + fixup_entry->base_ir = assignment; + } + + if (debug) + dump_ae(ae); + } + + /* Replace the expression in our current tree with the variable. */ + return new(rvalue) ir_dereference_variable(entry->var); + } + + return NULL; +} + +/** Add the rvalue to the list of available expressions for CSE. */ +void +cse_visitor::add_to_ae(ir_rvalue **rvalue) +{ + if (debug) { + printf("CSE: Add to AE: "); + (*rvalue)->print(); + printf("\n"); + } + + ae->push_tail(new(mem_ctx) ae_entry(base_ir, rvalue)); + + if (debug) + dump_ae(ae); +} + +void +cse_visitor::handle_rvalue(ir_rvalue **rvalue) +{ + if (!*rvalue) + return; + + if (debug) { + printf("CSE: handle_rvalue "); + (*rvalue)->print(); + printf("\n"); + } + + if (!is_cse_candidate(*rvalue)) + return; + + ir_rvalue *new_rvalue = try_cse(*rvalue); + if (new_rvalue) { + *rvalue = new_rvalue; + progress = true; + + if (debug) + validate_ir_tree(validate_instructions); + } else { + add_to_ae(rvalue); + } +} + +ir_visitor_status +cse_visitor::visit_enter(ir_if *ir) +{ + handle_rvalue(&ir->condition); + + ae->make_empty(); + visit_list_elements(this, &ir->then_instructions); + + ae->make_empty(); + visit_list_elements(this, &ir->else_instructions); + + ae->make_empty(); + return visit_continue_with_parent; +} + +ir_visitor_status +cse_visitor::visit_enter(ir_function_signature *ir) +{ + ae->make_empty(); + visit_list_elements(this, &ir->body); + + ae->make_empty(); + return visit_continue_with_parent; +} + +ir_visitor_status +cse_visitor::visit_enter(ir_loop *ir) +{ + ae->make_empty(); + visit_list_elements(this, &ir->body_instructions); + + ae->make_empty(); + return visit_continue_with_parent; +} + +ir_visitor_status +cse_visitor::visit_enter(ir_call *ir) +{ + /* Because call is an exec_list of ir_rvalues, handle_rvalue gets passed a + * pointer to the (ir_rvalue *) on the stack. Since we save those pointers + * in the AE list, we can't let handle_rvalue get called. + */ + return visit_continue_with_parent; +} + +/** + * Does a (uniform-value) constant subexpression elimination pass on the code + * present in the instruction stream. + */ +bool +do_cse(exec_list *instructions) +{ + cse_visitor v(instructions); + + visit_list_elements(&v, instructions); + + return v.progress; +} |