diff options
| -rw-r--r-- | src/glsl/Makefile | 1 | ||||
| -rw-r--r-- | src/glsl/Makefile.am | 3 | ||||
| -rw-r--r-- | src/glsl/loop_analysis.cpp | 479 | ||||
| -rw-r--r-- | src/glsl/loop_analysis.h | 190 |
4 files changed, 672 insertions, 1 deletions
diff --git a/src/glsl/Makefile b/src/glsl/Makefile index aedca0f0d15..e5375eff443 100644 --- a/src/glsl/Makefile +++ b/src/glsl/Makefile @@ -72,6 +72,7 @@ CXX_SOURCES = \ ir_vec_index_to_swizzle.cpp \ linker.cpp \ link_functions.cpp \ + loop_analysis.cpp \ s_expression.cpp LIBS = \ diff --git a/src/glsl/Makefile.am b/src/glsl/Makefile.am index 5728a8b63da..55e4332af53 100644 --- a/src/glsl/Makefile.am +++ b/src/glsl/Makefile.am @@ -62,7 +62,8 @@ glsl_SOURCES = \ ir_to_mesa.h \ ir_validate.cpp \ ir_vec_index_to_swizzle.cpp \ - linker.cpp + linker.cpp \ + loop_analysis.cpp BUILT_SOURCES = glsl_parser.h glsl_parser.cpp glsl_lexer.cpp CLEANFILES = $(BUILT_SOURCES) diff --git a/src/glsl/loop_analysis.cpp b/src/glsl/loop_analysis.cpp new file mode 100644 index 00000000000..2ea2f3dbe39 --- /dev/null +++ b/src/glsl/loop_analysis.cpp @@ -0,0 +1,479 @@ +/* + * Copyright © 2010 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 "glsl_types.h" +#include "loop_analysis.h" +#include "ir_hierarchical_visitor.h" + +static bool is_loop_terminator(ir_if *ir); + +static bool all_expression_operands_are_loop_constant(ir_rvalue *, + hash_table *); + +static ir_rvalue *get_basic_induction_increment(ir_assignment *, hash_table *); + + +loop_state::loop_state() +{ + this->ht = hash_table_ctor(0, hash_table_pointer_hash, + hash_table_pointer_compare); + this->mem_ctx = talloc_init("loop state"); +} + + +loop_state::~loop_state() +{ + hash_table_dtor(this->ht); +} + + +loop_variable_state * +loop_state::insert(ir_loop *ir) +{ + loop_variable_state *ls = new(this->mem_ctx) loop_variable_state; + hash_table_insert(this->ht, ls, ir); + + return ls; +} + + +loop_variable_state * +loop_state::get(const ir_loop *ir) +{ + return (loop_variable_state *) hash_table_find(this->ht, ir); +} + + +loop_variable * +loop_variable_state::get(const ir_variable *ir) +{ + return (loop_variable *) hash_table_find(this->var_hash, ir); +} + + +loop_variable * +loop_variable_state::insert(ir_variable *var) +{ + void *mem_ctx = talloc_parent(this); + loop_variable *lv = talloc_zero(mem_ctx, loop_variable); + + lv->var = var; + + hash_table_insert(this->var_hash, lv, lv->var); + this->variables.push_tail(lv); + + return lv; +} + + +loop_terminator * +loop_variable_state::insert(ir_if *if_stmt) +{ + void *mem_ctx = talloc_parent(this); + loop_terminator *t = talloc_zero(mem_ctx, loop_terminator); + + t->ir = if_stmt; + this->terminators.push_tail(t); + + return t; +} + + +class loop_analysis : public ir_hierarchical_visitor { +public: + loop_analysis(); + + virtual ir_visitor_status visit(ir_dereference_variable *); + + virtual ir_visitor_status visit_enter(ir_loop *); + virtual ir_visitor_status visit_leave(ir_loop *); + virtual ir_visitor_status visit_enter(ir_assignment *); + virtual ir_visitor_status visit_leave(ir_assignment *); + virtual ir_visitor_status visit_enter(ir_if *); + virtual ir_visitor_status visit_leave(ir_if *); + + loop_state *loops; + + int if_statement_depth; + + ir_assignment *current_assignment; + + exec_list state; +}; + + +loop_analysis::loop_analysis() +{ + this->loops = new loop_state; + + this->if_statement_depth = 0; + this->current_assignment = NULL; +} + + +ir_visitor_status +loop_analysis::visit(ir_dereference_variable *ir) +{ + /* If we're not somewhere inside a loop, there's nothing to do. + */ + if (this->state.is_empty()) + return visit_continue_with_parent; + + loop_variable_state *const ls = + (loop_variable_state *) this->state.get_head(); + + ir_variable *var = ir->variable_referenced(); + loop_variable *lv = ls->get(var); + + if (lv == NULL) { + lv = ls->insert(var); + lv->read_before_write = !this->in_assignee; + } + + if (this->in_assignee) { + assert(this->current_assignment != NULL); + + lv->conditional_assignment = (this->if_statement_depth > 0) + || (this->current_assignment->condition != NULL); + + if (lv->first_assignment == NULL) { + assert(lv->num_assignments == 0); + + lv->first_assignment = this->current_assignment; + } + + lv->num_assignments++; + } else if (lv->first_assignment == this->current_assignment) { + /* This catches the case where the variable is used in the RHS of an + * assignment where it is also in the LHS. + */ + lv->read_before_write = true; + } + + return visit_continue; +} + +ir_visitor_status +loop_analysis::visit_enter(ir_loop *ir) +{ + loop_variable_state *ls = this->loops->insert(ir); + this->state.push_head(ls); + + return visit_continue; +} + +ir_visitor_status +loop_analysis::visit_leave(ir_loop *ir) +{ + loop_variable_state *const ls = + (loop_variable_state *) this->state.pop_head(); + + + foreach_list(node, &ir->body_instructions) { + /* Skip over declarations at the start of a loop. + */ + if (((ir_instruction *) node)->as_variable()) + continue; + + ir_if *if_stmt = ((ir_instruction *) node)->as_if(); + + if ((if_stmt != NULL) && is_loop_terminator(if_stmt)) + ls->insert(if_stmt); + else + break; + } + + + foreach_list_safe(node, &ls->variables) { + loop_variable *lv = (loop_variable *) node; + + /* Move variables that are already marked as being loop constant to + * a separate list. These trivially don't need to be tested. + */ + if (lv->is_loop_constant()) { + lv->remove(); + ls->constants.push_tail(lv); + } + } + + /* Each variable assigned in the loop that isn't already marked as being loop + * constant might still be loop constant. The requirements at this point + * are: + * + * - Variable is written before it is read. + * + * - Only one assignment to the variable. + * + * - All operands on the RHS of the assignment are also loop constants. + * + * The last requirement is the reason for the progress loop. A variable + * marked as a loop constant on one pass may allow other variables to be + * marked as loop constant on following passes. + */ + bool progress; + do { + progress = false; + + foreach_list_safe(node, &ls->variables) { + loop_variable *lv = (loop_variable *) node; + + if (lv->conditional_assignment || (lv->num_assignments > 1)) + continue; + + /* Process the RHS of the assignment. If all of the variables + * accessed there are loop constants, then add this + */ + ir_rvalue *const rhs = lv->first_assignment->rhs; + if (all_expression_operands_are_loop_constant(rhs, ls->var_hash)) { + lv->rhs_clean = true; + + if (lv->is_loop_constant()) { + progress = true; + + lv->remove(); + ls->constants.push_tail(lv); + } + } + } + } while (progress); + + /* The remaining variables that are not loop invariant might be loop + * induction variables. + */ + foreach_list_safe(node, &ls->variables) { + loop_variable *lv = (loop_variable *) node; + + /* If there is more than one assignment to a variable, it cannot be a + * loop induction variable. This isn't strictly true, but this is a + * very simple induction variable detector, and it can't handle more + * complex cases. + */ + if (lv->num_assignments > 1) + continue; + + /* All of the variables with zero assignments in the loop are loop + * invariant, and they should have already been filtered out. + */ + assert(lv->num_assignments == 1); + assert(lv->first_assignment != NULL); + + /* The assignmnet to the variable in the loop must be unconditional. + */ + if (lv->conditional_assignment) + continue; + + /* Basic loop induction variables have a single assignment in the loop + * that has the form 'VAR = VAR + i' or 'VAR = VAR - i' where i is a + * loop invariant. + */ + ir_rvalue *const inc = + get_basic_induction_increment(lv->first_assignment, ls->var_hash); + if (inc != NULL) { + lv->iv_scale = NULL; + lv->biv = lv->var; + lv->increment = inc; + + lv->remove(); + ls->induction_variables.push_tail(lv); + } + } + + return visit_continue; +} + +ir_visitor_status +loop_analysis::visit_enter(ir_if *ir) +{ + (void) ir; + + if (!this->state.is_empty()) + this->if_statement_depth++; + + return visit_continue; +} + +ir_visitor_status +loop_analysis::visit_leave(ir_if *ir) +{ + (void) ir; + + if (!this->state.is_empty()) + this->if_statement_depth--; + + return visit_continue; +} + +ir_visitor_status +loop_analysis::visit_enter(ir_assignment *ir) +{ + /* If we're not somewhere inside a loop, there's nothing to do. + */ + if (this->state.is_empty()) + return visit_continue_with_parent; + + this->current_assignment = ir; + + return visit_continue; +} + +ir_visitor_status +loop_analysis::visit_leave(ir_assignment *ir) +{ + /* Since the visit_enter exits with visit_continue_with_parent for this + * case, the loop state stack should never be empty here. + */ + assert(!this->state.is_empty()); + + assert(this->current_assignment == ir); + this->current_assignment = NULL; + + return visit_continue; +} + + +class examine_rhs : public ir_hierarchical_visitor { +public: + examine_rhs(hash_table *loop_variables) + { + this->only_uses_loop_constants = true; + this->loop_variables = loop_variables; + } + + virtual ir_visitor_status visit(ir_dereference_variable *ir) + { + loop_variable *lv = + (loop_variable *) hash_table_find(this->loop_variables, ir->var); + + assert(lv != NULL); + + if (lv->is_loop_constant()) { + return visit_continue; + } else { + this->only_uses_loop_constants = false; + return visit_stop; + } + } + + hash_table *loop_variables; + bool only_uses_loop_constants; +}; + + +bool +all_expression_operands_are_loop_constant(ir_rvalue *ir, hash_table *variables) +{ + examine_rhs v(variables); + + ir->accept(&v); + + return v.only_uses_loop_constants; +} + + +ir_rvalue * +get_basic_induction_increment(ir_assignment *ir, hash_table *var_hash) +{ + /* The RHS must be a binary expression. + */ + ir_expression *const rhs = ir->rhs->as_expression(); + if ((rhs == NULL) + || ((rhs->operation != ir_binop_add) + && (rhs->operation != ir_binop_sub))) + return NULL; + + /* One of the of operands of the expression must be the variable assigned. + * If the operation is subtraction, the variable in question must be the + * "left" operand. + */ + ir_variable *const var = ir->lhs->variable_referenced(); + + ir_variable *const op0 = rhs->operands[0]->variable_referenced(); + ir_variable *const op1 = rhs->operands[1]->variable_referenced(); + + if (((op0 != var) && (op1 != var)) + || ((op1 == var) && (rhs->operation == ir_binop_sub))) + return NULL; + + ir_rvalue *inc = (op0 == var) ? rhs->operands[1] : rhs->operands[0]; + + if (inc->constant_expression_value() == NULL) { + ir_variable *const inc_var = inc->variable_referenced(); + if (inc_var != NULL) { + loop_variable *lv = + (loop_variable *) hash_table_find(var_hash, inc_var); + + if (!lv->is_loop_constant()) + inc = NULL; + } else + inc = NULL; + } + + if ((inc != NULL) && (rhs->operation == ir_binop_sub)) { + void *mem_ctx = talloc_parent(ir); + + inc = new(mem_ctx) ir_expression(ir_unop_neg, + inc->type, + inc->clone(mem_ctx, NULL), + NULL); + } + + return inc; +} + + +/** + * Detect whether an if-statement is a loop terminating condition + * + * Detects if-statements of the form + * + * (if (expression bool ...) (break)) + */ +bool +is_loop_terminator(ir_if *ir) +{ + if (!ir->else_instructions.is_empty()) + return false; + + ir_instruction *const inst = + (ir_instruction *) ir->then_instructions.get_head(); + assert(inst != NULL); + + if (inst->ir_type != ir_type_loop_jump) + return false; + + ir_loop_jump *const jump = (ir_loop_jump *) inst; + if (jump->mode != ir_loop_jump::jump_break) + return false; + + return true; +} + + +loop_state * +analyze_loop_variables(exec_list *instructions) +{ + loop_analysis v; + + v.run(instructions); + return v.loops; +} diff --git a/src/glsl/loop_analysis.h b/src/glsl/loop_analysis.h new file mode 100644 index 00000000000..50c512f847f --- /dev/null +++ b/src/glsl/loop_analysis.h @@ -0,0 +1,190 @@ +/* -*- c++ -*- */ +/* + * Copyright © 2010 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. + */ + +#pragma once +#ifndef LOOP_ANALYSIS_H +#define LOOP_ANALYSIS_H + +#include "ir.h" +#include "program/hash_table.h" + +/** + * Analyze and classify all variables used in all loops in the instruction list + */ +extern class loop_state * +analyze_loop_variables(exec_list *instructions); + + +/** + * Tracking for all variables used in a loop + */ +class loop_variable_state : public exec_node { +public: + class loop_variable *get(const ir_variable *); + class loop_variable *insert(ir_variable *); + class loop_terminator *insert(ir_if *); + + + /** + * Loop whose variable state is being tracked by this structure + */ + ir_loop *loop; + + /** + * Variables that have not yet been classified + */ + exec_list variables; + + /** + * Variables whose values are constant within the body of the loop + * + * This list contains \c loop_variable objects. + */ + exec_list constants; + + /** + * Induction variables for this loop + * + * This list contains \c loop_variable objects. + */ + exec_list induction_variables; + + /** + * Simple if-statements that lead to the termination of the loop + * + * This list contains \c loop_terminator objects. + * + * \sa is_loop_terminator + */ + exec_list terminators; + + /** + * Hash table containing all variables accessed in this loop + */ + hash_table *var_hash; + + loop_variable_state() + { + this->var_hash = hash_table_ctor(0, hash_table_pointer_hash, + hash_table_pointer_compare); + } + + ~loop_variable_state() + { + hash_table_dtor(this->var_hash); + } +}; + + +class loop_variable : public exec_node { +public: + /** The variable in question. */ + ir_variable *var; + + /** Is the variable read in the loop before it is written? */ + bool read_before_write; + + /** Are all variables in the RHS of the assignment loop constants? */ + bool rhs_clean; + + /** Is there an assignment to the variable that is conditional? */ + bool conditional_assignment; + + /** Reference to the first assignment to the variable in the loop body. */ + ir_assignment *first_assignment; + + /** Number of assignments to the variable in the loop body. */ + unsigned num_assignments; + + /** + * Increment values for loop induction variables + * + * Loop induction variables have a single increment of the form + * \c b * \c biv + \c c, where \c b and \c c are loop constants and \c i + * is a basic loop induction variable. + * + * If \c iv_scale is \c NULL, 1 is used. If \c biv is the same as \c var, + * then \c var is a basic loop induction variable. + */ + /*@{*/ + ir_rvalue *iv_scale; + ir_variable *biv; + ir_rvalue *increment; + /*@}*/ + + + inline bool is_loop_constant() const + { + const bool is_const = (this->num_assignments == 0) + || ((this->num_assignments == 1) + && !this->conditional_assignment + && !this->read_before_write + && this->rhs_clean); + + /* If the RHS of *the* assignment is clean, then there must be exactly + * one assignment of the variable. + */ + assert((this->rhs_clean && (this->num_assignments == 1)) + || !this->rhs_clean); + + /* Variables that are marked read-only *MUST* be loop constant. + */ + assert(!this->var->read_only || (this->var->read_only && is_const)); + + return is_const; + } +}; + + +class loop_terminator : public exec_node { +public: + ir_if *ir; +}; + + +class loop_state { +public: + ~loop_state(); + + /** + * Get the loop variable state data for a particular loop + */ + loop_variable_state *get(const ir_loop *); + + loop_variable_state *insert(ir_loop *ir); + +private: + loop_state(); + + /** + * Hash table containing all loops that have been analyzed. + */ + hash_table *ht; + + void *mem_ctx; + + friend class loop_analysis; +}; + +#endif /* LOOP_ANALYSIS_H */ |