2 * Copyright © 2010 Intel Corporation
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
21 * DEALINGS IN THE SOFTWARE.
25 * \file brw_wm_vector_splitting.cpp
27 * If a vector is only ever referenced by its components, then
28 * split those components out to individual variables so they can be
29 * handled normally by other optimization passes.
31 * This skips vectors in uniforms and varyings, which need to be
32 * accessible as vectors for their access by the GL. Also, vector
33 * results of non-variable-derefs in assignments aren't handled
34 * because to do so we would have to store the vector result to a
35 * temporary in order to unload each channel, and to do so would just
36 * loop us back to where we started. For the 965, this is exactly the
37 * behavior we want for the results of texture lookups, but probably not for
41 #include "main/core.h"
42 #include "intel_context.h"
44 #include "../glsl/ir.h"
45 #include "../glsl/ir_visitor.h"
46 #include "../glsl/ir_print_visitor.h"
47 #include "../glsl/ir_rvalue_visitor.h"
48 #include "../glsl/glsl_types.h"
50 static bool debug = false;
52 class variable_entry : public exec_node
55 variable_entry(ir_variable *var)
58 this->whole_vector_access = 0;
59 this->declaration = false;
63 ir_variable *var; /* The key: the variable's pointer. */
65 /** Number of times the variable is referenced, including assignments. */
66 unsigned whole_vector_access;
68 bool declaration; /* If the variable had a decl in the instruction stream */
70 ir_variable *components[4];
72 /** ralloc_parent(this->var) -- the shader's ralloc context. */
76 class ir_vector_reference_visitor : public ir_hierarchical_visitor {
78 ir_vector_reference_visitor(void)
80 this->mem_ctx = ralloc_context(NULL);
81 this->variable_list.make_empty();
84 ~ir_vector_reference_visitor(void)
89 virtual ir_visitor_status visit(ir_variable *);
90 virtual ir_visitor_status visit(ir_dereference_variable *);
91 virtual ir_visitor_status visit_enter(ir_swizzle *);
92 virtual ir_visitor_status visit_enter(ir_assignment *);
93 virtual ir_visitor_status visit_enter(ir_function_signature *);
95 variable_entry *get_variable_entry(ir_variable *var);
97 /* List of variable_entry */
98 exec_list variable_list;
104 ir_vector_reference_visitor::get_variable_entry(ir_variable *var)
108 if (!var->type->is_vector())
116 /* Can't split varyings or uniforms. Function in/outs won't get split
117 * either, so don't care about the ambiguity.
121 case ir_var_temporary:
125 foreach_iter(exec_list_iterator, iter, this->variable_list) {
126 variable_entry *entry = (variable_entry *)iter.get();
127 if (entry->var == var)
131 variable_entry *entry = new(mem_ctx) variable_entry(var);
132 this->variable_list.push_tail(entry);
138 ir_vector_reference_visitor::visit(ir_variable *ir)
140 variable_entry *entry = this->get_variable_entry(ir);
143 entry->declaration = true;
145 return visit_continue;
149 ir_vector_reference_visitor::visit(ir_dereference_variable *ir)
151 ir_variable *const var = ir->var;
152 variable_entry *entry = this->get_variable_entry(var);
155 entry->whole_vector_access++;
157 return visit_continue;
161 ir_vector_reference_visitor::visit_enter(ir_swizzle *ir)
163 /* Don't descend into a vector ir_dereference_variable below. */
164 if (ir->val->as_dereference_variable() && ir->type->is_scalar())
165 return visit_continue_with_parent;
167 return visit_continue;
171 ir_vector_reference_visitor::visit_enter(ir_assignment *ir)
173 if (ir->lhs->as_dereference_variable() &&
174 ir->rhs->as_dereference_variable() &&
176 /* We'll split copies of a vector to copies of channels, so don't
177 * descend to the ir_dereference_variables.
179 return visit_continue_with_parent;
181 if (ir->lhs->as_dereference_variable() &&
182 is_power_of_two(ir->write_mask) &&
184 /* If we're writing just a channel, then channel-splitting the LHS is OK.
186 ir->rhs->accept(this);
187 return visit_continue_with_parent;
189 return visit_continue;
193 ir_vector_reference_visitor::visit_enter(ir_function_signature *ir)
195 /* We don't want to descend into the function parameters and
196 * split them, so just accept the body here.
198 visit_list_elements(this, &ir->body);
199 return visit_continue_with_parent;
202 class ir_vector_splitting_visitor : public ir_rvalue_visitor {
204 ir_vector_splitting_visitor(exec_list *vars)
206 this->variable_list = vars;
209 virtual ir_visitor_status visit_leave(ir_assignment *);
211 void handle_rvalue(ir_rvalue **rvalue);
212 struct variable_entry *get_splitting_entry(ir_variable *var);
214 exec_list *variable_list;
217 struct variable_entry *
218 ir_vector_splitting_visitor::get_splitting_entry(ir_variable *var)
222 if (!var->type->is_vector())
225 foreach_iter(exec_list_iterator, iter, *this->variable_list) {
226 variable_entry *entry = (variable_entry *)iter.get();
227 if (entry->var == var) {
236 ir_vector_splitting_visitor::handle_rvalue(ir_rvalue **rvalue)
241 ir_swizzle *swiz = (*rvalue)->as_swizzle();
242 if (!swiz || !swiz->type->is_scalar())
245 ir_dereference_variable *deref_var = swiz->val->as_dereference_variable();
249 variable_entry *entry = get_splitting_entry(deref_var->var);
253 ir_variable *var = entry->components[swiz->mask.x];
254 *rvalue = new(entry->mem_ctx) ir_dereference_variable(var);
258 ir_vector_splitting_visitor::visit_leave(ir_assignment *ir)
260 ir_dereference_variable *lhs_deref = ir->lhs->as_dereference_variable();
261 ir_dereference_variable *rhs_deref = ir->rhs->as_dereference_variable();
262 variable_entry *lhs = lhs_deref ? get_splitting_entry(lhs_deref->var) : NULL;
263 variable_entry *rhs = rhs_deref ? get_splitting_entry(rhs_deref->var) : NULL;
265 if (lhs_deref && rhs_deref && (lhs || rhs) && !ir->condition) {
266 unsigned int rhs_chan = 0;
268 /* Straight assignment of vector variables. */
269 for (unsigned int i = 0; i < ir->lhs->type->vector_elements; i++) {
270 ir_dereference *new_lhs;
272 void *mem_ctx = lhs ? lhs->mem_ctx : rhs->mem_ctx;
273 unsigned int writemask;
275 if (!(ir->write_mask & (1 << i)))
279 new_lhs = new(mem_ctx) ir_dereference_variable(lhs->components[i]);
282 new_lhs = ir->lhs->clone(mem_ctx, NULL);
288 new(mem_ctx) ir_dereference_variable(rhs->components[rhs_chan]);
290 new_rhs = new(mem_ctx) ir_swizzle(ir->rhs->clone(mem_ctx, NULL),
291 rhs_chan, 0, 0, 0, 1);
294 ir->insert_before(new(mem_ctx) ir_assignment(new_lhs,
302 void *mem_ctx = lhs->mem_ctx;
305 switch (ir->write_mask) {
320 assert(!"not reached: non-channelwise dereference of LHS.");
323 ir->lhs = new(mem_ctx) ir_dereference_variable(lhs->components[elem]);
324 ir->write_mask = (1 << 0);
326 handle_rvalue(&ir->rhs);
328 handle_rvalue(&ir->rhs);
331 handle_rvalue(&ir->condition);
333 return visit_continue;
337 brw_do_vector_splitting(exec_list *instructions)
339 ir_vector_reference_visitor refs;
341 visit_list_elements(&refs, instructions);
343 /* Trim out variables we can't split. */
344 foreach_iter(exec_list_iterator, iter, refs.variable_list) {
345 variable_entry *entry = (variable_entry *)iter.get();
348 printf("vector %s@%p: decl %d, whole_access %d\n",
349 entry->var->name, (void *) entry->var, entry->declaration,
350 entry->whole_vector_access);
353 if (!entry->declaration || entry->whole_vector_access) {
358 if (refs.variable_list.is_empty())
361 void *mem_ctx = ralloc_context(NULL);
363 /* Replace the decls of the vectors to be split with their split
366 foreach_iter(exec_list_iterator, iter, refs.variable_list) {
367 variable_entry *entry = (variable_entry *)iter.get();
368 const struct glsl_type *type;
369 type = glsl_type::get_instance(entry->var->type->base_type, 1, 1);
371 entry->mem_ctx = ralloc_parent(entry->var);
373 for (unsigned int i = 0; i < entry->var->type->vector_elements; i++) {
374 const char *name = ralloc_asprintf(mem_ctx, "%s_%c",
378 entry->components[i] = new(entry->mem_ctx) ir_variable(type, name,
380 entry->var->insert_before(entry->components[i]);
383 entry->var->remove();
386 ir_vector_splitting_visitor split(&refs.variable_list);
387 visit_list_elements(&split, instructions);
389 ralloc_free(mem_ctx);