1 /*
2 * Copyright © 2013 Intel Corporation
3 *
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:
10 *
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
13 * Software.
14 *
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.
22 */
23 #include "ir.h"
24 #include "ir_builder.h"
25 #include "ir_rvalue_visitor.h"
26 #include "ir_optimization.h"
27 #include "main/shader_types.h"
28
29 using namespace ir_builder;
30
31 namespace {
32
33 class vector_deref_visitor : public ir_rvalue_enter_visitor {
34 public:
vector_deref_visitor(void * mem_ctx,gl_shader_stage shader_stage)35 vector_deref_visitor(void *mem_ctx, gl_shader_stage shader_stage)
36 : progress(false), shader_stage(shader_stage),
37 factory(&factory_instructions, mem_ctx)
38 {
39 }
40
~vector_deref_visitor()41 virtual ~vector_deref_visitor()
42 {
43 }
44
45 virtual void handle_rvalue(ir_rvalue **rv);
46 virtual ir_visitor_status visit_enter(ir_assignment *ir);
47
48 bool progress;
49 gl_shader_stage shader_stage;
50 exec_list factory_instructions;
51 ir_factory factory;
52 };
53
54 } /* anonymous namespace */
55
56 ir_visitor_status
visit_enter(ir_assignment * ir)57 vector_deref_visitor::visit_enter(ir_assignment *ir)
58 {
59 if (!ir->lhs || ir->lhs->ir_type != ir_type_dereference_array)
60 return ir_rvalue_enter_visitor::visit_enter(ir);
61
62 ir_dereference_array *const deref = (ir_dereference_array *) ir->lhs;
63 if (!deref->array->type->is_vector())
64 return ir_rvalue_enter_visitor::visit_enter(ir);
65
66 /* SSBOs and shared variables are backed by memory and may be accessed by
67 * multiple threads simultaneously. It's not safe to lower a single
68 * component store to a load-vec-store because it may race with writes to
69 * other components.
70 */
71 ir_variable *var = deref->variable_referenced();
72 if (var->data.mode == ir_var_shader_storage ||
73 var->data.mode == ir_var_shader_shared)
74 return ir_rvalue_enter_visitor::visit_enter(ir);
75
76 ir_rvalue *const new_lhs = deref->array;
77
78 void *mem_ctx = ralloc_parent(ir);
79 ir_constant *old_index_constant =
80 deref->array_index->constant_expression_value(mem_ctx);
81 if (!old_index_constant) {
82 if (shader_stage == MESA_SHADER_TESS_CTRL &&
83 deref->variable_referenced()->data.mode == ir_var_shader_out) {
84 /* Tessellation control shader outputs act as if they have memory
85 * backing them and if we have writes from multiple threads
86 * targeting the same vec4 (this can happen for patch outputs), the
87 * load-vec-store pattern of ir_triop_vector_insert doesn't work.
88 * Instead, we have to lower to a series of conditional write-masked
89 * assignments.
90 */
91 ir_variable *const src_temp =
92 factory.make_temp(ir->rhs->type, "scalar_tmp");
93
94 /* The newly created variable declaration goes before the assignment
95 * because we're going to set it as the new LHS.
96 */
97 ir->insert_before(factory.instructions);
98 ir->set_lhs(new(mem_ctx) ir_dereference_variable(src_temp));
99
100 ir_variable *const arr_index =
101 factory.make_temp(deref->array_index->type, "index_tmp");
102 factory.emit(assign(arr_index, deref->array_index));
103
104 for (unsigned i = 0; i < new_lhs->type->vector_elements; i++) {
105 ir_constant *const cmp_index =
106 ir_constant::zero(factory.mem_ctx, deref->array_index->type);
107 cmp_index->value.u[0] = i;
108
109 ir_rvalue *const lhs_clone = new_lhs->clone(factory.mem_ctx, NULL);
110 ir_dereference_variable *const src_temp_deref =
111 new(mem_ctx) ir_dereference_variable(src_temp);
112
113 if (new_lhs->ir_type != ir_type_swizzle) {
114 assert(lhs_clone->as_dereference());
115
116 factory.emit(if_tree(equal(arr_index, cmp_index),
117 assign(lhs_clone->as_dereference(),
118 src_temp_deref,
119 WRITEMASK_X << i)));
120 } else {
121 ir_assignment *cond_assign =
122 new(mem_ctx) ir_assignment(swizzle(lhs_clone, i, 1),
123 src_temp_deref);
124
125 factory.emit(if_tree(equal(arr_index, cmp_index), cond_assign));
126 }
127 }
128 ir->insert_after(factory.instructions);
129 } else {
130 ir->rhs = new(mem_ctx) ir_expression(ir_triop_vector_insert,
131 new_lhs->type,
132 new_lhs->clone(mem_ctx, NULL),
133 ir->rhs,
134 deref->array_index);
135 ir->write_mask = (1 << new_lhs->type->vector_elements) - 1;
136 ir->set_lhs(new_lhs);
137 }
138 } else {
139 unsigned index = old_index_constant->get_uint_component(0);
140
141 if (index >= new_lhs->type->vector_elements) {
142 /* Section 5.11 (Out-of-Bounds Accesses) of the GLSL 4.60 spec says:
143 *
144 * In the subsections described above for array, vector, matrix and
145 * structure accesses, any out-of-bounds access produced undefined
146 * behavior.... Out-of-bounds writes may be discarded or overwrite
147 * other variables of the active program.
148 */
149 ir->remove();
150 return visit_continue;
151 }
152
153 if (new_lhs->ir_type != ir_type_swizzle) {
154 ir->set_lhs(new_lhs);
155 ir->write_mask = 1 << index;
156 } else {
157 /* If the "new" LHS is a swizzle, use the set_lhs helper to instead
158 * swizzle the RHS.
159 */
160 unsigned component[1] = { index };
161 ir->set_lhs(new(mem_ctx) ir_swizzle(new_lhs, component, 1));
162 }
163 }
164
165 return ir_rvalue_enter_visitor::visit_enter(ir);
166 }
167
168 void
handle_rvalue(ir_rvalue ** rv)169 vector_deref_visitor::handle_rvalue(ir_rvalue **rv)
170 {
171 if (*rv == NULL || (*rv)->ir_type != ir_type_dereference_array)
172 return;
173
174 ir_dereference_array *const deref = (ir_dereference_array *) *rv;
175 if (!deref->array->type->is_vector())
176 return;
177
178 /* Back-ends need to be able to handle derefs on vectors for SSBOs, UBOs,
179 * and shared variables. They have to handle it for writes anyway so we
180 * may as well require it for reads.
181 */
182 ir_variable *var = deref->variable_referenced();
183 if (var && (var->data.mode == ir_var_shader_storage ||
184 var->data.mode == ir_var_shader_shared ||
185 (var->data.mode == ir_var_uniform &&
186 var->get_interface_type())))
187 return;
188
189 void *mem_ctx = ralloc_parent(deref);
190 *rv = new(mem_ctx) ir_expression(ir_binop_vector_extract,
191 deref->array,
192 deref->array_index);
193 }
194
195 bool
lower_vector_derefs(gl_linked_shader * shader)196 lower_vector_derefs(gl_linked_shader *shader)
197 {
198 vector_deref_visitor v(shader->ir, shader->Stage);
199
200 visit_list_elements(&v, shader->ir);
201
202 return v.progress;
203 }
204