1/*
2 * Copyright © 2010 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
24/**
25 * \file lower_vector.cpp
26 * IR lowering pass to remove some types of ir_quadop_vector
27 *
28 * \author Ian Romanick <ian.d.romanick@intel.com>
29 */
30
31#include "ir.h"
32#include "ir_rvalue_visitor.h"
33
34namespace {
35
36class lower_vector_visitor : public ir_rvalue_visitor {
37public:
38   lower_vector_visitor() : dont_lower_swz(false), progress(false)
39   {
40      /* empty */
41   }
42
43   void handle_rvalue(ir_rvalue **rvalue);
44
45   /**
46    * Should SWZ-like expressions be lowered?
47    */
48   bool dont_lower_swz;
49
50   bool progress;
51};
52
53} /* anonymous namespace */
54
55/**
56 * Determine if an IR expression tree looks like an extended swizzle
57 *
58 * Extended swizzles consist of access of a single vector source (with possible
59 * per component negation) and the constants -1, 0, or 1.
60 */
61static bool
62is_extended_swizzle(ir_expression *ir)
63{
64   /* Track any variables that are accessed by this expression.
65    */
66   ir_variable *var = NULL;
67
68   assert(ir->operation == ir_quadop_vector);
69
70   for (unsigned i = 0; i < ir->type->vector_elements; i++) {
71      ir_rvalue *op = ir->operands[i];
72
73      while (op != NULL) {
74	 switch (op->ir_type) {
75	 case ir_type_constant: {
76	    const ir_constant *const c = op->as_constant();
77
78	    if (!c->is_one() && !c->is_zero() && !c->is_negative_one())
79	       return false;
80
81	    op = NULL;
82	    break;
83	 }
84
85	 case ir_type_dereference_variable: {
86	    ir_dereference_variable *const d = (ir_dereference_variable *) op;
87
88	    if ((var != NULL) && (var != d->var))
89	       return false;
90
91	    var = d->var;
92	    op = NULL;
93	    break;
94	 }
95
96	 case ir_type_expression: {
97	    ir_expression *const ex = (ir_expression *) op;
98
99	    if (ex->operation != ir_unop_neg)
100	       return false;
101
102	    op = ex->operands[0];
103	    break;
104	 }
105
106	 case ir_type_swizzle:
107	    op = ((ir_swizzle *) op)->val;
108	    break;
109
110	 default:
111	    return false;
112	 }
113      }
114   }
115
116   return true;
117}
118
119void
120lower_vector_visitor::handle_rvalue(ir_rvalue **rvalue)
121{
122   if (!*rvalue)
123      return;
124
125   ir_expression *expr = (*rvalue)->as_expression();
126   if ((expr == NULL) || (expr->operation != ir_quadop_vector))
127      return;
128
129   if (this->dont_lower_swz && is_extended_swizzle(expr))
130      return;
131
132   /* FINISHME: Is this the right thing to use for the ralloc context?
133    */
134   void *const mem_ctx = expr;
135
136   assert(expr->type->vector_elements == expr->num_operands);
137
138   /* Generate a temporary with the same type as the ir_quadop_operation.
139    */
140   ir_variable *const temp =
141      new(mem_ctx) ir_variable(expr->type, "vecop_tmp", ir_var_temporary);
142
143   this->base_ir->insert_before(temp);
144
145   /* Counter of the number of components collected so far.
146    */
147   unsigned assigned;
148
149   /* Write-mask in the destination that receives counted by 'assigned'.
150    */
151   unsigned write_mask;
152
153
154   /* Generate upto four assignments to that variable.  Try to group component
155    * assignments together:
156    *
157    * - All constant components can be assigned at once.
158    * - All assigments of components from a single variable with the same
159    *   unary operator can be assigned at once.
160    */
161   ir_constant_data d = { { 0 } };
162
163   assigned = 0;
164   write_mask = 0;
165   for (unsigned i = 0; i < expr->type->vector_elements; i++) {
166      const ir_constant *const c = expr->operands[i]->as_constant();
167
168      if (c == NULL)
169	 continue;
170
171      switch (expr->type->base_type) {
172      case GLSL_TYPE_UINT:  d.u[assigned] = c->value.u[0]; break;
173      case GLSL_TYPE_INT:   d.i[assigned] = c->value.i[0]; break;
174      case GLSL_TYPE_FLOAT: d.f[assigned] = c->value.f[0]; break;
175      case GLSL_TYPE_BOOL:  d.b[assigned] = c->value.b[0]; break;
176      default:              assert(!"Should not get here."); break;
177      }
178
179      write_mask |= (1U << i);
180      assigned++;
181   }
182
183   assert((write_mask == 0) == (assigned == 0));
184
185   /* If there were constant values, generate an assignment.
186    */
187   if (assigned > 0) {
188      ir_constant *const c =
189	 new(mem_ctx) ir_constant(glsl_type::get_instance(expr->type->base_type,
190							  assigned, 1),
191				  &d);
192      ir_dereference *const lhs = new(mem_ctx) ir_dereference_variable(temp);
193      ir_assignment *const assign =
194	 new(mem_ctx) ir_assignment(lhs, c, NULL, write_mask);
195
196      this->base_ir->insert_before(assign);
197   }
198
199   /* FINISHME: This should try to coalesce assignments.
200    */
201   for (unsigned i = 0; i < expr->type->vector_elements; i++) {
202      if (expr->operands[i]->ir_type == ir_type_constant)
203	 continue;
204
205      ir_dereference *const lhs = new(mem_ctx) ir_dereference_variable(temp);
206      ir_assignment *const assign =
207	 new(mem_ctx) ir_assignment(lhs, expr->operands[i], NULL, (1U << i));
208
209      this->base_ir->insert_before(assign);
210      assigned++;
211   }
212
213   assert(assigned == expr->type->vector_elements);
214
215   *rvalue = new(mem_ctx) ir_dereference_variable(temp);
216   this->progress = true;
217}
218
219bool
220lower_quadop_vector(exec_list *instructions, bool dont_lower_swz)
221{
222   lower_vector_visitor v;
223
224   v.dont_lower_swz = dont_lower_swz;
225   visit_list_elements(&v, instructions);
226
227   return v.progress;
228}
229