1/*
2 * Copyright © 2014 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 DEALINGS
21 * IN THE SOFTWARE.
22 *
23 * Authors:
24 *    Connor Abbott (cwabbott0@gmail.com)
25 *
26 */
27
28#include "nir.h"
29#include <main/imports.h>
30
31/**
32 * SSA-based copy propagation
33 */
34
35static bool is_move(nir_alu_instr *instr)
36{
37   assert(instr->src[0].src.is_ssa);
38
39   if (instr->op != nir_op_fmov &&
40       instr->op != nir_op_imov)
41      return false;
42
43   if (instr->dest.saturate)
44      return false;
45
46   /* we handle modifiers in a separate pass */
47
48   if (instr->src[0].abs || instr->src[0].negate)
49      return false;
50
51   return true;
52
53}
54
55static bool is_vec(nir_alu_instr *instr)
56{
57   for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
58      assert(instr->src[i].src.is_ssa);
59
60      /* we handle modifiers in a separate pass */
61      if (instr->src[i].abs || instr->src[i].negate)
62         return false;
63   }
64
65   return instr->op == nir_op_vec2 ||
66          instr->op == nir_op_vec3 ||
67          instr->op == nir_op_vec4;
68}
69
70static bool
71is_swizzleless_move(nir_alu_instr *instr)
72{
73   if (is_move(instr)) {
74      for (unsigned i = 0; i < 4; i++) {
75         if (!((instr->dest.write_mask >> i) & 1))
76            break;
77         if (instr->src[0].swizzle[i] != i)
78            return false;
79      }
80      return true;
81   } else if (is_vec(instr)) {
82      nir_ssa_def *def = NULL;
83      for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
84         if (instr->src[i].swizzle[0] != i)
85            return false;
86
87         if (def == NULL) {
88            def = instr->src[i].src.ssa;
89         } else if (instr->src[i].src.ssa != def) {
90            return false;
91         }
92      }
93      return true;
94   } else {
95      return false;
96   }
97}
98
99static bool
100copy_prop_src(nir_src *src, nir_instr *parent_instr, nir_if *parent_if,
101              unsigned num_components)
102{
103   assert(src->is_ssa);
104
105   nir_instr *src_instr = src->ssa->parent_instr;
106   nir_ssa_def *copy_def;
107   if (src_instr->type == nir_instr_type_alu) {
108      nir_alu_instr *alu_instr = nir_instr_as_alu(src_instr);
109      if (!is_swizzleless_move(alu_instr))
110         return false;
111
112      if (alu_instr->src[0].src.ssa->num_components != num_components)
113         return false;
114
115      copy_def= alu_instr->src[0].src.ssa;
116   } else {
117      return false;
118   }
119
120   if (parent_instr) {
121      nir_instr_rewrite_src(parent_instr, src, nir_src_for_ssa(copy_def));
122   } else {
123      assert(src == &parent_if->condition);
124      nir_if_rewrite_condition(parent_if, nir_src_for_ssa(copy_def));
125   }
126
127   return true;
128}
129
130static bool
131copy_prop_alu_src(nir_alu_instr *parent_alu_instr, unsigned index)
132{
133   nir_alu_src *src = &parent_alu_instr->src[index];
134   assert(src->src.is_ssa);
135
136   nir_instr *src_instr =  src->src.ssa->parent_instr;
137   if (src_instr->type != nir_instr_type_alu)
138      return false;
139
140   nir_alu_instr *alu_instr = nir_instr_as_alu(src_instr);
141   if (!is_move(alu_instr) && !is_vec(alu_instr))
142      return false;
143
144   nir_ssa_def *def;
145   unsigned new_swizzle[NIR_MAX_VEC_COMPONENTS] = {0, 0, 0, 0};
146
147   if (alu_instr->op == nir_op_fmov ||
148       alu_instr->op == nir_op_imov) {
149      for (unsigned i = 0; i < NIR_MAX_VEC_COMPONENTS; i++)
150         new_swizzle[i] = alu_instr->src[0].swizzle[src->swizzle[i]];
151      def = alu_instr->src[0].src.ssa;
152   } else {
153      def = NULL;
154
155      for (unsigned i = 0; i < NIR_MAX_VEC_COMPONENTS; i++) {
156         if (!nir_alu_instr_channel_used(parent_alu_instr, index, i))
157            continue;
158
159         nir_ssa_def *new_def = alu_instr->src[src->swizzle[i]].src.ssa;
160         if (def == NULL)
161            def = new_def;
162         else {
163            if (def != new_def)
164               return false;
165         }
166         new_swizzle[i] = alu_instr->src[src->swizzle[i]].swizzle[0];
167      }
168   }
169
170   for (unsigned i = 0; i < NIR_MAX_VEC_COMPONENTS; i++)
171      src->swizzle[i] = new_swizzle[i];
172
173   nir_instr_rewrite_src(&parent_alu_instr->instr, &src->src,
174                         nir_src_for_ssa(def));
175
176   return true;
177}
178
179static bool
180copy_prop_instr(nir_instr *instr)
181{
182   bool progress = false;
183   switch (instr->type) {
184   case nir_instr_type_alu: {
185      nir_alu_instr *alu_instr = nir_instr_as_alu(instr);
186
187      for (unsigned i = 0; i < nir_op_infos[alu_instr->op].num_inputs; i++)
188         while (copy_prop_alu_src(alu_instr, i))
189            progress = true;
190
191      return progress;
192   }
193
194   case nir_instr_type_deref: {
195      nir_deref_instr *deref = nir_instr_as_deref(instr);
196
197      if (deref->deref_type != nir_deref_type_var) {
198         assert(deref->dest.is_ssa);
199         const unsigned comps = deref->dest.ssa.num_components;
200         while (copy_prop_src(&deref->parent, instr, NULL, comps))
201            progress = true;
202      }
203
204      if (deref->deref_type == nir_deref_type_array ||
205          deref->deref_type == nir_deref_type_ptr_as_array) {
206         while (copy_prop_src(&deref->arr.index, instr, NULL, 1))
207            progress = true;
208      }
209
210      return progress;
211   }
212
213   case nir_instr_type_tex: {
214      nir_tex_instr *tex = nir_instr_as_tex(instr);
215      for (unsigned i = 0; i < tex->num_srcs; i++) {
216         unsigned num_components = nir_tex_instr_src_size(tex, i);
217         while (copy_prop_src(&tex->src[i].src, instr, NULL, num_components))
218            progress = true;
219      }
220
221      return progress;
222   }
223
224   case nir_instr_type_intrinsic: {
225      nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
226      for (unsigned i = 0;
227           i < nir_intrinsic_infos[intrin->intrinsic].num_srcs; i++) {
228         unsigned num_components = nir_intrinsic_src_components(intrin, i);
229
230         while (copy_prop_src(&intrin->src[i], instr, NULL, num_components))
231            progress = true;
232      }
233
234      return progress;
235   }
236
237   case nir_instr_type_phi: {
238      nir_phi_instr *phi = nir_instr_as_phi(instr);
239      assert(phi->dest.is_ssa);
240      unsigned num_components = phi->dest.ssa.num_components;
241      nir_foreach_phi_src(src, phi) {
242         while (copy_prop_src(&src->src, instr, NULL, num_components))
243            progress = true;
244      }
245
246      return progress;
247   }
248
249   default:
250      return false;
251   }
252}
253
254static bool
255copy_prop_if(nir_if *if_stmt)
256{
257   return copy_prop_src(&if_stmt->condition, NULL, if_stmt, 1);
258}
259
260static bool
261nir_copy_prop_impl(nir_function_impl *impl)
262{
263   bool progress = false;
264
265   nir_foreach_block(block, impl) {
266      nir_foreach_instr(instr, block) {
267         if (copy_prop_instr(instr))
268            progress = true;
269      }
270
271      nir_if *if_stmt = nir_block_get_following_if(block);
272      if (if_stmt && copy_prop_if(if_stmt))
273         progress = true;
274      }
275
276   if (progress) {
277      nir_metadata_preserve(impl, nir_metadata_block_index |
278                                  nir_metadata_dominance);
279   } else {
280#ifndef NDEBUG
281      impl->valid_metadata &= ~nir_metadata_not_properly_reset;
282#endif
283   }
284
285   return progress;
286}
287
288bool
289nir_copy_prop(nir_shader *shader)
290{
291   bool progress = false;
292
293   nir_foreach_function(function, shader) {
294      if (function->impl && nir_copy_prop_impl(function->impl))
295         progress = true;
296   }
297
298   return progress;
299}
300