1 /*
2 * Copyright (c) 2015 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_buffer_access.cpp
26 *
27 * Helper for IR lowering pass to replace dereferences of buffer object based
28 * shader variables with intrinsic function calls.
29 *
30 * This helper is used by lowering passes for UBOs, SSBOs and compute shader
31 * shared variables.
32 */
33
34 #include "lower_buffer_access.h"
35 #include "ir_builder.h"
36 #include "main/macros.h"
37 #include "util/list.h"
38 #include "glsl_parser_extras.h"
39
40 using namespace ir_builder;
41
42 namespace lower_buffer_access {
43
44 static inline int
writemask_for_size(unsigned n)45 writemask_for_size(unsigned n)
46 {
47 return ((1 << n) - 1);
48 }
49
50 /**
51 * Takes a deref and recursively calls itself to break the deref down to the
52 * point that the reads or writes generated are contiguous scalars or vectors.
53 */
54 void
emit_access(void * mem_ctx,bool is_write,ir_dereference * deref,ir_variable * base_offset,unsigned int deref_offset,bool row_major,int matrix_columns,unsigned int packing,unsigned int write_mask)55 lower_buffer_access::emit_access(void *mem_ctx,
56 bool is_write,
57 ir_dereference *deref,
58 ir_variable *base_offset,
59 unsigned int deref_offset,
60 bool row_major,
61 int matrix_columns,
62 unsigned int packing,
63 unsigned int write_mask)
64 {
65 if (deref->type->is_record()) {
66 unsigned int field_offset = 0;
67
68 for (unsigned i = 0; i < deref->type->length; i++) {
69 const struct glsl_struct_field *field =
70 &deref->type->fields.structure[i];
71 ir_dereference *field_deref =
72 new(mem_ctx) ir_dereference_record(deref->clone(mem_ctx, NULL),
73 field->name);
74
75 field_offset =
76 glsl_align(field_offset,
77 field->type->std140_base_alignment(row_major));
78
79 emit_access(mem_ctx, is_write, field_deref, base_offset,
80 deref_offset + field_offset,
81 row_major, 1, packing,
82 writemask_for_size(field_deref->type->vector_elements));
83
84 field_offset += field->type->std140_size(row_major);
85 }
86 return;
87 }
88
89 if (deref->type->is_array()) {
90 unsigned array_stride = packing == GLSL_INTERFACE_PACKING_STD430 ?
91 deref->type->fields.array->std430_array_stride(row_major) :
92 glsl_align(deref->type->fields.array->std140_size(row_major), 16);
93
94 for (unsigned i = 0; i < deref->type->length; i++) {
95 ir_constant *element = new(mem_ctx) ir_constant(i);
96 ir_dereference *element_deref =
97 new(mem_ctx) ir_dereference_array(deref->clone(mem_ctx, NULL),
98 element);
99 emit_access(mem_ctx, is_write, element_deref, base_offset,
100 deref_offset + i * array_stride,
101 row_major, 1, packing,
102 writemask_for_size(element_deref->type->vector_elements));
103 }
104 return;
105 }
106
107 if (deref->type->is_matrix()) {
108 for (unsigned i = 0; i < deref->type->matrix_columns; i++) {
109 ir_constant *col = new(mem_ctx) ir_constant(i);
110 ir_dereference *col_deref =
111 new(mem_ctx) ir_dereference_array(deref->clone(mem_ctx, NULL), col);
112
113 if (row_major) {
114 /* For a row-major matrix, the next column starts at the next
115 * element.
116 */
117 int size_mul = deref->type->is_64bit() ? 8 : 4;
118 emit_access(mem_ctx, is_write, col_deref, base_offset,
119 deref_offset + i * size_mul,
120 row_major, deref->type->matrix_columns, packing,
121 writemask_for_size(col_deref->type->vector_elements));
122 } else {
123 int size_mul;
124
125 /* std430 doesn't round up vec2 size to a vec4 size */
126 if (packing == GLSL_INTERFACE_PACKING_STD430 &&
127 deref->type->vector_elements == 2 &&
128 !deref->type->is_64bit()) {
129 size_mul = 8;
130 } else {
131 /* std140 always rounds the stride of arrays (and matrices) to a
132 * vec4, so matrices are always 16 between columns/rows. With
133 * doubles, they will be 32 apart when there are more than 2 rows.
134 *
135 * For both std140 and std430, if the member is a
136 * three-'component vector with components consuming N basic
137 * machine units, the base alignment is 4N. For vec4, base
138 * alignment is 4N.
139 */
140 size_mul = (deref->type->is_64bit() &&
141 deref->type->vector_elements > 2) ? 32 : 16;
142 }
143
144 emit_access(mem_ctx, is_write, col_deref, base_offset,
145 deref_offset + i * size_mul,
146 row_major, deref->type->matrix_columns, packing,
147 writemask_for_size(col_deref->type->vector_elements));
148 }
149 }
150 return;
151 }
152
153 assert(deref->type->is_scalar() || deref->type->is_vector());
154
155 if (!row_major) {
156 ir_rvalue *offset =
157 add(base_offset, new(mem_ctx) ir_constant(deref_offset));
158 unsigned mask =
159 is_write ? write_mask : (1 << deref->type->vector_elements) - 1;
160 insert_buffer_access(mem_ctx, deref, deref->type, offset, mask, -1);
161 } else {
162 unsigned N = deref->type->is_64bit() ? 8 : 4;
163
164 /* We're dereffing a column out of a row-major matrix, so we
165 * gather the vector from each stored row.
166 */
167 assert(deref->type->base_type == GLSL_TYPE_FLOAT ||
168 deref->type->base_type == GLSL_TYPE_DOUBLE);
169 /* Matrices, row_major or not, are stored as if they were
170 * arrays of vectors of the appropriate size in std140.
171 * Arrays have their strides rounded up to a vec4, so the
172 * matrix stride is always 16. However a double matrix may either be 16
173 * or 32 depending on the number of columns.
174 */
175 assert(matrix_columns <= 4);
176 unsigned matrix_stride = 0;
177 /* Matrix stride for std430 mat2xY matrices are not rounded up to
178 * vec4 size. From OpenGL 4.3 spec, section 7.6.2.2 "Standard Uniform
179 * Block Layout":
180 *
181 * "2. If the member is a two- or four-component vector with components
182 * consuming N basic machine units, the base alignment is 2N or 4N,
183 * respectively." [...]
184 * "4. If the member is an array of scalars or vectors, the base alignment
185 * and array stride are set to match the base alignment of a single array
186 * element, according to rules (1), (2), and (3), and rounded up to the
187 * base alignment of a vec4." [...]
188 * "7. If the member is a row-major matrix with C columns and R rows, the
189 * matrix is stored identically to an array of R row vectors with C
190 * components each, according to rule (4)." [...]
191 * "When using the std430 storage layout, shader storage blocks will be
192 * laid out in buffer storage identically to uniform and shader storage
193 * blocks using the std140 layout, except that the base alignment and
194 * stride of arrays of scalars and vectors in rule 4 and of structures in
195 * rule 9 are not rounded up a multiple of the base alignment of a vec4."
196 */
197 if (packing == GLSL_INTERFACE_PACKING_STD430 && matrix_columns == 2)
198 matrix_stride = 2 * N;
199 else
200 matrix_stride = glsl_align(matrix_columns * N, 16);
201
202 const glsl_type *deref_type = deref->type->base_type == GLSL_TYPE_FLOAT ?
203 glsl_type::float_type : glsl_type::double_type;
204
205 for (unsigned i = 0; i < deref->type->vector_elements; i++) {
206 ir_rvalue *chan_offset =
207 add(base_offset,
208 new(mem_ctx) ir_constant(deref_offset + i * matrix_stride));
209 if (!is_write || ((1U << i) & write_mask))
210 insert_buffer_access(mem_ctx, deref, deref_type, chan_offset,
211 (1U << i), i);
212 }
213 }
214 }
215
216 /**
217 * Determine if a thing being dereferenced is row-major
218 *
219 * There is some trickery here.
220 *
221 * If the thing being dereferenced is a member of uniform block \b without an
222 * instance name, then the name of the \c ir_variable is the field name of an
223 * interface type. If this field is row-major, then the thing referenced is
224 * row-major.
225 *
226 * If the thing being dereferenced is a member of uniform block \b with an
227 * instance name, then the last dereference in the tree will be an
228 * \c ir_dereference_record. If that record field is row-major, then the
229 * thing referenced is row-major.
230 */
231 bool
is_dereferenced_thing_row_major(const ir_rvalue * deref)232 lower_buffer_access::is_dereferenced_thing_row_major(const ir_rvalue *deref)
233 {
234 bool matrix = false;
235 const ir_rvalue *ir = deref;
236
237 while (true) {
238 matrix = matrix || ir->type->without_array()->is_matrix();
239
240 switch (ir->ir_type) {
241 case ir_type_dereference_array: {
242 const ir_dereference_array *const array_deref =
243 (const ir_dereference_array *) ir;
244
245 ir = array_deref->array;
246 break;
247 }
248
249 case ir_type_dereference_record: {
250 const ir_dereference_record *const record_deref =
251 (const ir_dereference_record *) ir;
252
253 ir = record_deref->record;
254
255 const int idx = ir->type->field_index(record_deref->field);
256 assert(idx >= 0);
257
258 const enum glsl_matrix_layout matrix_layout =
259 glsl_matrix_layout(ir->type->fields.structure[idx].matrix_layout);
260
261 switch (matrix_layout) {
262 case GLSL_MATRIX_LAYOUT_INHERITED:
263 break;
264 case GLSL_MATRIX_LAYOUT_COLUMN_MAJOR:
265 return false;
266 case GLSL_MATRIX_LAYOUT_ROW_MAJOR:
267 return matrix || deref->type->without_array()->is_record();
268 }
269
270 break;
271 }
272
273 case ir_type_dereference_variable: {
274 const ir_dereference_variable *const var_deref =
275 (const ir_dereference_variable *) ir;
276
277 const enum glsl_matrix_layout matrix_layout =
278 glsl_matrix_layout(var_deref->var->data.matrix_layout);
279
280 switch (matrix_layout) {
281 case GLSL_MATRIX_LAYOUT_INHERITED: {
282 /* For interface block matrix variables we handle inherited
283 * layouts at HIR generation time, but we don't do that for shared
284 * variables, which are always column-major
285 */
286 MAYBE_UNUSED ir_variable *var = deref->variable_referenced();
287 assert((var->is_in_buffer_block() && !matrix) ||
288 var->data.mode == ir_var_shader_shared);
289 return false;
290 }
291 case GLSL_MATRIX_LAYOUT_COLUMN_MAJOR:
292 return false;
293 case GLSL_MATRIX_LAYOUT_ROW_MAJOR:
294 return matrix || deref->type->without_array()->is_record();
295 }
296
297 unreachable("invalid matrix layout");
298 break;
299 }
300
301 default:
302 return false;
303 }
304 }
305
306 /* The tree must have ended with a dereference that wasn't an
307 * ir_dereference_variable. That is invalid, and it should be impossible.
308 */
309 unreachable("invalid dereference tree");
310 return false;
311 }
312
313 /**
314 * This function initializes various values that will be used later by
315 * emit_access when actually emitting loads or stores.
316 *
317 * Note: const_offset is an input as well as an output, clients must
318 * initialize it to the offset of the variable in the underlying block, and
319 * this function will adjust it by adding the constant offset of the member
320 * being accessed into that variable.
321 */
322 void
setup_buffer_access(void * mem_ctx,ir_rvalue * deref,ir_rvalue ** offset,unsigned * const_offset,bool * row_major,int * matrix_columns,const glsl_struct_field ** struct_field,enum glsl_interface_packing packing)323 lower_buffer_access::setup_buffer_access(void *mem_ctx,
324 ir_rvalue *deref,
325 ir_rvalue **offset,
326 unsigned *const_offset,
327 bool *row_major,
328 int *matrix_columns,
329 const glsl_struct_field **struct_field,
330 enum glsl_interface_packing packing)
331 {
332 *offset = new(mem_ctx) ir_constant(0u);
333 *row_major = is_dereferenced_thing_row_major(deref);
334 *matrix_columns = 1;
335
336 /* Calculate the offset to the start of the region of the UBO
337 * dereferenced by *rvalue. This may be a variable offset if an
338 * array dereference has a variable index.
339 */
340 while (deref) {
341 switch (deref->ir_type) {
342 case ir_type_dereference_variable: {
343 deref = NULL;
344 break;
345 }
346
347 case ir_type_dereference_array: {
348 ir_dereference_array *deref_array = (ir_dereference_array *) deref;
349 unsigned array_stride;
350 if (deref_array->array->type->is_vector()) {
351 /* We get this when storing or loading a component out of a vector
352 * with a non-constant index. This happens for v[i] = f where v is
353 * a vector (or m[i][j] = f where m is a matrix). If we don't
354 * lower that here, it gets turned into v = vector_insert(v, i,
355 * f), which loads the entire vector, modifies one component and
356 * then write the entire thing back. That breaks if another
357 * thread or SIMD channel is modifying the same vector.
358 */
359 array_stride = 4;
360 if (deref_array->array->type->is_64bit())
361 array_stride *= 2;
362 } else if (deref_array->array->type->is_matrix() && *row_major) {
363 /* When loading a vector out of a row major matrix, the
364 * step between the columns (vectors) is the size of a
365 * float, while the step between the rows (elements of a
366 * vector) is handled below in emit_ubo_loads.
367 */
368 array_stride = 4;
369 if (deref_array->array->type->is_64bit())
370 array_stride *= 2;
371 *matrix_columns = deref_array->array->type->matrix_columns;
372 } else if (deref_array->type->without_array()->is_interface()) {
373 /* We're processing an array dereference of an interface instance
374 * array. The thing being dereferenced *must* be a variable
375 * dereference because interfaces cannot be embedded in other
376 * types. In terms of calculating the offsets for the lowering
377 * pass, we don't care about the array index. All elements of an
378 * interface instance array will have the same offsets relative to
379 * the base of the block that backs them.
380 */
381 deref = deref_array->array->as_dereference();
382 break;
383 } else {
384 /* Whether or not the field is row-major (because it might be a
385 * bvec2 or something) does not affect the array itself. We need
386 * to know whether an array element in its entirety is row-major.
387 */
388 const bool array_row_major =
389 is_dereferenced_thing_row_major(deref_array);
390
391 /* The array type will give the correct interface packing
392 * information
393 */
394 if (packing == GLSL_INTERFACE_PACKING_STD430) {
395 array_stride = deref_array->type->std430_array_stride(array_row_major);
396 } else {
397 array_stride = deref_array->type->std140_size(array_row_major);
398 array_stride = glsl_align(array_stride, 16);
399 }
400 }
401
402 ir_rvalue *array_index = deref_array->array_index;
403 if (array_index->type->base_type == GLSL_TYPE_INT)
404 array_index = i2u(array_index);
405
406 ir_constant *const_index =
407 array_index->constant_expression_value(NULL);
408 if (const_index) {
409 *const_offset += array_stride * const_index->value.u[0];
410 } else {
411 *offset = add(*offset,
412 mul(array_index,
413 new(mem_ctx) ir_constant(array_stride)));
414 }
415 deref = deref_array->array->as_dereference();
416 break;
417 }
418
419 case ir_type_dereference_record: {
420 ir_dereference_record *deref_record = (ir_dereference_record *) deref;
421 const glsl_type *struct_type = deref_record->record->type;
422 unsigned intra_struct_offset = 0;
423
424 for (unsigned int i = 0; i < struct_type->length; i++) {
425 const glsl_type *type = struct_type->fields.structure[i].type;
426
427 ir_dereference_record *field_deref = new(mem_ctx)
428 ir_dereference_record(deref_record->record,
429 struct_type->fields.structure[i].name);
430 const bool field_row_major =
431 is_dereferenced_thing_row_major(field_deref);
432
433 ralloc_free(field_deref);
434
435 unsigned field_align = 0;
436
437 if (packing == GLSL_INTERFACE_PACKING_STD430)
438 field_align = type->std430_base_alignment(field_row_major);
439 else
440 field_align = type->std140_base_alignment(field_row_major);
441
442 if (struct_type->fields.structure[i].offset != -1) {
443 intra_struct_offset = struct_type->fields.structure[i].offset;
444 }
445
446 intra_struct_offset = glsl_align(intra_struct_offset, field_align);
447
448 if (strcmp(struct_type->fields.structure[i].name,
449 deref_record->field) == 0) {
450 if (struct_field)
451 *struct_field = &struct_type->fields.structure[i];
452 break;
453 }
454
455 if (packing == GLSL_INTERFACE_PACKING_STD430)
456 intra_struct_offset += type->std430_size(field_row_major);
457 else
458 intra_struct_offset += type->std140_size(field_row_major);
459
460 /* If the field just examined was itself a structure, apply rule
461 * #9:
462 *
463 * "The structure may have padding at the end; the base offset
464 * of the member following the sub-structure is rounded up to
465 * the next multiple of the base alignment of the structure."
466 */
467 if (type->without_array()->is_record()) {
468 intra_struct_offset = glsl_align(intra_struct_offset,
469 field_align);
470
471 }
472 }
473
474 *const_offset += intra_struct_offset;
475 deref = deref_record->record->as_dereference();
476 break;
477 }
478
479 case ir_type_swizzle: {
480 ir_swizzle *deref_swizzle = (ir_swizzle *) deref;
481
482 assert(deref_swizzle->mask.num_components == 1);
483
484 *const_offset += deref_swizzle->mask.x * sizeof(int);
485 deref = deref_swizzle->val->as_dereference();
486 break;
487 }
488
489 default:
490 assert(!"not reached");
491 deref = NULL;
492 break;
493 }
494 }
495 }
496
497 } /* namespace lower_buffer_access */
498