src/panfrost/midgard/compiler.h

   1 /*
   2  * Copyright (C) 2019 Alyssa Rosenzweig <alyssa@rosenzweig.io>
   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 FROM,
  20  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  21  * SOFTWARE.
  22  */
  23
  24 #ifndef _MDG_COMPILER_H
  25 #define _MDG_COMPILER_H
  26
  27 #include "midgard.h"
  28 #include "helpers.h"
  29 #include "midgard_compile.h"
  30
  31 #include "util/hash_table.h"
  32 #include "util/u_dynarray.h"
  33 #include "util/set.h"
  34 #include "util/list.h"
  35
  36 #include "main/mtypes.h"
  37 #include "compiler/nir_types.h"
  38 #include "compiler/nir/nir.h"
  39
  40 /* Forward declare */
  41 struct midgard_block;
  42
  43 /* Target types. Defaults to TARGET_GOTO (the type corresponding directly to
  44  * the hardware), hence why that must be zero. TARGET_DISCARD signals this
  45  * instruction is actually a discard op. */
  46
  47 #define TARGET_GOTO 0
  48 #define TARGET_BREAK 1
  49 #define TARGET_CONTINUE 2
  50 #define TARGET_DISCARD 3
  51
  52 typedef struct midgard_branch {
  53         /* If conditional, the condition is specified in r31.w */
  54         bool conditional;
  55
  56         /* For conditionals, if this is true, we branch on FALSE. If false, we  branch on TRUE. */
  57         bool invert_conditional;
  58
  59         /* Branch targets: the start of a block, the start of a loop (continue), the end of a loop (break). Value is one of TARGET_ */
  60         unsigned target_type;
  61
  62         /* The actual target */
  63         union {
  64                 int target_block;
  65                 int target_break;
  66                 int target_continue;
  67         };
  68 } midgard_branch;
  69
  70 /* Instruction arguments represented as block-local SSA indices, rather than
  71  * registers. Negative values mean unused. */
  72
  73 typedef struct {
  74         int src[3];
  75         int dest;
  76
  77         bool inline_constant;
  78 } ssa_args;
  79
  80 /* Generic in-memory data type repesenting a single logical instruction, rather
  81  * than a single instruction group. This is the preferred form for code gen.
  82  * Multiple midgard_insturctions will later be combined during scheduling,
  83  * though this is not represented in this structure.  Its format bridges
  84  * the low-level binary representation with the higher level semantic meaning.
  85  *
  86  * Notably, it allows registers to be specified as block local SSA, for code
  87  * emitted before the register allocation pass.
  88  */
  89
  90 typedef struct midgard_instruction {
  91         /* Must be first for casting */
  92         struct list_head link;
  93
  94         unsigned type; /* ALU, load/store, texture */
  95
  96         /* If the register allocator has not run yet... */
  97         ssa_args ssa_args;
  98
  99         /* Special fields for an ALU instruction */
 100         midgard_reg_info registers;
 101
 102         /* I.e. (1 << alu_bit) */
 103         int unit;
 104
 105         /* When emitting bundle, should this instruction have a break forced
 106          * before it? Used for r31 writes which are valid only within a single
 107          * bundle and *need* to happen as early as possible... this is a hack,
 108          * TODO remove when we have a scheduler */
 109         bool precede_break;
 110
 111         bool has_constants;
 112         float constants[4];
 113         uint16_t inline_constant;
 114         bool has_blend_constant;
 115
 116         bool compact_branch;
 117         bool writeout;
 118         bool prepacked_branch;
 119
 120         /* Kind of a hack, but hint against aggressive DCE */
 121         bool dont_eliminate;
 122
 123         /* Masks in a saneish format. One bit per channel, not packed fancy.
 124          * Use this instead of the op specific ones, and switch over at emit
 125          * time */
 126
 127         uint16_t mask;
 128
 129         /* For ALU ops only: set to true to invert (bitwise NOT) the
 130          * destination of an integer-out op. Not imeplemented in hardware but
 131          * allows more optimizations */
 132
 133         bool invert;
 134
 135         /* Hint for the register allocator not to spill the destination written
 136          * from this instruction (because it is a spill/unspill node itself) */
 137
 138         bool no_spill;
 139
 140         /* Generic hint for intra-pass use */
 141         bool hint;
 142
 143         union {
 144                 midgard_load_store_word load_store;
 145                 midgard_vector_alu alu;
 146                 midgard_texture_word texture;
 147                 midgard_branch_extended branch_extended;
 148                 uint16_t br_compact;
 149
 150                 /* General branch, rather than packed br_compact. Higher level
 151                  * than the other components */
 152                 midgard_branch branch;
 153         };
 154 } midgard_instruction;
 155
 156 typedef struct midgard_block {
 157         /* Link to next block. Must be first for mir_get_block */
 158         struct list_head link;
 159
 160         /* List of midgard_instructions emitted for the current block */
 161         struct list_head instructions;
 162
 163         bool is_scheduled;
 164
 165         /* List of midgard_bundles emitted (after the scheduler has run) */
 166         struct util_dynarray bundles;
 167
 168         /* Number of quadwords _actually_ emitted, as determined after scheduling */
 169         unsigned quadword_count;
 170
 171         /* Succeeding blocks. The compiler should not necessarily rely on
 172          * source-order traversal */
 173         struct midgard_block *successors[2];
 174         unsigned nr_successors;
 175
 176         /* The successors pointer form a graph, and in the case of
 177          * complex control flow, this graph has a cycles. To aid
 178          * traversal during liveness analysis, we have a visited?
 179          * boolean for passes to use as they see fit, provided they
 180          * clean up later */
 181         bool visited;
 182 } midgard_block;
 183
 184 typedef struct midgard_bundle {
 185         /* Tag for the overall bundle */
 186         int tag;
 187
 188         /* Instructions contained by the bundle */
 189         int instruction_count;
 190         midgard_instruction *instructions[5];
 191
 192         /* Bundle-wide ALU configuration */
 193         int padding;
 194         int control;
 195         bool has_embedded_constants;
 196         float constants[4];
 197         bool has_blend_constant;
 198 } midgard_bundle;
 199
 200 typedef struct compiler_context {
 201         nir_shader *nir;
 202         gl_shader_stage stage;
 203
 204         /* The screen we correspond to */
 205         struct midgard_screen *screen;
 206
 207         /* Is internally a blend shader? Depends on stage == FRAGMENT */
 208         bool is_blend;
 209
 210         /* Tracking for blend constant patching */
 211         int blend_constant_offset;
 212
 213         /* Number of bytes used for Thread Local Storage */
 214         unsigned tls_size;
 215
 216         /* Count of spills and fills for shaderdb */
 217         unsigned spills;
 218         unsigned fills;
 219
 220         /* Current NIR function */
 221         nir_function *func;
 222
 223         /* Allocated compiler temporary counter */
 224         unsigned temp_alloc;
 225
 226         /* Unordered list of midgard_blocks */
 227         int block_count;
 228         struct list_head blocks;
 229
 230         /* List of midgard_instructions emitted for the current block */
 231         midgard_block *current_block;
 232
 233         /* If there is a preset after block, use this, otherwise emit_block will create one if NULL */
 234         midgard_block *after_block;
 235
 236         /* The current "depth" of the loop, for disambiguating breaks/continues
 237          * when using nested loops */
 238         int current_loop_depth;
 239
 240         /* Total number of loops for shader-db */
 241         unsigned loop_count;
 242
 243         /* Constants which have been loaded, for later inlining */
 244         struct hash_table_u64 *ssa_constants;
 245
 246         /* Mapping of hashes computed from NIR indices to the sequential temp indices ultimately used in MIR */
 247         struct hash_table_u64 *hash_to_temp;
 248         int temp_count;
 249         int max_hash;
 250
 251         /* Just the count of the max register used. Higher count => higher
 252          * register pressure */
 253         int work_registers;
 254
 255         /* Used for cont/last hinting. Increase when a tex op is added.
 256          * Decrease when a tex op is removed. */
 257         int texture_op_count;
 258
 259         /* Mapping of texture register -> SSA index for unaliasing */
 260         int texture_index[2];
 261
 262         /* The number of uniforms allowable for the fast path */
 263         int uniform_cutoff;
 264
 265         /* Count of instructions emitted from NIR overall, across all blocks */
 266         int instruction_count;
 267
 268         /* Alpha ref value passed in */
 269         float alpha_ref;
 270
 271         /* The mapping of sysvals to uniforms, the count, and the off-by-one inverse */
 272         unsigned sysvals[MAX_SYSVAL_COUNT];
 273         unsigned sysval_count;
 274         struct hash_table_u64 *sysval_to_id;
 275 } compiler_context;
 276
 277 /* Helpers for manipulating the above structures (forming the driver IR) */
 278
 279 /* Append instruction to end of current block */
 280
 281 static inline midgard_instruction *
 282 mir_upload_ins(struct midgard_instruction ins)
 283 {
 284         midgard_instruction *heap = malloc(sizeof(ins));
 285         memcpy(heap, &ins, sizeof(ins));
 286         return heap;
 287 }
 288
 289 static inline midgard_instruction *
 290 emit_mir_instruction(struct compiler_context *ctx, struct midgard_instruction ins)
 291 {
 292         midgard_instruction *u = mir_upload_ins(ins);
 293         list_addtail(&u->link, &ctx->current_block->instructions);
 294         return u;
 295 }
 296
 297 static inline struct midgard_instruction *
 298 mir_insert_instruction_before(struct midgard_instruction *tag, struct midgard_instruction ins)
 299 {
 300         struct midgard_instruction *u = mir_upload_ins(ins);
 301         list_addtail(&u->link, &tag->link);
 302         return u;
 303 }
 304
 305 static inline void
 306 mir_remove_instruction(struct midgard_instruction *ins)
 307 {
 308         list_del(&ins->link);
 309 }
 310
 311 static inline midgard_instruction*
 312 mir_prev_op(struct midgard_instruction *ins)
 313 {
 314         return list_last_entry(&(ins->link), midgard_instruction, link);
 315 }
 316
 317 static inline midgard_instruction*
 318 mir_next_op(struct midgard_instruction *ins)
 319 {
 320         return list_first_entry(&(ins->link), midgard_instruction, link);
 321 }
 322
 323 #define mir_foreach_block(ctx, v) \
 324         list_for_each_entry(struct midgard_block, v, &ctx->blocks, link)
 325
 326 #define mir_foreach_block_from(ctx, from, v) \
 327         list_for_each_entry_from(struct midgard_block, v, from, &ctx->blocks, link)
 328
 329 #define mir_foreach_instr(ctx, v) \
 330         list_for_each_entry(struct midgard_instruction, v, &ctx->current_block->instructions, link)
 331
 332 #define mir_foreach_instr_safe(ctx, v) \
 333         list_for_each_entry_safe(struct midgard_instruction, v, &ctx->current_block->instructions, link)
 334
 335 #define mir_foreach_instr_in_block(block, v) \
 336         list_for_each_entry(struct midgard_instruction, v, &block->instructions, link)
 337
 338 #define mir_foreach_instr_in_block_safe(block, v) \
 339         list_for_each_entry_safe(struct midgard_instruction, v, &block->instructions, link)
 340
 341 #define mir_foreach_instr_in_block_safe_rev(block, v) \
 342         list_for_each_entry_safe_rev(struct midgard_instruction, v, &block->instructions, link)
 343
 344 #define mir_foreach_instr_in_block_from(block, v, from) \
 345         list_for_each_entry_from(struct midgard_instruction, v, from, &block->instructions, link)
 346
 347 #define mir_foreach_instr_in_block_from_rev(block, v, from) \
 348         list_for_each_entry_from_rev(struct midgard_instruction, v, from, &block->instructions, link)
 349
 350 #define mir_foreach_bundle_in_block(block, v) \
 351         util_dynarray_foreach(&block->bundles, midgard_bundle, v)
 352
 353 #define mir_foreach_instr_global(ctx, v) \
 354         mir_foreach_block(ctx, v_block) \
 355                 mir_foreach_instr_in_block(v_block, v)
 356
 357 #define mir_foreach_instr_global_safe(ctx, v) \
 358         mir_foreach_block(ctx, v_block) \
 359                 mir_foreach_instr_in_block_safe(v_block, v)
 360
 361 static inline midgard_instruction *
 362 mir_last_in_block(struct midgard_block *block)
 363 {
 364         return list_last_entry(&block->instructions, struct midgard_instruction, link);
 365 }
 366
 367 static inline midgard_block *
 368 mir_get_block(compiler_context *ctx, int idx)
 369 {
 370         struct list_head *lst = &ctx->blocks;
 371
 372         while ((idx--) + 1)
 373                 lst = lst->next;
 374
 375         return (struct midgard_block *) lst;
 376 }
 377
 378 static inline bool
 379 mir_is_alu_bundle(midgard_bundle *bundle)
 380 {
 381         return IS_ALU(bundle->tag);
 382 }
 383
 384 /* Registers/SSA are distinguish in the backend by the bottom-most bit */
 385
 386 #define IS_REG (1)
 387
 388 static inline unsigned
 389 make_compiler_temp(compiler_context *ctx)
 390 {
 391         return (ctx->func->impl->ssa_alloc + ctx->temp_alloc++) << 1;
 392 }
 393
 394 static inline unsigned
 395 make_compiler_temp_reg(compiler_context *ctx)
 396 {
 397         return ((ctx->func->impl->reg_alloc + ctx->temp_alloc++) << 1) | IS_REG;
 398 }
 399
 400 static inline unsigned
 401 nir_src_index(compiler_context *ctx, nir_src *src)
 402 {
 403         if (src->is_ssa)
 404                 return (src->ssa->index << 1) | 0;
 405         else {
 406                 assert(!src->reg.indirect);
 407                 return (src->reg.reg->index << 1) | IS_REG;
 408         }
 409 }
 410
 411 static inline unsigned
 412 nir_alu_src_index(compiler_context *ctx, nir_alu_src *src)
 413 {
 414         return nir_src_index(ctx, &src->src);
 415 }
 416
 417 static inline unsigned
 418 nir_dest_index(compiler_context *ctx, nir_dest *dst)
 419 {
 420         if (dst->is_ssa)
 421                 return (dst->ssa.index << 1) | 0;
 422         else {
 423                 assert(!dst->reg.indirect);
 424                 return (dst->reg.reg->index << 1) | IS_REG;
 425         }
 426 }
 427
 428
 429
 430 /* MIR manipulation */
 431
 432 void mir_rewrite_index(compiler_context *ctx, unsigned old, unsigned new);
 433 void mir_rewrite_index_src(compiler_context *ctx, unsigned old, unsigned new);
 434 void mir_rewrite_index_dst(compiler_context *ctx, unsigned old, unsigned new);
 435 void mir_rewrite_index_dst_tag(compiler_context *ctx, unsigned old, unsigned new, unsigned tag);
 436 void mir_rewrite_index_src_single(midgard_instruction *ins, unsigned old, unsigned new);
 437 void mir_rewrite_index_src_tag(compiler_context *ctx, unsigned old, unsigned new, unsigned tag);
 438 void mir_rewrite_index_src_swizzle(compiler_context *ctx, unsigned old, unsigned new, unsigned swizzle);
 439 bool mir_single_use(compiler_context *ctx, unsigned value);
 440 bool mir_special_index(compiler_context *ctx, unsigned idx);
 441 unsigned mir_use_count(compiler_context *ctx, unsigned value);
 442 bool mir_is_written_before(compiler_context *ctx, midgard_instruction *ins, unsigned node);
 443 unsigned mir_mask_of_read_components(midgard_instruction *ins, unsigned node);
 444 unsigned mir_ubo_shift(midgard_load_store_op op);
 445
 446 /* MIR printing */
 447
 448 void mir_print_instruction(midgard_instruction *ins);
 449 void mir_print_bundle(midgard_bundle *ctx);
 450 void mir_print_block(midgard_block *block);
 451 void mir_print_shader(compiler_context *ctx);
 452 bool mir_nontrivial_source2_mod(midgard_instruction *ins);
 453 bool mir_nontrivial_source2_mod_simple(midgard_instruction *ins);
 454 bool mir_nontrivial_mod(midgard_vector_alu_src src, bool is_int, unsigned mask);
 455 bool mir_nontrivial_outmod(midgard_instruction *ins);
 456
 457 /* MIR goodies */
 458
 459 static const midgard_vector_alu_src blank_alu_src = {
 460         .swizzle = SWIZZLE(COMPONENT_X, COMPONENT_Y, COMPONENT_Z, COMPONENT_W),
 461 };
 462
 463 static const midgard_vector_alu_src blank_alu_src_xxxx = {
 464         .swizzle = SWIZZLE(COMPONENT_X, COMPONENT_X, COMPONENT_X, COMPONENT_X),
 465 };
 466
 467 static const midgard_scalar_alu_src blank_scalar_alu_src = {
 468         .full = true
 469 };
 470
 471 /* Used for encoding the unused source of 1-op instructions */
 472 static const midgard_vector_alu_src zero_alu_src = { 0 };
 473
 474 /* 'Intrinsic' move for aliasing */
 475
 476 static inline midgard_instruction
 477 v_mov(unsigned src, midgard_vector_alu_src mod, unsigned dest)
 478 {
 479         midgard_instruction ins = {
 480                 .type = TAG_ALU_4,
 481                 .mask = 0xF,
 482                 .ssa_args = {
 483                         .src = { SSA_UNUSED_1, src, -1 },
 484                         .dest = dest,
 485                 },
 486                 .alu = {
 487                         .op = midgard_alu_op_imov,
 488                         .reg_mode = midgard_reg_mode_32,
 489                         .dest_override = midgard_dest_override_none,
 490                         .outmod = midgard_outmod_int_wrap,
 491                         .src1 = vector_alu_srco_unsigned(zero_alu_src),
 492                         .src2 = vector_alu_srco_unsigned(mod)
 493                 },
 494         };
 495
 496         return ins;
 497 }
 498
 499 static inline bool
 500 mir_has_arg(midgard_instruction *ins, unsigned arg)
 501 {
 502         for (unsigned i = 0; i < ARRAY_SIZE(ins->ssa_args.src); ++i) {
 503                 if (ins->ssa_args.src[i] == arg)
 504                         return true;
 505         }
 506
 507         return false;
 508 }
 509
 510 /* Scheduling */
 511
 512 void schedule_program(compiler_context *ctx);
 513
 514 /* Register allocation */
 515
 516 struct ra_graph;
 517
 518 /* Broad types of register classes so we can handle special
 519  * registers */
 520
 521 #define NR_REG_CLASSES 5
 522
 523 #define REG_CLASS_WORK          0
 524 #define REG_CLASS_LDST          1
 525 #define REG_CLASS_LDST27        2
 526 #define REG_CLASS_TEXR          3
 527 #define REG_CLASS_TEXW          4
 528
 529 void mir_lower_special_reads(compiler_context *ctx);
 530 struct ra_graph* allocate_registers(compiler_context *ctx, bool *spilled);
 531 void install_registers(compiler_context *ctx, struct ra_graph *g);
 532 bool mir_is_live_after(compiler_context *ctx, midgard_block *block, midgard_instruction *start, int src);
 533 bool mir_has_multiple_writes(compiler_context *ctx, int src);
 534
 535 void mir_create_pipeline_registers(compiler_context *ctx);
 536
 537 void
 538 midgard_promote_uniforms(compiler_context *ctx, unsigned promoted_count);
 539
 540 midgard_instruction *
 541 emit_ubo_read(
 542         compiler_context *ctx,
 543         nir_instr *instr,
 544         unsigned dest,
 545         unsigned offset,
 546         nir_src *indirect_offset,
 547         unsigned index);
 548
 549 void
 550 emit_sysval_read(compiler_context *ctx, nir_instr *instr, signed dest_override, unsigned nr_components);
 551
 552 void
 553 midgard_emit_derivatives(compiler_context *ctx, nir_alu_instr *instr);
 554
 555 void
 556 midgard_lower_derivatives(compiler_context *ctx, midgard_block *block);
 557
 558 bool mir_op_computes_derivatives(unsigned op);
 559
 560 /* Final emission */
 561
 562 void emit_binary_bundle(
 563         compiler_context *ctx,
 564         midgard_bundle *bundle,
 565         struct util_dynarray *emission,
 566         int next_tag);
 567
 568 /* NIR stuff. TODO: Move? Share? Something? */
 569
 570 bool
 571 nir_undef_to_zero(nir_shader *shader);
 572
 573 void
 574 nir_clamp_psiz(nir_shader *shader, float min_size, float max_size);
 575
 576 /* Optimizations */
 577
 578 bool midgard_opt_copy_prop(compiler_context *ctx, midgard_block *block);
 579 bool midgard_opt_combine_projection(compiler_context *ctx, midgard_block *block);
 580 bool midgard_opt_varying_projection(compiler_context *ctx, midgard_block *block);
 581 bool midgard_opt_dead_code_eliminate(compiler_context *ctx, midgard_block *block);
 582 bool midgard_opt_dead_move_eliminate(compiler_context *ctx, midgard_block *block);
 583 void midgard_opt_post_move_eliminate(compiler_context *ctx, midgard_block *block, struct ra_graph *g);
 584
 585 void midgard_lower_invert(compiler_context *ctx, midgard_block *block);
 586 bool midgard_opt_not_propagate(compiler_context *ctx, midgard_block *block);
 587 bool midgard_opt_fuse_src_invert(compiler_context *ctx, midgard_block *block);
 588 bool midgard_opt_fuse_dest_invert(compiler_context *ctx, midgard_block *block);
 589
 590 #endif