src/panfrost/bifrost/compiler.h

   1 /*
   2  * Copyright (C) 2020 Collabora Ltd.
   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  * Authors (Collabora):
  24  *      Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
  25  */
  26
  27 #ifndef __BIFROST_COMPILER_H
  28 #define __BIFROST_COMPILER_H
  29
  30 #include "bifrost.h"
  31 #include "compiler/nir/nir.h"
  32 #include "panfrost/util/pan_ir.h"
  33
  34 /* Bifrost opcodes are tricky -- the same op may exist on both FMA and
  35  * ADD with two completely different opcodes, and opcodes can be varying
  36  * length in some cases. Then we have different opcodes for int vs float
  37  * and then sometimes even for different typesizes. Further, virtually
  38  * every op has a number of flags which depend on the op. In constrast
  39  * to Midgard where you have a strict ALU/LDST/TEX division and within
  40  * ALU you have strict int/float and that's it... here it's a *lot* more
  41  * involved. As such, we use something much higher level for our IR,
  42  * encoding "classes" of operations, letting the opcode details get
  43  * sorted out at emit time.
  44  *
  45  * Please keep this list alphabetized. Please use a dictionary if you
  46  * don't know how to do that.
  47  */
  48
  49 enum bi_class {
  50         BI_ADD,
  51         BI_ATEST,
  52         BI_BRANCH,
  53         BI_CMP,
  54         BI_BLEND,
  55         BI_BITWISE,
  56         BI_COMBINE,
  57         BI_CONVERT,
  58         BI_CSEL,
  59         BI_DISCARD,
  60         BI_FMA,
  61         BI_FMOV,
  62         BI_FREXP,
  63         BI_IMATH,
  64         BI_LOAD,
  65         BI_LOAD_UNIFORM,
  66         BI_LOAD_ATTR,
  67         BI_LOAD_VAR,
  68         BI_LOAD_VAR_ADDRESS,
  69         BI_MINMAX,
  70         BI_MOV,
  71         BI_REDUCE_FMA,
  72         BI_SELECT,
  73         BI_SHIFT,
  74         BI_STORE,
  75         BI_STORE_VAR,
  76         BI_SPECIAL, /* _FAST on supported GPUs */
  77         BI_TABLE,
  78         BI_TEX,
  79         BI_ROUND,
  80         BI_NUM_CLASSES
  81 };
  82
  83 /* Properties of a class... */
  84 extern unsigned bi_class_props[BI_NUM_CLASSES];
  85
  86 /* abs/neg/outmod valid for a float op */
  87 #define BI_MODS (1 << 0)
  88
  89 /* Accepts a bi_cond */
  90 #define BI_CONDITIONAL (1 << 1)
  91
  92 /* Accepts a bifrost_roundmode */
  93 #define BI_ROUNDMODE (1 << 2)
  94
  95 /* Can be scheduled to FMA */
  96 #define BI_SCHED_FMA (1 << 3)
  97
  98 /* Can be scheduled to ADD */
  99 #define BI_SCHED_ADD (1 << 4)
 100
 101 /* Most ALU ops can do either, actually */
 102 #define BI_SCHED_ALL (BI_SCHED_FMA | BI_SCHED_ADD)
 103
 104 /* Along with setting BI_SCHED_ADD, eats up the entire cycle, so FMA must be
 105  * nopped out. Used for _FAST operations. */
 106 #define BI_SCHED_SLOW (1 << 5)
 107
 108 /* Swizzling allowed for the 8/16-bit source */
 109 #define BI_SWIZZLABLE (1 << 6)
 110
 111 /* For scheduling purposes this is a high latency instruction and must be at
 112  * the end of a clause. Implies ADD */
 113 #define BI_SCHED_HI_LATENCY (1 << 7)
 114
 115 /* Intrinsic is vectorized and acts with `vector_channels` components */
 116 #define BI_VECTOR (1 << 8)
 117
 118 /* Use a data register for src0/dest respectively, bypassing the usual
 119  * register accessor. Mutually exclusive. */
 120 #define BI_DATA_REG_SRC (1 << 9)
 121 #define BI_DATA_REG_DEST (1 << 10)
 122
 123 /* Quirk: cannot encode multiple abs on FMA in fp16 mode */
 124 #define BI_NO_ABS_ABS_FP16_FMA (1 << 11)
 125
 126 /* It can't get any worse than csel4... can it? */
 127 #define BIR_SRC_COUNT 4
 128
 129 /* BI_LD_VARY */
 130 struct bi_load_vary {
 131         enum bifrost_interp_mode interp_mode;
 132         bool reuse;
 133         bool flat;
 134 };
 135
 136 /* BI_BRANCH encoding the details of the branch itself as well as a pointer to
 137  * the target. We forward declare bi_block since this is mildly circular (not
 138  * strictly, but this order of the file makes more sense I think)
 139  *
 140  * We define our own enum of conditions since the conditions in the hardware
 141  * packed in crazy ways that would make manipulation unweildly (meaning changes
 142  * based on port swapping, etc), so we defer dealing with that until emit time.
 143  * Likewise, we expose NIR types instead of the crazy branch types, although
 144  * the restrictions do eventually apply of course. */
 145
 146 struct bi_block;
 147
 148 enum bi_cond {
 149         BI_COND_ALWAYS,
 150         BI_COND_LT,
 151         BI_COND_LE,
 152         BI_COND_GE,
 153         BI_COND_GT,
 154         BI_COND_EQ,
 155         BI_COND_NE,
 156 };
 157
 158 /* Opcodes within a class */
 159 enum bi_minmax_op {
 160         BI_MINMAX_MIN,
 161         BI_MINMAX_MAX
 162 };
 163
 164 enum bi_bitwise_op {
 165         BI_BITWISE_AND,
 166         BI_BITWISE_OR,
 167         BI_BITWISE_XOR
 168 };
 169
 170 enum bi_imath_op {
 171         BI_IMATH_ADD,
 172         BI_IMATH_SUB,
 173 };
 174
 175 enum bi_table_op {
 176         /* fp32 log2() with low precision, suitable for GL or half_log2() in
 177          * CL. In the first argument, takes x. Letting u be such that x =
 178          * 2^{-m} u with m integer and 0.75 <= u < 1.5, returns
 179          * log2(u) / (u - 1). */
 180
 181         BI_TABLE_LOG2_U_OVER_U_1_LOW,
 182 };
 183
 184 enum bi_reduce_op {
 185         /* Takes two fp32 arguments and returns x + frexp(y). Used in
 186          * low-precision log2 argument reduction on newer models. */
 187
 188         BI_REDUCE_ADD_FREXPM,
 189 };
 190
 191 enum bi_frexp_op {
 192         BI_FREXPE_LOG,
 193 };
 194
 195 enum bi_special_op {
 196         BI_SPECIAL_FRCP,
 197         BI_SPECIAL_FRSQ,
 198
 199         /* fp32 exp2() with low precision, suitable for half_exp2() in CL or
 200          * exp2() in GL. In the first argument, it takes f2i_rte(x * 2^24). In
 201          * the second, it takes x itself. */
 202         BI_SPECIAL_EXP2_LOW,
 203 };
 204
 205 enum bi_tex_op {
 206         BI_TEX_NORMAL,
 207         BI_TEX_COMPACT,
 208         BI_TEX_DUAL
 209 };
 210
 211 struct bi_bitwise {
 212         bool src_invert[2];
 213         bool rshift; /* false for lshift */
 214 };
 215
 216 struct bi_texture {
 217         /* Constant indices. Indirect would need to be in src[..] like normal,
 218          * we can reserve some sentinels there for that for future. */
 219         unsigned texture_index, sampler_index;
 220 };
 221
 222 typedef struct {
 223         struct list_head link; /* Must be first */
 224         enum bi_class type;
 225
 226         /* Indices, see pan_ssa_index etc. Note zero is special cased
 227          * to "no argument" */
 228         unsigned dest;
 229         unsigned src[BIR_SRC_COUNT];
 230
 231         /* 32-bit word offset for destination, added to the register number in
 232          * RA when lowering combines */
 233         unsigned dest_offset;
 234
 235         /* If one of the sources has BIR_INDEX_CONSTANT */
 236         union {
 237                 uint64_t u64;
 238                 uint32_t u32;
 239                 uint16_t u16[2];
 240                 uint8_t u8[4];
 241         } constant;
 242
 243         /* Floating-point modifiers, type/class permitting. If not
 244          * allowed for the type/class, these are ignored. */
 245         enum bifrost_outmod outmod;
 246         bool src_abs[BIR_SRC_COUNT];
 247         bool src_neg[BIR_SRC_COUNT];
 248
 249         /* Round mode (requires BI_ROUNDMODE) */
 250         enum bifrost_roundmode roundmode;
 251
 252         /* Destination type. Usually the type of the instruction
 253          * itself, but if sources and destination have different
 254          * types, the type of the destination wins (so f2i would be
 255          * int). Zero if there is no destination. Bitsize included */
 256         nir_alu_type dest_type;
 257
 258         /* Source types if required by the class */
 259         nir_alu_type src_types[BIR_SRC_COUNT];
 260
 261         /* If the source type is 8-bit or 16-bit such that SIMD is possible,
 262          * and the class has BI_SWIZZLABLE, this is a swizzle in the usual
 263          * sense. On non-SIMD instructions, it can be used for component
 264          * selection, so we don't have to special case extraction. */
 265         uint8_t swizzle[BIR_SRC_COUNT][NIR_MAX_VEC_COMPONENTS];
 266
 267         /* For VECTOR ops, how many channels are written? */
 268         unsigned vector_channels;
 269
 270         /* The comparison op. BI_COND_ALWAYS may not be valid. */
 271         enum bi_cond cond;
 272
 273         /* A class-specific op from which the actual opcode can be derived
 274          * (along with the above information) */
 275
 276         union {
 277                 enum bi_minmax_op minmax;
 278                 enum bi_bitwise_op bitwise;
 279                 enum bi_special_op special;
 280                 enum bi_reduce_op reduce;
 281                 enum bi_table_op table;
 282                 enum bi_frexp_op frexp;
 283                 enum bi_tex_op texture;
 284                 enum bi_imath_op imath;
 285
 286                 /* For FMA/ADD, should we add a biased exponent? */
 287                 bool mscale;
 288         } op;
 289
 290         /* Union for class-specific information */
 291         union {
 292                 enum bifrost_minmax_mode minmax;
 293                 struct bi_load_vary load_vary;
 294                 struct bi_block *branch_target;
 295
 296                 /* For BLEND -- the location 0-7 */
 297                 unsigned blend_location;
 298
 299                 struct bi_bitwise bitwise;
 300                 struct bi_texture texture;
 301         };
 302 } bi_instruction;
 303
 304 /* Represents the assignment of ports for a given bi_bundle */
 305
 306 typedef struct {
 307         /* Register to assign to each port */
 308         unsigned port[4];
 309
 310         /* Read ports can be disabled */
 311         bool enabled[2];
 312
 313         /* Should we write FMA? what about ADD? If only a single port is
 314          * enabled it is in port 2, else ADD/FMA is 2/3 respectively */
 315         bool write_fma, write_add;
 316
 317         /* Should we read with port 3? */
 318         bool read_port3;
 319
 320         /* Packed uniform/constant */
 321         uint8_t uniform_constant;
 322
 323         /* Whether writes are actually for the last instruction */
 324         bool first_instruction;
 325 } bi_registers;
 326
 327 /* A bi_bundle contains two paired instruction pointers. If a slot is unfilled,
 328  * leave it NULL; the emitter will fill in a nop. Instructions reference
 329  * registers via ports which are assigned per bundle.
 330  */
 331
 332 typedef struct {
 333         bi_registers regs;
 334         bi_instruction *fma;
 335         bi_instruction *add;
 336 } bi_bundle;
 337
 338 struct bi_block;
 339
 340 typedef struct {
 341         struct list_head link;
 342
 343         /* Link back up for branch calculations */
 344         struct bi_block *block;
 345
 346         /* A clause can have 8 instructions in bundled FMA/ADD sense, so there
 347          * can be 8 bundles. */
 348
 349         unsigned bundle_count;
 350         bi_bundle bundles[8];
 351
 352         /* For scoreboarding -- the clause ID (this is not globally unique!)
 353          * and its dependencies in terms of other clauses, computed during
 354          * scheduling and used when emitting code. Dependencies expressed as a
 355          * bitfield matching the hardware, except shifted by a clause (the
 356          * shift back to the ISA's off-by-one encoding is worked out when
 357          * emitting clauses) */
 358         unsigned scoreboard_id;
 359         uint8_t dependencies;
 360
 361         /* Back-to-back corresponds directly to the back-to-back bit. Branch
 362          * conditional corresponds to the branch conditional bit except that in
 363          * the emitted code it's always set if back-to-bit is, whereas we use
 364          * the actual value (without back-to-back so to speak) internally */
 365         bool back_to_back;
 366         bool branch_conditional;
 367
 368         /* Assigned data register */
 369         unsigned data_register;
 370
 371         /* Corresponds to the usual bit but shifted by a clause */
 372         bool data_register_write_barrier;
 373
 374         /* Constants read by this clause. ISA limit. Must satisfy:
 375          *
 376          *      constant_count + bundle_count <= 13
 377          *
 378          * Also implicitly constant_count <= bundle_count since a bundle only
 379          * reads a single constant.
 380          */
 381         uint64_t constants[8];
 382         unsigned constant_count;
 383
 384         /* Branches encode a constant offset relative to the program counter
 385          * with some magic flags. By convention, if there is a branch, its
 386          * constant will be last. Set this flag to indicate this is required.
 387          */
 388         bool branch_constant;
 389
 390         /* What type of high latency instruction is here, basically */
 391         unsigned clause_type;
 392 } bi_clause;
 393
 394 typedef struct bi_block {
 395         pan_block base; /* must be first */
 396
 397         /* If true, uses clauses; if false, uses instructions */
 398         bool scheduled;
 399         struct list_head clauses; /* list of bi_clause */
 400 } bi_block;
 401
 402 typedef struct {
 403        nir_shader *nir;
 404        gl_shader_stage stage;
 405        struct list_head blocks; /* list of bi_block */
 406        struct panfrost_sysvals sysvals;
 407        uint32_t quirks;
 408
 409        /* During NIR->BIR */
 410        nir_function_impl *impl;
 411        bi_block *current_block;
 412        bi_block *after_block;
 413        bi_block *break_block;
 414        bi_block *continue_block;
 415        bool emitted_atest;
 416        nir_alu_type *blend_types;
 417
 418        /* For creating temporaries */
 419        unsigned temp_alloc;
 420
 421        /* Analysis results */
 422        bool has_liveness;
 423
 424        /* Stats for shader-db */
 425        unsigned instruction_count;
 426        unsigned loop_count;
 427 } bi_context;
 428
 429 static inline bi_instruction *
 430 bi_emit(bi_context *ctx, bi_instruction ins)
 431 {
 432         bi_instruction *u = rzalloc(ctx, bi_instruction);
 433         memcpy(u, &ins, sizeof(ins));
 434         list_addtail(&u->link, &ctx->current_block->base.instructions);
 435         return u;
 436 }
 437
 438 static inline bi_instruction *
 439 bi_emit_before(bi_context *ctx, bi_instruction *tag, bi_instruction ins)
 440 {
 441         bi_instruction *u = rzalloc(ctx, bi_instruction);
 442         memcpy(u, &ins, sizeof(ins));
 443         list_addtail(&u->link, &tag->link);
 444         return u;
 445 }
 446
 447 static inline void
 448 bi_remove_instruction(bi_instruction *ins)
 449 {
 450         list_del(&ins->link);
 451 }
 452
 453 /* If high bits are set, instead of SSA/registers, we have specials indexed by
 454  * the low bits if necessary.
 455  *
 456  *  Fixed register: do not allocate register, do not collect $200.
 457  *  Uniform: access a uniform register given by low bits.
 458  *  Constant: access the specified constant (specifies a bit offset / shift)
 459  *  Zero: special cased to avoid wasting a constant
 460  *  Passthrough: a bifrost_packed_src to passthrough T/T0/T1
 461  */
 462
 463 #define BIR_INDEX_REGISTER (1 << 31)
 464 #define BIR_INDEX_UNIFORM  (1 << 30)
 465 #define BIR_INDEX_CONSTANT (1 << 29)
 466 #define BIR_INDEX_ZERO     (1 << 28)
 467 #define BIR_INDEX_PASS     (1 << 27)
 468
 469 /* Keep me synced please so we can check src & BIR_SPECIAL */
 470
 471 #define BIR_SPECIAL        ((BIR_INDEX_REGISTER | BIR_INDEX_UNIFORM) | \
 472         (BIR_INDEX_CONSTANT | BIR_INDEX_ZERO | BIR_INDEX_PASS))
 473
 474 static inline unsigned
 475 bi_max_temp(bi_context *ctx)
 476 {
 477         unsigned alloc = MAX2(ctx->impl->reg_alloc, ctx->impl->ssa_alloc);
 478         return ((alloc + 2 + ctx->temp_alloc) << 1);
 479 }
 480
 481 static inline unsigned
 482 bi_make_temp(bi_context *ctx)
 483 {
 484         return (ctx->impl->ssa_alloc + 1 + ctx->temp_alloc++) << 1;
 485 }
 486
 487 static inline unsigned
 488 bi_make_temp_reg(bi_context *ctx)
 489 {
 490         return ((ctx->impl->reg_alloc + ctx->temp_alloc++) << 1) | PAN_IS_REG;
 491 }
 492
 493 /* Iterators for Bifrost IR */
 494
 495 #define bi_foreach_block(ctx, v) \
 496         list_for_each_entry(pan_block, v, &ctx->blocks, link)
 497
 498 #define bi_foreach_block_from(ctx, from, v) \
 499         list_for_each_entry_from(pan_block, v, from, &ctx->blocks, link)
 500
 501 #define bi_foreach_block_from_rev(ctx, from, v) \
 502         list_for_each_entry_from_rev(pan_block, v, from, &ctx->blocks, link)
 503
 504 #define bi_foreach_instr_in_block(block, v) \
 505         list_for_each_entry(bi_instruction, v, &(block)->base.instructions, link)
 506
 507 #define bi_foreach_instr_in_block_rev(block, v) \
 508         list_for_each_entry_rev(bi_instruction, v, &(block)->base.instructions, link)
 509
 510 #define bi_foreach_instr_in_block_safe(block, v) \
 511         list_for_each_entry_safe(bi_instruction, v, &(block)->base.instructions, link)
 512
 513 #define bi_foreach_instr_in_block_safe_rev(block, v) \
 514         list_for_each_entry_safe_rev(bi_instruction, v, &(block)->base.instructions, link)
 515
 516 #define bi_foreach_instr_in_block_from(block, v, from) \
 517         list_for_each_entry_from(bi_instruction, v, from, &(block)->base.instructions, link)
 518
 519 #define bi_foreach_instr_in_block_from_rev(block, v, from) \
 520         list_for_each_entry_from_rev(bi_instruction, v, from, &(block)->base.instructions, link)
 521
 522 #define bi_foreach_clause_in_block(block, v) \
 523         list_for_each_entry(bi_clause, v, &(block)->clauses, link)
 524
 525 #define bi_foreach_clause_in_block_from(block, v, from) \
 526         list_for_each_entry_from(bi_clause, v, from, &(block)->clauses, link)
 527
 528 #define bi_foreach_clause_in_block_from_rev(block, v, from) \
 529         list_for_each_entry_from_rev(bi_clause, v, from, &(block)->clauses, link)
 530
 531 #define bi_foreach_instr_global(ctx, v) \
 532         bi_foreach_block(ctx, v_block) \
 533                 bi_foreach_instr_in_block((bi_block *) v_block, v)
 534
 535 #define bi_foreach_instr_global_safe(ctx, v) \
 536         bi_foreach_block(ctx, v_block) \
 537                 bi_foreach_instr_in_block_safe((bi_block *) v_block, v)
 538
 539 /* Based on set_foreach, expanded with automatic type casts */
 540
 541 #define bi_foreach_predecessor(blk, v) \
 542         struct set_entry *_entry_##v; \
 543         bi_block *v; \
 544         for (_entry_##v = _mesa_set_next_entry(blk->base.predecessors, NULL), \
 545                 v = (bi_block *) (_entry_##v ? _entry_##v->key : NULL);  \
 546                 _entry_##v != NULL; \
 547                 _entry_##v = _mesa_set_next_entry(blk->base.predecessors, _entry_##v), \
 548                 v = (bi_block *) (_entry_##v ? _entry_##v->key : NULL))
 549
 550 #define bi_foreach_src(ins, v) \
 551         for (unsigned v = 0; v < ARRAY_SIZE(ins->src); ++v)
 552
 553 static inline bi_instruction *
 554 bi_prev_op(bi_instruction *ins)
 555 {
 556         return list_last_entry(&(ins->link), bi_instruction, link);
 557 }
 558
 559 static inline bi_instruction *
 560 bi_next_op(bi_instruction *ins)
 561 {
 562         return list_first_entry(&(ins->link), bi_instruction, link);
 563 }
 564
 565 static inline pan_block *
 566 pan_next_block(pan_block *block)
 567 {
 568         return list_first_entry(&(block->link), pan_block, link);
 569 }
 570
 571 /* Special functions */
 572
 573 void bi_emit_fexp2(bi_context *ctx, nir_alu_instr *instr);
 574 void bi_emit_flog2(bi_context *ctx, nir_alu_instr *instr);
 575
 576 /* BIR manipulation */
 577
 578 bool bi_has_outmod(bi_instruction *ins);
 579 bool bi_has_source_mods(bi_instruction *ins);
 580 bool bi_is_src_swizzled(bi_instruction *ins, unsigned s);
 581 bool bi_has_arg(bi_instruction *ins, unsigned arg);
 582 uint16_t bi_from_bytemask(uint16_t bytemask, unsigned bytes);
 583 unsigned bi_get_component_count(bi_instruction *ins, signed s);
 584 uint16_t bi_bytemask_of_read_components(bi_instruction *ins, unsigned node);
 585 uint64_t bi_get_immediate(bi_instruction *ins, unsigned index);
 586 bool bi_writes_component(bi_instruction *ins, unsigned comp);
 587 unsigned bi_writemask(bi_instruction *ins);
 588
 589 /* BIR passes */
 590
 591 void bi_lower_combine(bi_context *ctx, bi_block *block);
 592 bool bi_opt_dead_code_eliminate(bi_context *ctx, bi_block *block);
 593 void bi_schedule(bi_context *ctx);
 594 void bi_register_allocate(bi_context *ctx);
 595
 596 /* Liveness */
 597
 598 void bi_compute_liveness(bi_context *ctx);
 599 void bi_liveness_ins_update(uint16_t *live, bi_instruction *ins, unsigned max);
 600 void bi_invalidate_liveness(bi_context *ctx);
 601 bool bi_is_live_after(bi_context *ctx, bi_block *block, bi_instruction *start, int src);
 602
 603 /* Layout */
 604
 605 bool bi_can_insert_bundle(bi_clause *clause, bool constant);
 606 unsigned bi_clause_quadwords(bi_clause *clause);
 607 signed bi_block_offset(bi_context *ctx, bi_clause *start, bi_block *target);
 608
 609 /* Code emit */
 610
 611 void bi_pack(bi_context *ctx, struct util_dynarray *emission);
 612
 613 #endif