src/compiler/nir/nir_algebraic.py

   1 #
   2 # Copyright (C) 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 #    Jason Ekstrand (jason@jlekstrand.net)
  25
  26 from __future__ import print_function
  27 import ast
  28 from collections import OrderedDict
  29 import itertools
  30 import struct
  31 import sys
  32 import mako.template
  33 import re
  34 import traceback
  35
  36 from nir_opcodes import opcodes
  37
  38 if sys.version_info < (3, 0):
  39     integer_types = (int, long)
  40     string_type = unicode
  41
  42 else:
  43     integer_types = (int, )
  44     string_type = str
  45
  46 _type_re = re.compile(r"(?P<type>int|uint|bool|float)?(?P<bits>\d+)?")
  47
  48 def type_bits(type_str):
  49    m = _type_re.match(type_str)
  50    assert m.group('type')
  51
  52    if m.group('bits') is None:
  53       return 0
  54    else:
  55       return int(m.group('bits'))
  56
  57 # Represents a set of variables, each with a unique id
  58 class VarSet(object):
  59    def __init__(self):
  60       self.names = {}
  61       self.ids = itertools.count()
  62       self.immutable = False;
  63
  64    def __getitem__(self, name):
  65       if name not in self.names:
  66          assert not self.immutable, "Unknown replacement variable: " + name
  67          self.names[name] = next(self.ids)
  68
  69       return self.names[name]
  70
  71    def lock(self):
  72       self.immutable = True
  73
  74 class Value(object):
  75    @staticmethod
  76    def create(val, name_base, varset):
  77       if isinstance(val, bytes):
  78          val = val.decode('utf-8')
  79
  80       if isinstance(val, tuple):
  81          return Expression(val, name_base, varset)
  82       elif isinstance(val, Expression):
  83          return val
  84       elif isinstance(val, string_type):
  85          return Variable(val, name_base, varset)
  86       elif isinstance(val, (bool, float) + integer_types):
  87          return Constant(val, name_base)
  88
  89    __template = mako.template.Template("""
  90 static const ${val.c_type} ${val.name} = {
  91    { ${val.type_enum}, ${val.bit_size} },
  92 % if isinstance(val, Constant):
  93    ${val.type()}, { ${val.hex()} /* ${val.value} */ },
  94 % elif isinstance(val, Variable):
  95    ${val.index}, /* ${val.var_name} */
  96    ${'true' if val.is_constant else 'false'},
  97    ${val.type() or 'nir_type_invalid' },
  98    ${val.cond if val.cond else 'NULL'},
  99 % elif isinstance(val, Expression):
 100    ${'true' if val.inexact else 'false'},
 101    nir_op_${val.opcode},
 102    { ${', '.join(src.c_ptr for src in val.sources)} },
 103    ${val.cond if val.cond else 'NULL'},
 104 % endif
 105 };""")
 106
 107    def __init__(self, val, name, type_str):
 108       self.in_val = str(val)
 109       self.name = name
 110       self.type_str = type_str
 111
 112    def __str__(self):
 113       return self.in_val
 114
 115    @property
 116    def type_enum(self):
 117       return "nir_search_value_" + self.type_str
 118
 119    @property
 120    def c_type(self):
 121       return "nir_search_" + self.type_str
 122
 123    @property
 124    def c_ptr(self):
 125       return "&{0}.value".format(self.name)
 126
 127    def render(self):
 128       return self.__template.render(val=self,
 129                                     Constant=Constant,
 130                                     Variable=Variable,
 131                                     Expression=Expression)
 132
 133 _constant_re = re.compile(r"(?P<value>[^@\(]+)(?:@(?P<bits>\d+))?")
 134
 135 class Constant(Value):
 136    def __init__(self, val, name):
 137       Value.__init__(self, val, name, "constant")
 138
 139       self.in_val = str(val)
 140       if isinstance(val, (str)):
 141          m = _constant_re.match(val)
 142          self.value = ast.literal_eval(m.group('value'))
 143          self.bit_size = int(m.group('bits')) if m.group('bits') else 0
 144       else:
 145          self.value = val
 146          self.bit_size = 0
 147
 148       if isinstance(self.value, bool):
 149          assert self.bit_size == 0 or self.bit_size == 32
 150          self.bit_size = 32
 151
 152    def hex(self):
 153       if isinstance(self.value, (bool)):
 154          return 'NIR_TRUE' if self.value else 'NIR_FALSE'
 155       if isinstance(self.value, integer_types):
 156          return hex(self.value)
 157       elif isinstance(self.value, float):
 158          i = struct.unpack('Q', struct.pack('d', self.value))[0]
 159          h = hex(i)
 160
 161          # On Python 2 this 'L' suffix is automatically added, but not on Python 3
 162          # Adding it explicitly makes the generated file identical, regardless
 163          # of the Python version running this script.
 164          if h[-1] != 'L' and i > sys.maxsize:
 165             h += 'L'
 166
 167          return h
 168       else:
 169          assert False
 170
 171    def type(self):
 172       if isinstance(self.value, (bool)):
 173          return "nir_type_bool"
 174       elif isinstance(self.value, integer_types):
 175          return "nir_type_int"
 176       elif isinstance(self.value, float):
 177          return "nir_type_float"
 178
 179 _var_name_re = re.compile(r"(?P<const>#)?(?P<name>\w+)"
 180                           r"(?:@(?P<type>int|uint|bool|float)?(?P<bits>\d+)?)?"
 181                           r"(?P<cond>\([^\)]+\))?")
 182
 183 class Variable(Value):
 184    def __init__(self, val, name, varset):
 185       Value.__init__(self, val, name, "variable")
 186
 187       m = _var_name_re.match(val)
 188       assert m and m.group('name') is not None
 189
 190       self.var_name = m.group('name')
 191       self.is_constant = m.group('const') is not None
 192       self.cond = m.group('cond')
 193       self.required_type = m.group('type')
 194       self.bit_size = int(m.group('bits')) if m.group('bits') else 0
 195
 196       if self.required_type == 'bool':
 197          assert self.bit_size == 0 or self.bit_size == 32
 198          self.bit_size = 32
 199
 200       if self.required_type is not None:
 201          assert self.required_type in ('float', 'bool', 'int', 'uint')
 202
 203       self.index = varset[self.var_name]
 204
 205    def __str__(self):
 206       return self.in_val
 207
 208    def type(self):
 209       if self.required_type == 'bool':
 210          return "nir_type_bool"
 211       elif self.required_type in ('int', 'uint'):
 212          return "nir_type_int"
 213       elif self.required_type == 'float':
 214          return "nir_type_float"
 215
 216 _opcode_re = re.compile(r"(?P<inexact>~)?(?P<opcode>\w+)(?:@(?P<bits>\d+))?"
 217                         r"(?P<cond>\([^\)]+\))?")
 218
 219 class Expression(Value):
 220    def __init__(self, expr, name_base, varset):
 221       Value.__init__(self, expr, name_base, "expression")
 222       assert isinstance(expr, tuple)
 223
 224       m = _opcode_re.match(expr[0])
 225       assert m and m.group('opcode') is not None
 226
 227       self.opcode = m.group('opcode')
 228       self.bit_size = int(m.group('bits')) if m.group('bits') else 0
 229       self.inexact = m.group('inexact') is not None
 230       self.cond = m.group('cond')
 231       self.sources = [ Value.create(src, "{0}_{1}".format(name_base, i), varset)
 232                        for (i, src) in enumerate(expr[1:]) ]
 233
 234    def render(self):
 235       srcs = "\n".join(src.render() for src in self.sources)
 236       return srcs + super(Expression, self).render()
 237
 238 class IntEquivalenceRelation(object):
 239    """A class representing an equivalence relation on integers.
 240
 241    Each integer has a canonical form which is the maximum integer to which it
 242    is equivalent.  Two integers are equivalent precisely when they have the
 243    same canonical form.
 244
 245    The convention of maximum is explicitly chosen to make using it in
 246    BitSizeValidator easier because it means that an actual bit_size (if any)
 247    will always be the canonical form.
 248    """
 249    def __init__(self):
 250       self._remap = {}
 251
 252    def get_canonical(self, x):
 253       """Get the canonical integer corresponding to x."""
 254       if x in self._remap:
 255          return self.get_canonical(self._remap[x])
 256       else:
 257          return x
 258
 259    def add_equiv(self, a, b):
 260       """Add an equivalence and return the canonical form."""
 261       c = max(self.get_canonical(a), self.get_canonical(b))
 262       if a != c:
 263          assert a < c
 264          self._remap[a] = c
 265
 266       if b != c:
 267          assert b < c
 268          self._remap[b] = c
 269
 270       return c
 271
 272 class BitSizeValidator(object):
 273    """A class for validating bit sizes of expressions.
 274
 275    NIR supports multiple bit-sizes on expressions in order to handle things
 276    such as fp64.  The source and destination of every ALU operation is
 277    assigned a type and that type may or may not specify a bit size.  Sources
 278    and destinations whose type does not specify a bit size are considered
 279    "unsized" and automatically take on the bit size of the corresponding
 280    register or SSA value.  NIR has two simple rules for bit sizes that are
 281    validated by nir_validator:
 282
 283     1) A given SSA def or register has a single bit size that is respected by
 284        everything that reads from it or writes to it.
 285
 286     2) The bit sizes of all unsized inputs/outputs on any given ALU
 287        instruction must match.  They need not match the sized inputs or
 288        outputs but they must match each other.
 289
 290    In order to keep nir_algebraic relatively simple and easy-to-use,
 291    nir_search supports a type of bit-size inference based on the two rules
 292    above.  This is similar to type inference in many common programming
 293    languages.  If, for instance, you are constructing an add operation and you
 294    know the second source is 16-bit, then you know that the other source and
 295    the destination must also be 16-bit.  There are, however, cases where this
 296    inference can be ambiguous or contradictory.  Consider, for instance, the
 297    following transformation:
 298
 299    (('usub_borrow', a, b), ('b2i', ('ult', a, b)))
 300
 301    This transformation can potentially cause a problem because usub_borrow is
 302    well-defined for any bit-size of integer.  However, b2i always generates a
 303    32-bit result so it could end up replacing a 64-bit expression with one
 304    that takes two 64-bit values and produces a 32-bit value.  As another
 305    example, consider this expression:
 306
 307    (('bcsel', a, b, 0), ('iand', a, b))
 308
 309    In this case, in the search expression a must be 32-bit but b can
 310    potentially have any bit size.  If we had a 64-bit b value, we would end up
 311    trying to and a 32-bit value with a 64-bit value which would be invalid
 312
 313    This class solves that problem by providing a validation layer that proves
 314    that a given search-and-replace operation is 100% well-defined before we
 315    generate any code.  This ensures that bugs are caught at compile time
 316    rather than at run time.
 317
 318    The basic operation of the validator is very similar to the bitsize_tree in
 319    nir_search only a little more subtle.  Instead of simply tracking bit
 320    sizes, it tracks "bit classes" where each class is represented by an
 321    integer.  A value of 0 means we don't know anything yet, positive values
 322    are actual bit-sizes, and negative values are used to track equivalence
 323    classes of sizes that must be the same but have yet to receive an actual
 324    size.  The first stage uses the bitsize_tree algorithm to assign bit
 325    classes to each variable.  If it ever comes across an inconsistency, it
 326    assert-fails.  Then the second stage uses that information to prove that
 327    the resulting expression can always validly be constructed.
 328    """
 329
 330    def __init__(self, varset):
 331       self._num_classes = 0
 332       self._var_classes = [0] * len(varset.names)
 333       self._class_relation = IntEquivalenceRelation()
 334
 335    def validate(self, search, replace):
 336       dst_class = self._propagate_bit_size_up(search)
 337       if dst_class == 0:
 338          dst_class = self._new_class()
 339       self._propagate_bit_class_down(search, dst_class)
 340
 341       validate_dst_class = self._validate_bit_class_up(replace)
 342       assert validate_dst_class == 0 or validate_dst_class == dst_class
 343       self._validate_bit_class_down(replace, dst_class)
 344
 345    def _new_class(self):
 346       self._num_classes += 1
 347       return -self._num_classes
 348
 349    def _set_var_bit_class(self, var_id, bit_class):
 350       assert bit_class != 0
 351       var_class = self._var_classes[var_id]
 352       if var_class == 0:
 353          self._var_classes[var_id] = bit_class
 354       else:
 355          canon_class = self._class_relation.get_canonical(var_class)
 356          assert canon_class < 0 or canon_class == bit_class
 357          var_class = self._class_relation.add_equiv(var_class, bit_class)
 358          self._var_classes[var_id] = var_class
 359
 360    def _get_var_bit_class(self, var_id):
 361       return self._class_relation.get_canonical(self._var_classes[var_id])
 362
 363    def _propagate_bit_size_up(self, val):
 364       if isinstance(val, (Constant, Variable)):
 365          return val.bit_size
 366
 367       elif isinstance(val, Expression):
 368          nir_op = opcodes[val.opcode]
 369          val.common_size = 0
 370          for i in range(nir_op.num_inputs):
 371             src_bits = self._propagate_bit_size_up(val.sources[i])
 372             if src_bits == 0:
 373                continue
 374
 375             src_type_bits = type_bits(nir_op.input_types[i])
 376             if src_type_bits != 0:
 377                assert src_bits == src_type_bits
 378             else:
 379                assert val.common_size == 0 or src_bits == val.common_size
 380                val.common_size = src_bits
 381
 382          dst_type_bits = type_bits(nir_op.output_type)
 383          if dst_type_bits != 0:
 384             assert val.bit_size == 0 or val.bit_size == dst_type_bits
 385             return dst_type_bits
 386          else:
 387             if val.common_size != 0:
 388                assert val.bit_size == 0 or val.bit_size == val.common_size
 389             else:
 390                val.common_size = val.bit_size
 391             return val.common_size
 392
 393    def _propagate_bit_class_down(self, val, bit_class):
 394       if isinstance(val, Constant):
 395          assert val.bit_size == 0 or val.bit_size == bit_class
 396
 397       elif isinstance(val, Variable):
 398          assert val.bit_size == 0 or val.bit_size == bit_class
 399          self._set_var_bit_class(val.index, bit_class)
 400
 401       elif isinstance(val, Expression):
 402          nir_op = opcodes[val.opcode]
 403          dst_type_bits = type_bits(nir_op.output_type)
 404          if dst_type_bits != 0:
 405             assert bit_class == 0 or bit_class == dst_type_bits
 406          else:
 407             assert val.common_size == 0 or val.common_size == bit_class
 408             val.common_size = bit_class
 409
 410          if val.common_size:
 411             common_class = val.common_size
 412          elif nir_op.num_inputs:
 413             # If we got here then we have no idea what the actual size is.
 414             # Instead, we use a generic class
 415             common_class = self._new_class()
 416
 417          for i in range(nir_op.num_inputs):
 418             src_type_bits = type_bits(nir_op.input_types[i])
 419             if src_type_bits != 0:
 420                self._propagate_bit_class_down(val.sources[i], src_type_bits)
 421             else:
 422                self._propagate_bit_class_down(val.sources[i], common_class)
 423
 424    def _validate_bit_class_up(self, val):
 425       if isinstance(val, Constant):
 426          return val.bit_size
 427
 428       elif isinstance(val, Variable):
 429          var_class = self._get_var_bit_class(val.index)
 430          # By the time we get to validation, every variable should have a class
 431          assert var_class != 0
 432
 433          # If we have an explicit size provided by the user, the variable
 434          # *must* exactly match the search.  It cannot be implicitly sized
 435          # because otherwise we could end up with a conflict at runtime.
 436          assert val.bit_size == 0 or val.bit_size == var_class
 437
 438          return var_class
 439
 440       elif isinstance(val, Expression):
 441          nir_op = opcodes[val.opcode]
 442          val.common_class = 0
 443          for i in range(nir_op.num_inputs):
 444             src_class = self._validate_bit_class_up(val.sources[i])
 445             if src_class == 0:
 446                continue
 447
 448             src_type_bits = type_bits(nir_op.input_types[i])
 449             if src_type_bits != 0:
 450                assert src_class == src_type_bits
 451             else:
 452                assert val.common_class == 0 or src_class == val.common_class
 453                val.common_class = src_class
 454
 455          dst_type_bits = type_bits(nir_op.output_type)
 456          if dst_type_bits != 0:
 457             assert val.bit_size == 0 or val.bit_size == dst_type_bits
 458             return dst_type_bits
 459          else:
 460             if val.common_class != 0:
 461                assert val.bit_size == 0 or val.bit_size == val.common_class
 462             else:
 463                val.common_class = val.bit_size
 464             return val.common_class
 465
 466    def _validate_bit_class_down(self, val, bit_class):
 467       # At this point, everything *must* have a bit class.  Otherwise, we have
 468       # a value we don't know how to define.
 469       assert bit_class != 0
 470
 471       if isinstance(val, Constant):
 472          assert val.bit_size == 0 or val.bit_size == bit_class
 473
 474       elif isinstance(val, Variable):
 475          assert val.bit_size == 0 or val.bit_size == bit_class
 476
 477       elif isinstance(val, Expression):
 478          nir_op = opcodes[val.opcode]
 479          dst_type_bits = type_bits(nir_op.output_type)
 480          if dst_type_bits != 0:
 481             assert bit_class == dst_type_bits
 482          else:
 483             assert val.common_class == 0 or val.common_class == bit_class
 484             val.common_class = bit_class
 485
 486          for i in range(nir_op.num_inputs):
 487             src_type_bits = type_bits(nir_op.input_types[i])
 488             if src_type_bits != 0:
 489                self._validate_bit_class_down(val.sources[i], src_type_bits)
 490             else:
 491                self._validate_bit_class_down(val.sources[i], val.common_class)
 492
 493 _optimization_ids = itertools.count()
 494
 495 condition_list = ['true']
 496
 497 class SearchAndReplace(object):
 498    def __init__(self, transform):
 499       self.id = next(_optimization_ids)
 500
 501       search = transform[0]
 502       replace = transform[1]
 503       if len(transform) > 2:
 504          self.condition = transform[2]
 505       else:
 506          self.condition = 'true'
 507
 508       if self.condition not in condition_list:
 509          condition_list.append(self.condition)
 510       self.condition_index = condition_list.index(self.condition)
 511
 512       varset = VarSet()
 513       if isinstance(search, Expression):
 514          self.search = search
 515       else:
 516          self.search = Expression(search, "search{0}".format(self.id), varset)
 517
 518       varset.lock()
 519
 520       if isinstance(replace, Value):
 521          self.replace = replace
 522       else:
 523          self.replace = Value.create(replace, "replace{0}".format(self.id), varset)
 524
 525       BitSizeValidator(varset).validate(self.search, self.replace)
 526
 527 _algebraic_pass_template = mako.template.Template("""
 528 #include "nir.h"
 529 #include "nir_search.h"
 530 #include "nir_search_helpers.h"
 531
 532 #ifndef NIR_OPT_ALGEBRAIC_STRUCT_DEFS
 533 #define NIR_OPT_ALGEBRAIC_STRUCT_DEFS
 534
 535 struct transform {
 536    const nir_search_expression *search;
 537    const nir_search_value *replace;
 538    unsigned condition_offset;
 539 };
 540
 541 #endif
 542
 543 % for (opcode, xform_list) in xform_dict.items():
 544 % for xform in xform_list:
 545    ${xform.search.render()}
 546    ${xform.replace.render()}
 547 % endfor
 548
 549 static const struct transform ${pass_name}_${opcode}_xforms[] = {
 550 % for xform in xform_list:
 551    { &${xform.search.name}, ${xform.replace.c_ptr}, ${xform.condition_index} },
 552 % endfor
 553 };
 554 % endfor
 555
 556 static bool
 557 ${pass_name}_block(nir_block *block, const bool *condition_flags,
 558                    void *mem_ctx)
 559 {
 560    bool progress = false;
 561
 562    nir_foreach_instr_reverse_safe(instr, block) {
 563       if (instr->type != nir_instr_type_alu)
 564          continue;
 565
 566       nir_alu_instr *alu = nir_instr_as_alu(instr);
 567       if (!alu->dest.dest.is_ssa)
 568          continue;
 569
 570       switch (alu->op) {
 571       % for opcode in xform_dict.keys():
 572       case nir_op_${opcode}:
 573          for (unsigned i = 0; i < ARRAY_SIZE(${pass_name}_${opcode}_xforms); i++) {
 574             const struct transform *xform = &${pass_name}_${opcode}_xforms[i];
 575             if (condition_flags[xform->condition_offset] &&
 576                 nir_replace_instr(alu, xform->search, xform->replace,
 577                                   mem_ctx)) {
 578                progress = true;
 579                break;
 580             }
 581          }
 582          break;
 583       % endfor
 584       default:
 585          break;
 586       }
 587    }
 588
 589    return progress;
 590 }
 591
 592 static bool
 593 ${pass_name}_impl(nir_function_impl *impl, const bool *condition_flags)
 594 {
 595    void *mem_ctx = ralloc_parent(impl);
 596    bool progress = false;
 597
 598    nir_foreach_block_reverse(block, impl) {
 599       progress |= ${pass_name}_block(block, condition_flags, mem_ctx);
 600    }
 601
 602    if (progress)
 603       nir_metadata_preserve(impl, nir_metadata_block_index |
 604                                   nir_metadata_dominance);
 605
 606    return progress;
 607 }
 608
 609
 610 bool
 611 ${pass_name}(nir_shader *shader)
 612 {
 613    bool progress = false;
 614    bool condition_flags[${len(condition_list)}];
 615    const nir_shader_compiler_options *options = shader->options;
 616    (void) options;
 617
 618    % for index, condition in enumerate(condition_list):
 619    condition_flags[${index}] = ${condition};
 620    % endfor
 621
 622    nir_foreach_function(function, shader) {
 623       if (function->impl)
 624          progress |= ${pass_name}_impl(function->impl, condition_flags);
 625    }
 626
 627    return progress;
 628 }
 629 """)
 630
 631 class AlgebraicPass(object):
 632    def __init__(self, pass_name, transforms):
 633       self.xform_dict = OrderedDict()
 634       self.pass_name = pass_name
 635
 636       error = False
 637
 638       for xform in transforms:
 639          if not isinstance(xform, SearchAndReplace):
 640             try:
 641                xform = SearchAndReplace(xform)
 642             except:
 643                print("Failed to parse transformation:", file=sys.stderr)
 644                print("  " + str(xform), file=sys.stderr)
 645                traceback.print_exc(file=sys.stderr)
 646                print('', file=sys.stderr)
 647                error = True
 648                continue
 649
 650          if xform.search.opcode not in self.xform_dict:
 651             self.xform_dict[xform.search.opcode] = []
 652
 653          self.xform_dict[xform.search.opcode].append(xform)
 654
 655       if error:
 656          sys.exit(1)
 657
 658    def render(self):
 659       return _algebraic_pass_template.render(pass_name=self.pass_name,
 660                                              xform_dict=self.xform_dict,
 661                                              condition_list=condition_list)