[Mesa-dev] [PATCH v3] nir/algebraic: Rewrite bit-size inference
Dylan Baker
dylan at pnwbakers.com
Wed Dec 5 16:55:04 UTC 2018
For the python bits:
Reviewed-by: Dylan Baker <dylan at pnwbakers.com>
Quoting Connor Abbott (2018-12-05 04:20:30)
> Before this commit, there were two copies of the algorithm: one in C,
> that we would use to figure out what bit-size to give the replacement
> expression, and one in Python, that emulated the C one and tried to
> prove that the C algorithm would never fail to correctly assign
> bit-sizes. That seemed pretty fragile, and likely to fall over if we
> make any changes. Furthermore, the C code was really just recomputing
> more-or-less the same thing as the Python code every time. Instead, we
> can just store the results of the Python algorithm in the C
> datastructure, and consult it to compute the bitsize of each value,
> moving the "brains" entirely into Python. Since the Python algorithm no
> longer has to match C, it's also a lot easier to change it to something
> more closely approximating an actual type-inference algorithm. The
> algorithm used is based on Hindley-Milner, although deliberately
> weakened a little. It's a few more lines than the old one, judging by
> the diffstat, but I think it's easier to verify that it's correct while
> being as general as possible.
>
> We could split this up into two changes, first making the C code use the
> results of the Python code and then rewriting the Python algorithm, but
> since the old algorithm never tracked which variable each equivalence
> class, it would mean we'd have to add some non-trivial code which would
> then get thrown away. I think it's better to see the final state all at
> once, although I could also try splitting it up.
>
> v2:
> - Replace instances of "== None" and "!= None" with "is None" and
> "is not None".
> - Rename first_src to first_unsized_src
> - Only merge the destination with the first unsized source, since the
> sources have already been merged.
> - Add a comment explaining what nir_search_value::bit_size now means.
> v3:
> - Fix one last instance to use "is not" instead of !=
> - Don't try to be so clever when choosing which error message to print
> based on whether we're in the search or replace expression.
> - Fix trailing whitespace.
> ---
> src/compiler/nir/nir_algebraic.py | 520 ++++++++++++++++--------------
> src/compiler/nir/nir_search.c | 146 +--------
> src/compiler/nir/nir_search.h | 17 +-
> 3 files changed, 317 insertions(+), 366 deletions(-)
>
> diff --git a/src/compiler/nir/nir_algebraic.py b/src/compiler/nir/nir_algebraic.py
> index 728196136ab..efd6e52cdb9 100644
> --- a/src/compiler/nir/nir_algebraic.py
> +++ b/src/compiler/nir/nir_algebraic.py
> @@ -88,7 +88,7 @@ class Value(object):
>
> __template = mako.template.Template("""
> static const ${val.c_type} ${val.name} = {
> - { ${val.type_enum}, ${val.bit_size} },
> + { ${val.type_enum}, ${val.c_bit_size} },
> % if isinstance(val, Constant):
> ${val.type()}, { ${val.hex()} /* ${val.value} */ },
> % elif isinstance(val, Variable):
> @@ -112,6 +112,40 @@ static const ${val.c_type} ${val.name} = {
> def __str__(self):
> return self.in_val
>
> + def get_bit_size(self):
> + """Get the physical bit-size that has been chosen for this value, or if
> + there is none, the canonical value which currently represents this
> + bit-size class. Variables will be preferred, i.e. if there are any
> + variables in the equivalence class, the canonical value will be a
> + variable. We do this since we'll need to know which variable each value
> + is equivalent to when constructing the replacement expression. This is
> + the "find" part of the union-find algorithm.
> + """
> + bit_size = self
> +
> + while isinstance(bit_size, Value):
> + if bit_size._bit_size is None:
> + break
> + bit_size = bit_size._bit_size
> +
> + if bit_size is not self:
> + self._bit_size = bit_size
> + return bit_size
> +
> + def set_bit_size(self, other):
> + """Make self.get_bit_size() return what other.get_bit_size() return
> + before calling this, or just "other" if it's a concrete bit-size. This is
> + the "union" part of the union-find algorithm.
> + """
> +
> + self_bit_size = self.get_bit_size()
> + other_bit_size = other if isinstance(other, int) else other.get_bit_size()
> +
> + if self_bit_size == other_bit_size:
> + return
> +
> + self_bit_size._bit_size = other_bit_size
> +
> @property
> def type_enum(self):
> return "nir_search_value_" + self.type_str
> @@ -124,6 +158,21 @@ static const ${val.c_type} ${val.name} = {
> def c_ptr(self):
> return "&{0}.value".format(self.name)
>
> + @property
> + def c_bit_size(self):
> + bit_size = self.get_bit_size()
> + if isinstance(bit_size, int):
> + return bit_size
> + elif isinstance(bit_size, Variable):
> + return -bit_size.index - 1
> + else:
> + # If the bit-size class is neither a variable, nor an actual bit-size, then
> + # - If it's in the search expression, we don't need to check anything
> + # - If it's in the replace expression, either it's ambiguous (in which
> + # case we'd reject it), or it equals the bit-size of the search value
> + # We represent these cases with a 0 bit-size.
> + return 0
> +
> def render(self):
> return self.__template.render(val=self,
> Constant=Constant,
> @@ -140,14 +189,14 @@ class Constant(Value):
> if isinstance(val, (str)):
> m = _constant_re.match(val)
> self.value = ast.literal_eval(m.group('value'))
> - self.bit_size = int(m.group('bits')) if m.group('bits') else 0
> + self._bit_size = int(m.group('bits')) if m.group('bits') else None
> else:
> self.value = val
> - self.bit_size = 0
> + self._bit_size = None
>
> if isinstance(self.value, bool):
> - assert self.bit_size == 0 or self.bit_size == 32
> - self.bit_size = 32
> + assert self._bit_size is None or self._bit_size == 32
> + self._bit_size = 32
>
> def hex(self):
> if isinstance(self.value, (bool)):
> @@ -191,11 +240,11 @@ class Variable(Value):
> self.is_constant = m.group('const') is not None
> self.cond = m.group('cond')
> self.required_type = m.group('type')
> - self.bit_size = int(m.group('bits')) if m.group('bits') else 0
> + self._bit_size = int(m.group('bits')) if m.group('bits') else None
>
> if self.required_type == 'bool':
> - assert self.bit_size == 0 or self.bit_size == 32
> - self.bit_size = 32
> + assert self._bit_size is None or self._bit_size == 32
> + self._bit_size = 32
>
> if self.required_type is not None:
> assert self.required_type in ('float', 'bool', 'int', 'uint')
> @@ -225,7 +274,7 @@ class Expression(Value):
> assert m and m.group('opcode') is not None
>
> self.opcode = m.group('opcode')
> - self.bit_size = int(m.group('bits')) if m.group('bits') else 0
> + self._bit_size = int(m.group('bits')) if m.group('bits') else None
> self.inexact = m.group('inexact') is not None
> self.cond = m.group('cond')
> self.sources = [ Value.create(src, "{0}_{1}".format(name_base, i), varset)
> @@ -235,40 +284,6 @@ class Expression(Value):
> srcs = "\n".join(src.render() for src in self.sources)
> return srcs + super(Expression, self).render()
>
> -class IntEquivalenceRelation(object):
> - """A class representing an equivalence relation on integers.
> -
> - Each integer has a canonical form which is the maximum integer to which it
> - is equivalent. Two integers are equivalent precisely when they have the
> - same canonical form.
> -
> - The convention of maximum is explicitly chosen to make using it in
> - BitSizeValidator easier because it means that an actual bit_size (if any)
> - will always be the canonical form.
> - """
> - def __init__(self):
> - self._remap = {}
> -
> - def get_canonical(self, x):
> - """Get the canonical integer corresponding to x."""
> - if x in self._remap:
> - return self.get_canonical(self._remap[x])
> - else:
> - return x
> -
> - def add_equiv(self, a, b):
> - """Add an equivalence and return the canonical form."""
> - c = max(self.get_canonical(a), self.get_canonical(b))
> - if a != c:
> - assert a < c
> - self._remap[a] = c
> -
> - if b != c:
> - assert b < c
> - self._remap[b] = c
> -
> - return c
> -
> class BitSizeValidator(object):
> """A class for validating bit sizes of expressions.
>
> @@ -296,7 +311,7 @@ class BitSizeValidator(object):
> inference can be ambiguous or contradictory. Consider, for instance, the
> following transformation:
>
> - (('usub_borrow', a, b), ('b2i', ('ult', a, b)))
> + (('usub_borrow', a, b), ('b2i at 32', ('ult', a, b)))
>
> This transformation can potentially cause a problem because usub_borrow is
> well-defined for any bit-size of integer. However, b2i always generates a
> @@ -315,217 +330,250 @@ class BitSizeValidator(object):
> generate any code. This ensures that bugs are caught at compile time
> rather than at run time.
>
> - The basic operation of the validator is very similar to the bitsize_tree in
> - nir_search only a little more subtle. Instead of simply tracking bit
> - sizes, it tracks "bit classes" where each class is represented by an
> - integer. A value of 0 means we don't know anything yet, positive values
> - are actual bit-sizes, and negative values are used to track equivalence
> - classes of sizes that must be the same but have yet to receive an actual
> - size. The first stage uses the bitsize_tree algorithm to assign bit
> - classes to each variable. If it ever comes across an inconsistency, it
> - assert-fails. Then the second stage uses that information to prove that
> - the resulting expression can always validly be constructed.
> - """
> -
> - def __init__(self, varset):
> - self._num_classes = 0
> - self._var_classes = [0] * len(varset.names)
> - self._class_relation = IntEquivalenceRelation()
> -
> - def validate(self, search, replace):
> - search_dst_class = self._propagate_bit_size_up(search)
> - if search_dst_class == 0:
> - search_dst_class = self._new_class()
> - self._propagate_bit_class_down(search, search_dst_class)
> -
> - replace_dst_class = self._validate_bit_class_up(replace)
> - if replace_dst_class != 0:
> - assert search_dst_class != 0, \
> - 'Search expression matches any bit size but replace ' \
> - 'expression can only generate {0}-bit values' \
> - .format(replace_dst_class)
> -
> - assert search_dst_class == replace_dst_class, \
> - 'Search expression matches any {0}-bit values but replace ' \
> - 'expression can only generates {1}-bit values' \
> - .format(search_dst_class, replace_dst_class)
> -
> - self._validate_bit_class_down(replace, search_dst_class)
> -
> - def _new_class(self):
> - self._num_classes += 1
> - return -self._num_classes
> -
> - def _set_var_bit_class(self, var, bit_class):
> - assert bit_class != 0
> - var_class = self._var_classes[var.index]
> - if var_class == 0:
> - self._var_classes[var.index] = bit_class
> - else:
> - canon_var_class = self._class_relation.get_canonical(var_class)
> - canon_bit_class = self._class_relation.get_canonical(bit_class)
> - assert canon_var_class < 0 or canon_bit_class < 0 or \
> - canon_var_class == canon_bit_class, \
> - 'Variable {0} cannot be both {1}-bit and {2}-bit' \
> - .format(str(var), bit_class, var_class)
> - var_class = self._class_relation.add_equiv(var_class, bit_class)
> - self._var_classes[var.index] = var_class
> -
> - def _get_var_bit_class(self, var):
> - return self._class_relation.get_canonical(self._var_classes[var.index])
> -
> - def _propagate_bit_size_up(self, val):
> - if isinstance(val, (Constant, Variable)):
> - return val.bit_size
> -
> - elif isinstance(val, Expression):
> - nir_op = opcodes[val.opcode]
> - val.common_size = 0
> - for i in range(nir_op.num_inputs):
> - src_bits = self._propagate_bit_size_up(val.sources[i])
> - if src_bits == 0:
> - continue
> -
> - src_type_bits = type_bits(nir_op.input_types[i])
> - if src_type_bits != 0:
> - assert src_bits == src_type_bits, \
> - 'Source {0} of nir_op_{1} must be a {2}-bit value but ' \
> - 'the only possible matched values are {3}-bit: {4}' \
> - .format(i, val.opcode, src_type_bits, src_bits, str(val))
> - else:
> - assert val.common_size == 0 or src_bits == val.common_size, \
> - 'Expression cannot have both {0}-bit and {1}-bit ' \
> - 'variable-width sources: {2}' \
> - .format(src_bits, val.common_size, str(val))
> - val.common_size = src_bits
> -
> - dst_type_bits = type_bits(nir_op.output_type)
> - if dst_type_bits != 0:
> - assert val.bit_size == 0 or val.bit_size == dst_type_bits, \
> - 'nir_op_{0} produces a {1}-bit result but a {2}-bit ' \
> - 'result was requested' \
> - .format(val.opcode, dst_type_bits, val.bit_size)
> - return dst_type_bits
> - else:
> - if val.common_size != 0:
> - assert val.bit_size == 0 or val.bit_size == val.common_size, \
> - 'Variable width expression musr be {0}-bit based on ' \
> - 'the sources but a {1}-bit result was requested: {2}' \
> - .format(val.common_size, val.bit_size, str(val))
> - else:
> - val.common_size = val.bit_size
> - return val.common_size
> + Each value maintains a "bit-size class", which is either an actual bit size
> + or an equivalence class with other values that must have the same bit size.
> + The validator works by combining bit-size classes with each other according
> + to the NIR rules outlined above, checking that there are no inconsistencies.
> + When doing this for the replacement expression, we make sure to never change
> + the equivalence class of any of the search values. We could make the example
> + transforms above work by doing some extra run-time checking of the search
> + expression, but we make the user specify those constraints themselves, to
> + avoid any surprises. Since the replacement bitsizes can only be connected to
> + the source bitsize via variables (variables must have the same bitsize in
> + the source and replacment expressions) or the roots of the expression (the
> + replacement expression must produce the same bit size as the search
> + expression), we prevent merging a variable with anything when processing the
> + replacement expression, or specializing the search bitsize
> + with anything. The former prevents
>
> - def _propagate_bit_class_down(self, val, bit_class):
> - if isinstance(val, Constant):
> - assert val.bit_size == 0 or val.bit_size == bit_class, \
> - 'Constant is {0}-bit but a {1}-bit value is required: {2}' \
> - .format(val.bit_size, bit_class, str(val))
> + (('bcsel', a, b, 0), ('iand', a, b))
>
> - elif isinstance(val, Variable):
> - assert val.bit_size == 0 or val.bit_size == bit_class, \
> - 'Variable is {0}-bit but a {1}-bit value is required: {2}' \
> - .format(val.bit_size, bit_class, str(val))
> - self._set_var_bit_class(val, bit_class)
> + from being allowed, since we'd have to merge the bitsizes for a and b due to
> + the 'iand', while the latter prevents
>
> - elif isinstance(val, Expression):
> - nir_op = opcodes[val.opcode]
> - dst_type_bits = type_bits(nir_op.output_type)
> - if dst_type_bits != 0:
> - assert bit_class == 0 or bit_class == dst_type_bits, \
> - 'nir_op_{0} produces a {1}-bit result but the parent ' \
> - 'expression wants a {2}-bit value' \
> - .format(val.opcode, dst_type_bits, bit_class)
> - else:
> - assert val.common_size == 0 or val.common_size == bit_class, \
> - 'Variable-width expression produces a {0}-bit result ' \
> - 'based on the source widths but the parent expression ' \
> - 'wants a {1}-bit value: {2}' \
> - .format(val.common_size, bit_class, str(val))
> - val.common_size = bit_class
> -
> - if val.common_size:
> - common_class = val.common_size
> - elif nir_op.num_inputs:
> - # If we got here then we have no idea what the actual size is.
> - # Instead, we use a generic class
> - common_class = self._new_class()
> -
> - for i in range(nir_op.num_inputs):
> - src_type_bits = type_bits(nir_op.input_types[i])
> - if src_type_bits != 0:
> - self._propagate_bit_class_down(val.sources[i], src_type_bits)
> - else:
> - self._propagate_bit_class_down(val.sources[i], common_class)
> + (('usub_borrow', a, b), ('b2i at 32', ('ult', a, b)))
>
> - def _validate_bit_class_up(self, val):
> - if isinstance(val, Constant):
> - return val.bit_size
> + from being allowed, since the search expression has the bit size of a and b,
> + which can't be specialized to 32 which is the bitsize of the replace
> + expression. It also prevents something like:
>
> - elif isinstance(val, Variable):
> - var_class = self._get_var_bit_class(val)
> - # By the time we get to validation, every variable should have a class
> - assert var_class != 0
> + (('b2i', ('i2b', a)), ('ineq', a, 0))
>
> - # If we have an explicit size provided by the user, the variable
> - # *must* exactly match the search. It cannot be implicitly sized
> - # because otherwise we could end up with a conflict at runtime.
> - assert val.bit_size == 0 or val.bit_size == var_class
> + since the bitsize of 'b2i', which can be anything, can't be specialized to
> + the bitsize of a.
>
> - return var_class
> + After doing all this, we check that every subexpression of the replacement
> + was assigned a constant bitsize, the bitsize of a variable, or the bitsize
> + of the search expresssion, since those are the things that are known when
> + constructing the replacement expresssion. Finally, we record the bitsize
> + needed in nir_search_value so that we know what to do when building the
> + replacement expression.
> + """
>
> + def __init__(self, varset):
> + self._var_classes = [None] * len(varset.names)
> +
> + def compare_bitsizes(self, a, b):
> + """Determines which bitsize class is a specialization of the other, or
> + whether neither is. When we merge two different bitsizes, the
> + less-specialized bitsize always points to the more-specialized one, so
> + that calling get_bit_size() always gets you the most specialized bitsize.
> + The specialization partial order is given by:
> + - Physical bitsizes are always the most specialized, and a different
> + bitsize can never specialize another.
> + - In the search expression, variables can always be specialized to each
> + other and to physical bitsizes. In the replace expression, we disallow
> + this to avoid adding extra constraints to the search expression that
> + the user didn't specify.
> + - Expressions and constants without a bitsize can always be specialized to
> + each other and variables, but not the other way around.
> +
> + We return -1 if a <= b (b can be specialized to a), 0 if a = b, 1 if a >= b,
> + and None if they are not comparable (neither a <= b nor b <= a).
> + """
> + if isinstance(a, int):
> + if isinstance(b, int):
> + return 0 if a == b else None
> + elif isinstance(b, Variable):
> + return -1 if self.is_search else None
> + else:
> + return -1
> + elif isinstance(a, Variable):
> + if isinstance(b, int):
> + return 1 if self.is_search else None
> + elif isinstance(b, Variable):
> + return 0 if self.is_search or a.index == b.index else None
> + else:
> + return -1
> + else:
> + if isinstance(b, int):
> + return 1
> + elif isinstance(b, Variable):
> + return 1
> + else:
> + return 0
> +
> + def unify_bit_size(self, a, b, error_msg):
> + """Record that a must have the same bit-size as b. If both
> + have been assigned conflicting physical bit-sizes, call "error_msg" with
> + the bit-sizes of self and other to get a message and raise an error.
> + In the replace expression, disallow merging variables with other
> + variables and physical bit-sizes as well.
> + """
> + a_bit_size = a.get_bit_size()
> + b_bit_size = b if isinstance(b, int) else b.get_bit_size()
> +
> + cmp_result = self.compare_bitsizes(a_bit_size, b_bit_size)
> +
> + assert cmp_result is not None, \
> + error_msg(a_bit_size, b_bit_size)
> +
> + if cmp_result < 0:
> + b_bit_size.set_bit_size(a)
> + elif not isinstance(a_bit_size, int):
> + a_bit_size.set_bit_size(b)
> +
> + def merge_variables(self, val):
> + """Perform the first part of type inference by merging all the different
> + uses of the same variable. We always do this as if we're in the search
> + expression, even if we're actually not, since otherwise we'd get errors
> + if the search expression specified some constraint but the replace
> + expression didn't, because we'd be merging a variable and a constant.
> + """
> + if isinstance(val, Variable):
> + if self._var_classes[val.index] is None:
> + self._var_classes[val.index] = val
> + else:
> + other = self._var_classes[val.index]
> + self.unify_bit_size(other, val,
> + lambda other_bit_size, bit_size:
> + 'Variable {} has conflicting bit size requirements: ' \
> + 'it must have bit size {} and {}'.format(
> + val.var_name, other_bit_size, bit_size))
> elif isinstance(val, Expression):
> - nir_op = opcodes[val.opcode]
> - val.common_class = 0
> - for i in range(nir_op.num_inputs):
> - src_class = self._validate_bit_class_up(val.sources[i])
> - if src_class == 0:
> + for src in val.sources:
> + self.merge_variables(src)
> +
> + def validate_value(self, val):
> + """Validate the an expression by performing classic Hindley-Milner
> + type inference on bitsizes. This will detect if there are any conflicting
> + requirements, and unify variables so that we know which variables must
> + have the same bitsize. If we're operating on the replace expression, we
> + will refuse to merge different variables together or merge a variable
> + with a constant, in order to prevent surprises due to rules unexpectedly
> + not matching at runtime.
> + """
> + if not isinstance(val, Expression):
> + return
> +
> + nir_op = opcodes[val.opcode]
> + assert len(val.sources) == nir_op.num_inputs, \
> + "Expression {} has {} sources, expected {}".format(
> + val, len(val.sources), nir_op.num_inputs)
> +
> + for src in val.sources:
> + self.validate_value(src)
> +
> + dst_type_bits = type_bits(nir_op.output_type)
> +
> + # First, unify all the sources. That way, an error coming up because two
> + # sources have an incompatible bit-size won't produce an error message
> + # involving the destination.
> + first_unsized_src = None
> + for src_type, src in zip(nir_op.input_types, val.sources):
> + src_type_bits = type_bits(src_type)
> + if src_type_bits == 0:
> + if first_unsized_src is None:
> + first_unsized_src = src
> continue
>
> - src_type_bits = type_bits(nir_op.input_types[i])
> - if src_type_bits != 0:
> - assert src_class == src_type_bits
> + if self.is_search:
> + self.unify_bit_size(first_unsized_src, src,
> + lambda first_unsized_src_bit_size, src_bit_size:
> + 'Source {} of {} must have bit size {}, while source {} ' \
> + 'must have incompatible bit size {}'.format(
> + first_unsized_src, val, first_unsized_src_bit_size,
> + src, src_bit_size))
> else:
> - assert val.common_class == 0 or src_class == val.common_class
> - val.common_class = src_class
> -
> - dst_type_bits = type_bits(nir_op.output_type)
> - if dst_type_bits != 0:
> - assert val.bit_size == 0 or val.bit_size == dst_type_bits
> - return dst_type_bits
> + self.unify_bit_size(first_unsized_src, src,
> + lambda first_unsized_src_bit_size, src_bit_size:
> + 'Sources {} (bit size of {}) and {} (bit size of {}) ' \
> + 'of {} may not have the same bit size when building the ' \
> + 'replacement expression.'.format(
> + first_unsized_src, first_unsized_src_bit_size, src,
> + src_bit_size, val))
> else:
> - if val.common_class != 0:
> - assert val.bit_size == 0 or val.bit_size == val.common_class
> + if self.is_search:
> + self.unify_bit_size(src, src_type_bits,
> + lambda src_bit_size, unused:
> + '{} must have {} bits, but as a source of nir_op_{} '\
> + 'it must have {} bits'.format(
> + src, src_bit_size, nir_op.name, src_type_bits))
> + else:
> + self.unify_bit_size(src, src_type_bits,
> + lambda src_bit_size, unused:
> + '{} has the bit size of {}, but as a source of ' \
> + 'nir_op_{} it must have {} bits, which may not be the ' \
> + 'same'.format(
> + src, src_bit_size, nir_op.name, src_type_bits))
> +
> + if dst_type_bits == 0:
> + if first_unsized_src is not None:
> + if self.is_search:
> + self.unify_bit_size(val, first_unsized_src,
> + lambda val_bit_size, src_bit_size:
> + '{} must have the bit size of {}, while its source {} ' \
> + 'must have incompatible bit size {}'.format(
> + val, val_bit_size, first_unsized_src, src_bit_size))
> else:
> - val.common_class = val.bit_size
> - return val.common_class
> + self.unify_bit_size(val, first_unsized_src,
> + lambda val_bit_size, src_bit_size:
> + '{} must have {} bits, but its source {} ' \
> + '(bit size of {}) may not have that bit size ' \
> + 'when building the replacement.'.format(
> + val, val_bit_size, first_unsized_src, src_bit_size))
> + else:
> + self.unify_bit_size(val, dst_type_bits,
> + lambda dst_bit_size, unused:
> + '{} must have {} bits, but as a destination of nir_op_{} ' \
> + 'it must have {} bits'.format(
> + val, dst_bit_size, nir_op.name, dst_type_bits))
> +
> + def validate_replace(self, val, search):
> + bit_size = val.get_bit_size()
> + assert isinstance(bit_size, int) or isinstance(bit_size, Variable) or \
> + bit_size == search.get_bit_size(), \
> + 'Ambiguous bit size for replacement value {}: ' \
> + 'it cannot be deduced from a variable, a fixed bit size ' \
> + 'somewhere, or the search expression.'.format(val)
> +
> + if isinstance(val, Expression):
> + for src in val.sources:
> + self.validate_replace(src, search)
>
> - def _validate_bit_class_down(self, val, bit_class):
> - # At this point, everything *must* have a bit class. Otherwise, we have
> - # a value we don't know how to define.
> - assert bit_class != 0
> + def validate(self, search, replace):
> + self.is_search = True
> + self.merge_variables(search)
> + self.merge_variables(replace)
> + self.validate_value(search)
>
> - if isinstance(val, Constant):
> - assert val.bit_size == 0 or val.bit_size == bit_class
> + self.is_search = False
> + self.validate_value(replace)
>
> - elif isinstance(val, Variable):
> - assert val.bit_size == 0 or val.bit_size == bit_class
> + # Check that search is always more specialized than replace. Note that
> + # we're doing this in replace mode, disallowing merging variables.
> + search_bit_size = search.get_bit_size()
> + replace_bit_size = replace.get_bit_size()
> + cmp_result = self.compare_bitsizes(search_bit_size, replace_bit_size)
>
> - elif isinstance(val, Expression):
> - nir_op = opcodes[val.opcode]
> - dst_type_bits = type_bits(nir_op.output_type)
> - if dst_type_bits != 0:
> - assert bit_class == dst_type_bits
> - else:
> - assert val.common_class == 0 or val.common_class == bit_class
> - val.common_class = bit_class
> + assert cmp_result is not None and cmp_result <= 0, \
> + 'The search expression bit size {} and replace expression ' \
> + 'bit size {} may not be the same'.format(
> + search_bit_size, replace_bit_size)
>
> - for i in range(nir_op.num_inputs):
> - src_type_bits = type_bits(nir_op.input_types[i])
> - if src_type_bits != 0:
> - self._validate_bit_class_down(val.sources[i], src_type_bits)
> - else:
> - self._validate_bit_class_down(val.sources[i], val.common_class)
> + replace.set_bit_size(search)
> +
> + self.validate_replace(replace, search)
>
> _optimization_ids = itertools.count()
>
> diff --git a/src/compiler/nir/nir_search.c b/src/compiler/nir/nir_search.c
> index 0270302fd3d..a41fca876d5 100644
> --- a/src/compiler/nir/nir_search.c
> +++ b/src/compiler/nir/nir_search.c
> @@ -118,7 +118,7 @@ match_value(const nir_search_value *value, nir_alu_instr *instr, unsigned src,
> new_swizzle[i] = instr->src[src].swizzle[swizzle[i]];
>
> /* If the value has a specific bit size and it doesn't match, bail */
> - if (value->bit_size &&
> + if (value->bit_size > 0 &&
> nir_src_bit_size(instr->src[src].src) != value->bit_size)
> return false;
>
> @@ -228,7 +228,7 @@ match_expression(const nir_search_expression *expr, nir_alu_instr *instr,
>
> assert(instr->dest.dest.is_ssa);
>
> - if (expr->value.bit_size &&
> + if (expr->value.bit_size > 0 &&
> instr->dest.dest.ssa.bit_size != expr->value.bit_size)
> return false;
>
> @@ -290,128 +290,21 @@ match_expression(const nir_search_expression *expr, nir_alu_instr *instr,
> }
> }
>
> -typedef struct bitsize_tree {
> - unsigned num_srcs;
> - struct bitsize_tree *srcs[4];
> -
> - unsigned common_size;
> - bool is_src_sized[4];
> - bool is_dest_sized;
> -
> - unsigned dest_size;
> - unsigned src_size[4];
> -} bitsize_tree;
> -
> -static bitsize_tree *
> -build_bitsize_tree(void *mem_ctx, struct match_state *state,
> - const nir_search_value *value)
> -{
> - bitsize_tree *tree = rzalloc(mem_ctx, bitsize_tree);
> -
> - switch (value->type) {
> - case nir_search_value_expression: {
> - nir_search_expression *expr = nir_search_value_as_expression(value);
> - nir_op_info info = nir_op_infos[expr->opcode];
> - tree->num_srcs = info.num_inputs;
> - tree->common_size = 0;
> - for (unsigned i = 0; i < info.num_inputs; i++) {
> - tree->is_src_sized[i] = !!nir_alu_type_get_type_size(info.input_types[i]);
> - if (tree->is_src_sized[i])
> - tree->src_size[i] = nir_alu_type_get_type_size(info.input_types[i]);
> - tree->srcs[i] = build_bitsize_tree(mem_ctx, state, expr->srcs[i]);
> - }
> - tree->is_dest_sized = !!nir_alu_type_get_type_size(info.output_type);
> - if (tree->is_dest_sized)
> - tree->dest_size = nir_alu_type_get_type_size(info.output_type);
> - break;
> - }
> -
> - case nir_search_value_variable: {
> - nir_search_variable *var = nir_search_value_as_variable(value);
> - tree->num_srcs = 0;
> - tree->is_dest_sized = true;
> - tree->dest_size = nir_src_bit_size(state->variables[var->variable].src);
> - break;
> - }
> -
> - case nir_search_value_constant: {
> - tree->num_srcs = 0;
> - tree->is_dest_sized = false;
> - tree->common_size = 0;
> - break;
> - }
> - }
> -
> - if (value->bit_size) {
> - assert(!tree->is_dest_sized || tree->dest_size == value->bit_size);
> - tree->common_size = value->bit_size;
> - }
> -
> - return tree;
> -}
> -
> static unsigned
> -bitsize_tree_filter_up(bitsize_tree *tree)
> +replace_bitsize(const nir_search_value *value, unsigned search_bitsize,
> + struct match_state *state)
> {
> - for (unsigned i = 0; i < tree->num_srcs; i++) {
> - unsigned src_size = bitsize_tree_filter_up(tree->srcs[i]);
> - if (src_size == 0)
> - continue;
> -
> - if (tree->is_src_sized[i]) {
> - assert(src_size == tree->src_size[i]);
> - } else if (tree->common_size != 0) {
> - assert(src_size == tree->common_size);
> - tree->src_size[i] = src_size;
> - } else {
> - tree->common_size = src_size;
> - tree->src_size[i] = src_size;
> - }
> - }
> -
> - if (tree->num_srcs && tree->common_size) {
> - if (tree->dest_size == 0)
> - tree->dest_size = tree->common_size;
> - else if (!tree->is_dest_sized)
> - assert(tree->dest_size == tree->common_size);
> -
> - for (unsigned i = 0; i < tree->num_srcs; i++) {
> - if (!tree->src_size[i])
> - tree->src_size[i] = tree->common_size;
> - }
> - }
> -
> - return tree->dest_size;
> -}
> -
> -static void
> -bitsize_tree_filter_down(bitsize_tree *tree, unsigned size)
> -{
> - if (tree->dest_size)
> - assert(tree->dest_size == size);
> - else
> - tree->dest_size = size;
> -
> - if (!tree->is_dest_sized) {
> - if (tree->common_size)
> - assert(tree->common_size == size);
> - else
> - tree->common_size = size;
> - }
> -
> - for (unsigned i = 0; i < tree->num_srcs; i++) {
> - if (!tree->src_size[i]) {
> - assert(tree->common_size);
> - tree->src_size[i] = tree->common_size;
> - }
> - bitsize_tree_filter_down(tree->srcs[i], tree->src_size[i]);
> - }
> + if (value->bit_size > 0)
> + return value->bit_size;
> + if (value->bit_size < 0)
> + return nir_src_bit_size(state->variables[-value->bit_size - 1].src);
> + return search_bitsize;
> }
>
> static nir_alu_src
> construct_value(nir_builder *build,
> const nir_search_value *value,
> - unsigned num_components, bitsize_tree *bitsize,
> + unsigned num_components, unsigned search_bitsize,
> struct match_state *state,
> nir_instr *instr)
> {
> @@ -424,7 +317,7 @@ construct_value(nir_builder *build,
>
> nir_alu_instr *alu = nir_alu_instr_create(build->shader, expr->opcode);
> nir_ssa_dest_init(&alu->instr, &alu->dest.dest, num_components,
> - bitsize->dest_size, NULL);
> + replace_bitsize(value, search_bitsize, state), NULL);
> alu->dest.write_mask = (1 << num_components) - 1;
> alu->dest.saturate = false;
>
> @@ -443,7 +336,7 @@ construct_value(nir_builder *build,
> num_components = nir_op_infos[alu->op].input_sizes[i];
>
> alu->src[i] = construct_value(build, expr->srcs[i],
> - num_components, bitsize->srcs[i],
> + num_components, search_bitsize,
> state, instr);
> }
>
> @@ -472,16 +365,17 @@ construct_value(nir_builder *build,
>
> case nir_search_value_constant: {
> const nir_search_constant *c = nir_search_value_as_constant(value);
> + unsigned bit_size = replace_bitsize(value, search_bitsize, state);
>
> nir_ssa_def *cval;
> switch (c->type) {
> case nir_type_float:
> - cval = nir_imm_floatN_t(build, c->data.d, bitsize->dest_size);
> + cval = nir_imm_floatN_t(build, c->data.d, bit_size);
> break;
>
> case nir_type_int:
> case nir_type_uint:
> - cval = nir_imm_intN_t(build, c->data.i, bitsize->dest_size);
> + cval = nir_imm_intN_t(build, c->data.i, bit_size);
> break;
>
> case nir_type_bool:
> @@ -526,16 +420,12 @@ nir_replace_instr(nir_builder *build, nir_alu_instr *instr,
> swizzle, &state))
> return NULL;
>
> - void *bitsize_ctx = ralloc_context(NULL);
> - bitsize_tree *tree = build_bitsize_tree(bitsize_ctx, &state, replace);
> - bitsize_tree_filter_up(tree);
> - bitsize_tree_filter_down(tree, instr->dest.dest.ssa.bit_size);
> -
> build->cursor = nir_before_instr(&instr->instr);
>
> nir_alu_src val = construct_value(build, replace,
> instr->dest.dest.ssa.num_components,
> - tree, &state, &instr->instr);
> + instr->dest.dest.ssa.bit_size,
> + &state, &instr->instr);
>
> /* Inserting a mov may be unnecessary. However, it's much easier to
> * simply let copy propagation clean this up than to try to go through
> @@ -551,7 +441,5 @@ nir_replace_instr(nir_builder *build, nir_alu_instr *instr,
> */
> nir_instr_remove(&instr->instr);
>
> - ralloc_free(bitsize_ctx);
> -
> return ssa_val;
> }
> diff --git a/src/compiler/nir/nir_search.h b/src/compiler/nir/nir_search.h
> index df4189ede74..a76f39e0f40 100644
> --- a/src/compiler/nir/nir_search.h
> +++ b/src/compiler/nir/nir_search.h
> @@ -43,7 +43,22 @@ typedef enum {
> typedef struct {
> nir_search_value_type type;
>
> - unsigned bit_size;
> + /**
> + * Bit size of the value. It is interpreted as follows:
> + *
> + * For a search expression:
> + * - If bit_size > 0, then the value only matches an SSA value with the
> + * given bit size.
> + * - If bit_size <= 0, then the value matches any size SSA value.
> + *
> + * For a replace expression:
> + * - If bit_size > 0, then the value is constructed with the given bit size.
> + * - If bit_size == 0, then the value is constructed with the same bit size
> + * as the search value.
> + * - If bit_size < 0, then the value is constructed with the same bit size
> + * as variable (-bit_size - 1).
> + */
> + int bit_size;
> } nir_search_value;
>
> typedef struct {
> --
> 2.17.2
>
> _______________________________________________
> mesa-dev mailing list
> mesa-dev at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/mesa-dev
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