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fix transfer semantics for set/clear high/low bits #79

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fix transfer semantics for set/clear high/low bits #79

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107 changes: 83 additions & 24 deletions xdsl_smt/semantics/transfer_semantics.py
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Original file line number Diff line number Diff line change
@@ -1,14 +1,11 @@
from dataclasses import dataclass
from xdsl.pattern_rewriter import (
PatternRewriter,
)
from typing import Mapping, Sequence

from xdsl.pattern_rewriter import PatternRewriter
from xdsl_smt.dialects import smt_bitvector_dialect as smt_bv
from xdsl_smt.dialects import smt_dialect as smt
from xdsl_smt.dialects import transfer
from xdsl_smt.passes.lower_to_smt.smt_lowerer import (
SMTLowerer,
)
from xdsl_smt.passes.lower_to_smt.smt_lowerer import SMTLowerer
from xdsl_smt.dialects.smt_utils_dialect import (
AnyPairType,
PairType,
Expand All @@ -19,13 +16,10 @@
from xdsl_smt.dialects.smt_dialect import BoolType
from xdsl_smt.semantics.semantics import OperationSemantics, TypeSemantics
from xdsl.ir import Operation, SSAValue, Attribute
from typing import Mapping, Sequence
from xdsl.utils.hints import isa
from xdsl.dialects.builtin import IntegerAttr, IntegerType
from xdsl_smt.utils.transfer_to_smt_util import (
get_low_bits,
set_high_bits,
set_low_bits,
count_lzeros,
count_rzeros,
count_lones,
Expand All @@ -34,15 +28,21 @@
is_non_negative,
is_negative,
get_high_bits,
clear_high_bits,
clear_low_bits,
)


class AbstractValueTypeSemantics(TypeSemantics):
"""Lower all types in an abstract value to SMT types
But the last element is useless, this makes GetOp easier"""

def lower_type(self, ty: Attribute) -> Attribute:
"""
If the input type is already a smt type, skip lowering
"""
if ty.name.startswith("smt"):
return ty
return SMTLowerer.lower_type(ty)

def get_semantics(self, type: Attribute) -> Attribute:
assert isinstance(type, transfer.AbstractValueType) or isinstance(
type, transfer.TupleType
Expand Down Expand Up @@ -266,6 +266,7 @@ def get_semantics(
bv_res, ops = smt_bool_to_bv1(umul_overflow.res)

poison_op = smt.ConstantBoolOp(False)

res = PairOp(bv_res, poison_op.result)
rewriter.insert_op_before_matched_op([umul_overflow] + ops + [poison_op, res])
return ((res.res,), effect_state)
Expand Down Expand Up @@ -639,9 +640,27 @@ def get_semantics(
effect_state: SSAValue | None,
rewriter: PatternRewriter,
) -> tuple[Sequence[SSAValue], SSAValue | None]:
result = set_high_bits(operands[0], operands[1])
rewriter.insert_op_before_matched_op(result)
return ((result[-1].results[0],), effect_state)
arg = operands[0]
count = operands[1]
assert isinstance(bv_type := arg.type, smt_bv.BitVectorType)

const_bw = smt_bv.ConstantOp(bv_type.width, bv_type.width)
const_one = smt_bv.ConstantOp(1, bv_type.width)

umin = smt_bv.UltOp(count, const_bw.res)
clamped_count = smt.IteOp(umin.res, count, const_bw.res)

sub = smt_bv.SubOp(const_bw.res, clamped_count.res)
shl = smt_bv.ShlOp(const_one.res, clamped_count.res)
sub2 = smt_bv.SubOp(shl.res, const_one.res)
shl2 = smt_bv.ShlOp(sub2.res, sub.res)
or_op = smt_bv.OrOp(arg, shl2.res)

rewriter.insert_op_before_matched_op(
[const_bw, const_one, umin, clamped_count, sub, shl, sub2, shl2, or_op]
)

return ((or_op.res,), effect_state)


class SetLowBitsOpSemantics(OperationSemantics):
Expand All @@ -653,9 +672,19 @@ def get_semantics(
effect_state: SSAValue | None,
rewriter: PatternRewriter,
) -> tuple[Sequence[SSAValue], SSAValue | None]:
result = set_low_bits(operands[0], operands[1])
rewriter.insert_op_before_matched_op(result)
return ((result[-1].results[0],), effect_state)
arg = operands[0]
count = operands[1]
assert isinstance(bv_type := arg.type, smt_bv.BitVectorType)

const_one = smt_bv.ConstantOp(1, bv_type.width)

shl = smt_bv.ShlOp(const_one.res, count)
sub = smt_bv.SubOp(shl.res, const_one.res)
or_op = smt_bv.OrOp(arg, sub.res)

rewriter.insert_op_before_matched_op([const_one, shl, sub, or_op])

return ((or_op.res,), effect_state)


class SetSignBitOpSemantics(OperationSemantics):
Expand Down Expand Up @@ -692,7 +721,7 @@ def get_semantics(
operand_type = operand.type
assert isinstance(operand_type, smt_bv.BitVectorType)
width = operand_type.width.data
signed_max_value = smt_bv.ConstantOp(1 << (width - 1) - 1, width)
signed_max_value = smt_bv.ConstantOp((1 << (width - 1)) - 1, width)
and_op = smt_bv.AndOp(signed_max_value.res, operand)
result = [signed_max_value, and_op]

Expand Down Expand Up @@ -737,9 +766,27 @@ def get_semantics(
effect_state: SSAValue | None,
rewriter: PatternRewriter,
) -> tuple[Sequence[SSAValue], SSAValue | None]:
result = clear_high_bits(operands[0], operands[1])
rewriter.insert_op_before_matched_op(result)
return ((result[-1].results[0],), effect_state)
arg = operands[0]
count = operands[1]
assert isinstance(bv_type := arg.type, smt_bv.BitVectorType)

const_bw = smt_bv.ConstantOp(bv_type.width, bv_type.width)
one = smt_bv.ConstantOp(1, bv_type.width)

umin = smt_bv.UltOp(count, const_bw.res)
new_count = smt.IteOp(umin.res, count, const_bw.res)

# mask = (1 << (width - count)) - 1
sub = smt_bv.SubOp(const_bw.res, new_count.res)
shl = smt_bv.ShlOp(one.res, sub.res)
mask = smt_bv.SubOp(shl.res, one.res)
masked = smt_bv.AndOp(arg, mask.res)

rewriter.insert_op_before_matched_op(
[const_bw, one, umin, new_count, sub, shl, mask, masked]
)

return ((masked.res,), effect_state)


class ClearLowBitsOpSemantics(OperationSemantics):
Expand All @@ -751,9 +798,21 @@ def get_semantics(
effect_state: SSAValue | None,
rewriter: PatternRewriter,
) -> tuple[Sequence[SSAValue], SSAValue | None]:
result = clear_low_bits(operands[0], operands[1])
rewriter.insert_op_before_matched_op(result)
return ((result[-1].results[0],), effect_state)
arg = operands[0]
count = operands[1]
assert isinstance(bv_type := arg.type, smt_bv.BitVectorType)

const_one = smt_bv.ConstantOp(1, bv_type.width)

# mask = ~((1 << count) - 1)
shl = smt_bv.ShlOp(const_one.res, count)
sub = smt_bv.SubOp(shl.res, const_one.res)
not_mask = smt_bv.NotOp(sub.res)
masked = smt_bv.AndOp(arg, not_mask.res)

rewriter.insert_op_before_matched_op([const_one, shl, sub, not_mask, masked])

return ((masked.res,), effect_state)


class SMinOpSemantics(OperationSemantics):
Expand Down
38 changes: 0 additions & 38 deletions xdsl_smt/utils/transfer_to_smt_util.py
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Original file line number Diff line number Diff line change
Expand Up @@ -73,26 +73,6 @@ def get_high_bits_constant(high_bits: SSAValue) -> list[Operation]:
return result + get_bits_constant(result[-1].results[0], width_constant)


def clear_low_bits(b: SSAValue, low_bits: SSAValue) -> list[Operation]:
"""
clear_low_bits(x, low_bits) -> x & ~(get_low_bits_constant(low_bits))
"""
result = get_low_bits_constant(low_bits)
result.append(smt_bv.NotOp(result[-1].results[0]))
result.append(smt_bv.AndOp(result[-1].results[0], b))
return result


def clear_high_bits(b: SSAValue, low_bits: SSAValue) -> list[Operation]:
"""
clear_high_bits(x, high_bits) -> x & ~(get_high_bits_constant(high_bits))
"""
result = get_high_bits_constant(low_bits)
result.append(smt_bv.NotOp(result[-1].results[0]))
result.append(smt_bv.AndOp(result[-1].results[0], b))
return result


def get_low_bits(b: SSAValue, low_bits: SSAValue) -> list[Operation]:
"""
get_low_bits(x, low_bits) -> x & (get_low_bits_constant(low_bits))
Expand All @@ -111,24 +91,6 @@ def get_high_bits(b: SSAValue, low_bits: SSAValue) -> list[Operation]:
return result


def set_high_bits(b: SSAValue, high_bits: SSAValue) -> list[Operation]:
"""
set_high_bits(x, high_bits) -> x | (get_high_bits_constant(high_bits))
"""
result = get_high_bits_constant(high_bits)
result.append(smt_bv.OrOp(result[-1].results[0], b))
return result


def set_low_bits(b: SSAValue, low_bits: SSAValue) -> list[Operation]:
"""
set_low_bits(x, low_bits) -> x | (get_low_bits_constant(low_bits))
"""
result = get_low_bits_constant(low_bits)
result.append(smt_bv.OrOp(result[-1].results[0], b))
return result


def count_ones(b: SSAValue) -> list[Operation]:
assert isinstance(b.type, smt_bv.BitVectorType)
n = b.type.width.data
Expand Down
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