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140 | @dataclass
class LowerFuncOp(RewritePattern):
arch: Arch
@op_type_rewrite_pattern
def match_and_rewrite(self, op: func.FuncOp, rewriter: PatternRewriter):
if op.body.blocks.first is None:
raise DiagnosticException(
"Cannot lower external functions (not implemented)"
)
for ty in op.function_type.inputs.data:
if isinstance(ty, builtin.ShapedType):
raise DiagnosticException(
"Cannot lower shaped function parameters (not implemented)"
)
elif isinstance(ty, builtin.FixedBitwidthType) and ty.bitwidth > 64:
raise DiagnosticException(
"Cannot lower function parameters bigger than 64 bits (not implemented)"
)
num_inputs = len(op.function_type.inputs.data)
new_region = rewriter.move_region_contents_to_new_regions(op.body)
first_block = new_region.blocks.first
assert isinstance(first_block, Block)
reg_args_types = tuple(
self.arch.register_type_for_type(arg.type).from_index(register_index)
for register_index, arg in zip(
ARG_PASSING_REGISTER_INDICES, first_block.args
)
)
insertion_point = InsertPoint.at_start(first_block)
# Load the register-carried parameters
for i, register_type in enumerate(reg_args_types):
arg = first_block.args[i]
register = first_block.insert_arg(register_type, i)
mov_op = x86.DS_MovOp(
source=register, destination=register_type.unallocated()
)
cast_op, parameter = builtin.UnrealizedConversionCastOp.cast_one(
mov_op.destination, arg.type
)
rewriter.insert_op([mov_op, cast_op], insertion_point)
arg.replace_all_uses_with(parameter)
first_block.erase_arg(arg)
# The last argument of the basic block should be the stack pointer
sp = first_block.insert_arg(
x86.registers.RSP, min(num_inputs, MAX_REG_PASSING_INPUTS)
)
# If needed, load the stack-carried parameters by iteratively
# consuming the 7th argument of the basic block. Once the 7th argument
# has been read from the stack, it is removed from the
# basic block arguments, and the former 8th becomes the 7th.
for i in range(num_inputs - MAX_REG_PASSING_INPUTS):
arg = first_block.args[MAX_REG_PASSING_INPUTS + 1]
assert sp != arg
destination_reg = self.arch.register_type_for_type(arg.type).unallocated()
assert isinstance(destination_reg, GeneralRegisterType)
mov_op = x86.DM_MovOp(
memory=sp,
memory_offset=STACK_SLOT_SIZE_BYTES * (i + 1),
destination=destination_reg,
comment=f"Load the {i + MAX_REG_PASSING_INPUTS + 1}th argument of the function",
)
cast_op = builtin.UnrealizedConversionCastOp.get(
(mov_op.destination,), (arg.type,)
)
rewriter.insert_op([mov_op, cast_op], insertion_point)
arg.replace_all_uses_with(cast_op.results[0])
first_block.erase_arg(arg)
outputs_types: list[Attribute] = []
if len(op.function_type.outputs.data) == 1:
output_reg = self.arch.register_type_for_type(
op.function_type.outputs.data[0]
).from_index(RETURN_PASSING_REGISTER)
outputs_types.append(output_reg)
new_func = x86_func.FuncOp(
op.sym_name.data,
new_region,
(reg_args_types + (x86.registers.RSP,), outputs_types),
visibility=op.sym_visibility,
)
rewriter.replace_op(op, new_func)
|