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Add the posibility to type saved registers #284

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Add the posibility to type saved registers #284

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38 changes: 35 additions & 3 deletions m2c/translate.py
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Original file line number Diff line number Diff line change
Expand Up @@ -476,8 +476,11 @@ def get_stack_var(self, location: int, *, store: bool) -> Expression:
def maybe_get_register_var(self, reg: Register) -> Optional[Var]:
return self.reg_vars.get(reg)

def add_register_var(self, reg: Register, name: str) -> None:
type = Type.floatish() if reg.is_float() else Type.intptr()
def add_register_var(self, reg: Register, name: str, given_type: Type) -> None:
if given_type is not None:
type = given_type
else:
type = Type.floatish() if reg.is_float() else Type.intptr()
var = Var(self, prefix=f"var_{name}", type=type)
self.reg_vars[reg] = var
self.temp_vars.append(var)
Expand Down Expand Up @@ -4365,6 +4368,34 @@ def setup_planned_vars(
stack_info.planned_vars[key] = var


def get_declared_reg_types(
stack_info: StackInfo, regs: List[Register]
) -> [Dict[Register, Type]]:
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this is invalid type syntax -- the [] need to be removed. Can you run mypy?

# Use a struct where the type of the member var_x represents the type of the register
reg_struct_name = f"_m2c_reg_{stack_info.function.name}"
reg_struct = stack_info.global_info.typepool.get_struct_by_tag_name(
reg_struct_name, stack_info.global_info.typemap
)
if reg_struct is None:
return {}
types = {}
for reg_field in reg_struct.fields:
corresponding_regs = [
r
for r in regs
if reg_field.name.endswith(str(r).removeprefix("$")) and not r.is_float()
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reg_name = stack_info.function.reg_formatter.format(reg)
name == f"var_{reg_name}"

I think. Why the and not r.is_float()?

Actually, hm, instead of hard-coding variable name, it might be cleaner if this function just parsed out a struct field name -> type mapping, and then add_register_var did the register -> struct field name lookup, since that is the one who knows the variable name.

]
if len(corresponding_regs) > 2:
raise DecompFailure(
f"Function {stack_info.function.name} has a provided register type struct {stack_info.reg_struct_name} "
f"where a register was declared multiple times."
)
elif len(corresponding_regs) == 1:
types[corresponding_regs[0]] = reg_field.type

return types


def setup_reg_vars(stack_info: StackInfo, options: Options) -> None:
"""Set up per-register planned vars based on command line flags."""
arch = stack_info.global_info.arch
Expand All @@ -4379,9 +4410,10 @@ def setup_reg_vars(stack_info: StackInfo, options: Options) -> None:
reg_vars = [
stack_info.function.reg_formatter.parse(x, arch) for x in options.reg_vars
]
types = get_declared_reg_types(stack_info, reg_vars)
for reg in reg_vars:
reg_name = stack_info.function.reg_formatter.format(reg)
stack_info.add_register_var(reg, reg_name)
stack_info.add_register_var(reg, reg_name, types.get(reg))


def setup_initial_registers(state: NodeState, fn_sig: FunctionSignature) -> None:
Expand Down
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