mirror of
https://github.com/varun-r-mallya/Python-BPF.git
synced 2025-12-31 21:06:25 +00:00
219 lines
8.5 KiB
Python
219 lines
8.5 KiB
Python
from llvmlite import ir
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import ast
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from .bpf_helper_handler import bpf_printk_emitter, bpf_ktime_get_ns_emitter
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from .type_deducer import ctypes_to_ir
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def get_probe_string(func_node):
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"""Extract the probe string from the decorator of the function node."""
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# TODO: right now we have the whole string in the section decorator
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# But later we can implement typed tuples for tracepoints and kprobes
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# For helper functions, we return "helper"
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for decorator in func_node.decorator_list:
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if isinstance(decorator, ast.Call) and isinstance(decorator.func, ast.Name):
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if decorator.func.id == "section" and len(decorator.args) == 1:
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arg = decorator.args[0]
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if isinstance(arg, ast.Constant) and isinstance(arg.value, str):
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return arg.value
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return "helper"
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def handle_assign(module, builder, stmt, map_sym_tab):
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"""Handle assignment statements in the function body."""
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if len(stmt.targets) != 1:
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print("Unsupported multiassignment")
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return
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num_types = ("c_int32", "c_int64", "c_uint32", "c_uint64")
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target = stmt.targets[0]
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if not isinstance(target, ast.Name):
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print("Unsupported assignment target")
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return
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var_name = target.id
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rval = stmt.value
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if isinstance(rval, ast.Constant):
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if isinstance(rval.value, int):
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# Assume c_int64 for now
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# TODO: make symtab for this
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var = builder.alloca(ir.IntType(64), name=var_name)
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var.align = 8
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builder.store(ir.Constant(ir.IntType(64), rval.value), var)
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print(f"Assigned constant {rval.value} to {var_name}")
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elif isinstance(rval, ast.Call):
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if isinstance(rval.func, ast.Name):
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call_type = rval.func.id
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print(f"Assignment call type: {call_type}")
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if call_type in num_types and len(rval.args) == 1 and isinstance(rval.args[0], ast.Constant) and isinstance(rval.args[0].value, int):
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ir_type = ctypes_to_ir(call_type)
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var = builder.alloca(ir_type, name=var_name)
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var.align = ir_type.width // 8
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builder.store(ir.Constant(ir_type, rval.args[0].value), var)
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print(f"Assigned {call_type} constant "
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f"{rval.args[0].value} to {var_name}")
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else:
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print(f"Unsupported assignment call type: {call_type}")
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elif isinstance(rval.func, ast.Attribute):
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if isinstance(rval.func.attr, str) and rval.func.attr == "lookup":
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# Get map name and check symtab
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# maps are called as funcs
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if isinstance(rval.func.value, ast.Call) and isinstance(rval.func.value.func, ast.Name):
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map_name = rval.func.value.func.id
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if map_name in map_sym_tab:
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map_global = map_sym_tab[map_name]
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print(f"Found map {map_name} in symtab for lookup")
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if len(rval.args) != 1:
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print("Unsupported lookup with != 1 arg")
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return
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key_arg = rval.args[0]
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print(f"Lookup key arg type: {type(key_arg)}")
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else:
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print(f"Map {map_name} not found in symbol table")
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else:
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print("Unsupported assignment from method call")
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def process_func_body(module, builder, func_node, func, ret_type, map_sym_tab):
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"""Process the body of a bpf function"""
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# TODO: A lot. We just have print -> bpf_trace_printk for now
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did_return = False
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for stmt in func_node.body:
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if isinstance(stmt, ast.Expr) and isinstance(stmt.value, ast.Call):
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call = stmt.value
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if isinstance(call.func, ast.Name) and call.func.id == "print":
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bpf_printk_emitter(call, module, builder, func)
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if isinstance(call.func, ast.Name) and call.func.id == "bpf_ktime_get_ns":
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bpf_ktime_get_ns_emitter(call, module, builder, func)
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elif isinstance(stmt, ast.Assign):
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handle_assign(module, builder, stmt, map_sym_tab)
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elif isinstance(stmt, ast.Return):
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if stmt.value is None:
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builder.ret(ir.Constant(ir.IntType(32), 0))
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did_return = True
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elif isinstance(stmt.value, ast.Call) and isinstance(stmt.value.func, ast.Name) and len(stmt.value.args) == 1 and isinstance(stmt.value.args[0], ast.Constant) and isinstance(stmt.value.args[0].value, int):
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call_type = stmt.value.func.id
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if ctypes_to_ir(call_type) != ret_type:
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raise ValueError("Return type mismatch: expected"
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f"{ctypes_to_ir(call_type)}, got {call_type}")
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else:
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builder.ret(ir.Constant(
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ret_type, stmt.value.args[0].value))
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did_return = True
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else:
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print("Unsupported return value")
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if not did_return:
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builder.ret(ir.Constant(ir.IntType(32), 0))
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def process_bpf_chunk(func_node, module, return_type, map_sym_tab):
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"""Process a single BPF chunk (function) and emit corresponding LLVM IR."""
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func_name = func_node.name
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ret_type = return_type
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# TODO: parse parameters
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param_types = []
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if func_node.args.args:
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# Assume first arg to be ctx
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param_types.append(ir.PointerType())
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func_ty = ir.FunctionType(ret_type, param_types)
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func = ir.Function(module, func_ty, func_name)
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func.linkage = "dso_local"
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func.attributes.add("nounwind")
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func.attributes.add("noinline")
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func.attributes.add("optnone")
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if func_node.args.args:
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# Only look at the first argument for now
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param = func.args[0]
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param.add_attribute("nocapture")
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func.section = get_probe_string(func_node)
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block = func.append_basic_block(name="entry")
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builder = ir.IRBuilder(block)
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process_func_body(module, builder, func_node, func, ret_type, map_sym_tab)
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return func
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def func_proc(tree, module, chunks, map_sym_tab):
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for func_node in chunks:
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is_global = False
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for decorator in func_node.decorator_list:
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if isinstance(decorator, ast.Name) and decorator.id == "map":
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is_global = True
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break
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if is_global:
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continue
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func_type = get_probe_string(func_node)
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print(f"Found probe_string of {func_node.name}: {func_type}")
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process_bpf_chunk(func_node, module, ctypes_to_ir(
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infer_return_type(func_node)), map_sym_tab)
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def infer_return_type(func_node: ast.FunctionDef):
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if not isinstance(func_node, (ast.FunctionDef, ast.AsyncFunctionDef)):
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raise TypeError("Expected ast.FunctionDef")
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if func_node.returns is not None:
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try:
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return ast.unparse(func_node.returns)
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except Exception:
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node = func_node.returns
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if isinstance(node, ast.Name):
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return node.id
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if isinstance(node, ast.Attribute):
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return getattr(node, "attr", type(node).__name__)
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try:
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return str(node)
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except Exception:
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return type(node).__name__
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found_type = None
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def _expr_type(e):
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if e is None:
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return "None"
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if isinstance(e, ast.Constant):
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return type(e.value).__name__
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if isinstance(e, ast.Name):
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return e.id
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if isinstance(e, ast.Call):
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f = e.func
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if isinstance(f, ast.Name):
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return f.id
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if isinstance(f, ast.Attribute):
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try:
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return ast.unparse(f)
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except Exception:
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return getattr(f, "attr", type(f).__name__)
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try:
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return ast.unparse(f)
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except Exception:
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return type(f).__name__
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if isinstance(e, ast.Attribute):
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try:
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return ast.unparse(e)
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except Exception:
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return getattr(e, "attr", type(e).__name__)
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try:
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return ast.unparse(e)
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except Exception:
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return type(e).__name__
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for node in ast.walk(func_node):
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if isinstance(node, ast.Return):
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t = _expr_type(node.value)
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if found_type is None:
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found_type = t
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elif found_type != t:
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raise ValueError("Conflicting return types:"
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f"{found_type} vs {t}")
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return found_type or "None"
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