mirror of
https://github.com/varun-r-mallya/Python-BPF.git
synced 2025-12-31 21:06:25 +00:00
451 lines
20 KiB
Python
451 lines
20 KiB
Python
import ast
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from llvmlite import ir
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from pythonbpf.expr_pass import eval_expr
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from enum import Enum
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from .helper_utils import HelperHandlerRegistry, get_or_create_ptr_from_arg
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class BPFHelperID(Enum):
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BPF_MAP_LOOKUP_ELEM = 1
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BPF_MAP_UPDATE_ELEM = 2
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BPF_MAP_DELETE_ELEM = 3
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BPF_KTIME_GET_NS = 5
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BPF_PRINTK = 6
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BPF_GET_CURRENT_PID_TGID = 14
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BPF_PERF_EVENT_OUTPUT = 25
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@HelperHandlerRegistry.register("ktime")
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def bpf_ktime_get_ns_emitter(call, map_ptr, module, builder, func,
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local_sym_tab=None, struct_sym_tab=None,
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local_var_metadata=None):
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"""
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Emit LLVM IR for bpf_ktime_get_ns helper function call.
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"""
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# func is an arg to just have a uniform signature with other emitters
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helper_id = ir.Constant(ir.IntType(64), BPFHelperID.BPF_KTIME_GET_NS.value)
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fn_type = ir.FunctionType(ir.IntType(64), [], var_arg=False)
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fn_ptr_type = ir.PointerType(fn_type)
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fn_ptr = builder.inttoptr(helper_id, fn_ptr_type)
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result = builder.call(fn_ptr, [], tail=False)
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return result, ir.IntType(64)
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@HelperHandlerRegistry.register("lookup")
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def bpf_map_lookup_elem_emitter(call, map_ptr, module, builder, func,
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local_sym_tab=None, struct_sym_tab=None,
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local_var_metadata=None):
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"""
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Emit LLVM IR for bpf_map_lookup_elem helper function call.
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"""
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if not call.args or len(call.args) != 1:
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raise ValueError("Map lookup expects exactly one argument (key), got "
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f"{len(call.args)}")
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key_ptr = get_or_create_ptr_from_arg(call.args[0], builder, local_sym_tab)
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map_void_ptr = builder.bitcast(map_ptr, ir.PointerType())
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fn_type = ir.FunctionType(
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ir.PointerType(), # Return type: void*
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[ir.PointerType(), ir.PointerType()], # Args: (void*, void*)
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var_arg=False
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)
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fn_ptr_type = ir.PointerType(fn_type)
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fn_addr = ir.Constant(ir.IntType(
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64), BPFHelperID.BPF_MAP_LOOKUP_ELEM.value)
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fn_ptr = builder.inttoptr(fn_addr, fn_ptr_type)
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result = builder.call(fn_ptr, [map_void_ptr, key_ptr], tail=False)
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return result, ir.PointerType()
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@HelperHandlerRegistry.register("print")
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def bpf_printk_emitter(call, map_ptr, module, builder, func,
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local_sym_tab=None, struct_sym_tab=None,
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local_var_metadata=None):
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if not hasattr(func, "_fmt_counter"):
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func._fmt_counter = 0
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if not call.args:
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raise ValueError("print expects at least one argument")
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if isinstance(call.args[0], ast.JoinedStr):
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fmt_parts = []
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exprs = []
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for value in call.args[0].values:
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print("Value in f-string:", ast.dump(value))
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if isinstance(value, ast.Constant):
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if isinstance(value.value, str):
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fmt_parts.append(value.value)
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elif isinstance(value.value, int):
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fmt_parts.append("%lld")
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exprs.append(ir.Constant(ir.IntType(64), value.value))
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else:
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raise NotImplementedError(
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"Only string and integer constants are supported in f-string.")
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elif isinstance(value, ast.FormattedValue):
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print("Formatted value:", ast.dump(value))
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# TODO: Dirty handling here, only checks for int or str
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if isinstance(value.value, ast.Name):
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if local_sym_tab and value.value.id in local_sym_tab:
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var_ptr, var_type = local_sym_tab[value.value.id]
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if isinstance(var_type, ir.IntType):
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fmt_parts.append("%lld")
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exprs.append(value.value)
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elif var_type == ir.PointerType(ir.IntType(8)):
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# Case with string
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fmt_parts.append("%s")
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exprs.append(value.value)
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else:
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raise NotImplementedError(
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"Only integer and pointer types are supported in formatted values.")
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else:
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raise ValueError(
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f"Variable {value.value.id} not found in local symbol table.")
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elif isinstance(value.value, ast.Attribute):
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# object field access from struct
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if (isinstance(value.value.value, ast.Name) and
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local_sym_tab and
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value.value.value.id in local_sym_tab):
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var_name = value.value.value.id
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field_name = value.value.attr
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if local_var_metadata and var_name in local_var_metadata:
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var_type = local_var_metadata[var_name]
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if var_type in struct_sym_tab:
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struct_info = struct_sym_tab[var_type]
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if field_name in struct_info.fields:
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field_type = struct_info.field_type(
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field_name)
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if isinstance(field_type, ir.IntType):
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fmt_parts.append("%lld")
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exprs.append(value.value)
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elif field_type == ir.PointerType(ir.IntType(8)):
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fmt_parts.append("%s")
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exprs.append(value.value)
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else:
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raise NotImplementedError(
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"Only integer and pointer types are supported in formatted values.")
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else:
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raise ValueError(
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f"Field {field_name} not found in struct {var_type}.")
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else:
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raise ValueError(
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f"Struct type {var_type} for variable {var_name} not found in struct symbol table.")
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else:
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raise ValueError(
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f"Metadata for variable {var_name} not found in local variable metadata.")
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else:
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raise ValueError(
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f"Variable {value.value.value.id} not found in local symbol table.")
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else:
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raise NotImplementedError(
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"Only simple variable names are supported in formatted values.")
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else:
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raise NotImplementedError(
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"Unsupported value type in f-string.")
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fmt_str = "".join(fmt_parts) + "\n" + "\0"
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fmt_name = f"{func.name}____fmt{func._fmt_counter}"
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func._fmt_counter += 1
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fmt_gvar = ir.GlobalVariable(
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module, ir.ArrayType(ir.IntType(8), len(fmt_str)), name=fmt_name)
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fmt_gvar.global_constant = True
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fmt_gvar.initializer = ir.Constant( # type: ignore
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ir.ArrayType(ir.IntType(8), len(fmt_str)),
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bytearray(fmt_str.encode("utf8"))
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)
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fmt_gvar.linkage = "internal"
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fmt_gvar.align = 1 # type: ignore
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fmt_ptr = builder.bitcast(fmt_gvar, ir.PointerType())
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args = [fmt_ptr, ir.Constant(ir.IntType(32), len(fmt_str))]
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# Only 3 args supported in bpf_printk
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if len(exprs) > 3:
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print(
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"Warning: bpf_printk supports up to 3 arguments, extra arguments will be ignored.")
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for expr in exprs[:3]:
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print(f"{ast.dump(expr)}")
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val, _ = eval_expr(func, module, builder,
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expr, local_sym_tab, None, struct_sym_tab, local_var_metadata)
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if val:
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if isinstance(val.type, ir.PointerType):
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val = builder.ptrtoint(val, ir.IntType(64))
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elif isinstance(val.type, ir.IntType):
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if val.type.width < 64:
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val = builder.sext(val, ir.IntType(64))
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else:
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print(
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"Warning: Only integer and pointer types are supported in bpf_printk arguments. Others will be converted to 0.")
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val = ir.Constant(ir.IntType(64), 0)
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args.append(val)
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else:
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print(
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"Warning: Failed to evaluate expression for bpf_printk argument. It will be converted to 0.")
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args.append(ir.Constant(ir.IntType(64), 0))
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fn_type = ir.FunctionType(ir.IntType(
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64), [ir.PointerType(), ir.IntType(32)], var_arg=True)
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fn_ptr_type = ir.PointerType(fn_type)
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fn_addr = ir.Constant(ir.IntType(64), 6)
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fn_ptr = builder.inttoptr(fn_addr, fn_ptr_type)
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return builder.call(fn_ptr, args, tail=True)
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for arg in call.args:
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if isinstance(arg, ast.Constant) and isinstance(arg.value, str):
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fmt_str = arg.value + "\n" + "\0"
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fmt_name = f"{func.name}____fmt{func._fmt_counter}"
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func._fmt_counter += 1
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fmt_gvar = ir.GlobalVariable(
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module, ir.ArrayType(ir.IntType(8), len(fmt_str)), name=fmt_name)
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fmt_gvar.global_constant = True
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fmt_gvar.initializer = ir.Constant( # type: ignore
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ir.ArrayType(ir.IntType(8), len(fmt_str)),
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bytearray(fmt_str.encode("utf8"))
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)
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fmt_gvar.linkage = "internal"
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fmt_gvar.align = 1 # type: ignore
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fmt_ptr = builder.bitcast(fmt_gvar, ir.PointerType())
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fn_type = ir.FunctionType(ir.IntType(
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64), [ir.PointerType(), ir.IntType(32)], var_arg=True)
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fn_ptr_type = ir.PointerType(fn_type)
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fn_addr = ir.Constant(ir.IntType(64), BPFHelperID.BPF_PRINTK.value)
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fn_ptr = builder.inttoptr(fn_addr, fn_ptr_type)
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builder.call(fn_ptr, [fmt_ptr, ir.Constant(
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ir.IntType(32), len(fmt_str))], tail=True)
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return None
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@HelperHandlerRegistry.register("update")
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def bpf_map_update_elem_emitter(call, map_ptr, module, builder, func,
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local_sym_tab=None, struct_sym_tab=None,
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local_var_metadata=None):
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"""
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Emit LLVM IR for bpf_map_update_elem helper function call.
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Expected call signature: map.update(key, value, flags=0)
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"""
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if (not call.args or
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len(call.args) < 2 or
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len(call.args) > 3):
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raise ValueError("Map update expects 2 or 3 arguments (key, value, flags), got "
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f"{len(call.args)}")
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key_arg = call.args[0]
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value_arg = call.args[1]
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flags_arg = call.args[2] if len(call.args) > 2 else None
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key_ptr = get_or_create_ptr_from_arg(key_arg, builder, local_sym_tab)
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value_ptr = get_or_create_ptr_from_arg(value_arg, builder, local_sym_tab)
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# Handle flags argument (defaults to 0)
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if flags_arg is not None:
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if isinstance(flags_arg, ast.Constant) and isinstance(flags_arg.value, int):
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flags_val = flags_arg.value
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elif isinstance(flags_arg, ast.Name):
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flags_name = flags_arg.id
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if local_sym_tab and flags_name in local_sym_tab:
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# Assume it's a stored integer value, load it
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flags_ptr = local_sym_tab[flags_name][0]
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flags_val = builder.load(flags_ptr)
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else:
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raise ValueError(
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f"Flags variable {flags_name} not found in local symbol table.")
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else:
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raise NotImplementedError(
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"Only integer constants and simple variable names are supported as flags in map update.")
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else:
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flags_val = 0
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if key_ptr is None or value_ptr is None:
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raise ValueError("Key pointer or value pointer is None.")
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map_void_ptr = builder.bitcast(map_ptr, ir.PointerType())
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fn_type = ir.FunctionType(
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ir.IntType(64),
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[ir.PointerType(), ir.PointerType(), ir.PointerType(), ir.IntType(64)],
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var_arg=False
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)
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fn_ptr_type = ir.PointerType(fn_type)
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# helper id
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fn_addr = ir.Constant(ir.IntType(
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64), BPFHelperID.BPF_MAP_UPDATE_ELEM.value)
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fn_ptr = builder.inttoptr(fn_addr, fn_ptr_type)
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if isinstance(flags_val, int):
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flags_const = ir.Constant(ir.IntType(64), flags_val)
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else:
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flags_const = flags_val
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result = builder.call(
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fn_ptr, [map_void_ptr, key_ptr, value_ptr, flags_const], tail=False)
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return result, None
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@HelperHandlerRegistry.register("delete")
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def bpf_map_delete_elem_emitter(call, map_ptr, module, builder, func,
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local_sym_tab=None, struct_sym_tab=None,
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local_var_metadata=None):
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"""
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Emit LLVM IR for bpf_map_delete_elem helper function call.
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Expected call signature: map.delete(key)
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"""
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if not call.args or len(call.args) != 1:
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raise ValueError("Map delete expects exactly one argument (key), got "
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f"{len(call.args)}")
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key_ptr = get_or_create_ptr_from_arg(call.args[0], builder, local_sym_tab)
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map_void_ptr = builder.bitcast(map_ptr, ir.PointerType())
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# Define function type for bpf_map_delete_elem
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fn_type = ir.FunctionType(
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ir.IntType(64), # Return type: int64 (status code)
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[ir.PointerType(), ir.PointerType()], # Args: (void*, void*)
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var_arg=False
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)
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fn_ptr_type = ir.PointerType(fn_type)
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fn_addr = ir.Constant(ir.IntType(
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64), BPFHelperID.BPF_MAP_DELETE_ELEM.value)
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fn_ptr = builder.inttoptr(fn_addr, fn_ptr_type)
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result = builder.call(fn_ptr, [map_void_ptr, key_ptr], tail=False)
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return result, None
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@HelperHandlerRegistry.register("pid")
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def bpf_get_current_pid_tgid_emitter(call, map_ptr, module, builder, func,
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local_sym_tab=None, struct_sym_tab=None,
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local_var_metadata=None):
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"""
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Emit LLVM IR for bpf_get_current_pid_tgid helper function call.
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"""
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# func is an arg to just have a uniform signature with other emitters
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helper_id = ir.Constant(ir.IntType(
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64), BPFHelperID.BPF_GET_CURRENT_PID_TGID.value)
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fn_type = ir.FunctionType(ir.IntType(64), [], var_arg=False)
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fn_ptr_type = ir.PointerType(fn_type)
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fn_ptr = builder.inttoptr(helper_id, fn_ptr_type)
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result = builder.call(fn_ptr, [], tail=False)
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# Extract the lower 32 bits (PID) using bitwise AND with 0xFFFFFFFF
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mask = ir.Constant(ir.IntType(64), 0xFFFFFFFF)
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pid = builder.and_(result, mask)
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return pid, ir.IntType(64)
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def bpf_perf_event_output_handler(call, map_ptr, module, builder, func,
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local_sym_tab=None, struct_sym_tab=None,
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local_var_metadata=None):
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if len(call.args) != 1:
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raise ValueError("Perf event output expects exactly one argument (data), got "
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f"{len(call.args)}")
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data_arg = call.args[0]
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ctx_ptr = func.args[0] # First argument to the function is ctx
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if isinstance(data_arg, ast.Name):
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data_name = data_arg.id
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if local_sym_tab and data_name in local_sym_tab:
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data_ptr = local_sym_tab[data_name][0]
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else:
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raise ValueError(
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f"Data variable {data_name} not found in local symbol table.")
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# Check is data_name is a struct
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if local_var_metadata and data_name in local_var_metadata:
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data_type = local_var_metadata[data_name]
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if data_type in struct_sym_tab:
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struct_info = struct_sym_tab[data_type]
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size_val = ir.Constant(ir.IntType(64), struct_info.size)
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else:
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raise ValueError(
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f"Struct type {data_type} for variable {data_name} not found in struct symbol table.")
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else:
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raise ValueError(
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f"Metadata for variable {data_name} not found in local variable metadata.")
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# BPF_F_CURRENT_CPU is -1 in 32 bit
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flags_val = ir.Constant(ir.IntType(64), 0xFFFFFFFF)
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map_void_ptr = builder.bitcast(map_ptr, ir.PointerType())
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data_void_ptr = builder.bitcast(data_ptr, ir.PointerType())
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fn_type = ir.FunctionType(
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ir.IntType(64),
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[ir.PointerType(ir.IntType(8)), ir.PointerType(), ir.IntType(64),
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ir.PointerType(), ir.IntType(64)],
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var_arg=False
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)
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fn_ptr_type = ir.PointerType(fn_type)
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# helper id
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fn_addr = ir.Constant(ir.IntType(
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64), BPFHelperID.BPF_PERF_EVENT_OUTPUT.value)
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fn_ptr = builder.inttoptr(fn_addr, fn_ptr_type)
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result = builder.call(
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fn_ptr, [ctx_ptr, map_void_ptr, flags_val, data_void_ptr, size_val], tail=False)
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return result, None
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else:
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raise NotImplementedError(
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"Only simple object names are supported as data in perf event output.")
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def handle_helper_call(call, module, builder, func,
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local_sym_tab=None, map_sym_tab=None,
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struct_sym_tab=None, local_var_metadata=None):
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print(local_var_metadata)
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if isinstance(call.func, ast.Name):
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func_name = call.func.id
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hdl_func = HelperHandlerRegistry.get_handler(func_name)
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if hdl_func:
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# it is not a map method call
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return hdl_func(call, None, module, builder, func, local_sym_tab, struct_sym_tab, local_var_metadata)
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else:
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raise NotImplementedError(
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f"Function {func_name} is not implemented as a helper function.")
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elif isinstance(call.func, ast.Attribute):
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# likely a map method call
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if isinstance(call.func.value, ast.Call) and isinstance(call.func.value.func, ast.Name):
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map_name = call.func.value.func.id
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method_name = call.func.attr
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if map_sym_tab and map_name in map_sym_tab:
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map_ptr = map_sym_tab[map_name]
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hdl_func = HelperHandlerRegistry.get_handler(method_name)
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if hdl_func:
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print(local_var_metadata)
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return hdl_func(
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call, map_ptr, module, builder, func, local_sym_tab, struct_sym_tab, local_var_metadata)
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else:
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raise NotImplementedError(
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f"Map method {method_name} is not implemented as a helper function.")
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else:
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raise ValueError(
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f"Map variable {map_name} not found in symbol tables.")
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elif isinstance(call.func.value, ast.Name):
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obj_name = call.func.value.id
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method_name = call.func.attr
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if map_sym_tab and obj_name in map_sym_tab:
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map_ptr = map_sym_tab[obj_name]
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hdl_func = HelperHandlerRegistry.get_handler(method_name)
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if hdl_func:
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return hdl_func(
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call, map_ptr, module, builder, func, local_sym_tab, struct_sym_tab, local_var_metadata)
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else:
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raise NotImplementedError(
|
|
f"Map method {method_name} is not implemented as a helper function.")
|
|
else:
|
|
raise ValueError(
|
|
f"Map variable {obj_name} not found in symbol tables.")
|
|
else:
|
|
raise NotImplementedError(
|
|
"Attribute not supported for map method calls.")
|
|
return None
|