Merge pull request #40 from pythonbpf/refactor_assign

Refactor assignment statement handling and the typing mechanism around it

Author: r41k0u

pythonbpf/allocation_pass.py

@@ -0,0 +1,191 @@
+import ast
+import logging
+
+from llvmlite import ir
+from dataclasses import dataclass
+from typing import Any
+from pythonbpf.helper import HelperHandlerRegistry
+from pythonbpf.type_deducer import ctypes_to_ir
+
+logger = logging.getLogger(__name__)
+
+
+@dataclass
+class LocalSymbol:
+    var: ir.AllocaInstr
+    ir_type: ir.Type
+    metadata: Any = None
+
+    def __iter__(self):
+        yield self.var
+        yield self.ir_type
+        yield self.metadata
+
+
+def _is_helper_call(call_node):
+    """Check if a call node is a BPF helper function call."""
+    if isinstance(call_node.func, ast.Name):
+        # Exclude print from requiring temps (handles f-strings differently)
+        func_name = call_node.func.id
+        return HelperHandlerRegistry.has_handler(func_name) and func_name != "print"
+
+    elif isinstance(call_node.func, ast.Attribute):
+        return HelperHandlerRegistry.has_handler(call_node.func.attr)
+
+    return False
+
+
+def handle_assign_allocation(builder, stmt, local_sym_tab, structs_sym_tab):
+    """Handle memory allocation for assignment statements."""
+
+    # Validate assignment
+    if len(stmt.targets) != 1:
+        logger.warning("Multi-target assignment not supported, skipping allocation")
+        return
+
+    target = stmt.targets[0]
+
+    # Skip non-name targets (e.g., struct field assignments)
+    if isinstance(target, ast.Attribute):
+        logger.debug(f"Struct field assignment to {target.attr}, no allocation needed")
+        return
+
+    if not isinstance(target, ast.Name):
+        logger.warning(f"Unsupported assignment target type: {type(target).__name__}")
+        return
+
+    var_name = target.id
+    rval = stmt.value
+
+    # Skip if already allocated
+    if var_name in local_sym_tab:
+        logger.debug(f"Variable {var_name} already allocated, skipping")
+        return
+
+    # Determine type and allocate based on rval
+    if isinstance(rval, ast.Call):
+        _allocate_for_call(builder, var_name, rval, local_sym_tab, structs_sym_tab)
+    elif isinstance(rval, ast.Constant):
+        _allocate_for_constant(builder, var_name, rval, local_sym_tab)
+    elif isinstance(rval, ast.BinOp):
+        _allocate_for_binop(builder, var_name, local_sym_tab)
+    else:
+        logger.warning(
+            f"Unsupported assignment value type for {var_name}: {type(rval).__name__}"
+        )
+
+
+def _allocate_for_call(builder, var_name, rval, local_sym_tab, structs_sym_tab):
+    """Allocate memory for variable assigned from a call."""
+
+    if isinstance(rval.func, ast.Name):
+        call_type = rval.func.id
+
+        # C type constructors
+        if call_type in ("c_int32", "c_int64", "c_uint32", "c_uint64"):
+            ir_type = ctypes_to_ir(call_type)
+            var = builder.alloca(ir_type, name=var_name)
+            var.align = ir_type.width // 8
+            local_sym_tab[var_name] = LocalSymbol(var, ir_type)
+            logger.info(f"Pre-allocated {var_name} as {call_type}")
+
+        # Helper functions
+        elif HelperHandlerRegistry.has_handler(call_type):
+            ir_type = ir.IntType(64)  # Assume i64 return type
+            var = builder.alloca(ir_type, name=var_name)
+            var.align = 8
+            local_sym_tab[var_name] = LocalSymbol(var, ir_type)
+            logger.info(f"Pre-allocated {var_name} for helper {call_type}")
+
+        # Deref function
+        elif call_type == "deref":
+            ir_type = ir.IntType(64)  # Assume i64 return type
+            var = builder.alloca(ir_type, name=var_name)
+            var.align = 8
+            local_sym_tab[var_name] = LocalSymbol(var, ir_type)
+            logger.info(f"Pre-allocated {var_name} for deref")
+
+        # Struct constructors
+        elif call_type in structs_sym_tab:
+            struct_info = structs_sym_tab[call_type]
+            var = builder.alloca(struct_info.ir_type, name=var_name)
+            local_sym_tab[var_name] = LocalSymbol(var, struct_info.ir_type, call_type)
+            logger.info(f"Pre-allocated {var_name} for struct {call_type}")
+
+        else:
+            logger.warning(f"Unknown call type for allocation: {call_type}")
+
+    elif isinstance(rval.func, ast.Attribute):
+        # Map method calls - need double allocation for ptr handling
+        _allocate_for_map_method(builder, var_name, local_sym_tab)
+
+    else:
+        logger.warning(f"Unsupported call function type for {var_name}")
+
+
+def _allocate_for_map_method(builder, var_name, local_sym_tab):
+    """Allocate memory for variable assigned from map method (double alloc)."""
+
+    # Main variable (pointer to pointer)
+    ir_type = ir.PointerType(ir.IntType(64))
+    var = builder.alloca(ir_type, name=var_name)
+    local_sym_tab[var_name] = LocalSymbol(var, ir_type)
+
+    # Temporary variable for computed values
+    tmp_ir_type = ir.IntType(64)
+    var_tmp = builder.alloca(tmp_ir_type, name=f"{var_name}_tmp")
+    local_sym_tab[f"{var_name}_tmp"] = LocalSymbol(var_tmp, tmp_ir_type)
+
+    logger.info(f"Pre-allocated {var_name} and {var_name}_tmp for map method")
+
+
+def _allocate_for_constant(builder, var_name, rval, local_sym_tab):
+    """Allocate memory for variable assigned from a constant."""
+
+    if isinstance(rval.value, bool):
+        ir_type = ir.IntType(1)
+        var = builder.alloca(ir_type, name=var_name)
+        var.align = 1
+        local_sym_tab[var_name] = LocalSymbol(var, ir_type)
+        logger.info(f"Pre-allocated {var_name} as bool")
+
+    elif isinstance(rval.value, int):
+        ir_type = ir.IntType(64)
+        var = builder.alloca(ir_type, name=var_name)
+        var.align = 8
+        local_sym_tab[var_name] = LocalSymbol(var, ir_type)
+        logger.info(f"Pre-allocated {var_name} as i64")
+
+    elif isinstance(rval.value, str):
+        ir_type = ir.PointerType(ir.IntType(8))
+        var = builder.alloca(ir_type, name=var_name)
+        var.align = 8
+        local_sym_tab[var_name] = LocalSymbol(var, ir_type)
+        logger.info(f"Pre-allocated {var_name} as string")
+
+    else:
+        logger.warning(
+            f"Unsupported constant type for {var_name}: {type(rval.value).__name__}"
+        )
+
+
+def _allocate_for_binop(builder, var_name, local_sym_tab):
+    """Allocate memory for variable assigned from a binary operation."""
+    ir_type = ir.IntType(64)  # Assume i64 result
+    var = builder.alloca(ir_type, name=var_name)
+    var.align = 8
+    local_sym_tab[var_name] = LocalSymbol(var, ir_type)
+    logger.info(f"Pre-allocated {var_name} for binop result")
+
+
+def allocate_temp_pool(builder, max_temps, local_sym_tab):
+    """Allocate the temporary scratch space pool for helper arguments."""
+    if max_temps == 0:
+        return
+
+    logger.info(f"Allocating temp pool of {max_temps} variables")
+    for i in range(max_temps):
+        temp_name = f"__helper_temp_{i}"
+        temp_var = builder.alloca(ir.IntType(64), name=temp_name)
+        temp_var.align = 8
+        local_sym_tab[temp_name] = LocalSymbol(temp_var, ir.IntType(64))

pythonbpf/assign_pass.py

@@ -0,0 +1,108 @@
+import ast
+import logging
+from llvmlite import ir
+from pythonbpf.expr import eval_expr
+
+logger = logging.getLogger(__name__)
+
+
+def handle_struct_field_assignment(
+    func, module, builder, target, rval, local_sym_tab, map_sym_tab, structs_sym_tab
+):
+    """Handle struct field assignment (obj.field = value)."""
+
+    var_name = target.value.id
+    field_name = target.attr
+
+    if var_name not in local_sym_tab:
+        logger.error(f"Variable '{var_name}' not found in symbol table")
+        return
+
+    struct_type = local_sym_tab[var_name].metadata
+    struct_info = structs_sym_tab[struct_type]
+
+    if field_name not in struct_info.fields:
+        logger.error(f"Field '{field_name}' not found in struct '{struct_type}'")
+        return
+
+    # Get field pointer and evaluate value
+    field_ptr = struct_info.gep(builder, local_sym_tab[var_name].var, field_name)
+    val = eval_expr(
+        func, module, builder, rval, local_sym_tab, map_sym_tab, structs_sym_tab
+    )
+
+    if val is None:
+        logger.error(f"Failed to evaluate value for {var_name}.{field_name}")
+        return
+
+    # TODO: Handle string assignment to char array (not a priority)
+    field_type = struct_info.field_type(field_name)
+    if isinstance(field_type, ir.ArrayType) and val[1] == ir.PointerType(ir.IntType(8)):
+        logger.warning(
+            f"String to char array assignment not implemented for {var_name}.{field_name}"
+        )
+        return
+
+    # Store the value
+    builder.store(val[0], field_ptr)
+    logger.info(f"Assigned to struct field {var_name}.{field_name}")
+
+
+def handle_variable_assignment(
+    func, module, builder, var_name, rval, local_sym_tab, map_sym_tab, structs_sym_tab
+):
+    """Handle single named variable assignment."""
+
+    if var_name not in local_sym_tab:
+        logger.error(f"Variable {var_name} not declared.")
+        return False
+
+    var_ptr = local_sym_tab[var_name].var
+    var_type = local_sym_tab[var_name].ir_type
+
+    # NOTE: Special case for struct initialization
+    if isinstance(rval, ast.Call) and isinstance(rval.func, ast.Name):
+        struct_name = rval.func.id
+        if struct_name in structs_sym_tab and len(rval.args) == 0:
+            struct_info = structs_sym_tab[struct_name]
+            ir_struct = struct_info.ir_type
+
+            builder.store(ir.Constant(ir_struct, None), var_ptr)
+            logger.info(f"Initialized struct {struct_name} for variable {var_name}")
+            return True
+
+    val_result = eval_expr(
+        func, module, builder, rval, local_sym_tab, map_sym_tab, structs_sym_tab
+    )
+    if val_result is None:
+        logger.error(f"Failed to evaluate value for {var_name}")
+        return False
+
+    val, val_type = val_result
+    logger.info(f"Evaluated value for {var_name}: {val} of type {val_type}, {var_type}")
+    if val_type != var_type:
+        if isinstance(val_type, ir.IntType) and isinstance(var_type, ir.IntType):
+            # Allow implicit int widening
+            if val_type.width < var_type.width:
+                val = builder.sext(val, var_type)
+                logger.info(f"Implicitly widened int for variable {var_name}")
+            elif val_type.width > var_type.width:
+                val = builder.trunc(val, var_type)
+                logger.info(f"Implicitly truncated int for variable {var_name}")
+        elif isinstance(val_type, ir.IntType) and isinstance(var_type, ir.PointerType):
+            # NOTE: This is assignment to a PTR_TO_MAP_VALUE_OR_NULL
+            logger.info(
+                f"Creating temporary variable for pointer assignment to {var_name}"
+            )
+            var_ptr_tmp = local_sym_tab[f"{var_name}_tmp"].var
+            builder.store(val, var_ptr_tmp)
+            val = var_ptr_tmp
+        else:
+            logger.error(
+                f"Type mismatch for variable {var_name}: {val_type} vs {var_type}"
+            )
+            return False
+
+    builder.store(val, var_ptr)
+    logger.info(f"Assigned value to variable {var_name}")
+    return True