Merge pull request #19 from pythonbpf/fix-expr

Refactor expr_pass

pythonbpf/binary_ops.py

@@ -8,68 +8,59 @@ logger: Logger = logging.getLogger(__name__)
 
 def recursive_dereferencer(var, builder):
     """dereference until primitive type comes out"""
-    if var.type == ir.PointerType(ir.PointerType(ir.IntType(64))):
+    # TODO: Not worrying about stack overflow for now
+    if isinstance(var.type, ir.PointerType):
         a = builder.load(var)
         return recursive_dereferencer(a, builder)
-    elif var.type == ir.PointerType(ir.IntType(64)):
-        a = builder.load(var)
-        return recursive_dereferencer(a, builder)
-    elif var.type == ir.IntType(64):
+    elif isinstance(var.type, ir.IntType):
         return var
     else:
         raise TypeError(f"Unsupported type for dereferencing: {var.type}")
 
 
-def handle_binary_op(rval, module, builder, var_name, local_sym_tab, map_sym_tab, func):
-    logger.info(f"module {module}")
-    left = rval.left
-    right = rval.right
+def get_operand_value(operand, module, builder, local_sym_tab):
+    """Extract the value from an operand, handling variables and constants."""
+    if isinstance(operand, ast.Name):
+        if operand.id in local_sym_tab:
+            return recursive_dereferencer(local_sym_tab[operand.id].var, builder)
+        raise ValueError(f"Undefined variable: {operand.id}")
+    elif isinstance(operand, ast.Constant):
+        if isinstance(operand.value, int):
+            return ir.Constant(ir.IntType(64), operand.value)
+        raise TypeError(f"Unsupported constant type: {type(operand.value)}")
+    elif isinstance(operand, ast.BinOp):
+        return handle_binary_op_impl(operand, module, builder, local_sym_tab)
+    raise TypeError(f"Unsupported operand type: {type(operand)}")
+
+
+def handle_binary_op_impl(rval, module, builder, local_sym_tab):
     op = rval.op
-
-    # Handle left operand
-    if isinstance(left, ast.Name):
-        if left.id in local_sym_tab:
-            left = recursive_dereferencer(local_sym_tab[left.id].var, builder)
-        else:
-            raise SyntaxError(f"Undefined variable: {left.id}")
-    elif isinstance(left, ast.Constant):
-        left = ir.Constant(ir.IntType(64), left.value)
-    else:
-        raise SyntaxError("Unsupported left operand type")
-
-    if isinstance(right, ast.Name):
-        if right.id in local_sym_tab:
-            right = recursive_dereferencer(local_sym_tab[right.id].var, builder)
-        else:
-            raise SyntaxError(f"Undefined variable: {right.id}")
-    elif isinstance(right, ast.Constant):
-        right = ir.Constant(ir.IntType(64), right.value)
-    else:
-        raise SyntaxError("Unsupported right operand type")
-
+    left = get_operand_value(rval.left, module, builder, local_sym_tab)
+    right = get_operand_value(rval.right, module, builder, local_sym_tab)
     logger.info(f"left is {left}, right is {right}, op is {op}")
 
-    if isinstance(op, ast.Add):
-        builder.store(builder.add(left, right), local_sym_tab[var_name].var)
-    elif isinstance(op, ast.Sub):
-        builder.store(builder.sub(left, right), local_sym_tab[var_name].var)
-    elif isinstance(op, ast.Mult):
-        builder.store(builder.mul(left, right), local_sym_tab[var_name].var)
-    elif isinstance(op, ast.Div):
-        builder.store(builder.sdiv(left, right), local_sym_tab[var_name].var)
-    elif isinstance(op, ast.Mod):
-        builder.store(builder.srem(left, right), local_sym_tab[var_name].var)
-    elif isinstance(op, ast.LShift):
-        builder.store(builder.shl(left, right), local_sym_tab[var_name].var)
-    elif isinstance(op, ast.RShift):
-        builder.store(builder.lshr(left, right), local_sym_tab[var_name].var)
-    elif isinstance(op, ast.BitOr):
-        builder.store(builder.or_(left, right), local_sym_tab[var_name].var)
-    elif isinstance(op, ast.BitXor):
-        builder.store(builder.xor(left, right), local_sym_tab[var_name].var)
-    elif isinstance(op, ast.BitAnd):
-        builder.store(builder.and_(left, right), local_sym_tab[var_name].var)
-    elif isinstance(op, ast.FloorDiv):
-        builder.store(builder.udiv(left, right), local_sym_tab[var_name].var)
+    # Map AST operation nodes to LLVM IR builder methods
+    op_map = {
+        ast.Add: builder.add,
+        ast.Sub: builder.sub,
+        ast.Mult: builder.mul,
+        ast.Div: builder.sdiv,
+        ast.Mod: builder.srem,
+        ast.LShift: builder.shl,
+        ast.RShift: builder.lshr,
+        ast.BitOr: builder.or_,
+        ast.BitXor: builder.xor,
+        ast.BitAnd: builder.and_,
+        ast.FloorDiv: builder.udiv,
+    }
+
+    if type(op) in op_map:
+        result = op_map[type(op)](left, right)
+        return result
     else:
         raise SyntaxError("Unsupported binary operation")
+
+
+def handle_binary_op(rval, module, builder, var_name, local_sym_tab):
+    result = handle_binary_op_impl(rval, module, builder, local_sym_tab)
+    builder.store(result, local_sym_tab[var_name].var)

pythonbpf/expr_pass.py

@@ -2,10 +2,92 @@ import ast
 from llvmlite import ir
 from logging import Logger
 import logging
+from typing import Dict
 
 logger: Logger = logging.getLogger(__name__)
 
 
+def _handle_name_expr(expr: ast.Name, local_sym_tab: Dict, builder: ir.IRBuilder):
+    """Handle ast.Name expressions."""
+    if expr.id in local_sym_tab:
+        var = local_sym_tab[expr.id].var
+        val = builder.load(var)
+        return val, local_sym_tab[expr.id].ir_type
+    else:
+        logger.info(f"Undefined variable {expr.id}")
+        return None
+
+
+def _handle_constant_expr(expr: ast.Constant):
+    """Handle ast.Constant expressions."""
+    if isinstance(expr.value, int):
+        return ir.Constant(ir.IntType(64), expr.value), ir.IntType(64)
+    elif isinstance(expr.value, bool):
+        return ir.Constant(ir.IntType(1), int(expr.value)), ir.IntType(1)
+    else:
+        logger.info("Unsupported constant type")
+        return None
+
+
+def _handle_attribute_expr(
+    expr: ast.Attribute,
+    local_sym_tab: Dict,
+    structs_sym_tab: Dict,
+    builder: ir.IRBuilder,
+):
+    """Handle ast.Attribute expressions for struct field access."""
+    if isinstance(expr.value, ast.Name):
+        var_name = expr.value.id
+        attr_name = expr.attr
+        if var_name in local_sym_tab:
+            var_ptr, var_type, var_metadata = local_sym_tab[var_name]
+            logger.info(f"Loading attribute {attr_name} from variable {var_name}")
+            logger.info(f"Variable type: {var_type}, Variable ptr: {var_ptr}")
+
+            metadata = structs_sym_tab[var_metadata]
+            if attr_name in metadata.fields:
+                gep = metadata.gep(builder, var_ptr, attr_name)
+                val = builder.load(gep)
+                field_type = metadata.field_type(attr_name)
+                return val, field_type
+    return None
+
+
+def _handle_deref_call(expr: ast.Call, local_sym_tab: Dict, builder: ir.IRBuilder):
+    """Handle deref function calls."""
+    logger.info(f"Handling deref {ast.dump(expr)}")
+    if len(expr.args) != 1:
+        logger.info("deref takes exactly one argument")
+        return None
+
+    arg = expr.args[0]
+    if (
+        isinstance(arg, ast.Call)
+        and isinstance(arg.func, ast.Name)
+        and arg.func.id == "deref"
+    ):
+        logger.info("Multiple deref not supported")
+        return None
+
+    if isinstance(arg, ast.Name):
+        if arg.id in local_sym_tab:
+            arg_ptr = local_sym_tab[arg.id].var
+        else:
+            logger.info(f"Undefined variable {arg.id}")
+            return None
+    else:
+        logger.info("Unsupported argument type for deref")
+        return None
+
+    if arg_ptr is None:
+        logger.info("Failed to evaluate deref argument")
+        return None
+
+    # Load the value from pointer
+    val = builder.load(arg_ptr)
+    return val, local_sym_tab[arg.id].ir_type
+
+
 def eval_expr(
     func,
     module,
@@ -17,64 +99,28 @@ def eval_expr(
 ):
     logger.info(f"Evaluating expression: {ast.dump(expr)}")
     if isinstance(expr, ast.Name):
-        if expr.id in local_sym_tab:
-            var = local_sym_tab[expr.id].var
-            val = builder.load(var)
-            return val, local_sym_tab[expr.id].ir_type  # return value and type
-        else:
-            logger.info(f"Undefined variable {expr.id}")
-            return None
+        return _handle_name_expr(expr, local_sym_tab, builder)
     elif isinstance(expr, ast.Constant):
-        if isinstance(expr.value, int):
-            return ir.Constant(ir.IntType(64), expr.value), ir.IntType(64)
-        elif isinstance(expr.value, bool):
-            return ir.Constant(ir.IntType(1), int(expr.value)), ir.IntType(1)
-        else:
-            logger.info("Unsupported constant type")
-            return None
+        return _handle_constant_expr(expr)
     elif isinstance(expr, ast.Call):
+        if isinstance(expr.func, ast.Name) and expr.func.id == "deref":
+            return _handle_deref_call(expr, local_sym_tab, builder)
+
         # delayed import to avoid circular dependency
         from pythonbpf.helper import HelperHandlerRegistry, handle_helper_call
 
-        if isinstance(expr.func, ast.Name):
-            # check deref
-            if expr.func.id == "deref":
-                logger.info(f"Handling deref {ast.dump(expr)}")
-                if len(expr.args) != 1:
-                    logger.info("deref takes exactly one argument")
-                    return None
-                arg = expr.args[0]
-                if (
-                    isinstance(arg, ast.Call)
-                    and isinstance(arg.func, ast.Name)
-                    and arg.func.id == "deref"
-                ):
-                    logger.info("Multiple deref not supported")
-                    return None
-                if isinstance(arg, ast.Name):
-                    if arg.id in local_sym_tab:
-                        arg = local_sym_tab[arg.id].var
-                    else:
-                        logger.info(f"Undefined variable {arg.id}")
-                        return None
-                if arg is None:
-                    logger.info("Failed to evaluate deref argument")
-                    return None
-                # Since we are handling only name case, directly take type from sym tab
-                val = builder.load(arg)
-                return val, local_sym_tab[expr.args[0].id].ir_type
-
-            # check for helpers
-            if HelperHandlerRegistry.has_handler(expr.func.id):
-                return handle_helper_call(
-                    expr,
-                    module,
-                    builder,
-                    func,
-                    local_sym_tab,
-                    map_sym_tab,
-                    structs_sym_tab,
-                )
+        if isinstance(expr.func, ast.Name) and HelperHandlerRegistry.has_handler(
+            expr.func.id
+        ):
+            return handle_helper_call(
+                expr,
+                module,
+                builder,
+                func,
+                local_sym_tab,
+                map_sym_tab,
+                structs_sym_tab,
+            )
         elif isinstance(expr.func, ast.Attribute):
             logger.info(f"Handling method call: {ast.dump(expr.func)}")
             if isinstance(expr.func.value, ast.Call) and isinstance(
@@ -106,19 +152,7 @@ def eval_expr(
                             structs_sym_tab,
                         )
     elif isinstance(expr, ast.Attribute):
-        if isinstance(expr.value, ast.Name):
-            var_name = expr.value.id
-            attr_name = expr.attr
-            if var_name in local_sym_tab:
-                var_ptr, var_type, var_metadata = local_sym_tab[var_name]
-                logger.info(f"Loading attribute {attr_name} from variable {var_name}")
-                logger.info(f"Variable type: {var_type}, Variable ptr: {var_ptr}")
-                metadata = structs_sym_tab[var_metadata]
-                if attr_name in metadata.fields:
-                    gep = metadata.gep(builder, var_ptr, attr_name)
-                    val = builder.load(gep)
-                    field_type = metadata.field_type(attr_name)
-                    return val, field_type
+        return _handle_attribute_expr(expr, local_sym_tab, structs_sym_tab, builder)
     logger.info("Unsupported expression evaluation")
     return None
 

pythonbpf/functions_pass.py

@@ -233,9 +233,7 @@ def handle_assign(
         else:
             logger.info("Unsupported assignment call function type")
     elif isinstance(rval, ast.BinOp):
-        handle_binary_op(
-            rval, module, builder, var_name, local_sym_tab, map_sym_tab, func
-        )
+        handle_binary_op(rval, module, builder, var_name, local_sym_tab)
     else:
         logger.info("Unsupported assignment value type")
 

tests/passing_tests/binops.py

@@ -3,9 +3,9 @@ from ctypes import c_void_p, c_int64
 
 
 @bpf
-@section("sometag1")
+@section("tracepoint/syscalls/sys_enter_sync")
 def sometag(ctx: c_void_p) -> c_int64:
-    a = 1 + 2 + 1
+    a = 1 + 2 + 1 + 12 + 13
     print(f"{a}")
     return c_int64(0)
 

tests/passing_tests/binops1.py

@@ -3,11 +3,12 @@ from ctypes import c_void_p, c_int64
 
 
 @bpf
-@section("sometag1")
+@section("tracepoint/syscalls/sys_enter_sync")
 def sometag(ctx: c_void_p) -> c_int64:
     b = 1 + 2
     a = 1 + b
-    return c_int64(a)
+    print(f"{a}")
+    return c_int64(0)
 
 
 @bpf