Allocate hashmap lookup return vars based on the value type of said hashmap

pythonbpf/allocation_pass.py

@@ -7,6 +7,7 @@ from pythonbpf.helper import HelperHandlerRegistry
 from pythonbpf.vmlinux_parser.dependency_node import Field
 from .expr import VmlinuxHandlerRegistry
 from pythonbpf.type_deducer import ctypes_to_ir
+from pythonbpf.maps import BPFMapType
 
 logger = logging.getLogger(__name__)
 
@@ -25,7 +26,9 @@ def create_targets_and_rvals(stmt):
     return stmt.targets, [stmt.value]
 
 
-def handle_assign_allocation(builder, stmt, local_sym_tab, structs_sym_tab):
+def handle_assign_allocation(
+    builder, stmt, local_sym_tab, map_sym_tab, structs_sym_tab
+):
     """Handle memory allocation for assignment statements."""
 
     logger.info(f"Handling assignment for allocation: {ast.dump(stmt)}")
@@ -55,7 +58,9 @@ def handle_assign_allocation(builder, stmt, local_sym_tab, structs_sym_tab):
 
         # 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)
+            _allocate_for_call(
+                builder, var_name, rval, local_sym_tab, map_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):
@@ -74,7 +79,9 @@ def handle_assign_allocation(builder, stmt, local_sym_tab, structs_sym_tab):
             )
 
 
-def _allocate_for_call(builder, var_name, rval, local_sym_tab, structs_sym_tab):
+def _allocate_for_call(
+    builder, var_name, rval, local_sym_tab, map_sym_tab, structs_sym_tab
+):
     """Allocate memory for variable assigned from a call."""
 
     if isinstance(rval.func, ast.Name):
@@ -116,15 +123,74 @@ def _allocate_for_call(builder, var_name, rval, local_sym_tab, structs_sym_tab):
 
     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)
+        _allocate_for_map_method(
+            builder, var_name, rval, local_sym_tab, map_sym_tab, structs_sym_tab
+        )
 
     else:
         logger.warning(f"Unsupported call function type for {var_name}")
 
 
-def _allocate_for_map_method(builder, var_name, local_sym_tab):
+def _allocate_for_map_method(
+    builder, var_name, rval, local_sym_tab, map_sym_tab, structs_sym_tab
+):
     """Allocate memory for variable assigned from map method (double alloc)."""
 
+    map_name = rval.func.value.id
+    method_name = rval.func.attr
+
+    # NOTE: We will have to special case HashMap.lookup which returns a pointer to value type
+    # The value type can be a struct as well, so we need to handle that properly
+    # This special casing is not ideal, as over time other map methods may need similar handling
+    # But for now, we will just handle lookup specifically
+    if map_name not in map_sym_tab:
+        logger.error(f"Map '{map_name}' not found for allocation")
+        return
+
+    if method_name != "lookup":
+        # Fallback allocation for other map methods
+        _allocate_for_map_method_fallback(builder, var_name, local_sym_tab)
+        return
+
+    map_params = map_sym_tab[map_name].params
+    if map_params["type"] != BPFMapType.HASH:
+        logger.warning(
+            "Map method lookup used on non-hash map, using fallback allocation"
+        )
+        _allocate_for_map_method_fallback(builder, var_name, local_sym_tab)
+        return
+
+    value_type = map_params["value"]
+    # Determine IR type for value
+    if isinstance(value_type, str) and value_type in structs_sym_tab:
+        struct_info = structs_sym_tab[value_type]
+        value_ir_type = struct_info.ir_type
+    else:
+        value_ir_type = ctypes_to_ir(value_type)
+
+    if value_ir_type is None:
+        logger.warning(
+            f"Could not determine IR type for map value '{value_type}', using fallback allocation"
+        )
+        _allocate_for_map_method_fallback(builder, var_name, local_sym_tab)
+        return
+
+    # Main variable (pointer to pointer)
+    ir_type = ir.PointerType(value_ir_type)
+    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 = value_ir_type
+    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 lookup of type {value_ir_type}"
+    )
+
+
+def _allocate_for_map_method_fallback(builder, var_name, local_sym_tab):
+    """Fallback allocation for map method variable (i64* and i64**)."""
+
     # Main variable (pointer to pointer)
     ir_type = ir.PointerType(ir.IntType(64))
     var = builder.alloca(ir_type, name=var_name)
@@ -135,7 +201,9 @@ def _allocate_for_map_method(builder, var_name, local_sym_tab):
     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")
+    logger.info(
+        f"Pre-allocated {var_name} and {var_name}_tmp for map method (fallback)"
+    )
 
 
 def _allocate_for_constant(builder, var_name, rval, local_sym_tab):

pythonbpf/functions/functions_pass.py

@@ -147,7 +147,9 @@ def allocate_mem(
                 structs_sym_tab,
             )
         elif isinstance(stmt, ast.Assign):
-            handle_assign_allocation(builder, stmt, local_sym_tab, structs_sym_tab)
+            handle_assign_allocation(
+                builder, stmt, local_sym_tab, map_sym_tab, structs_sym_tab
+            )
 
     allocate_temp_pool(builder, max_temps_needed, local_sym_tab)
 

pythonbpf/maps/maps_pass.py

@@ -48,7 +48,7 @@ def create_bpf_map(module, map_name, map_params):
     map_global.align = 8
 
     logger.info(f"Created BPF map: {map_name} with params {map_params}")
-    return MapSymbol(type=map_params["type"], sym=map_global)
+    return MapSymbol(type=map_params["type"], sym=map_global, params=map_params)
 
 
 def _parse_map_params(rval, expected_args=None):

pythonbpf/maps/maps_utils.py

@@ -11,6 +11,7 @@ class MapSymbol:
 
     type: BPFMapType
     sym: ir.GlobalVariable
+    params: dict[str, Any] | None = None
 
 
 class MapProcessorRegistry: