add callsite to calloca

vyper/codegen/context.py

@@ -35,6 +35,9 @@ class Alloca:
 
     _id: int
 
+    # special metadata for calloca. hint for venom to tie calloca to call site.
+    _callsite: Optional[str] = None
+
     def __post_init__(self):
         assert self.typ.memory_bytes_required == self.size
 

vyper/codegen/self_call.py

@@ -1,4 +1,5 @@
 import copy
+import dataclasses
 
 from vyper.codegen.core import _freshname, eval_once_check, make_setter
 from vyper.codegen.ir_node import IRnode
@@ -81,6 +82,7 @@ def ir_for_self_call(stmt_expr, context):
                 continue
             newname = var.pos.replace("$palloca", "$calloca")
             var.pos = newname
+            alloca = dataclasses.replace(alloca, _callsite=return_label)
             irnode = var.as_ir_node()
             irnode.passthrough_metadata["alloca"] = alloca
             arg_items.append(irnode)

vyper/venom/ir_node_to_venom.py

@@ -551,8 +551,10 @@ def emit_body_blocks():
         elif ir.value.startswith("$calloca"):
             alloca = ir.passthrough_metadata["alloca"]
             if alloca._id not in _alloca_table:
+                assert alloca._callsite is not None
+                callsite = IRLabel(alloca._callsite)
                 ptr = fn.get_basic_block().append_instruction(
-                    "calloca", alloca.offset, alloca.size, alloca._id
+                    "calloca", alloca.offset, alloca.size, alloca._id, callsite
                 )
                 _alloca_table[alloca._id] = ptr
             return _alloca_table[alloca._id]