cleanup: address API cleanup review comments

devdocs/porting-guide.md

@@ -632,7 +632,7 @@ Constant* dataArr = ConstantDataArray::get(ctx, arrayRef);
 
 **Python:**
 ```python
-arr = llvm.array_const(elem_ty, [elem1, elem2])
+arr = elem_ty.array_const([elem1, elem2])
 data_arr = elem_ty.array_const(string_data)
 ```
 
@@ -645,7 +645,7 @@ Constant* s = ConstantStruct::get(structTy, {field1, field2});
 
 **Python:**
 ```python
-s = llvm.named_struct_const(struct_ty, [field1, field2])
+s = struct_ty.named_struct_const([field1, field2])
 ```
 
 ---

tests/regressions/test_ollvm_obf_pipeline.py

@@ -3,7 +3,12 @@
 from pathlib import Path
 import llvm
 
-from tools.obfuscation.ollvm_obf import PipelineOptions, apply_pipeline, main
+from tools.obfuscation.ollvm_obf import (
+    PipelineOptions,
+    apply_pipeline,
+    main,
+    poison_internal_uses_before_erasing,
+)
 
 
 def test_ollvm_if_convert_eliminates_phi_and_introduces_select() -> None:
@@ -218,6 +223,37 @@ def test_ollvm_loop_to_recursion_smoke() -> None:
 
 
 
+def test_loop_to_recursion_rejects_unresolved_escaping_values() -> None:
+    ir = r'''
+    define i32 @f(i32 %x) {
+    entry:
+      br label %body
+    body:
+      %v = add i32 %x, 1
+      br label %exit
+    exit:
+      %use = add i32 %v, 2
+      ret i32 %use
+    }
+    '''
+
+    with llvm.create_context() as ctx:
+        with ctx.parse_ir(ir) as mod:
+            fn = mod.get_function("f")
+            assert fn is not None
+            body = next(bb for bb in fn.basic_blocks if bb.name == "body")
+            inst = body.first_instruction
+            assert inst is not None
+            try:
+                poison_internal_uses_before_erasing(inst, {body})
+            except RuntimeError as exc:
+                assert "unresolved external use" in str(exc)
+                assert "poison" in str(exc)
+            else:
+                raise AssertionError("expected unresolved external use to be rejected")
+            assert "poison" not in mod.to_string()
+
+
 def test_ollvm_loop_to_recursion_skips_multi_exit_loop() -> None:
     ir = r'''
     define i32 @f(i32 %n) {

tools/obfuscation/ollvm_obf.py

@@ -246,9 +246,21 @@ def replace_all_uses_with_if(
         user.replace_uses_of_with(old_value, new_value)
 
 
-def poison_uses_before_erasing(inst: llvm.Value) -> None:
-    if inst.type.kind != llvm.TypeKind.Void and inst.has_uses:
-        inst.replace_all_uses_with(inst.type.poison())
+def poison_internal_uses_before_erasing(
+    inst: llvm.Value,
+    doomed_blocks: set[llvm.BasicBlock],
+) -> None:
+    if inst.type.kind == llvm.TypeKind.Void or not inst.has_uses:
+        return
+
+    for user in inst.users:
+        if not user.is_instruction or user.block not in doomed_blocks:
+            raise RuntimeError(
+                "loop-to-recursion left an unresolved external use of "
+                f"{inst.name or '<unnamed>'}; refusing to rewrite it to poison"
+            )
+
+    inst.replace_all_uses_with(inst.type.poison())
 
 
 def position_after_instruction(builder: llvm.Builder, inst: llvm.Value) -> None:
@@ -2512,7 +2524,7 @@ def loop_to_recursion_module(mod: llvm.Module, seed: int, cfg: FilterConfig) ->
             for inst in bb.instructions
         ]
         for inst in loop_instructions:
-            poison_uses_before_erasing(inst)
+            poison_internal_uses_before_erasing(inst, loop_block_set)
         for bb in loop_blocks:
             for inst in reversed(list(bb.instructions)):
                 inst.erase_from_parent()