Bytecode parity: align borrow optimization with CFG traversal (#7773)

* Align CFG cleanup bytecode with CPython

* Bytecode parity: fblock unwind, fstring join, folding, scope

- compile.rs: unwind_fblock_stack returns whether a finally ran so
  return-statement emission can adjust location handling; restructure
  try/except/finally cleanup to preserve or drop boundary NOPs based on
  whether the body falls through; rework f-string lowering with
  count/join helpers; remove the per-collection-type heuristic for
  AST-level folding and defer to flowgraph passes; add several folding
  helpers and a ComprehensionLoopControl enum.
- ir.rs: re-run unary/binop folding around tuple folding, add
  reorder_conditional_scope_exit_and_jump_back_blocks and several block
  classification helpers, add MAX_STR_SIZE, change is_exit_without_lineno
  to take the block list.
- symboltable.rs: in analyze_cells, remove names owned as cells in
  function-like scopes from the parent's free set; mark lambda scope
  type explicitly.

* Refine CFG scope-exit backedge ordering

.cspell.json

@@ -60,9 +60,11 @@
     "dedentations",
     "dedents",
     "deduped",
+    "deoptimized",
     "deoptimize",
     "emscripten",
     "excs",
+    "fnfe",
     "interps",
     "jitted",
     "jitting",
@@ -72,6 +74,9 @@
     "oparg",
     "opargs",
     "pyc",
+    "reborrow",
+    "reraises",
+    "reraising",
     "significand",
     "summands",
     "unraisable",

Lib/test/test_coroutines.py

@@ -2065,7 +2065,6 @@ class CoroutineTest(unittest.TestCase):
             run_async(f()),
             ([], {1: 1, 2: 2, 3: 3}))
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; AttributeError: __aiter__
     def test_nested_comp(self):
         async def run_list_inside_list():
             return [[i + j async for i in asynciter([1, 2])] for j in [10, 20]]

Lib/test/test_peepholer.py

@@ -243,7 +243,6 @@ class TestTranforms(BytecodeTestCase):
         self.assertTrue(g(4))
         self.check_lnotab(g)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON
     def test_constant_folding_small_int(self):
         tests = [
             ('(0, )[0]', 0),
@@ -278,7 +277,6 @@ class TestTranforms(BytecodeTestCase):
                     self.assertNotInBytecode(code, 'LOAD_SMALL_INT')
                 self.check_lnotab(code)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; AssertionError: 'UNARY_NEGATIVE' starts with 'UNARY_'
     def test_constant_folding_unaryop(self):
         intrinsic_positive = 5
         tests = [
@@ -324,7 +322,6 @@ class TestTranforms(BytecodeTestCase):
             self.assertNotStartsWith(instr.opname, 'UNARY_')
         self.check_lnotab(negzero)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; BINARY_OP               26 ([])
     def test_constant_folding_binop(self):
         tests = [
             ('1 + 2', 'NB_ADD', True, 'LOAD_SMALL_INT', 3),
@@ -672,7 +669,6 @@ class TestTranforms(BytecodeTestCase):
             return 6
         self.check_lnotab(f)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; AssertionError: 2 != 1
     def test_assignment_idiom_in_comprehensions(self):
         def listcomp():
             return [y for x in a for y in [f(x)]]

crates/codegen/src/symboltable.rs

@@ -591,6 +591,14 @@ impl SymbolTableAnalyzer {
         }
 
         // Analyze symbols in current scope
+        let remove_owned_cells_from_free = matches!(
+            symbol_table.typ,
+            CompilerScope::Function
+                | CompilerScope::AsyncFunction
+                | CompilerScope::Lambda
+                | CompilerScope::Comprehension
+                | CompilerScope::Annotation
+        );
         for symbol in symbol_table.symbols.values_mut() {
             self.analyze_symbol(
                 symbol,
@@ -600,6 +608,13 @@ impl SymbolTableAnalyzer {
                 class_entry,
             )?;
 
+            // CPython analyze_cells(): once a function-like scope owns a
+            // child-requested name as a cell, that name is no longer free in
+            // the enclosing scope.
+            if remove_owned_cells_from_free && symbol.scope == SymbolScope::Cell {
+                newfree.shift_remove(symbol.name.as_str());
+            }
+
             // Collect free variables from this scope
             if symbol.scope == SymbolScope::Free || symbol.flags.contains(SymbolFlags::FREE_CLASS) {
                 newfree.insert(symbol.name.clone());
@@ -2128,6 +2143,7 @@ impl SymbolTableBuilder {
                         false, // lambdas are never async
                         false, // don't skip defaults
                     )?;
+                    self.tables.last_mut().unwrap().typ = CompilerScope::Lambda;
                 } else {
                     self.enter_scope(
                         "lambda",

scripts/compare_bytecode.py

@@ -74,10 +74,16 @@ def _start_one(interpreter, targets, base_dir):
     output_file = None
     try:
         files_file = tempfile.NamedTemporaryFile(
-            mode="w", encoding="utf-8", delete=False, dir=PROJECT_ROOT
+            mode="w",
+            encoding="utf-8",
+            delete=False,
+            prefix="compare-bytecode-files-",
         )
         output_file = tempfile.NamedTemporaryFile(
-            mode="w", encoding="utf-8", delete=False, dir=PROJECT_ROOT
+            mode="w",
+            encoding="utf-8",
+            delete=False,
+            prefix="compare-bytecode-output-",
         )
         for _, path in targets:
             files_file.write(path)