GH-118926: Better distinguish between pointer and arrays in interpreter generator (GH-121496)

Lib/test/test_generated_cases.py

@@ -815,7 +815,6 @@ class TestGeneratedCases(unittest.TestCase):
         """
         self.run_cases_test(input, output)
 
-
     def test_deopt_and_exit(self):
         input = """
         pure op(OP, (arg1 -- out)) {
@@ -827,6 +826,49 @@ class TestGeneratedCases(unittest.TestCase):
         with self.assertRaises(Exception):
             self.run_cases_test(input, output)
 
+    def test_array_of_one(self):
+        input = """
+        inst(OP, (arg[1] -- out[1])) {
+            out[0] = arg[0];
+        }
+        """
+        output = """
+        TARGET(OP) {
+            frame->instr_ptr = next_instr;
+            next_instr += 1;
+            INSTRUCTION_STATS(OP);
+            _PyStackRef *arg;
+            _PyStackRef *out;
+            arg = &stack_pointer[-1];
+            out = &stack_pointer[-1];
+            out[0] = arg[0];
+            DISPATCH();
+        }
+        """
+        self.run_cases_test(input, output)
+
+    def test_pointer_to_stackref(self):
+        input = """
+        inst(OP, (arg: _PyStackRef * -- out)) {
+            out = *arg;
+        }
+        """
+        output = """
+        TARGET(OP) {
+            frame->instr_ptr = next_instr;
+            next_instr += 1;
+            INSTRUCTION_STATS(OP);
+            _PyStackRef *arg;
+            _PyStackRef out;
+            arg = (_PyStackRef *)stack_pointer[-1].bits;
+            out = *arg;
+            stack_pointer[-1] = out;
+            DISPATCH();
+        }
+        """
+        self.run_cases_test(input, output)
+
+
 class TestGeneratedAbstractCases(unittest.TestCase):
     def setUp(self) -> None:
         super().setUp()

Tools/cases_generator/analyzer.py

@@ -106,13 +106,15 @@ class StackItem:
 
     def __str__(self) -> str:
         cond = f" if ({self.condition})" if self.condition else ""
-        size = f"[{self.size}]" if self.size != "1" else ""
+        size = f"[{self.size}]" if self.size else ""
         type = "" if self.type is None else f"{self.type} "
         return f"{type}{self.name}{size}{cond} {self.peek}"
 
     def is_array(self) -> bool:
-        return self.type == "_PyStackRef *"
+        return self.size != ""
 
+    def get_size(self) -> str:
+        return self.size if self.size else "1"
 
 @dataclass
 class StackEffect:
@@ -293,7 +295,7 @@ def convert_stack_item(item: parser.StackEffect, replace_op_arg_1: str | None) -
     if replace_op_arg_1 and OPARG_AND_1.match(item.cond):
         cond = replace_op_arg_1
     return StackItem(
-        item.name, item.type, cond, (item.size or "1")
+        item.name, item.type, cond, item.size
     )
 
 def analyze_stack(op: parser.InstDef | parser.Pseudo, replace_op_arg_1: str | None = None) -> StackEffect:

Tools/cases_generator/generators_common.py

@@ -5,9 +5,10 @@ from analyzer import (
     Instruction,
     Uop,
     Properties,
+    StackItem,
 )
 from cwriter import CWriter
-from typing import Callable, Mapping, TextIO, Iterator
+from typing import Callable, Mapping, TextIO, Iterator, Tuple
 from lexer import Token
 from stack import Stack
 
@@ -24,6 +25,15 @@ def root_relative_path(filename: str) -> str:
         return filename
 
 
+def type_and_null(var: StackItem) -> Tuple[str, str]:
+    if var.type:
+        return var.type, "NULL"
+    elif var.is_array():
+        return "_PyStackRef *", "NULL"
+    else:
+        return "_PyStackRef", "PyStackRef_NULL"
+
+
 def write_header(
     generator: str, sources: list[str], outfile: TextIO, comment: str = "//"
 ) -> None:
@@ -126,7 +136,7 @@ def replace_decrefs(
     for var in uop.stack.inputs:
         if var.name == "unused" or var.name == "null" or var.peek:
             continue
-        if var.size != "1":
+        if var.size:
             out.emit(f"for (int _i = {var.size}; --_i >= 0;) {{\n")
             out.emit(f"PyStackRef_CLOSE({var.name}[_i]);\n")
             out.emit("}\n")

Tools/cases_generator/parsing.py

@@ -285,7 +285,6 @@ class Parser(PLexer):
                 if not (size := self.expression()):
                     raise self.make_syntax_error("Expected expression")
                 self.require(lx.RBRACKET)
-                type_text = "_PyStackRef *"
                 size_text = size.text.strip()
             return StackEffect(tkn.text, type_text, cond_text, size_text)
         return None

Tools/cases_generator/stack.py

@@ -28,14 +28,15 @@ def var_size(var: StackItem) -> str:
         if var.condition == "0":
             return "0"
         elif var.condition == "1":
-            return var.size
+            return var.get_size()
-        elif var.condition == "oparg & 1" and var.size == "1":
+        elif var.condition == "oparg & 1" and not var.size:
             return f"({var.condition})"
         else:
-            return f"(({var.condition}) ? {var.size} : 0)"
+            return f"(({var.condition}) ? {var.get_size()} : 0)"
-    else:
+    elif var.size:
         return var.size
-
+    else:
+        return "1"
 
 @dataclass
 class StackOffset:

Tools/cases_generator/tier1_generator.py

@@ -13,12 +13,14 @@ from analyzer import (
     analyze_files,
     Skip,
     analysis_error,
+    StackItem,
 )
 from generators_common import (
     DEFAULT_INPUT,
     ROOT,
     write_header,
     emit_tokens,
+    type_and_null,
 )
 from cwriter import CWriter
 from typing import TextIO
@@ -38,19 +40,16 @@ def declare_variables(inst: Instruction, out: CWriter) -> None:
             for var in reversed(uop.stack.inputs):
                 if var.name not in variables:
                     variables.add(var.name)
-                    type, null = (var.type, "NULL") if var.type else ("_PyStackRef", "PyStackRef_NULL")
+                    type, null = type_and_null(var)
                     space = " " if type[-1].isalnum() else ""
                     if var.condition:
                         out.emit(f"{type}{space}{var.name} = {null};\n")
                     else:
-                        if var.is_array():
+                        out.emit(f"{type}{space}{var.name};\n")
-                            out.emit(f"{var.type}{space}{var.name};\n")
-                        else:
-                            out.emit(f"{type}{space}{var.name};\n")
             for var in uop.stack.outputs:
                 if var.name not in variables:
                     variables.add(var.name)
-                    type, null = (var.type, "NULL") if var.type else ("_PyStackRef", "PyStackRef_NULL")
+                    type, null = type_and_null(var)
                     space = " " if type[-1].isalnum() else ""
                     if var.condition:
                         out.emit(f"{type}{space}{var.name} = {null};\n")

Tools/cases_generator/tier2_generator.py

@@ -20,6 +20,7 @@ from generators_common import (
     emit_tokens,
     emit_to,
     REPLACEMENT_FUNCTIONS,
+    type_and_null,
 )
 from cwriter import CWriter
 from typing import TextIO, Iterator
@@ -35,7 +36,7 @@ def declare_variable(
     if var.name in variables:
         return
     variables.add(var.name)
-    type, null = (var.type, "NULL") if var.type else ("_PyStackRef", "PyStackRef_NULL")
+    type, null = type_and_null(var)
     space = " " if type[-1].isalnum() else ""
     if var.condition:
         out.emit(f"{type}{space}{var.name} = {null};\n")