gh-98831: Finish the UNPACK_SEQUENCE family (#101666)

New generator feature: Generate useful glue for output arrays, so you can just write values to the output array (no bounds checking). Rewrote UNPACK_SEQUENCE_TWO_TUPLE to use this, and also UNPACK_SEQUENCE_{TUPLE,LIST}.

2 files changed, 26 insertions, 18 deletions

diff --git a/Tools/cases_generator/generate_cases.py b/Tools/cases_generator/generate_cases.py
index 3925583b40e..4f94b48d114 100644
--- a/Tools/cases_generator/generate_cases.py
+++ b/Tools/cases_generator/generate_cases.py
@@ -180,11 +180,8 @@ class Formatter:
                 stmt = f"if ({src.cond}) {{ {stmt} }}"
             self.emit(stmt)
         elif m := re.match(r"^&PEEK\(.*\)$", dst.name):
-            # NOTE: MOVE_ITEMS() does not actually exist.
-            # The only supported output array forms are:
-            # - unused[...]
-            # - X[...] where X[...] matches an input array exactly
-            self.emit(f"MOVE_ITEMS({dst.name}, {src.name}, {src.size});")
+            # The user code is responsible for writing to the output array.
+            pass
         elif m := re.match(r"^REG\(oparg(\d+)\)$", dst.name):
             self.emit(f"Py_XSETREF({dst.name}, {cast}{src.name});")
         else:
@@ -309,10 +306,24 @@ class Instruction:
                 out.declare(ieffect, src)
 
         # Write output stack effect variable declarations
+        isize = string_effect_size(list_effect_size(self.input_effects))
         input_names = {ieffect.name for ieffect in self.input_effects}
-        for oeffect in self.output_effects:
+        for i, oeffect in enumerate(self.output_effects):
             if oeffect.name not in input_names:
-                out.declare(oeffect, None)
+                if oeffect.size:
+                    osize = string_effect_size(
+                        list_effect_size([oeff for oeff in self.output_effects[:i]])
+                    )
+                    offset = "stack_pointer"
+                    if isize != osize:
+                        if isize != "0":
+                            offset += f" - ({isize})"
+                        if osize != "0":
+                            offset += f" + {osize}"
+                    src = StackEffect(offset, "PyObject **")
+                    out.declare(oeffect, src)
+                else:
+                    out.declare(oeffect, None)
 
         # out.emit(f"JUMPBY(OPSIZE({self.inst.name}) - 1);")
 
diff --git a/Tools/cases_generator/test_generator.py b/Tools/cases_generator/test_generator.py
index 9df97d24ab6..0c3d04b45dd 100644
--- a/Tools/cases_generator/test_generator.py
+++ b/Tools/cases_generator/test_generator.py
@@ -424,20 +424,18 @@ def test_array_input():
 
 def test_array_output():
     input = """
-        inst(OP, (-- below, values[oparg*3], above)) {
-            spam();
+        inst(OP, (unused, unused -- below, values[oparg*3], above)) {
+            spam(values, oparg);
         }
     """
     output = """
         TARGET(OP) {
             PyObject *below;
-            PyObject **values;
+            PyObject **values = stack_pointer - (2) + 1;
             PyObject *above;
-            spam();
-            STACK_GROW(2);
+            spam(values, oparg);
             STACK_GROW(oparg*3);
             POKE(1, above);
-            MOVE_ITEMS(&PEEK(1 + oparg*3), values, oparg*3);
             POKE(2 + oparg*3, below);
             DISPATCH();
         }
@@ -446,18 +444,17 @@ def test_array_output():
 
 def test_array_input_output():
     input = """
-        inst(OP, (below, values[oparg] -- values[oparg], above)) {
-            spam();
+        inst(OP, (values[oparg] -- values[oparg], above)) {
+            spam(values, oparg);
         }
     """
     output = """
         TARGET(OP) {
             PyObject **values = &PEEK(oparg);
-            PyObject *below = PEEK(1 + oparg);
             PyObject *above;
-            spam();
+            spam(values, oparg);
+            STACK_GROW(1);
             POKE(1, above);
-            MOVE_ITEMS(&PEEK(1 + oparg), values, oparg);
             DISPATCH();
         }
     """