GH-125837: Split `LOAD_CONST` into three. (GH-125972)

* Add LOAD_CONST_IMMORTAL opcode

* Add LOAD_SMALL_INT opcode

* Remove RETURN_CONST opcode

1 files changed, 32 insertions, 16 deletions

diff --git a/Lib/test/test_peepholer.py b/Lib/test/test_peepholer.py
index b143f3d..c7da151 100644
--- a/Lib/test/test_peepholer.py
+++ b/Lib/test/test_peepholer.py
@@ -114,7 +114,7 @@ class TestTranforms(BytecodeTestCase):
             return None
 
         self.assertNotInBytecode(f, 'LOAD_GLOBAL')
-        self.assertInBytecode(f, 'RETURN_CONST', None)
+        self.assertInBytecode(f, 'LOAD_CONST', None)
         self.check_lnotab(f)
 
     def test_while_one(self):
@@ -131,7 +131,7 @@ class TestTranforms(BytecodeTestCase):
 
     def test_pack_unpack(self):
         for line, elem in (
-            ('a, = a,', 'RETURN_CONST',),
+            ('a, = a,', 'LOAD_CONST',),
             ('a, b = a, b', 'SWAP',),
             ('a, b, c = a, b, c', 'SWAP',),
             ):
@@ -162,7 +162,7 @@ class TestTranforms(BytecodeTestCase):
         # One LOAD_CONST for the tuple, one for the None return value
         load_consts = [instr for instr in dis.get_instructions(code)
                               if instr.opname == 'LOAD_CONST']
-        self.assertEqual(len(load_consts), 1)
+        self.assertEqual(len(load_consts), 2)
         self.check_lnotab(code)
 
         # Bug 1053819:  Tuple of constants misidentified when presented with:
@@ -248,14 +248,17 @@ class TestTranforms(BytecodeTestCase):
             ):
             with self.subTest(line=line):
                 code = compile(line, '', 'single')
-                self.assertInBytecode(code, 'LOAD_CONST', elem)
+                if isinstance(elem, int):
+                    self.assertInBytecode(code, 'LOAD_SMALL_INT', elem)
+                else:
+                    self.assertInBytecode(code, 'LOAD_CONST', elem)
                 for instr in dis.get_instructions(code):
                     self.assertFalse(instr.opname.startswith('BINARY_'))
                 self.check_lnotab(code)
 
         # Verify that unfoldables are skipped
         code = compile('a=2+"b"', '', 'single')
-        self.assertInBytecode(code, 'LOAD_CONST', 2)
+        self.assertInBytecode(code, 'LOAD_SMALL_INT', 2)
         self.assertInBytecode(code, 'LOAD_CONST', 'b')
         self.check_lnotab(code)
 
@@ -307,7 +310,10 @@ class TestTranforms(BytecodeTestCase):
         ):
             with self.subTest(line=line):
                 code = compile(line, '', 'single')
-                self.assertInBytecode(code, 'LOAD_CONST', elem)
+                if isinstance(elem, int):
+                    self.assertInBytecode(code, 'LOAD_SMALL_INT', elem)
+                else:
+                    self.assertInBytecode(code, 'LOAD_CONST', elem)
                 for instr in dis.get_instructions(code):
                     self.assertFalse(instr.opname.startswith('UNARY_'))
                 self.check_lnotab(code)
@@ -989,9 +995,11 @@ class DirectCfgOptimizerTests(CfgOptimizationTestCase):
         expected_insts = [
             ('LOAD_NAME', 1, 11),
             ('POP_JUMP_IF_TRUE', lbl := self.Label(), 12),
-            ('RETURN_CONST', 1, 13),
+            ('LOAD_CONST', 1, 13),
+            ('RETURN_VALUE', None, 13),
             lbl,
-            ('RETURN_CONST', 2, 14),
+            ('LOAD_CONST', 2, 14),
+            ('RETURN_VALUE', None, 14),
         ]
         self.cfg_optimization_test(insts,
                                    expected_insts,
@@ -1013,7 +1021,8 @@ class DirectCfgOptimizerTests(CfgOptimizationTestCase):
         expected_insts = [
             ('NOP', None, 11),
             ('NOP', None, 12),
-            ('RETURN_CONST', 1, 14),
+            ('LOAD_CONST', 1, 14),
+            ('RETURN_VALUE', None, 14),
         ]
         self.cfg_optimization_test(insts,
                                    expected_insts,
@@ -1057,15 +1066,19 @@ class DirectCfgOptimizerTests(CfgOptimizationTestCase):
         insts = [
             ('SETUP_FINALLY', handler := self.Label(), 10),
             ('POP_BLOCK', None, -1),
-            ('RETURN_CONST', 1, 11),
+            ('LOAD_CONST', 1, 11),
+            ('RETURN_VALUE', None, 11),
             handler,
-            ('RETURN_CONST', 2, 12),
+            ('LOAD_CONST', 2, 12),
+            ('RETURN_VALUE', None, 12),
         ]
         expected_insts = [
             ('SETUP_FINALLY', handler := self.Label(), 10),
-            ('RETURN_CONST', 1, 11),
+            ('LOAD_CONST', 1, 11),
+            ('RETURN_VALUE', None, 11),
             handler,
-            ('RETURN_CONST', 2, 12),
+            ('LOAD_CONST', 2, 12),
+            ('RETURN_VALUE', None, 12),
         ]
         self.cfg_optimization_test(insts, expected_insts, consts=list(range(5)))
 
@@ -1088,7 +1101,8 @@ class DirectCfgOptimizerTests(CfgOptimizationTestCase):
             ('NOP', None, 3),
             ('STORE_FAST', 1, 4),
             ('POP_TOP', None, 4),
-            ('RETURN_CONST', 0)
+            ('LOAD_CONST', 0, 5),
+            ('RETURN_VALUE', None, 5)
         ]
         self.cfg_optimization_test(insts, expected_insts, consts=list(range(3)), nlocals=1)
 
@@ -1109,7 +1123,8 @@ class DirectCfgOptimizerTests(CfgOptimizationTestCase):
             ('NOP', None, 3),
             ('POP_TOP', None, 4),
             ('STORE_FAST', 1, 4),
-            ('RETURN_CONST', 0, 5)
+            ('LOAD_CONST', 0, 5),
+            ('RETURN_VALUE', None, 5)
         ]
         self.cfg_optimization_test(insts, expected_insts, consts=list(range(3)), nlocals=1)
 
@@ -1131,7 +1146,8 @@ class DirectCfgOptimizerTests(CfgOptimizationTestCase):
             ('STORE_FAST', 1, 4),
             ('STORE_FAST', 1, 5),
             ('STORE_FAST', 1, 6),
-            ('RETURN_CONST', 0, 5)
+            ('LOAD_CONST', 0, 5),
+            ('RETURN_VALUE', None, 5)
         ]
         self.cfg_optimization_test(insts, expected_insts, consts=list(range(3)), nlocals=1)