Remove _SWAP_FAST for now, only specialize POP_TOP

python · Fidget-Spinner · Jun 23, 2025 · Jun 20, 2025 · Jun 20, 2025 · Jun 20, 2025
commit 23197eb2e8cbe492174a8767e674e86b7414d211
diff --git a/Include/internal/pycore_opcode_metadata.h b/Include/internal/pycore_opcode_metadata.h
diff --git a/Include/internal/pycore_uop_ids.h b/Include/internal/pycore_uop_ids.h
diff --git a/Include/internal/pycore_uop_metadata.h b/Include/internal/pycore_uop_metadata.h
diff --git a/Lib/test/test_capi/test_opt.py b/Lib/test/test_capi/test_opt.py
@@ -2349,11 +2349,10 @@ def testfunc(n):
         assert ex is not None
         """))
 
-    def test_store_fast_pop_top_specialize_immortal(self):
+    def test_store_pop_top_specialize_none(self):
         def testfunc(n):
             for _ in range(n):
-                x = None # _POP_TOP, as x's type is not yet known by optimizer.
-                x = None # _POP_TOP_NOP, as x = None
+                global_identity(None)
 
         testfunc(TIER2_THRESHOLD)
 
@@ -2363,12 +2362,10 @@ def testfunc(n):
 
         self.assertIn("_POP_TOP_NOP", uops)
 
-    def test_store_fast_pop_top_specialize_int(self):
+    def test_store_pop_top_specialize_int(self):
         def testfunc(n):
-            y = int(1e6) # Big number so no int caching
             for _ in range(n):
-                x = y + y  # _POP_TOP, as x's type is not yet known by optimizer.
-                x = None # _POP_TOP_INT, as x = int
+                global_identity(100000)
 
         testfunc(TIER2_THRESHOLD)
 
@@ -2378,12 +2375,10 @@ def testfunc(n):
 
         self.assertIn("_POP_TOP_INT", uops)
 
-    def test_store_fast_pop_top_specialize_float(self):
+    def test_store_pop_top_specialize_float(self):
         def testfunc(n):
-            y = 1.0
             for _ in range(n):
-                x = y + y  # _POP_TOP, as x's type is not yet known by optimizer.
-                x = None # _POP_TOP_FLOAT, as x = int
+                global_identity(1e6)
 
         testfunc(TIER2_THRESHOLD)
 
@@ -2393,12 +2388,10 @@ def testfunc(n):
 
         self.assertIn("_POP_TOP_FLOAT", uops)
 
-    def test_store_fast_pop_top_specialize_unicode(self):
+    def test_store_pop_top_specialize_str(self):
         def testfunc(n):
-            y = "hi"
             for _ in range(n):
-                x = y + y  # _POP_TOP, as x's type is not yet known by optimizer.
-                x = None # _POP_TOP_STR, as x = int
+                global_identity("2" + "1")
 
         testfunc(TIER2_THRESHOLD)
 
@@ -2408,20 +2401,6 @@ def testfunc(n):
 
         self.assertIn("_POP_TOP_UNICODE", uops)
 
-    def test_store_pop_top_specialize_none(self):
-        def testfunc(n):
-            for _ in range(n):
-                global_identity(None)
-
-        testfunc(TIER2_THRESHOLD)
-
-        ex = get_first_executor(testfunc)
-        self.assertIsNotNone(ex)
-        uops = get_opnames(ex)
-
-        self.assertIn("_POP_TOP_NOP", uops)
-
-
 
 def global_identity(x):
     return x

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-06-20-14-50-44.gh-issue-134584.3CJdAI.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-06-20-14-50-44.gh-issue-134584.3CJdAI.rst
@@ -1 +1 @@
-Specialize :opcode:`POP_TOP` and thus :opcode:`STORE_FAST` in the JIT compiler by specializing for reference lifetime and type. This will also enable easier top of stack caching in the JIT compiler.
+Specialize :opcode:`POP_TOP` in the JIT compiler by specializing for reference lifetime and type. This will also enable easier top of stack caching in the JIT compiler.
@@ -306,14 +306,13 @@ dummy_func(
             value = PyStackRef_FromPyObjectBorrow(obj);
         }
 
-        replicate(8) op(_SWAP_FAST, (value -- trash)) {
-            trash = GETLOCAL(oparg);
+        replicate(8) inst(STORE_FAST, (value --)) {
+            _PyStackRef tmp = GETLOCAL(oparg);
             GETLOCAL(oparg) = value;
             DEAD(value);
+            PyStackRef_XCLOSE(tmp);
         }
 
-        macro(STORE_FAST) = _SWAP_FAST + POP_TOP;
-
         pseudo(STORE_FAST_MAYBE_NULL, (unused --)) = {
             STORE_FAST,
         };
Original file line number	Diff line number	Diff line change
		@@ -1 +1 @@
		Specialize :opcode:`POP_TOP` and thus :opcode:`STORE_FAST` in the JIT compiler by specializing for reference lifetime and type. This will also enable easier top of stack caching in the JIT compiler.
		Specialize :opcode:`POP_TOP` in the JIT compiler by specializing for reference lifetime and type. This will also enable easier top of stack caching in the JIT compiler.