gh-115859: Re-enable T2 optimizer pass by default (#116062)

This undoes the *temporary* default disabling of the T2 optimizer pass in gh-115860.

- Add a new test that reproduces Brandt's example from gh-115859; it indeed crashes before gh-116028 with PYTHONUOPSOPTIMIZE=1
- Re-enable the optimizer pass in T2, stop checking PYTHONUOPSOPTIMIZE
- Rename the env var to disable T2 entirely to PYTHON_UOPS_OPTIMIZE (must be explicitly set to 0 to disable)
- Fix skipIf conditions on tests in test_opt.py accordingly
- Export sym_is_bottom() (for debugging)
- Fix various things in the `_BINARY_OP_` specializations in the abstract interpreter:
  - DECREF(temp)
  - out-of-space check after sym_new_const()
  - add sym_matches_type() checks, so even if we somehow reach a binary op with symbolic constants of the wrong type on the stack we won't trigger the type assert

1 files changed, 34 insertions, 9 deletions

diff --git a/Python/optimizer_bytecodes.c b/Python/optimizer_bytecodes.c
index b65e90bf980..928c22da16b 100644
--- a/Python/optimizer_bytecodes.c
+++ b/Python/optimizer_bytecodes.c
@@ -25,6 +25,7 @@ typedef struct _Py_UOpsAbstractFrame _Py_UOpsAbstractFrame;
 #define sym_set_non_null _Py_uop_sym_set_non_null
 #define sym_set_type _Py_uop_sym_set_type
 #define sym_set_const _Py_uop_sym_set_const
+#define sym_is_bottom _Py_uop_sym_is_bottom
 #define frame_new _Py_uop_frame_new
 #define frame_pop _Py_uop_frame_pop
 
@@ -107,7 +108,9 @@ dummy_func(void) {
     }
 
     op(_BINARY_OP_ADD_INT, (left, right -- res)) {
-        if (sym_is_const(left) && sym_is_const(right)) {
+        if (sym_is_const(left) && sym_is_const(right) &&
+            sym_matches_type(left, &PyLong_Type) && sym_matches_type(right, &PyLong_Type))
+        {
             assert(PyLong_CheckExact(sym_get_const(left)));
             assert(PyLong_CheckExact(sym_get_const(right)));
             PyObject *temp = _PyLong_Add((PyLongObject *)sym_get_const(left),
@@ -115,7 +118,9 @@ dummy_func(void) {
             if (temp == NULL) {
                 goto error;
             }
-            OUT_OF_SPACE_IF_NULL(res = sym_new_const(ctx, temp));
+            res = sym_new_const(ctx, temp);
+            Py_DECREF(temp);
+            OUT_OF_SPACE_IF_NULL(res);
             // TODO gh-115506:
             // replace opcode with constant propagated one and add tests!
         }
@@ -125,7 +130,9 @@ dummy_func(void) {
     }
 
     op(_BINARY_OP_SUBTRACT_INT, (left, right -- res)) {
-        if (sym_is_const(left) && sym_is_const(right)) {
+        if (sym_is_const(left) && sym_is_const(right) &&
+            sym_matches_type(left, &PyLong_Type) && sym_matches_type(right, &PyLong_Type))
+        {
             assert(PyLong_CheckExact(sym_get_const(left)));
             assert(PyLong_CheckExact(sym_get_const(right)));
             PyObject *temp = _PyLong_Subtract((PyLongObject *)sym_get_const(left),
@@ -133,7 +140,9 @@ dummy_func(void) {
             if (temp == NULL) {
                 goto error;
             }
-            OUT_OF_SPACE_IF_NULL(res = sym_new_const(ctx, temp));
+            res = sym_new_const(ctx, temp);
+            Py_DECREF(temp);
+            OUT_OF_SPACE_IF_NULL(res);
             // TODO gh-115506:
             // replace opcode with constant propagated one and add tests!
         }
@@ -143,7 +152,9 @@ dummy_func(void) {
     }
 
     op(_BINARY_OP_MULTIPLY_INT, (left, right -- res)) {
-        if (sym_is_const(left) && sym_is_const(right)) {
+        if (sym_is_const(left) && sym_is_const(right) &&
+            sym_matches_type(left, &PyLong_Type) && sym_matches_type(right, &PyLong_Type))
+        {
             assert(PyLong_CheckExact(sym_get_const(left)));
             assert(PyLong_CheckExact(sym_get_const(right)));
             PyObject *temp = _PyLong_Multiply((PyLongObject *)sym_get_const(left),
@@ -151,7 +162,9 @@ dummy_func(void) {
             if (temp == NULL) {
                 goto error;
             }
-            OUT_OF_SPACE_IF_NULL(res = sym_new_const(ctx, temp));
+            res = sym_new_const(ctx, temp);
+            Py_DECREF(temp);
+            OUT_OF_SPACE_IF_NULL(res);
             // TODO gh-115506:
             // replace opcode with constant propagated one and add tests!
         }
@@ -161,7 +174,9 @@ dummy_func(void) {
     }
 
     op(_BINARY_OP_ADD_FLOAT, (left, right -- res)) {
-        if (sym_is_const(left) && sym_is_const(right)) {
+        if (sym_is_const(left) && sym_is_const(right) &&
+            sym_matches_type(left, &PyFloat_Type) && sym_matches_type(right, &PyFloat_Type))
+        {
             assert(PyFloat_CheckExact(sym_get_const(left)));
             assert(PyFloat_CheckExact(sym_get_const(right)));
             PyObject *temp = PyFloat_FromDouble(
@@ -171,6 +186,8 @@ dummy_func(void) {
                 goto error;
             }
             res = sym_new_const(ctx, temp);
+            Py_DECREF(temp);
+            OUT_OF_SPACE_IF_NULL(res);
             // TODO gh-115506:
             // replace opcode with constant propagated one and update tests!
         }
@@ -180,7 +197,9 @@ dummy_func(void) {
     }
 
     op(_BINARY_OP_SUBTRACT_FLOAT, (left, right -- res)) {
-        if (sym_is_const(left) && sym_is_const(right)) {
+        if (sym_is_const(left) && sym_is_const(right) &&
+            sym_matches_type(left, &PyFloat_Type) && sym_matches_type(right, &PyFloat_Type))
+        {
             assert(PyFloat_CheckExact(sym_get_const(left)));
             assert(PyFloat_CheckExact(sym_get_const(right)));
             PyObject *temp = PyFloat_FromDouble(
@@ -190,6 +209,8 @@ dummy_func(void) {
                 goto error;
             }
             res = sym_new_const(ctx, temp);
+            Py_DECREF(temp);
+            OUT_OF_SPACE_IF_NULL(res);
             // TODO gh-115506:
             // replace opcode with constant propagated one and update tests!
         }
@@ -199,7 +220,9 @@ dummy_func(void) {
     }
 
     op(_BINARY_OP_MULTIPLY_FLOAT, (left, right -- res)) {
-        if (sym_is_const(left) && sym_is_const(right)) {
+        if (sym_is_const(left) && sym_is_const(right) &&
+            sym_matches_type(left, &PyFloat_Type) && sym_matches_type(right, &PyFloat_Type))
+        {
             assert(PyFloat_CheckExact(sym_get_const(left)));
             assert(PyFloat_CheckExact(sym_get_const(right)));
             PyObject *temp = PyFloat_FromDouble(
@@ -209,6 +232,8 @@ dummy_func(void) {
                 goto error;
             }
             res = sym_new_const(ctx, temp);
+            Py_DECREF(temp);
+            OUT_OF_SPACE_IF_NULL(res);
             // TODO gh-115506:
             // replace opcode with constant propagated one and update tests!
         }