gh-134584: Eliminate redundant refcounting from `TO_BOOL_STR` (GH-143417)

Signed-off-by: Manjusaka <me@manjusaka.me>

diff --git a/Include/internal/pycore_opcode_metadata.h b/Include/internal/pycore_opcode_metadata.h
index 05d22ea7c468e991941429c7dda8a656cb7d2182..489efba8ca02991df86b14520c5e25d40f216086 100644 (file)
--- a/Include/internal/pycore_opcode_metadata.h
+++ b/Include/internal/pycore_opcode_metadata.h
@@ -1307,7 +1307,7 @@ const struct opcode_metadata _PyOpcode_opcode_metadata[267] = {
     [TO_BOOL_INT] = { true, INSTR_FMT_IXC00, HAS_EXIT_FLAG | HAS_ESCAPES_FLAG },
     [TO_BOOL_LIST] = { true, INSTR_FMT_IXC00, HAS_EXIT_FLAG | HAS_ESCAPES_FLAG },
     [TO_BOOL_NONE] = { true, INSTR_FMT_IXC00, HAS_EXIT_FLAG },
-    [TO_BOOL_STR] = { true, INSTR_FMT_IXC00, HAS_EXIT_FLAG | HAS_ESCAPES_FLAG },
+    [TO_BOOL_STR] = { true, INSTR_FMT_IXC00, HAS_EXIT_FLAG },
     [TRACE_RECORD] = { true, INSTR_FMT_IB, HAS_ARG_FLAG | HAS_ERROR_FLAG | HAS_ESCAPES_FLAG },
     [UNARY_INVERT] = { true, INSTR_FMT_IX, HAS_ERROR_FLAG | HAS_ESCAPES_FLAG },
     [UNARY_NEGATIVE] = { true, INSTR_FMT_IX, HAS_ERROR_FLAG | HAS_ESCAPES_FLAG },
@@ -1520,7 +1520,7 @@ _PyOpcode_macro_expansion[256] = {
     [TO_BOOL_INT] = { .nuops = 1, .uops = { { _TO_BOOL_INT, OPARG_SIMPLE, 3 } } },
     [TO_BOOL_LIST] = { .nuops = 2, .uops = { { _GUARD_TOS_LIST, OPARG_SIMPLE, 0 }, { _TO_BOOL_LIST, OPARG_SIMPLE, 3 } } },
     [TO_BOOL_NONE] = { .nuops = 1, .uops = { { _TO_BOOL_NONE, OPARG_SIMPLE, 3 } } },
-    [TO_BOOL_STR] = { .nuops = 2, .uops = { { _GUARD_TOS_UNICODE, OPARG_SIMPLE, 0 }, { _TO_BOOL_STR, OPARG_SIMPLE, 3 } } },
+    [TO_BOOL_STR] = { .nuops = 3, .uops = { { _GUARD_TOS_UNICODE, OPARG_SIMPLE, 0 }, { _TO_BOOL_STR, OPARG_SIMPLE, 3 }, { _POP_TOP_UNICODE, OPARG_SIMPLE, 3 } } },
     [UNARY_INVERT] = { .nuops = 1, .uops = { { _UNARY_INVERT, OPARG_SIMPLE, 0 } } },
     [UNARY_NEGATIVE] = { .nuops = 1, .uops = { { _UNARY_NEGATIVE, OPARG_SIMPLE, 0 } } },
     [UNARY_NOT] = { .nuops = 1, .uops = { { _UNARY_NOT, OPARG_SIMPLE, 0 } } },

diff --git a/Include/internal/pycore_uop_ids.h b/Include/internal/pycore_uop_ids.h
index 01f99deb05db93d415a1a574a0930de222ff8105..4d71f3526f99dbc62feb03141d6bda095701ce1c 100644 (file)
--- a/Include/internal/pycore_uop_ids.h
+++ b/Include/internal/pycore_uop_ids.h
@@ -1159,22 +1159,24 @@ extern "C" {
 #define _TO_BOOL_NONE_r11 1353
 #define _TO_BOOL_NONE_r22 1354
 #define _TO_BOOL_NONE_r33 1355
-#define _TO_BOOL_STR_r11 1356
-#define _TRACE_RECORD_r00 1357
-#define _UNARY_INVERT_r11 1358
-#define _UNARY_NEGATIVE_r11 1359
-#define _UNARY_NOT_r01 1360
-#define _UNARY_NOT_r11 1361
-#define _UNARY_NOT_r22 1362
-#define _UNARY_NOT_r33 1363
-#define _UNPACK_EX_r10 1364
-#define _UNPACK_SEQUENCE_r10 1365
-#define _UNPACK_SEQUENCE_LIST_r10 1366
-#define _UNPACK_SEQUENCE_TUPLE_r10 1367
-#define _UNPACK_SEQUENCE_TWO_TUPLE_r12 1368
-#define _WITH_EXCEPT_START_r33 1369
-#define _YIELD_VALUE_r11 1370
-#define MAX_UOP_REGS_ID 1370
+#define _TO_BOOL_STR_r02 1356
+#define _TO_BOOL_STR_r12 1357
+#define _TO_BOOL_STR_r23 1358
+#define _TRACE_RECORD_r00 1359
+#define _UNARY_INVERT_r11 1360
+#define _UNARY_NEGATIVE_r11 1361
+#define _UNARY_NOT_r01 1362
+#define _UNARY_NOT_r11 1363
+#define _UNARY_NOT_r22 1364
+#define _UNARY_NOT_r33 1365
+#define _UNPACK_EX_r10 1366
+#define _UNPACK_SEQUENCE_r10 1367
+#define _UNPACK_SEQUENCE_LIST_r10 1368
+#define _UNPACK_SEQUENCE_TUPLE_r10 1369
+#define _UNPACK_SEQUENCE_TWO_TUPLE_r12 1370
+#define _WITH_EXCEPT_START_r33 1371
+#define _YIELD_VALUE_r11 1372
+#define MAX_UOP_REGS_ID 1372
 
 #ifdef __cplusplus
 }

diff --git a/Include/internal/pycore_uop_metadata.h b/Include/internal/pycore_uop_metadata.h
index 4e00651573328bd31de869c181d7cad6b275d175..1613dbd7b9ebdfe573c7436ab8bcf9ebf45be8af 100644 (file)
--- a/Include/internal/pycore_uop_metadata.h
+++ b/Include/internal/pycore_uop_metadata.h
@@ -97,7 +97,7 @@ const uint32_t _PyUop_Flags[MAX_UOP_ID+1] = {
     [_GUARD_NOS_COMPACT_ASCII] = HAS_EXIT_FLAG,
     [_GUARD_NOS_UNICODE] = HAS_EXIT_FLAG,
     [_GUARD_TOS_UNICODE] = HAS_EXIT_FLAG,
-    [_TO_BOOL_STR] = HAS_ESCAPES_FLAG,
+    [_TO_BOOL_STR] = 0,
     [_REPLACE_WITH_TRUE] = 0,
     [_UNARY_INVERT] = HAS_ERROR_FLAG | HAS_ESCAPES_FLAG,
     [_GUARD_NOS_INT] = HAS_EXIT_FLAG,
@@ -934,11 +934,11 @@ const _PyUopCachingInfo _PyUop_Caching[MAX_UOP_ID+1] = {
         },
     },
     [_TO_BOOL_STR] = {
-        .best = { 1, 1, 1, 1 },
+        .best = { 0, 1, 2, 2 },
         .entries = {
-            { -1, -1, -1 },
-            { 1, 1, _TO_BOOL_STR_r11 },
-            { -1, -1, -1 },
+            { 2, 0, _TO_BOOL_STR_r02 },
+            { 2, 1, _TO_BOOL_STR_r12 },
+            { 3, 2, _TO_BOOL_STR_r23 },
             { -1, -1, -1 },
         },
     },
@@ -3500,7 +3500,9 @@ const uint16_t _PyUop_Uncached[MAX_UOP_REGS_ID+1] = {
     [_GUARD_TOS_UNICODE_r11] = _GUARD_TOS_UNICODE,
     [_GUARD_TOS_UNICODE_r22] = _GUARD_TOS_UNICODE,
     [_GUARD_TOS_UNICODE_r33] = _GUARD_TOS_UNICODE,
-    [_TO_BOOL_STR_r11] = _TO_BOOL_STR,
+    [_TO_BOOL_STR_r02] = _TO_BOOL_STR,
+    [_TO_BOOL_STR_r12] = _TO_BOOL_STR,
+    [_TO_BOOL_STR_r23] = _TO_BOOL_STR,
     [_REPLACE_WITH_TRUE_r02] = _REPLACE_WITH_TRUE,
     [_REPLACE_WITH_TRUE_r12] = _REPLACE_WITH_TRUE,
     [_REPLACE_WITH_TRUE_r23] = _REPLACE_WITH_TRUE,
@@ -5099,7 +5101,9 @@ const char *const _PyOpcode_uop_name[MAX_UOP_REGS_ID+1] = {
     [_TO_BOOL_NONE_r22] = "_TO_BOOL_NONE_r22",
     [_TO_BOOL_NONE_r33] = "_TO_BOOL_NONE_r33",
     [_TO_BOOL_STR] = "_TO_BOOL_STR",
-    [_TO_BOOL_STR_r11] = "_TO_BOOL_STR_r11",
+    [_TO_BOOL_STR_r02] = "_TO_BOOL_STR_r02",
+    [_TO_BOOL_STR_r12] = "_TO_BOOL_STR_r12",
+    [_TO_BOOL_STR_r23] = "_TO_BOOL_STR_r23",
     [_UNARY_INVERT] = "_UNARY_INVERT",
     [_UNARY_INVERT_r11] = "_UNARY_INVERT_r11",
     [_UNARY_NEGATIVE] = "_UNARY_NEGATIVE",

diff --git a/Lib/test/test_capi/test_opt.py b/Lib/test/test_capi/test_opt.py
index 271681a80d62acb86bb116565d460126a2f82f86..37b2fbe0a71452a4c2ad2399e27bda7241c07738 100644 (file)
--- a/Lib/test/test_capi/test_opt.py
+++ b/Lib/test/test_capi/test_opt.py
@@ -2937,6 +2937,23 @@ class TestUopsOptimization(unittest.TestCase):
         self.assertLessEqual(count_ops(ex, "_POP_TOP"), 1)
         self.assertIn("_POP_TOP_NOP", uops)
 
+    def test_to_bool_str(self):
+        def f(n):
+            for i in range(n):
+                false = i == TIER2_THRESHOLD
+                empty = "X"[:false]
+                if empty:
+                    return 1
+            return 0
+
+        res, ex = self._run_with_optimizer(f, TIER2_THRESHOLD)
+        self.assertEqual(res, 0)
+        self.assertIsNotNone(ex)
+        uops = get_opnames(ex)
+        self.assertIn("_TO_BOOL_STR", uops)
+        self.assertLessEqual(count_ops(ex, "_POP_TOP"), 3)
+        self.assertIn("_POP_TOP_NOP", uops)
+
     def test_to_bool_always_true(self):
         def testfunc(n):
             class A:

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-01-04-23-53-42.gh-issue-134584.CNrxI_.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-01-04-23-53-42.gh-issue-134584.CNrxI_.rst
new file mode 100644 (file)
index 0000000..cc59971
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-01-04-23-53-42.gh-issue-134584.CNrxI_.rst
@@ -0,0 +1 @@
+Eliminate redundant refcounting from ``TO_BOOL_STR``.

diff --git a/Python/bytecodes.c b/Python/bytecodes.c
index c83f5033af7b0ac707b0952e4419c8d35a0060df..8db1de6ca384bb2c0d3f75f53516fc1985542972 100644 (file)
--- a/Python/bytecodes.c
+++ b/Python/bytecodes.c
@@ -547,23 +547,16 @@ dummy_func(
             EXIT_IF(!PyUnicode_CheckExact(value_o));
         }
 
-        op(_TO_BOOL_STR, (value -- res)) {
+        op(_TO_BOOL_STR, (value -- res, v)) {
             STAT_INC(TO_BOOL, hit);
             PyObject *value_o = PyStackRef_AsPyObjectBorrow(value);
-            if (value_o == &_Py_STR(empty)) {
-                assert(_Py_IsImmortal(value_o));
-                DEAD(value);
-                res = PyStackRef_False;
-            }
-            else {
-                assert(Py_SIZE(value_o));
-                PyStackRef_CLOSE(value);
-                res = PyStackRef_True;
-            }
+            res = value_o == &_Py_STR(empty) ? PyStackRef_False : PyStackRef_True;
+            v = value;
+            DEAD(value);
         }
 
         macro(TO_BOOL_STR) =
-            _GUARD_TOS_UNICODE + unused/1 + unused/2 + _TO_BOOL_STR;
+            _GUARD_TOS_UNICODE + unused/1 + unused/2 + _TO_BOOL_STR + _POP_TOP_UNICODE;
 
         op(_REPLACE_WITH_TRUE, (value -- res, v)) {
             res = PyStackRef_True;

diff --git a/Python/executor_cases.c.h b/Python/executor_cases.c.h
index a56482d411fe1b45030456f7ad18a3ec1613d3b1..e78c37611ce6b87784d96a5edd0e3f0d5a4875f8 100644 (file)
--- a/Python/executor_cases.c.h
+++ b/Python/executor_cases.c.h
@@ -3553,30 +3553,62 @@
             break;
         }
 
-        case _TO_BOOL_STR_r11: {
+        case _TO_BOOL_STR_r02: {
+            CHECK_CURRENT_CACHED_VALUES(0);
+            assert(WITHIN_STACK_BOUNDS_IGNORING_CACHE());
+            _PyStackRef value;
+            _PyStackRef res;
+            _PyStackRef v;
+            value = stack_pointer[-1];
+            STAT_INC(TO_BOOL, hit);
+            PyObject *value_o = PyStackRef_AsPyObjectBorrow(value);
+            res = value_o == &_Py_STR(empty) ? PyStackRef_False : PyStackRef_True;
+            v = value;
+            _tos_cache1 = v;
+            _tos_cache0 = res;
+            SET_CURRENT_CACHED_VALUES(2);
+            stack_pointer += -1;
+            ASSERT_WITHIN_STACK_BOUNDS(__FILE__, __LINE__);
+            assert(WITHIN_STACK_BOUNDS_IGNORING_CACHE());
+            break;
+        }
+
+        case _TO_BOOL_STR_r12: {
             CHECK_CURRENT_CACHED_VALUES(1);
             assert(WITHIN_STACK_BOUNDS_IGNORING_CACHE());
             _PyStackRef value;
             _PyStackRef res;
+            _PyStackRef v;
             _PyStackRef _stack_item_0 = _tos_cache0;
             value = _stack_item_0;
             STAT_INC(TO_BOOL, hit);
             PyObject *value_o = PyStackRef_AsPyObjectBorrow(value);
-            if (value_o == &_Py_STR(empty)) {
-                assert(_Py_IsImmortal(value_o));
-                res = PyStackRef_False;
-            }
-            else {
-                assert(Py_SIZE(value_o));
-                _PyFrame_SetStackPointer(frame, stack_pointer);
-                PyStackRef_CLOSE(value);
-                stack_pointer = _PyFrame_GetStackPointer(frame);
-                res = PyStackRef_True;
-            }
+            res = value_o == &_Py_STR(empty) ? PyStackRef_False : PyStackRef_True;
+            v = value;
+            _tos_cache1 = v;
             _tos_cache0 = res;
-            _tos_cache1 = PyStackRef_ZERO_BITS;
-            _tos_cache2 = PyStackRef_ZERO_BITS;
-            SET_CURRENT_CACHED_VALUES(1);
+            SET_CURRENT_CACHED_VALUES(2);
+            assert(WITHIN_STACK_BOUNDS_IGNORING_CACHE());
+            break;
+        }
+
+        case _TO_BOOL_STR_r23: {
+            CHECK_CURRENT_CACHED_VALUES(2);
+            assert(WITHIN_STACK_BOUNDS_IGNORING_CACHE());
+            _PyStackRef value;
+            _PyStackRef res;
+            _PyStackRef v;
+            _PyStackRef _stack_item_0 = _tos_cache0;
+            _PyStackRef _stack_item_1 = _tos_cache1;
+            value = _stack_item_1;
+            STAT_INC(TO_BOOL, hit);
+            PyObject *value_o = PyStackRef_AsPyObjectBorrow(value);
+            res = value_o == &_Py_STR(empty) ? PyStackRef_False : PyStackRef_True;
+            v = value;
+            _tos_cache2 = v;
+            _tos_cache1 = res;
+            _tos_cache0 = _stack_item_0;
+            SET_CURRENT_CACHED_VALUES(3);
             assert(WITHIN_STACK_BOUNDS_IGNORING_CACHE());
             break;
         }

diff --git a/Python/generated_cases.c.h b/Python/generated_cases.c.h
index b134d6c12cf4b71a751058f07befc1f26f469464..ece1146924bc1fe4af273076ff2932fc070d7725 100644 (file)
--- a/Python/generated_cases.c.h
+++ b/Python/generated_cases.c.h
@@ -11759,6 +11759,7 @@
             static_assert(INLINE_CACHE_ENTRIES_TO_BOOL == 3, "incorrect cache size");
             _PyStackRef value;
             _PyStackRef res;
+            _PyStackRef v;
             // _GUARD_TOS_UNICODE
             {
                 value = stack_pointer[-1];
@@ -11775,20 +11776,14 @@
             {
                 STAT_INC(TO_BOOL, hit);
                 PyObject *value_o = PyStackRef_AsPyObjectBorrow(value);
-                if (value_o == &_Py_STR(empty)) {
-                    assert(_Py_IsImmortal(value_o));
-                    res = PyStackRef_False;
-                }
-                else {
-                    assert(Py_SIZE(value_o));
-                    stack_pointer += -1;
-                    ASSERT_WITHIN_STACK_BOUNDS(__FILE__, __LINE__);
-                    _PyFrame_SetStackPointer(frame, stack_pointer);
-                    PyStackRef_CLOSE(value);
-                    stack_pointer = _PyFrame_GetStackPointer(frame);
-                    res = PyStackRef_True;
-                    stack_pointer += 1;
-                }
+                res = value_o == &_Py_STR(empty) ? PyStackRef_False : PyStackRef_True;
+                v = value;
+            }
+            // _POP_TOP_UNICODE
+            {
+                value = v;
+                assert(PyUnicode_CheckExact(PyStackRef_AsPyObjectBorrow(value)));
+                PyStackRef_CLOSE_SPECIALIZED(value, _PyUnicode_ExactDealloc);
             }
             stack_pointer[-1] = res;
             DISPATCH();

diff --git a/Python/optimizer_analysis.c b/Python/optimizer_analysis.c
index 81479a8f28e3191f579a96e4279135218bc6c058..29a088e43c2a0f779b3de0aed5cf44c156dda0eb 100644 (file)
--- a/Python/optimizer_analysis.c
+++ b/Python/optimizer_analysis.c
@@ -214,7 +214,8 @@ optimize_to_bool(
     _PyUOpInstruction *this_instr,
     JitOptContext *ctx,
     JitOptRef value,
-    JitOptRef *result_ptr)
+    JitOptRef *result_ptr,
+    bool insert_mode)
 {
     if (sym_matches_type(value, &PyBool_Type)) {
         REPLACE_OP(this_instr, _NOP, 0, 0);
@@ -224,7 +225,10 @@ optimize_to_bool(
     int truthiness = sym_truthiness(ctx, value);
     if (truthiness >= 0) {
         PyObject *load = truthiness ? Py_True : Py_False;
-        REPLACE_OP(this_instr, _POP_TOP_LOAD_CONST_INLINE_BORROW, 0, (uintptr_t)load);
+        int opcode = insert_mode ?
+            _INSERT_1_LOAD_CONST_INLINE_BORROW :
+            _POP_TOP_LOAD_CONST_INLINE_BORROW;
+        REPLACE_OP(this_instr, opcode, 0, (uintptr_t)load);
         *result_ptr = sym_new_const(ctx, load);
         return 1;
     }

diff --git a/Python/optimizer_bytecodes.c b/Python/optimizer_bytecodes.c
index 9388862e7dbc89bed0e1dc8788a5b2d14063bccc..ef7bc1d8cd87a5869d16687240c7a50c27fbbf68 100644 (file)
--- a/Python/optimizer_bytecodes.c
+++ b/Python/optimizer_bytecodes.c
@@ -44,7 +44,8 @@ optimize_to_bool(
     _PyUOpInstruction *this_instr,
     JitOptContext *ctx,
     JitOptSymbol *value,
-    JitOptSymbol **result_ptr);
+    JitOptSymbol **result_ptr,
+    bool insert_mode);
 
 extern void
 eliminate_pop_guard(_PyUOpInstruction *this_instr, bool exit);
@@ -377,21 +378,21 @@ dummy_func(void) {
     }
 
     op(_TO_BOOL, (value -- res)) {
-        int already_bool = optimize_to_bool(this_instr, ctx, value, &res);
+        int already_bool = optimize_to_bool(this_instr, ctx, value, &res, false);
         if (!already_bool) {
             res = sym_new_truthiness(ctx, value, true);
         }
     }
 
     op(_TO_BOOL_BOOL, (value -- value)) {
-        int already_bool = optimize_to_bool(this_instr, ctx, value, &value);
+        int already_bool = optimize_to_bool(this_instr, ctx, value, &value, false);
         if (!already_bool) {
             sym_set_type(value, &PyBool_Type);
         }
     }
 
     op(_TO_BOOL_INT, (value -- res)) {
-        int already_bool = optimize_to_bool(this_instr, ctx, value, &res);
+        int already_bool = optimize_to_bool(this_instr, ctx, value, &res, false);
         if (!already_bool) {
             sym_set_type(value, &PyLong_Type);
             res = sym_new_truthiness(ctx, value, true);
@@ -399,14 +400,14 @@ dummy_func(void) {
     }
 
     op(_TO_BOOL_LIST, (value -- res)) {
-        int already_bool = optimize_to_bool(this_instr, ctx, value, &res);
+        int already_bool = optimize_to_bool(this_instr, ctx, value, &res, false);
         if (!already_bool) {
             res = sym_new_type(ctx, &PyBool_Type);
         }
     }
 
     op(_TO_BOOL_NONE, (value -- res)) {
-        int already_bool = optimize_to_bool(this_instr, ctx, value, &res);
+        int already_bool = optimize_to_bool(this_instr, ctx, value, &res, false);
         if (!already_bool) {
             sym_set_const(value, Py_None);
             res = sym_new_const(ctx, Py_False);
@@ -431,8 +432,9 @@ dummy_func(void) {
         sym_set_type(value, &PyUnicode_Type);
     }
 
-    op(_TO_BOOL_STR, (value -- res)) {
-        int already_bool = optimize_to_bool(this_instr, ctx, value, &res);
+    op(_TO_BOOL_STR, (value -- res, v)) {
+        int already_bool = optimize_to_bool(this_instr, ctx, value, &res, true);
+        v = value;
         if (!already_bool) {
             res = sym_new_truthiness(ctx, value, true);
         }

diff --git a/Python/optimizer_cases.c.h b/Python/optimizer_cases.c.h
index 9e877cea8c8d47c056bf7b14087e348659a1d292..f25cb6b5fd58a614939b1d3123d00ae33394bef4 100644 (file)
--- a/Python/optimizer_cases.c.h
+++ b/Python/optimizer_cases.c.h
@@ -299,7 +299,7 @@
             JitOptRef value;
             JitOptRef res;
             value = stack_pointer[-1];
-            int already_bool = optimize_to_bool(this_instr, ctx, value, &res);
+            int already_bool = optimize_to_bool(this_instr, ctx, value, &res, false);
             if (!already_bool) {
                 res = sym_new_truthiness(ctx, value, true);
             }
@@ -310,7 +310,7 @@
         case _TO_BOOL_BOOL: {
             JitOptRef value;
             value = stack_pointer[-1];
-            int already_bool = optimize_to_bool(this_instr, ctx, value, &value);
+            int already_bool = optimize_to_bool(this_instr, ctx, value, &value, false);
             if (!already_bool) {
                 sym_set_type(value, &PyBool_Type);
             }
@@ -322,7 +322,7 @@
             JitOptRef value;
             JitOptRef res;
             value = stack_pointer[-1];
-            int already_bool = optimize_to_bool(this_instr, ctx, value, &res);
+            int already_bool = optimize_to_bool(this_instr, ctx, value, &res, false);
             if (!already_bool) {
                 sym_set_type(value, &PyLong_Type);
                 res = sym_new_truthiness(ctx, value, true);
@@ -359,7 +359,7 @@
             JitOptRef value;
             JitOptRef res;
             value = stack_pointer[-1];
-            int already_bool = optimize_to_bool(this_instr, ctx, value, &res);
+            int already_bool = optimize_to_bool(this_instr, ctx, value, &res, false);
             if (!already_bool) {
                 res = sym_new_type(ctx, &PyBool_Type);
             }
@@ -371,7 +371,7 @@
             JitOptRef value;
             JitOptRef res;
             value = stack_pointer[-1];
-            int already_bool = optimize_to_bool(this_instr, ctx, value, &res);
+            int already_bool = optimize_to_bool(this_instr, ctx, value, &res, false);
             if (!already_bool) {
                 sym_set_const(value, Py_None);
                 res = sym_new_const(ctx, Py_False);
@@ -410,12 +410,18 @@
         case _TO_BOOL_STR: {
             JitOptRef value;
             JitOptRef res;
+            JitOptRef v;
             value = stack_pointer[-1];
-            int already_bool = optimize_to_bool(this_instr, ctx, value, &res);
+            int already_bool = optimize_to_bool(this_instr, ctx, value, &res, true);
+            v = value;
             if (!already_bool) {
                 res = sym_new_truthiness(ctx, value, true);
             }
+            CHECK_STACK_BOUNDS(1);
             stack_pointer[-1] = res;
+            stack_pointer[0] = v;
+            stack_pointer += 1;
+            ASSERT_WITHIN_STACK_BOUNDS(__FILE__, __LINE__);
             break;
         }