https://github.com/python/cpython/commit/71009cb835f9fa37647b0f2f7dcc0d6ca8aa36b6
commit: 71009cb835f9fa37647b0f2f7dcc0d6ca8aa36b6
branch: main
author: Tomas R. <tomas.ro...@gmail.com>
committer: brandtbucher <brandtbuc...@gmail.com>
date: 2025-04-08T08:22:54-07:00
summary:
GH-131798: Narrow the result type of _BINARY_OP_SUBSCR_STR_INT to str in the
JIT (GH-132153)
files:
A
Misc/NEWS.d/next/Core_and_Builtins/2025-04-06-13-17-10.gh-issue-131798.uMrfha.rst
M Lib/test/test_capi/test_opt.py
M Python/optimizer_bytecodes.c
M Python/optimizer_cases.c.h
diff --git a/Lib/test/test_capi/test_opt.py b/Lib/test/test_capi/test_opt.py
index 0e13799ad47381..3ade7cb7a2b6af 100644
--- a/Lib/test/test_capi/test_opt.py
+++ b/Lib/test/test_capi/test_opt.py
@@ -1646,6 +1646,26 @@ def f(n):
self.assertIn("_TO_BOOL_STR", uops)
self.assertNotIn("_GUARD_TOS_UNICODE", uops)
+ def test_binary_subcsr_str_int_narrows_to_str(self):
+ def testfunc(n):
+ x = []
+ s = "foo"
+ for _ in range(n):
+ y = s[0] # _BINARY_OP_SUBSCR_STR_INT
+ z = "bar" + y # (_GUARD_TOS_UNICODE) + _BINARY_OP_ADD_UNICODE
+ x.append(z)
+ return x
+
+ res, ex = self._run_with_optimizer(testfunc, TIER2_THRESHOLD)
+ self.assertEqual(res, ["barf"] * TIER2_THRESHOLD)
+ self.assertIsNotNone(ex)
+ uops = get_opnames(ex)
+ self.assertIn("_BINARY_OP_SUBSCR_STR_INT", uops)
+ # _BINARY_OP_SUBSCR_STR_INT narrows the result to 'str' so
+ # the unicode guard before _BINARY_OP_ADD_UNICODE is removed.
+ self.assertNotIn("_GUARD_TOS_UNICODE", uops)
+ self.assertIn("_BINARY_OP_ADD_UNICODE", uops)
+
def global_identity(x):
return x
diff --git
a/Misc/NEWS.d/next/Core_and_Builtins/2025-04-06-13-17-10.gh-issue-131798.uMrfha.rst
b/Misc/NEWS.d/next/Core_and_Builtins/2025-04-06-13-17-10.gh-issue-131798.uMrfha.rst
new file mode 100644
index 00000000000000..5ea5fcecc33517
--- /dev/null
+++
b/Misc/NEWS.d/next/Core_and_Builtins/2025-04-06-13-17-10.gh-issue-131798.uMrfha.rst
@@ -0,0 +1,2 @@
+Allow the JIT to remove unicode guards after ``_BINARY_OP_SUBSCR_STR_INT``
+by setting the return type to string.
diff --git a/Python/optimizer_bytecodes.c b/Python/optimizer_bytecodes.c
index d7b3564db1b90a..72dc2bbd44e71c 100644
--- a/Python/optimizer_bytecodes.c
+++ b/Python/optimizer_bytecodes.c
@@ -366,6 +366,10 @@ dummy_func(void) {
ctx->done = true;
}
+ op(_BINARY_OP_SUBSCR_STR_INT, (left, right -- res)) {
+ res = sym_new_type(ctx, &PyUnicode_Type);
+ }
+
op(_TO_BOOL, (value -- res)) {
int already_bool = optimize_to_bool(this_instr, ctx, value, &res);
if (!already_bool) {
diff --git a/Python/optimizer_cases.c.h b/Python/optimizer_cases.c.h
index 870c32d74ac913..160d09ca7c5580 100644
--- a/Python/optimizer_cases.c.h
+++ b/Python/optimizer_cases.c.h
@@ -569,7 +569,7 @@
case _BINARY_OP_SUBSCR_STR_INT: {
JitOptSymbol *res;
- res = sym_new_not_null(ctx);
+ res = sym_new_type(ctx, &PyUnicode_Type);
stack_pointer[-2] = res;
stack_pointer += -1;
assert(WITHIN_STACK_BOUNDS());
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