Assign truthiness to empty strings in JIT

Author: fluhus

Python/optimizer_bytecodes.c

@@ -426,22 +426,9 @@ dummy_func(void) {
 
     op(_TO_BOOL_STR, (value -- res)) {
         if (!optimize_to_bool(this_instr, ctx, value, &res)) {
-            res = sym_new_type(ctx, &PyBool_Type);
+            res = sym_new_truthiness(ctx, value, true);
             sym_set_type(value, &PyUnicode_Type);
         }
-        if (!sym_is_const(value)) {
-            assert(sym_matches_type(value, &PyUnicode_Type));
-            int next_opcode = (this_instr + 1)->opcode;
-            assert(next_opcode == _CHECK_VALIDITY_AND_SET_IP);
-            next_opcode = (this_instr + 2)->opcode;
-            // If the next uop is a guard, we can narrow value. However, we
-            // *can't* narrow res, since that would cause the guard to be
-            // removed and the narrowed value to be invalid:
-            if (next_opcode == _GUARD_IS_FALSE_POP) {
-                sym_set_const(value, Py_GetConstant(Py_CONSTANT_EMPTY_STR));
-                res = sym_new_type(ctx, &PyBool_Type);
-            }
-        }
     }
 
     op(_UNARY_NOT, (value -- res)) {

Python/optimizer_cases.c.h

@@ -299,6 +299,9 @@ _Py_uop_sym_set_const(JitOptContext *ctx, JitOptSymbol *sym, PyObject *const_val
             else if (type == &PyBool_Type) {
                 _Py_uop_sym_set_const(ctx, value, Py_False);
             }
+            else if (type == &PyUnicode_Type) {
+                _Py_uop_sym_set_const(ctx, value, Py_GetConstant(Py_CONSTANT_EMPTY_STR));
+            }
             // TODO: More types (GH-130415)!
             make_const(sym, const_val);
             return;