GH-112354: Treat _EXIT_TRACE like an unconditional side exit (GH-113104)

Author: markshannon

Include/internal/pycore_opcode_metadata.h

@@ -4027,7 +4027,7 @@ dummy_func(
 
         op(_EXIT_TRACE, (--)) {
             TIER_TWO_ONLY
-            GOTO_TIER_ONE();
+            DEOPT_IF(1);
         }
 
         op(_INSERT, (unused[oparg], top -- top, unused[oparg])) {

Python/bytecodes.c

@@ -1063,31 +1063,16 @@ _PyEval_EvalFrameDefault(PyThreadState *tstate, _PyInterpreterFrame *frame, int
 
 // Jump here from DEOPT_IF()
 deoptimize:
-    // On DEOPT_IF we just repeat the last instruction.
-    // This presumes nothing was popped from the stack (nor pushed).
-    frame->instr_ptr = next_uop[-1].target + _PyCode_CODE(_PyFrame_GetCode(frame));
+    next_instr = next_uop[-1].target + _PyCode_CODE(_PyFrame_GetCode(frame));
     DPRINTF(2, "DEOPT: [UOp %d (%s), oparg %d, operand %" PRIu64 ", target %d @ %d -> %s]\n",
             uopcode, _PyUOpName(uopcode), next_uop[-1].oparg, next_uop[-1].operand, next_uop[-1].target,
             (int)(next_uop - current_executor->trace - 1),
             _PyOpcode_OpName[frame->instr_ptr->op.code]);
     OPT_HIST(trace_uop_execution_counter, trace_run_length_hist);
     UOP_STAT_INC(uopcode, miss);
-    frame->return_offset = 0;  // Dispatch to frame->instr_ptr
-    _PyFrame_SetStackPointer(frame, stack_pointer);
     Py_DECREF(current_executor);
-    // Fall through
-// Jump here from ENTER_EXECUTOR
-enter_tier_one:
-    next_instr = frame->instr_ptr;
-    goto resume_frame;
+    DISPATCH();
 
-// Jump here from _EXIT_TRACE
-exit_trace:
-    _PyFrame_SetStackPointer(frame, stack_pointer);
-    frame->instr_ptr = next_uop[-1].target + _PyCode_CODE(_PyFrame_GetCode(frame));
-    Py_DECREF(current_executor);
-    OPT_HIST(trace_uop_execution_counter, trace_run_length_hist);
-    goto enter_tier_one;
 }
 #if defined(__GNUC__)
 #  pragma GCC diagnostic pop

Python/ceval.c

@@ -392,8 +392,6 @@ stack_pointer = _PyFrame_GetStackPointer(frame);
 
 #define GOTO_TIER_TWO() goto enter_tier_two;
 
-#define GOTO_TIER_ONE() goto exit_trace;
-
 #define CURRENT_OPARG() (next_uop[-1].oparg)
 
 #define CURRENT_OPERAND() (next_uop[-1].operand)