Don't JIT short traces except if they end in a loop

Fidget-Spinner · Fidget-Spinner · commit d820e2237896 · 2025-10-20T00:43:35.000+01:00
diff --git a/Python/optimizer.c b/Python/optimizer.c
@@ -1234,7 +1234,7 @@ uop_optimize(
     int curr_stackentries = tstate->interp->jit_state.jit_tracer_initial_stack_depth;
     int length = interp->jit_state.jit_tracer_code_curr_size;
     // Trace too short, don't bother.
-    if (length <= 20) {
+    if (length <= 20 && buffer[length-1].opcode != _JUMP_TO_TOP) {
         return 0;
     }
     assert(length > 0);

Original file line number	Diff line number	Diff line change
`@@ -1234,7 +1234,7 @@ uop_optimize(`
`1234`	`1234`	`int curr_stackentries = tstate->interp->jit_state.jit_tracer_initial_stack_depth;`
`1235`	`1235`	`int length = interp->jit_state.jit_tracer_code_curr_size;`
`1236`	`1236`	`// Trace too short, don't bother.`
`1237`		`- if (length <= 20) {`
	`1237`	`+ if (length <= 20 && buffer[length-1].opcode != _JUMP_TO_TOP) {`
`1238`	`1238`	`return 0;`
`1239`	`1239`	`}`
`1240`	`1240`	`assert(length > 0);`