test(jit): strengthen side trace import coverage

Author: fffonion

src/vm/jit/deopt.rs

@@ -49,6 +49,7 @@ pub(crate) struct SideTraceImport {
     pub(crate) parent_exit: SsaExitId,
     pub(crate) stack_depth: usize,
     pub(crate) local_count: usize,
+    pub(crate) dirty_locals: Vec<bool>,
     pub(crate) args: Vec<SsaMaterialization>,
 }
 
@@ -103,6 +104,7 @@ pub(crate) fn side_trace_import(
         parent_exit,
         stack_depth: exit.stack.len(),
         local_count: exit.locals.len(),
+        dirty_locals: exit.dirty_locals.clone(),
         args: exit.stack.iter().chain(&exit.locals).cloned().collect(),
     })
 }
@@ -152,6 +154,7 @@ mod tests {
         assert_eq!(import.parent_exit, exit_id);
         assert_eq!(import.stack_depth, 1);
         assert_eq!(import.local_count, 1);
+        assert_eq!(import.dirty_locals, vec![true]);
         assert_eq!(
             import.args,
             vec![

tests/jit/jit_tests.rs

@@ -2184,14 +2184,14 @@ fn trace_jit_reports_exact_parent_exit_profiles() {
         return;
     }
     let source = r#"
+        fn choose(i) {
+            if i % 2 == 0 => { 3 } else => { 5 }
+        }
+
         let mut i = 0;
         let mut total = 0;
         while i < 64 {
-            if i % 2 == 0 {
-                total = total + 3;
-            } else {
-                total = total + 5;
-            }
+            total = total + choose(i);
             i = i + 1;
         }
         total;
@@ -2221,6 +2221,13 @@ fn trace_jit_reports_exact_parent_exit_profiles() {
         assert!(profile.exit_id < parent.ssa_exit_count() as u32);
         assert!(profile.executions > 0);
     }
+    assert!(
+        snapshot.exit_profiles.iter().any(|profile| {
+            snapshot.traces[profile.parent_trace_id].frame_key != u64::MAX && profile.executions > 1
+        }),
+        "expected a repeated exact exit inside a callable frame:\n{}",
+        vm.dump_jit_info()
+    );
 }
 
 #[test]