ZJIT: Inline methods with rest parameters

Author: k0kubun

zjit/src/codegen_tests.rs

@@ -6693,6 +6693,19 @@ fn test_inlined_method_returns_correct_value() {
     });
 }
 
+#[test]
+fn test_inlined_method_with_rest_parameter() {
+    with_inlining(|| {
+        assert_snapshot!(assert_inlines("
+            def add_rest(*rest) = rest[0] + rest[1]
+            def test = add_rest(1, 2)
+
+            test
+            test
+        "), @"3");
+    });
+}
+
 #[test]
 fn test_inlined_method_deoptimizes_on_redefinition() {
     with_inlining(|| {

zjit/src/hir.rs

@@ -4951,11 +4951,11 @@ impl Function {
     fn can_inline(callee_iseq: IseqPtr) -> bool {
         // Inline callees with required, optional, post-required positional, keyword, and
         // block parameters, including callees that dispatch to a passed block with `yield`.
-        // Rest params, double-splat (kwrest), and forwardable params stay out of the
-        // general inliner for now; rest-aware direct sends are still handled by codegen.
+        // Double-splat (kwrest) and forwardable params stay out of the general
+        // inliner for now. Rest params are already normalized to a packed Array by
+        // prepare_direct_send_args, so the inliner can map that Array to the rest local.
         let params = unsafe { callee_iseq.params() };
-        if params.flags.has_rest() != 0
-            || params.flags.forwardable() != 0
+        if params.flags.forwardable() != 0
             || params.flags.has_kwrest() != 0
         {
             incr_counter!(inline_reject_complex_params);

zjit/src/hir/opt_tests.rs

@@ -26,6 +26,17 @@ mod hir_opt_tests {
         hir_string_proc(&format!("{}.method(:{})", "self", method))
     }
 
+    // Keep tests for rest-aware SendDirect snapshots focused on argument packing
+    // even though rest callees are now eligible for the general inliner.
+    #[track_caller]
+    fn hir_string_without_inlining(method: &str) -> String {
+        let old_threshold = get_option!(inline_threshold);
+        unsafe { OPTIONS.as_mut().unwrap().inline_threshold = 0; }
+        let result = hir_string(method);
+        unsafe { OPTIONS.as_mut().unwrap().inline_threshold = old_threshold; }
+        result
+    }
+
     #[test]
     fn test_fold_iftrue_away() {
         eval("
@@ -4008,7 +4019,7 @@ mod hir_opt_tests {
             test
             test
         ");
-        assert_snapshot!(hir_string("test"), @"
+        assert_snapshot!(hir_string_without_inlining("test"), @"
         fn test@<compiled>:3:
         bb1():
           EntryPoint interpreter
@@ -4039,7 +4050,7 @@ mod hir_opt_tests {
             test
             test
         ");
-        assert_snapshot!(hir_string("test"), @"
+        assert_snapshot!(hir_string_without_inlining("test"), @"
         fn test@<compiled>:3:
         bb1():
           EntryPoint interpreter
@@ -4074,7 +4085,7 @@ mod hir_opt_tests {
             test
             test
         ");
-        assert_snapshot!(hir_string("test"), @"
+        assert_snapshot!(hir_string_without_inlining("test"), @"
         fn test@<compiled>:3:
         bb1():
           EntryPoint interpreter
@@ -4105,7 +4116,7 @@ mod hir_opt_tests {
             test
             test
         ");
-        assert_snapshot!(hir_string("test"), @"
+        assert_snapshot!(hir_string_without_inlining("test"), @"
         fn test@<compiled>:3:
         bb1():
           EntryPoint interpreter
@@ -4136,7 +4147,7 @@ mod hir_opt_tests {
             test
             test
         ");
-        assert_snapshot!(hir_string("test"), @"
+        assert_snapshot!(hir_string_without_inlining("test"), @"
         fn test@<compiled>:3:
         bb1():
           EntryPoint interpreter
@@ -4168,7 +4179,7 @@ mod hir_opt_tests {
             test
             test
         ");
-        assert_snapshot!(hir_string("test"), @"
+        assert_snapshot!(hir_string_without_inlining("test"), @"
         fn test@<compiled>:3:
         bb1():
           EntryPoint interpreter
@@ -4199,7 +4210,7 @@ mod hir_opt_tests {
             test
             test
         ");
-        assert_snapshot!(hir_string("test"), @"
+        assert_snapshot!(hir_string_without_inlining("test"), @"
         fn test@<compiled>:3:
         bb1():
           EntryPoint interpreter
@@ -4230,7 +4241,7 @@ mod hir_opt_tests {
             test
             test
         ");
-        assert_snapshot!(hir_string("test"), @"
+        assert_snapshot!(hir_string_without_inlining("test"), @"
         fn test@<compiled>:3:
         bb1():
           EntryPoint interpreter