Only inline FnPtr and FnDef shims in inliner

Author: compiler-errors

compiler/rustc_mir_transform/src/inline.rs

@@ -625,6 +625,12 @@ fn try_inlining<'tcx, I: Inliner<'tcx>>(
         return Err("implementation limitation -- return type mismatch");
     }
     if callsite.fn_sig.abi() == ExternAbi::RustCall {
+        match callsite.callee.def {
+            InstanceKind::Item(def_id) if tcx.is_closure_like(def_id) => {}
+            InstanceKind::FnPtrShim(..) | InstanceKind::ClosureOnceShim { .. } => {}
+            _ => return Err("not inlining non-builtin call"),
+        }
+
         let (self_arg, arg_tuple) = match &args[..] {
             [arg_tuple] => (None, arg_tuple),
             [self_arg, arg_tuple] => (Some(self_arg), arg_tuple),

tests/mir-opt/inline/inline_cycle.two.Inline.panic-unwind.diff

@@ -5,9 +5,15 @@
       let mut _0: ();
       let _1: ();
 +     let mut _2: fn() {f};
++     let mut _4: ();
 +     scope 1 (inlined call::<fn() {f}>) {
 +         debug f => _2;
 +         let _3: ();
++         scope 2 (inlined <fn() {f} as FnOnce<()>>::call_once - shim(fn() {f})) {
++             scope 3 (inlined f) {
++                 let _5: ();
++             }
++         }
 +     }
 
       bb0: {
@@ -16,10 +22,15 @@
 +         StorageLive(_2);
 +         _2 = f;
 +         StorageLive(_3);
-+         _3 = <fn() {f} as FnOnce<()>>::call_once(move _2, const ()) -> [return: bb1, unwind continue];
++         StorageLive(_4);
++         _4 = const ();
++         StorageLive(_5);
++         _5 = call::<fn() {f}>(f) -> [return: bb1, unwind continue];
       }
 
       bb1: {
++         StorageDead(_5);
++         StorageDead(_4);
 +         StorageDead(_3);
 +         StorageDead(_2);
           StorageDead(_1);

tests/mir-opt/inline/inline_diverging.h.Inline.panic-unwind.diff

@@ -5,6 +5,7 @@
       let mut _0: ();
       let _1: (!, !);
 +     let mut _2: fn() -> ! {sleep};
++     let mut _8: ();
 +     scope 1 (inlined call_twice::<!, fn() -> ! {sleep}>) {
 +         debug f => _2;
 +         let mut _3: &fn() -> ! {sleep};
@@ -18,6 +19,10 @@
 +                 debug b => _6;
 +             }
 +         }
++         scope 4 (inlined <fn() -> ! {sleep} as Fn<()>>::call - shim(fn() -> ! {sleep})) {
++             scope 5 (inlined sleep) {
++             }
++         }
 +     }
 
       bb0: {
@@ -29,40 +34,13 @@
 +         StorageLive(_4);
 +         StorageLive(_3);
 +         _3 = &_2;
-+         _4 = <fn() -> ! {sleep} as Fn<()>>::call(move _3, const ()) -> [return: bb1, unwind: bb5];
++         StorageLive(_8);
++         _8 = const ();
++         goto -> bb1;
 +     }
 + 
 +     bb1: {
-+         StorageDead(_3);
-+         StorageLive(_5);
-+         _5 = &_2;
-+         _6 = <fn() -> ! {sleep} as Fn<()>>::call(move _5, const ()) -> [return: bb2, unwind: bb4];
-+     }
-+ 
-+     bb2: {
-+         StorageDead(_5);
-+         StorageLive(_7);
-+         _7 = move _4;
-+         _1 = (move _7, copy _6);
-+         StorageDead(_7);
-+         StorageDead(_4);
-+         drop(_2) -> [return: bb3, unwind continue];
-+     }
-+ 
-+     bb3: {
-+         unreachable;
-+     }
-+ 
-+     bb4 (cleanup): {
-+         drop(_4) -> [return: bb5, unwind terminate(cleanup)];
-+     }
-+ 
-+     bb5 (cleanup): {
-+         drop(_2) -> [return: bb6, unwind terminate(cleanup)];
-+     }
-+ 
-+     bb6 (cleanup): {
-+         resume;
++         goto -> bb1;
       }
   }
 

tests/mir-opt/inline/inline_diverging.rs

@@ -26,7 +26,8 @@ pub fn g(i: i32) -> u32 {
 pub fn h() {
     // CHECK-LABEL: fn h(
     // CHECK: (inlined call_twice::<!, fn() -> ! {sleep}>)
-    // CHECK-NOT: inlined
+    // CHECK: (inlined <fn() -> ! {sleep} as Fn<()>>::call - shim(fn() -> ! {sleep}))
+    // CHECK: (inlined sleep)
     call_twice(sleep);
 }
 

tests/mir-opt/inline/issue_78442.bar.Inline.panic-unwind.diff

@@ -9,6 +9,10 @@
       let _4: fn() {foo};
       let mut _5: ();
 +     scope 1 (inlined hide_foo) {
++     }
++     scope 2 (inlined <fn() {foo} as Fn<()>>::call - shim(fn() {foo})) {
++         scope 3 (inlined foo) {
++         }
 +     }
 
       bb0: {
@@ -23,33 +27,29 @@
           StorageLive(_5);
           _5 = ();
 -         _2 = <fn() {foo} as Fn<()>>::call(move _3, move _5) -> [return: bb2, unwind: bb4];
-+         _2 = <fn() {foo} as Fn<()>>::call(move _3, move _5) -> [return: bb1, unwind: bb3];
-      }
-  
+-     }
+- 
 -     bb2: {
-+     bb1: {
           StorageDead(_5);
           StorageDead(_3);
           StorageDead(_4);
           StorageDead(_2);
           _0 = const ();
 -         drop(_1) -> [return: bb3, unwind: bb5];
-+         drop(_1) -> [return: bb2, unwind: bb4];
++         drop(_1) -> [return: bb1, unwind: bb2];
       }
 
 -     bb3: {
-+     bb2: {
++     bb1: {
           return;
       }
 
 -     bb4 (cleanup): {
 -         drop(_1) -> [return: bb5, unwind terminate(cleanup)];
-+     bb3 (cleanup): {
-+         drop(_1) -> [return: bb4, unwind terminate(cleanup)];
-      }
-  
+-     }
+- 
 -     bb5 (cleanup): {
-+     bb4 (cleanup): {
++     bb2 (cleanup): {
           resume;
       }
   }

tests/mir-opt/inline/issue_78442.rs

@@ -9,10 +9,9 @@ pub fn bar<P>(
     _baz: P,
 ) {
     // CHECK-LABEL: fn bar(
-    // CHECK: let mut {{.*}}: &fn() {foo};
-    // CHECK: let {{.*}}: fn() {foo};
     // CHECK: (inlined hide_foo)
-    // CHECK-NOT: inlined
+    // CHECK: (inlined <fn() {foo} as Fn<()>>::call - shim(fn() {foo}))
+    // CHECK: (inlined foo)
     hide_foo()();
 }