Remove semi-nondeterminism of DefPathHash ordering from inliner

compiler/rustc_mir_transform/src/inline.rs

@@ -357,16 +357,6 @@ impl<'tcx> Inliner<'tcx> {
         }
 
         if callee_def_id.is_local() {
-            // Avoid a cycle here by only using `instance_mir` only if we have
-            // a lower `DefPathHash` than the callee. This ensures that the callee will
-            // not inline us. This trick even works with incremental compilation,
-            // since `DefPathHash` is stable.
-            if self.tcx.def_path_hash(caller_def_id).local_hash()
-                < self.tcx.def_path_hash(callee_def_id).local_hash()
-            {
-                return Ok(());
-            }
-
             // If we know for sure that the function we're calling will itself try to
             // call us, then we avoid inlining that function.
             if self.tcx.mir_callgraph_reachable((callee, caller_def_id.expect_local())) {

tests/mir-opt/inline/cycle.main.Inline.panic-abort.diff

@@ -4,35 +4,16 @@
   fn main() -> () {
       let mut _0: ();
       let _1: ();
-+     let mut _2: fn() {g};
-+     scope 1 (inlined f::<fn() {g}>) {
-+         debug g => _2;
-+         let mut _3: &fn() {g};
-+         let _4: ();
-+     }
   
       bb0: {
           StorageLive(_1);
--         _1 = f::<fn() {g}>(g) -> [return: bb1, unwind unreachable];
-+         StorageLive(_2);
-+         _2 = g;
-+         StorageLive(_4);
-+         StorageLive(_3);
-+         _3 = &_2;
-+         _4 = <fn() {g} as Fn<()>>::call(move _3, const ()) -> [return: bb2, unwind unreachable];
+          _1 = f::<fn() {g}>(g) -> [return: bb1, unwind unreachable];
       }
   
       bb1: {
-+         StorageDead(_4);
-+         StorageDead(_2);
           StorageDead(_1);
           _0 = const ();
           return;
-+     }
-+ 
-+     bb2: {
-+         StorageDead(_3);
-+         drop(_2) -> [return: bb1, unwind unreachable];
       }
   }
   

tests/mir-opt/inline/cycle.main.Inline.panic-unwind.diff

@@ -4,43 +4,16 @@
   fn main() -> () {
       let mut _0: ();
       let _1: ();
-+     let mut _2: fn() {g};
-+     scope 1 (inlined f::<fn() {g}>) {
-+         debug g => _2;
-+         let mut _3: &fn() {g};
-+         let _4: ();
-+     }
   
       bb0: {
           StorageLive(_1);
--         _1 = f::<fn() {g}>(g) -> [return: bb1, unwind continue];
-+         StorageLive(_2);
-+         _2 = g;
-+         StorageLive(_4);
-+         StorageLive(_3);
-+         _3 = &_2;
-+         _4 = <fn() {g} as Fn<()>>::call(move _3, const ()) -> [return: bb2, unwind: bb3];
+          _1 = f::<fn() {g}>(g) -> [return: bb1, unwind continue];
       }
   
       bb1: {
-+         StorageDead(_4);
-+         StorageDead(_2);
           StorageDead(_1);
           _0 = const ();
           return;
-+     }
-+ 
-+     bb2: {
-+         StorageDead(_3);
-+         drop(_2) -> [return: bb1, unwind continue];
-+     }
-+ 
-+     bb3 (cleanup): {
-+         drop(_2) -> [return: bb4, unwind terminate(cleanup)];
-+     }
-+ 
-+     bb4 (cleanup): {
-+         resume;
       }
   }
   

tests/mir-opt/inline/cycle.rs

@@ -19,9 +19,5 @@ fn g() {
 
 // EMIT_MIR cycle.main.Inline.diff
 fn main() {
-    // CHECK-LABEL: fn main(
-    // CHECK-NOT: inlined
-    // CHECK: (inlined f::<fn() {g}>)
-    // CHECK-NOT: inlined
     f(g);
 }

tests/mir-opt/inline/inline_cycle_generic.main.Inline.panic-abort.diff

@@ -7,10 +7,6 @@
 +     scope 1 (inlined <C as Call>::call) {
 +         scope 2 (inlined <B<A> as Call>::call) {
 +             scope 3 (inlined <A as Call>::call) {
-+                 scope 4 (inlined <B<C> as Call>::call) {
-+                     scope 5 (inlined <C as Call>::call) {
-+                     }
-+                 }
 +             }
 +         }
 +     }
@@ -18,7 +14,7 @@
       bb0: {
           StorageLive(_1);
 -         _1 = <C as Call>::call() -> [return: bb1, unwind unreachable];
-+         _1 = <B<A> as Call>::call() -> [return: bb1, unwind unreachable];
++         _1 = <B<C> as Call>::call() -> [return: bb1, unwind unreachable];
       }
   
       bb1: {

tests/mir-opt/inline/inline_cycle_generic.main.Inline.panic-unwind.diff

@@ -7,10 +7,6 @@
 +     scope 1 (inlined <C as Call>::call) {
 +         scope 2 (inlined <B<A> as Call>::call) {
 +             scope 3 (inlined <A as Call>::call) {
-+                 scope 4 (inlined <B<C> as Call>::call) {
-+                     scope 5 (inlined <C as Call>::call) {
-+                     }
-+                 }
 +             }
 +         }
 +     }
@@ -18,7 +14,7 @@
       bb0: {
           StorageLive(_1);
 -         _1 = <C as Call>::call() -> [return: bb1, unwind continue];
-+         _1 = <B<A> as Call>::call() -> [return: bb1, unwind continue];
++         _1 = <B<C> as Call>::call() -> [return: bb1, unwind continue];
       }
   
       bb1: {