Move Derefer before Retag

compiler/rustc_middle/src/mir/mod.rs

@@ -1079,6 +1079,8 @@ pub enum LocalInfo<'tcx> {
     /// A temporary created during the creation of an aggregate
     /// (e.g. a temporary for `foo` in `MyStruct { my_field: foo }`)
     AggregateTemp,
+    /// A temporary created during the pass `Derefer` to avoid it's retagging
+    Temp,
 }
 
 impl<'tcx> LocalDecl<'tcx> {
@@ -1178,6 +1180,10 @@ impl<'tcx> LocalDecl<'tcx> {
         }
     }
 
+    pub fn temp(mut self) {
+        self.local_info = Some(Box::new(LocalInfo::Temp));
+    }
+
     /// Converts `self` into same `LocalDecl` except tagged as internal.
     #[inline]
     pub fn internal(mut self) -> Self {

compiler/rustc_middle/src/mir/patch.rs

@@ -78,6 +78,15 @@ impl<'tcx> MirPatch<'tcx> {
         Location { block: bb, statement_index: offset }
     }
 
+    pub fn new_local_temp(&mut self, ty: Ty<'tcx>, span: Span) -> Local {
+        let index = self.next_local;
+        self.next_local += 1;
+        let mut new_decl = LocalDecl::new(ty, span);
+        new_decl.local_info = Some(Box::new(LocalInfo::Temp));
+        self.new_locals.push(new_decl);
+        Local::new(index as usize)
+    }
+
     pub fn new_temp(&mut self, ty: Ty<'tcx>, span: Span) -> Local {
         let index = self.next_local;
         self.next_local += 1;

compiler/rustc_mir_transform/src/add_retag.rs

@@ -57,6 +57,17 @@ fn may_be_reference(ty: Ty<'_>) -> bool {
     }
 }
 
+/// Determines whether or not this LocalDecl is temp, if not it needs retagging.
+fn is_not_temp<'tcx>(local_decl: &LocalDecl<'tcx>) -> bool {
+    if local_decl.local_info.is_some() {
+        match local_decl.local_info.as_ref().unwrap().as_ref() {
+            LocalInfo::Temp => return false,
+            _ => (),
+        };
+    }
+    return true;
+}
+
 impl<'tcx> MirPass<'tcx> for AddRetag {
     fn is_enabled(&self, sess: &rustc_session::Session) -> bool {
         sess.opts.debugging_opts.mir_emit_retag
@@ -71,7 +82,9 @@ impl<'tcx> MirPass<'tcx> for AddRetag {
         let needs_retag = |place: &Place<'tcx>| {
             // FIXME: Instead of giving up for unstable places, we should introduce
             // a temporary and retag on that.
-            is_stable(place.as_ref()) && may_be_reference(place.ty(&*local_decls, tcx).ty)
+            is_stable(place.as_ref())
+                && may_be_reference(place.ty(&*local_decls, tcx).ty)
+                && is_not_temp(&local_decls[place.local])
         };
         let place_base_raw = |place: &Place<'tcx>| {
             // If this is a `Deref`, get the type of what we are deref'ing.

compiler/rustc_mir_transform/src/deref_separator.rs

@@ -34,20 +34,20 @@ impl<'tcx> MutVisitor<'tcx> for DerefChecker<'tcx> {
             if p_elem == ProjectionElem::Deref && !p_ref.projection.is_empty() {
                 let ty = p_ref.ty(&self.local_decls, self.tcx).ty;
                 let temp =
-                    self.patcher.new_temp(ty, self.local_decls[p_ref.local].source_info.span);
+                    self.patcher.new_local_temp(ty, self.local_decls[p_ref.local].source_info.span);
 
                 self.patcher.add_statement(loc, StatementKind::StorageLive(temp));
 
                 // We are adding current p_ref's projections to our
                 // temp value, excluding projections we already covered.
                 let deref_place = Place::from(place_local)
                     .project_deeper(&p_ref.projection[last_len..], self.tcx);
+
                 self.patcher.add_assign(
                     loc,
                     Place::from(temp),
                     Rvalue::Use(Operand::Move(deref_place)),
                 );
-
                 place_local = temp;
                 last_len = p_ref.projection.len();
 
@@ -58,7 +58,7 @@ impl<'tcx> MutVisitor<'tcx> for DerefChecker<'tcx> {
                     *place = temp_place;
                 }
 
-                // We are destroying last temp since it's no longer used.
+                // We are destroying the previous temp since it's no longer used.
                 if let Some(prev_temp) = prev_temp {
                     self.patcher.add_statement(loc, StatementKind::StorageDead(prev_temp));
                 }

compiler/rustc_mir_transform/src/lib.rs

@@ -426,13 +426,13 @@ fn run_post_borrowck_cleanup_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tc
         &add_moves_for_packed_drops::AddMovesForPackedDrops,
         // `AddRetag` needs to run after `ElaborateDrops`. Otherwise it should run fairly late,
         // but before optimizations begin.
+        &deref_separator::Derefer,
         &add_retag::AddRetag,
         &lower_intrinsics::LowerIntrinsics,
         &simplify::SimplifyCfg::new("elaborate-drops"),
         // `Deaggregator` is conceptually part of MIR building, some backends rely on it happening
         // and it can help optimizations.
         &deaggregator::Deaggregator,
-        &deref_separator::Derefer,
         &Lint(const_prop_lint::ConstProp),
     ];
 

src/test/mir-opt/derefer_complex_case.main.Derefer.diff

@@ -102,10 +102,10 @@
           StorageDead(_6);                 // scope 1 at $DIR/derefer_complex_case.rs:4:39: 4:40
           _5 = const ();                   // scope 1 at $DIR/derefer_complex_case.rs:4:5: 4:40
           goto -> bb2;                     // scope 1 at $DIR/derefer_complex_case.rs:4:5: 4:40
-+     }
-+ 
-+     bb8 (cleanup): {
-+         resume;                          // scope 0 at $DIR/derefer_complex_case.rs:3:1: 5:2
+      }
+  
+      bb8 (cleanup): {
+          resume;                          // scope 0 at $DIR/derefer_complex_case.rs:3:1: 5:2
       }
   }
 

src/test/mir-opt/derefer_terminator_test.main.Derefer.diff

@@ -94,10 +94,10 @@
           StorageDead(_2);                 // scope 1 at $DIR/derefer_terminator_test.rs:10:1: 10:2
           StorageDead(_1);                 // scope 0 at $DIR/derefer_terminator_test.rs:10:1: 10:2
           return;                          // scope 0 at $DIR/derefer_terminator_test.rs:10:2: 10:2
-+     }
-+ 
-+     bb6 (cleanup): {
-+         resume;                          // scope 0 at $DIR/derefer_terminator_test.rs:2:1: 10:2
+      }
+  
+      bb6 (cleanup): {
+          resume;                          // scope 0 at $DIR/derefer_terminator_test.rs:2:1: 10:2
       }
   }
 

src/test/mir-opt/derefer_test.main.Derefer.diff

@@ -25,15 +25,11 @@
 
       bb0: {
           StorageLive(_1);                 // scope 0 at $DIR/derefer_test.rs:3:9: 3:14
-          Deinit(_1);                      // scope 0 at $DIR/derefer_test.rs:3:17: 3:24
-          (_1.0: i32) = const 42_i32;      // scope 0 at $DIR/derefer_test.rs:3:17: 3:24
-          (_1.1: i32) = const 43_i32;      // scope 0 at $DIR/derefer_test.rs:3:17: 3:24
+          _1 = (const 42_i32, const 43_i32); // scope 0 at $DIR/derefer_test.rs:3:17: 3:24
           StorageLive(_2);                 // scope 1 at $DIR/derefer_test.rs:4:9: 4:14
           StorageLive(_3);                 // scope 1 at $DIR/derefer_test.rs:4:22: 4:28
           _3 = &mut _1;                    // scope 1 at $DIR/derefer_test.rs:4:22: 4:28
-          Deinit(_2);                      // scope 1 at $DIR/derefer_test.rs:4:17: 4:29
-          (_2.0: i32) = const 99_i32;      // scope 1 at $DIR/derefer_test.rs:4:17: 4:29
-          (_2.1: &mut (i32, i32)) = move _3; // scope 1 at $DIR/derefer_test.rs:4:17: 4:29
+          _2 = (const 99_i32, move _3);    // scope 1 at $DIR/derefer_test.rs:4:17: 4:29
           StorageDead(_3);                 // scope 1 at $DIR/derefer_test.rs:4:28: 4:29
           StorageLive(_4);                 // scope 2 at $DIR/derefer_test.rs:5:9: 5:10
 -         _4 = &mut ((*(_2.1: &mut (i32, i32))).0: i32); // scope 2 at $DIR/derefer_test.rs:5:13: 5:26
@@ -53,10 +49,10 @@
           StorageDead(_2);                 // scope 1 at $DIR/derefer_test.rs:7:1: 7:2
           StorageDead(_1);                 // scope 0 at $DIR/derefer_test.rs:7:1: 7:2
           return;                          // scope 0 at $DIR/derefer_test.rs:7:2: 7:2
-+     }
-+ 
-+     bb1 (cleanup): {
-+         resume;                          // scope 0 at $DIR/derefer_test.rs:2:1: 7:2
+      }
+  
+      bb1 (cleanup): {
+          resume;                          // scope 0 at $DIR/derefer_test.rs:2:1: 7:2
       }
   }
 

src/test/mir-opt/derefer_test_multiple.main.Derefer.diff

@@ -39,29 +39,21 @@
 
       bb0: {
           StorageLive(_1);                 // scope 0 at $DIR/derefer_test_multiple.rs:3:9: 3:14
-          Deinit(_1);                      // scope 0 at $DIR/derefer_test_multiple.rs:3:17: 3:25
-          (_1.0: i32) = const 42_i32;      // scope 0 at $DIR/derefer_test_multiple.rs:3:17: 3:25
-          (_1.1: i32) = const 43_i32;      // scope 0 at $DIR/derefer_test_multiple.rs:3:17: 3:25
+          _1 = (const 42_i32, const 43_i32); // scope 0 at $DIR/derefer_test_multiple.rs:3:17: 3:25
           StorageLive(_2);                 // scope 1 at $DIR/derefer_test_multiple.rs:4:9: 4:14
           StorageLive(_3);                 // scope 1 at $DIR/derefer_test_multiple.rs:4:22: 4:28
           _3 = &mut _1;                    // scope 1 at $DIR/derefer_test_multiple.rs:4:22: 4:28
-          Deinit(_2);                      // scope 1 at $DIR/derefer_test_multiple.rs:4:17: 4:29
-          (_2.0: i32) = const 99_i32;      // scope 1 at $DIR/derefer_test_multiple.rs:4:17: 4:29
-          (_2.1: &mut (i32, i32)) = move _3; // scope 1 at $DIR/derefer_test_multiple.rs:4:17: 4:29
+          _2 = (const 99_i32, move _3);    // scope 1 at $DIR/derefer_test_multiple.rs:4:17: 4:29
           StorageDead(_3);                 // scope 1 at $DIR/derefer_test_multiple.rs:4:28: 4:29
           StorageLive(_4);                 // scope 2 at $DIR/derefer_test_multiple.rs:5:9: 5:14
           StorageLive(_5);                 // scope 2 at $DIR/derefer_test_multiple.rs:5:22: 5:28
           _5 = &mut _2;                    // scope 2 at $DIR/derefer_test_multiple.rs:5:22: 5:28
-          Deinit(_4);                      // scope 2 at $DIR/derefer_test_multiple.rs:5:17: 5:29
-          (_4.0: i32) = const 11_i32;      // scope 2 at $DIR/derefer_test_multiple.rs:5:17: 5:29
-          (_4.1: &mut (i32, &mut (i32, i32))) = move _5; // scope 2 at $DIR/derefer_test_multiple.rs:5:17: 5:29
+          _4 = (const 11_i32, move _5);    // scope 2 at $DIR/derefer_test_multiple.rs:5:17: 5:29
           StorageDead(_5);                 // scope 2 at $DIR/derefer_test_multiple.rs:5:28: 5:29
           StorageLive(_6);                 // scope 3 at $DIR/derefer_test_multiple.rs:6:9: 6:14
           StorageLive(_7);                 // scope 3 at $DIR/derefer_test_multiple.rs:6:22: 6:28
           _7 = &mut _4;                    // scope 3 at $DIR/derefer_test_multiple.rs:6:22: 6:28
-          Deinit(_6);                      // scope 3 at $DIR/derefer_test_multiple.rs:6:17: 6:29
-          (_6.0: i32) = const 13_i32;      // scope 3 at $DIR/derefer_test_multiple.rs:6:17: 6:29
-          (_6.1: &mut (i32, &mut (i32, &mut (i32, i32)))) = move _7; // scope 3 at $DIR/derefer_test_multiple.rs:6:17: 6:29
+          _6 = (const 13_i32, move _7);    // scope 3 at $DIR/derefer_test_multiple.rs:6:17: 6:29
           StorageDead(_7);                 // scope 3 at $DIR/derefer_test_multiple.rs:6:28: 6:29
           StorageLive(_8);                 // scope 4 at $DIR/derefer_test_multiple.rs:7:9: 7:10
 -         _8 = &mut ((*((*((*(_6.1: &mut (i32, &mut (i32, &mut (i32, i32))))).1: &mut (i32, &mut (i32, i32)))).1: &mut (i32, i32))).1: i32); // scope 4 at $DIR/derefer_test_multiple.rs:7:13: 7:30
@@ -95,10 +87,10 @@
           StorageDead(_2);                 // scope 1 at $DIR/derefer_test_multiple.rs:9:1: 9:2
           StorageDead(_1);                 // scope 0 at $DIR/derefer_test_multiple.rs:9:1: 9:2
           return;                          // scope 0 at $DIR/derefer_test_multiple.rs:9:2: 9:2
-+     }
-+ 
-+     bb1 (cleanup): {
-+         resume;                          // scope 0 at $DIR/derefer_test_multiple.rs:2:1: 9:2
+      }
+  
+      bb1 (cleanup): {
+          resume;                          // scope 0 at $DIR/derefer_test_multiple.rs:2:1: 9:2
       }
   }
 

src/test/mir-opt/early_otherwise_branch.opt1.EarlyOtherwiseBranch.diff

@@ -68,10 +68,8 @@
 +     bb3: {
           StorageDead(_3);                 // scope 0 at $DIR/early_otherwise_branch.rs:8:1: 8:2
           return;                          // scope 0 at $DIR/early_otherwise_branch.rs:8:2: 8:2
-      }
-
--     bb5 (cleanup): {
--         resume;                          // scope 0 at $DIR/early_otherwise_branch.rs:3:1: 8:2
++     }
++ 
 +     bb4: {
 +         StorageDead(_11);                // scope 0 at $DIR/early_otherwise_branch.rs:4:5: 4:17
 +         switchInt(_7) -> [1_isize: bb2, otherwise: bb1]; // scope 0 at $DIR/early_otherwise_branch.rs:4:5: 4:17

src/test/mir-opt/early_otherwise_branch.opt2.EarlyOtherwiseBranch.diff

@@ -82,10 +82,8 @@
 +     bb4: {
           StorageDead(_3);                 // scope 0 at $DIR/early_otherwise_branch.rs:17:1: 17:2
           return;                          // scope 0 at $DIR/early_otherwise_branch.rs:17:2: 17:2
-      }
-
--     bb7 (cleanup): {
--         resume;                          // scope 0 at $DIR/early_otherwise_branch.rs:11:1: 17:2
++     }
++ 
 +     bb5: {
 +         StorageDead(_12);                // scope 0 at $DIR/early_otherwise_branch.rs:12:5: 12:17
 +         switchInt(_8) -> [0_isize: bb3, 1_isize: bb2, otherwise: bb1]; // scope 0 at $DIR/early_otherwise_branch.rs:12:5: 12:17

src/test/mir-opt/early_otherwise_branch.opt3.EarlyOtherwiseBranch.diff

@@ -68,10 +68,8 @@
 +     bb3: {
           StorageDead(_3);                 // scope 0 at $DIR/early_otherwise_branch.rs:26:1: 26:2
           return;                          // scope 0 at $DIR/early_otherwise_branch.rs:26:2: 26:2
-      }
-
--     bb5 (cleanup): {
--         resume;                          // scope 0 at $DIR/early_otherwise_branch.rs:21:1: 26:2
++     }
++ 
 +     bb4: {
 +         StorageDead(_11);                // scope 0 at $DIR/early_otherwise_branch.rs:22:5: 22:17
 +         switchInt(_7) -> [1_isize: bb2, otherwise: bb1]; // scope 0 at $DIR/early_otherwise_branch.rs:22:5: 22:17

src/test/mir-opt/early_otherwise_branch_3_element_tuple.opt1.EarlyOtherwiseBranch.diff

@@ -90,10 +90,8 @@
 +     bb4: {
           StorageDead(_4);                 // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:9:1: 9:2
           return;                          // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:9:2: 9:2
-      }
-
--     bb6 (cleanup): {
--         resume;                          // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:4:1: 9:2
++     }
++ 
 +     bb5: {
 +         StorageDead(_15);                // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:5:5: 5:20
 +         switchInt(_10) -> [1_isize: bb2, otherwise: bb1]; // scope 0 at $DIR/early_otherwise_branch_3_element_tuple.rs:5:5: 5:20

src/test/mir-opt/early_otherwise_branch_noopt.noopt1.EarlyOtherwiseBranch.diff

@@ -91,9 +91,5 @@
           StorageDead(_3);                 // scope 0 at $DIR/early_otherwise_branch_noopt.rs:14:1: 14:2
           return;                          // scope 0 at $DIR/early_otherwise_branch_noopt.rs:14:2: 14:2
       }
-
-      bb9 (cleanup): {
-          resume;                          // scope 0 at $DIR/early_otherwise_branch_noopt.rs:7:1: 14:2
-      }
   }
 

src/test/mir-opt/early_otherwise_branch_soundness.no_deref_ptr.EarlyOtherwiseBranch.diff

@@ -43,9 +43,5 @@
       bb5: {
           return;                          // scope 0 at $DIR/early_otherwise_branch_soundness.rs:27:2: 27:2
       }
-
-      bb6 (cleanup): {
-          resume;                          // scope 0 at $DIR/early_otherwise_branch_soundness.rs:18:1: 27:2
-      }
   }
 

src/test/mir-opt/early_otherwise_branch_soundness.no_downcast.EarlyOtherwiseBranch.diff

@@ -34,9 +34,5 @@
       bb4: {
           return;                          // scope 0 at $DIR/early_otherwise_branch_soundness.rs:14:2: 14:2
       }
-
-      bb5 (cleanup): {
-          resume;                          // scope 0 at $DIR/early_otherwise_branch_soundness.rs:12:1: 14:2
-      }
   }
 

src/test/mir-opt/if_condition_int.dont_opt_bool.SimplifyComparisonIntegral.diff

@@ -26,9 +26,5 @@
           StorageDead(_2);                 // scope 0 at $DIR/if-condition-int.rs:17:25: 17:26
           return;                          // scope 0 at $DIR/if-condition-int.rs:18:2: 18:2
       }
-
-      bb4 (cleanup): {
-          resume;                          // scope 0 at $DIR/if-condition-int.rs:16:1: 18:2
-      }
   }
 

src/test/mir-opt/if_condition_int.dont_opt_floats.SimplifyComparisonIntegral.diff

@@ -30,9 +30,5 @@
           StorageDead(_2);                 // scope 0 at $DIR/if-condition-int.rs:53:34: 53:35
           return;                          // scope 0 at $DIR/if-condition-int.rs:54:2: 54:2
       }
-
-      bb4 (cleanup): {
-          resume;                          // scope 0 at $DIR/if-condition-int.rs:52:1: 54:2
-      }
   }
 

src/test/mir-opt/if_condition_int.dont_remove_comparison.SimplifyComparisonIntegral.diff

@@ -54,9 +54,5 @@
           StorageDead(_2);                 // scope 0 at $DIR/if-condition-int.rs:49:1: 49:2
           return;                          // scope 0 at $DIR/if-condition-int.rs:49:2: 49:2
       }
-
-      bb4 (cleanup): {
-          resume;                          // scope 0 at $DIR/if-condition-int.rs:43:1: 49:2
-      }
   }
 

src/test/mir-opt/if_condition_int.opt_char.SimplifyComparisonIntegral.diff

@@ -35,9 +35,5 @@
           StorageDead(_2);                 // scope 0 at $DIR/if-condition-int.rs:21:32: 21:33
           return;                          // scope 0 at $DIR/if-condition-int.rs:22:2: 22:2
       }
-
-      bb4 (cleanup): {
-          resume;                          // scope 0 at $DIR/if-condition-int.rs:20:1: 22:2
-      }
   }
 

src/test/mir-opt/if_condition_int.opt_i8.SimplifyComparisonIntegral.diff

@@ -35,9 +35,5 @@
           StorageDead(_2);                 // scope 0 at $DIR/if-condition-int.rs:25:31: 25:32
           return;                          // scope 0 at $DIR/if-condition-int.rs:26:2: 26:2
       }
-
-      bb4 (cleanup): {
-          resume;                          // scope 0 at $DIR/if-condition-int.rs:24:1: 26:2
-      }
   }
 

src/test/mir-opt/if_condition_int.opt_multiple_ifs.SimplifyComparisonIntegral.diff

@@ -61,9 +61,5 @@
           StorageDead(_2);                 // scope 0 at $DIR/if-condition-int.rs:39:5: 39:6
           return;                          // scope 0 at $DIR/if-condition-int.rs:40:2: 40:2
       }
-
-      bb7 (cleanup): {
-          resume;                          // scope 0 at $DIR/if-condition-int.rs:32:1: 40:2
-      }
   }
 

src/test/mir-opt/if_condition_int.opt_negative.SimplifyComparisonIntegral.diff

@@ -35,9 +35,5 @@
           StorageDead(_2);                 // scope 0 at $DIR/if-condition-int.rs:29:32: 29:33
           return;                          // scope 0 at $DIR/if-condition-int.rs:30:2: 30:2
       }
-
-      bb4 (cleanup): {
-          resume;                          // scope 0 at $DIR/if-condition-int.rs:28:1: 30:2
-      }
   }
 

src/test/mir-opt/if_condition_int.opt_u32.SimplifyComparisonIntegral.diff

@@ -35,9 +35,5 @@
           StorageDead(_2);                 // scope 0 at $DIR/if-condition-int.rs:12:31: 12:32
           return;                          // scope 0 at $DIR/if-condition-int.rs:13:2: 13:2
       }
-
-      bb4 (cleanup): {
-          resume;                          // scope 0 at $DIR/if-condition-int.rs:11:1: 13:2
-      }
   }
 

src/test/mir-opt/lower_array_len.array_bound.NormalizeArrayLen.diff

@@ -64,9 +64,5 @@
           StorageDead(_3);                 // scope 0 at $DIR/lower_array_len.rs:11:5: 11:6
           return;                          // scope 0 at $DIR/lower_array_len.rs:12:2: 12:2
       }
-
-      bb6 (cleanup): {
-          resume;                          // scope 0 at $DIR/lower_array_len.rs:6:1: 12:2
-      }
   }