GVN borrowed locals too.

Author: cjgillot

compiler/rustc_mir_transform/src/copy_prop.rs

@@ -112,6 +112,9 @@ impl<'tcx> MutVisitor<'tcx> for Replacer<'_, 'tcx> {
 
     fn visit_local(&mut self, local: &mut Local, ctxt: PlaceContext, _: Location) {
         let new_local = self.copy_classes[*local];
+        if self.borrowed_locals.contains(*local) || self.borrowed_locals.contains(new_local) {
+            return;
+        }
         match ctxt {
             // Do not modify the local in storage statements.
             PlaceContext::NonUse(NonUseContext::StorageLive | NonUseContext::StorageDead) => {}
@@ -122,32 +125,16 @@ impl<'tcx> MutVisitor<'tcx> for Replacer<'_, 'tcx> {
         }
     }
 
-    fn visit_place(&mut self, place: &mut Place<'tcx>, ctxt: PlaceContext, loc: Location) {
+    fn visit_place(&mut self, place: &mut Place<'tcx>, _: PlaceContext, loc: Location) {
         if let Some(new_projection) = self.process_projection(place.projection, loc) {
             place.projection = self.tcx().mk_place_elems(&new_projection);
         }
 
-        let observes_address = match ctxt {
-            PlaceContext::NonMutatingUse(
-                NonMutatingUseContext::SharedBorrow
-                | NonMutatingUseContext::FakeBorrow
-                | NonMutatingUseContext::AddressOf,
-            ) => true,
-            // For debuginfo, merging locals is ok.
-            PlaceContext::NonUse(NonUseContext::VarDebugInfo) => {
-                self.borrowed_locals.contains(place.local)
-            }
-            _ => false,
-        };
-        if observes_address && !place.is_indirect() {
-            // We observe the address of `place.local`. Do not replace it.
-        } else {
-            self.visit_local(
-                &mut place.local,
-                PlaceContext::NonMutatingUse(NonMutatingUseContext::Copy),
-                loc,
-            )
-        }
+        self.visit_local(
+            &mut place.local,
+            PlaceContext::NonMutatingUse(NonMutatingUseContext::Copy),
+            loc,
+        )
     }
 
     fn visit_operand(&mut self, operand: &mut Operand<'tcx>, loc: Location) {

compiler/rustc_mir_transform/src/ssa.rs

@@ -235,11 +235,7 @@ impl<'tcx> Visitor<'tcx> for SsaVisitor<'tcx, '_> {
             // Anything can happen with raw pointers, so remove them.
             // We do not verify that all uses of the borrow dominate the assignment to `local`,
             // so we have to remove them too.
-            PlaceContext::NonMutatingUse(
-                NonMutatingUseContext::SharedBorrow
-                | NonMutatingUseContext::FakeBorrow
-                | NonMutatingUseContext::AddressOf,
-            )
+            PlaceContext::NonMutatingUse(NonMutatingUseContext::AddressOf)
             | PlaceContext::MutatingUse(_) => {
                 self.assignments[local] = Set1::Many;
             }

tests/mir-opt/pre-codegen/slice_filter.variant_a-{closure#0}.PreCodegen.after.mir

@@ -18,10 +18,10 @@ fn variant_a::{closure#0}(_1: &mut {closure@$DIR/slice_filter.rs:8:25: 8:39}, _2
     let mut _24: &&usize;
     let _25: &usize;
     let mut _26: &&usize;
-    let mut _31: bool;
+    let mut _29: bool;
+    let mut _30: &&usize;
+    let _31: &usize;
     let mut _32: &&usize;
-    let _33: &usize;
-    let mut _34: &&usize;
     scope 1 {
         debug a => _4;
         debug b => _5;
@@ -59,83 +59,69 @@ fn variant_a::{closure#0}(_1: &mut {closure@$DIR/slice_filter.rs:8:25: 8:39}, _2
             scope 7 (inlined std::cmp::impls::<impl PartialOrd for usize>::le) {
                 debug self => _27;
                 debug other => _28;
-                let mut _29: usize;
-                let mut _30: usize;
             }
         }
         scope 8 (inlined std::cmp::impls::<impl PartialOrd for &usize>::le) {
-            debug self => _32;
-            debug other => _34;
-            let mut _35: &usize;
-            let mut _36: &usize;
+            debug self => _30;
+            debug other => _32;
+            let mut _33: &usize;
+            let mut _34: &usize;
             scope 9 (inlined std::cmp::impls::<impl PartialOrd for usize>::le) {
-                debug self => _35;
-                debug other => _36;
-                let mut _37: usize;
-                let mut _38: usize;
+                debug self => _33;
+                debug other => _34;
+                let mut _35: usize;
+                let mut _36: usize;
             }
         }
     }
 
     bb0: {
-        StorageLive(_4);
         _3 = (*_2);
         _4 = &((*_3).0: usize);
-        StorageLive(_5);
         _5 = &((*_3).1: usize);
-        StorageLive(_6);
         _6 = &((*_3).2: usize);
-        StorageLive(_7);
         _7 = &((*_3).3: usize);
         StorageLive(_15);
         StorageLive(_8);
         _8 = &_4;
         StorageLive(_10);
-        StorageLive(_9);
-        _9 = _6;
+        _9 = &((*_3).2: usize);
         _10 = &_9;
         StorageLive(_11);
         StorageLive(_12);
         _11 = _4;
         _12 = _9;
-        StorageLive(_13);
-        _13 = (*_11);
-        StorageLive(_14);
-        _14 = (*_12);
-        _15 = Le(move _13, move _14);
-        StorageDead(_14);
-        StorageDead(_13);
+        _13 = ((*_3).0: usize);
+        _14 = ((*_3).2: usize);
+        _15 = Le(_13, _14);
         StorageDead(_12);
         StorageDead(_11);
         switchInt(move _15) -> [0: bb1, otherwise: bb2];
     }
 
     bb1: {
-        StorageDead(_9);
         StorageDead(_10);
         StorageDead(_8);
         goto -> bb4;
     }
 
     bb2: {
-        StorageDead(_9);
         StorageDead(_10);
         StorageDead(_8);
         StorageLive(_23);
         StorageLive(_16);
         _16 = &_7;
         StorageLive(_18);
-        StorageLive(_17);
-        _17 = _5;
+        _17 = &((*_3).1: usize);
         _18 = &_17;
         StorageLive(_19);
         StorageLive(_20);
         _19 = _7;
         _20 = _17;
         StorageLive(_21);
-        _21 = (*_19);
+        _21 = ((*_3).3: usize);
         StorageLive(_22);
-        _22 = (*_20);
+        _22 = ((*_3).1: usize);
         _23 = Le(move _21, move _22);
         StorageDead(_22);
         StorageDead(_21);
@@ -145,80 +131,67 @@ fn variant_a::{closure#0}(_1: &mut {closure@$DIR/slice_filter.rs:8:25: 8:39}, _2
     }
 
     bb3: {
-        StorageDead(_17);
         StorageDead(_18);
         StorageDead(_16);
         goto -> bb4;
     }
 
     bb4: {
-        StorageLive(_31);
+        StorageLive(_29);
         StorageLive(_24);
         _24 = &_6;
         StorageLive(_26);
-        StorageLive(_25);
-        _25 = _4;
+        _25 = &((*_3).0: usize);
         _26 = &_25;
         StorageLive(_27);
         StorageLive(_28);
         _27 = _6;
         _28 = _25;
-        StorageLive(_29);
-        _29 = (*_27);
-        StorageLive(_30);
-        _30 = (*_28);
-        _31 = Le(move _29, move _30);
-        StorageDead(_30);
-        StorageDead(_29);
+        _29 = Le(_14, _13);
         StorageDead(_28);
         StorageDead(_27);
-        switchInt(move _31) -> [0: bb5, otherwise: bb6];
+        switchInt(move _29) -> [0: bb5, otherwise: bb6];
     }
 
     bb5: {
-        StorageDead(_25);
         StorageDead(_26);
         StorageDead(_24);
         _0 = const false;
         goto -> bb7;
     }
 
     bb6: {
-        StorageDead(_25);
         StorageDead(_26);
         StorageDead(_24);
+        StorageLive(_30);
+        _30 = &_5;
         StorageLive(_32);
-        _32 = &_5;
-        StorageLive(_34);
+        _31 = &((*_3).3: usize);
+        _32 = &_31;
         StorageLive(_33);
-        _33 = _7;
-        _34 = &_33;
+        StorageLive(_34);
+        _33 = _5;
+        _34 = _31;
         StorageLive(_35);
+        _35 = ((*_3).1: usize);
         StorageLive(_36);
-        _35 = _5;
-        _36 = _33;
-        StorageLive(_37);
-        _37 = (*_35);
-        StorageLive(_38);
-        _38 = (*_36);
-        _0 = Le(move _37, move _38);
-        StorageDead(_38);
-        StorageDead(_37);
+        _36 = ((*_3).3: usize);
+        _0 = Le(move _35, move _36);
         StorageDead(_36);
         StorageDead(_35);
-        StorageDead(_33);
         StorageDead(_34);
+        StorageDead(_33);
         StorageDead(_32);
+        StorageDead(_30);
         goto -> bb7;
     }
 
     bb7: {
-        StorageDead(_31);
+        StorageDead(_29);
         goto -> bb9;
     }
 
     bb8: {
-        StorageDead(_17);
         StorageDead(_18);
         StorageDead(_16);
         _0 = const true;
@@ -228,10 +201,6 @@ fn variant_a::{closure#0}(_1: &mut {closure@$DIR/slice_filter.rs:8:25: 8:39}, _2
     bb9: {
         StorageDead(_23);
         StorageDead(_15);
-        StorageDead(_7);
-        StorageDead(_6);
-        StorageDead(_5);
-        StorageDead(_4);
         return;
     }
 }

tests/mir-opt/reference_prop.reference_propagation.ReferencePropagation.diff

@@ -247,7 +247,8 @@
           StorageLive(_21);
           _21 = &_20;
           StorageLive(_22);
-          _22 = (*_20);
+-         _22 = (*_20);
++         _22 = _19;
           StorageLive(_23);
           StorageLive(_24);
           _24 = _21;
@@ -394,7 +395,8 @@
           StorageLive(_62);
           _62 = &_61;
           StorageLive(_63);
-          _63 = (*_61);
+-         _63 = (*_61);
++         _63 = _60;
           StorageLive(_64);
           StorageLive(_65);
           _65 = ();

tests/mir-opt/reference_prop.reference_propagation_const_ptr.ReferencePropagation.diff

@@ -282,7 +282,8 @@
           StorageLive(_20);
           _20 = &_19;
           StorageLive(_21);
-          _21 = (*_19);
+-         _21 = (*_19);
++         _21 = _18;
           StorageLive(_22);
           StorageLive(_23);
           _23 = _20;
@@ -451,7 +452,8 @@
           StorageLive(_67);
           _67 = &_66;
           StorageLive(_68);
-          _68 = (*_66);
+-         _68 = (*_66);
++         _68 = _65;
           StorageLive(_69);
           StorageLive(_70);
           _70 = ();

tests/mir-opt/reference_prop.rs

@@ -49,7 +49,7 @@ fn reference_propagation<'a, T: Copy>(single: &'a T, mut multiple: &'a T) {
         // CHECK: [[a:_.*]] = const 5_usize;
         // CHECK: [[b:_.*]] = &[[a]];
         // CHECK: [[d:_.*]] = &[[b]];
-        // CHECK: [[c:_.*]] = (*[[b]]);
+        // CHECK: [[c:_.*]] = [[a]];
 
         let a = 5_usize;
         let b = &a;
@@ -138,8 +138,7 @@ fn reference_propagation<'a, T: Copy>(single: &'a T, mut multiple: &'a T) {
         // CHECK: [[a:_.*]] = const 5_usize;
         // CHECK: [[b:_.*]] = &[[a]];
         // CHECK: [[d:_.*]] = &[[b]];
-        // FIXME this could be [[a]]
-        // CHECK: [[c:_.*]] = (*[[b]]);
+        // CHECK: [[c:_.*]] = [[a]];
 
         let a = 5_usize;
         let b = &a;
@@ -363,7 +362,7 @@ fn reference_propagation_const_ptr<T: Copy>(single: *const T, mut multiple: *con
         // CHECK: [[a:_.*]] = const 5_usize;
         // CHECK: [[b:_.*]] = &raw const [[a]];
         // CHECK: [[d:_.*]] = &[[b]];
-        // CHECK: [[c:_.*]] = (*[[b]]);
+        // CHECK: [[c:_.*]] = [[a]];
 
         let a = 5_usize;
         let b = &raw const a;
@@ -467,8 +466,7 @@ fn reference_propagation_const_ptr<T: Copy>(single: *const T, mut multiple: *con
         // CHECK: [[a:_.*]] = const 5_usize;
         // CHECK: [[b:_.*]] = &raw const [[a]];
         // CHECK: [[d:_.*]] = &[[b]];
-        // FIXME this could be [[a]]
-        // CHECK: [[c:_.*]] = (*[[b]]);
+        // CHECK: [[c:_.*]] = [[a]];
 
         let a = 5_usize;
         let b = &raw const a;