Auto merge of rust-lang#132527 - DianQK:gvn-stmt-iter, r=<try>

[WIP] Invalidate all dereferences when encountering non-local assignments

Fixes rust-lang#132353.

r? ghost

Author: bors

compiler/rustc_data_structures/src/fx.rs

@@ -9,6 +9,8 @@ pub type FxIndexSet<V> = indexmap::IndexSet<V, BuildHasherDefault<FxHasher>>;
 pub type IndexEntry<'a, K, V> = indexmap::map::Entry<'a, K, V>;
 pub type IndexOccupiedEntry<'a, K, V> = indexmap::map::OccupiedEntry<'a, K, V>;
 
+pub use indexmap::set::MutableValues;
+
 #[macro_export]
 macro_rules! define_id_collections {
     ($map_name:ident, $set_name:ident, $entry_name:ident, $key:ty) => {

compiler/rustc_mir_transform/src/gvn.rs

@@ -32,12 +32,6 @@ pub(super) struct SsaLocals {
     borrowed_locals: BitSet<Local>,
 }
 
-pub(super) enum AssignedValue<'a, 'tcx> {
-    Arg,
-    Rvalue(&'a mut Rvalue<'tcx>),
-    Terminator,
-}
-
 impl SsaLocals {
     pub(super) fn new<'tcx>(
         tcx: TyCtxt<'tcx>,
@@ -152,37 +146,6 @@ impl SsaLocals {
         })
     }
 
-    pub(super) fn for_each_assignment_mut<'tcx>(
-        &self,
-        basic_blocks: &mut IndexSlice<BasicBlock, BasicBlockData<'tcx>>,
-        mut f: impl FnMut(Local, AssignedValue<'_, 'tcx>, Location),
-    ) {
-        for &local in &self.assignment_order {
-            match self.assignments[local] {
-                Set1::One(DefLocation::Argument) => f(local, AssignedValue::Arg, Location {
-                    block: START_BLOCK,
-                    statement_index: 0,
-                }),
-                Set1::One(DefLocation::Assignment(loc)) => {
-                    let bb = &mut basic_blocks[loc.block];
-                    // `loc` must point to a direct assignment to `local`.
-                    let stmt = &mut bb.statements[loc.statement_index];
-                    let StatementKind::Assign(box (target, ref mut rvalue)) = stmt.kind else {
-                        bug!()
-                    };
-                    assert_eq!(target.as_local(), Some(local));
-                    f(local, AssignedValue::Rvalue(rvalue), loc)
-                }
-                Set1::One(DefLocation::CallReturn { call, .. }) => {
-                    let bb = &mut basic_blocks[call];
-                    let loc = Location { block: call, statement_index: bb.statements.len() };
-                    f(local, AssignedValue::Terminator, loc)
-                }
-                _ => {}
-            }
-        }
-    }
-
     /// Compute the equivalence classes for locals, based on copy statements.
     ///
     /// The returned vector maps each local to the one it copies. In the following case:

compiler/rustc_mir_transform/src/ssa.rs

@@ -8,8 +8,9 @@
 
       bb0: {
           StorageLive(_1);
-          _1 = const <bool as NeedsDrop>::NEEDS;
+-         _1 = const <bool as NeedsDrop>::NEEDS;
 -         switchInt(move _1) -> [0: bb2, otherwise: bb1];
++         _1 = const false;
 +         switchInt(const false) -> [0: bb2, otherwise: bb1];
       }
 

tests/mir-opt/const_prop/control_flow_simplification.hello.GVN.panic-abort.diff

@@ -8,8 +8,9 @@
 
       bb0: {
           StorageLive(_1);
-          _1 = const <bool as NeedsDrop>::NEEDS;
+-         _1 = const <bool as NeedsDrop>::NEEDS;
 -         switchInt(move _1) -> [0: bb2, otherwise: bb1];
++         _1 = const false;
 +         switchInt(const false) -> [0: bb2, otherwise: bb1];
       }
 

tests/mir-opt/const_prop/control_flow_simplification.hello.GVN.panic-unwind.diff

@@ -19,14 +19,14 @@ fn old(_1: Result<T, E>) -> Result<T, E> {
     }
 
     bb1: {
-        _3 = move ((_1 as Ok).0: T);
-        _0 = Result::<T, E>::Ok(copy _3);
+        _3 = copy ((_1 as Ok).0: T);
+        _0 = copy _1;
         goto -> bb3;
     }
 
     bb2: {
-        _4 = move ((_1 as Err).0: E);
-        _0 = Result::<T, E>::Err(copy _4);
+        _4 = copy ((_1 as Err).0: E);
+        _0 = copy _1;
         goto -> bb3;
     }
 

tests/mir-opt/pre-codegen/try_identity.old.PreCodegen.after.mir

@@ -19,8 +19,7 @@
       }
 
       bb0: {
--         StorageLive(_2);
-+         nop;
+          StorageLive(_2);
           StorageLive(_3);
           StorageLive(_4);
           _4 = &_1;
@@ -50,13 +49,12 @@
           StorageLive(_9);
           _9 = copy _6;
 -         _0 = Option::<i32>::Some(move _9);
-+         _0 = copy (*_2);
++         _0 = Option::<i32>::Some(copy _6);
           StorageDead(_9);
 -         StorageDead(_6);
 +         nop;
           StorageDead(_4);
--         StorageDead(_2);
-+         nop;
+          StorageDead(_2);
           return;
       }