diff options
8 files changed, 204 insertions, 56 deletions
diff --git a/src/librustc_mir/transform/const_prop.rs b/src/librustc_mir/transform/const_prop.rs index 529e63ab967..0044ed36bdf 100644 --- a/src/librustc_mir/transform/const_prop.rs +++ b/src/librustc_mir/transform/const_prop.rs @@ -575,8 +575,16 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> { } // Do not try creating references (#67862) - Rvalue::Ref(_, _, place_ref) => { - trace!("skipping Ref({:?})", place_ref); + Rvalue::AddressOf(_, place) | Rvalue::Ref(_, _, place) => { + trace!("skipping AddressOf | Ref for {:?}", place); + + // This may be creating mutable references or immutable references to cells. + // If that happens, the pointed to value could be mutated via that reference. + // Since we aren't tracking references, the const propagator loses track of what + // value the local has right now. + // Thus, all locals that have their reference taken + // must not take part in propagation. + Self::remove_const(&mut self.ecx, place.local); return None; } @@ -716,6 +724,9 @@ enum ConstPropMode { OnlyInsideOwnBlock, /// The `Local` can be propagated into but reads cannot be propagated. OnlyPropagateInto, + /// The `Local` cannot be part of propagation at all. Any statement + /// referencing it either for reading or writing will not get propagated. + NoPropagation, } struct CanConstProp { @@ -781,7 +792,9 @@ impl<'tcx> Visitor<'tcx> for CanConstProp { // end of the block anyway, and inside the block we overwrite previous // states as applicable. ConstPropMode::OnlyInsideOwnBlock => {} - other => { + ConstPropMode::NoPropagation => {} + ConstPropMode::OnlyPropagateInto => {} + other @ ConstPropMode::FullConstProp => { trace!( "local {:?} can't be propagated because of multiple assignments", local, @@ -813,7 +826,7 @@ impl<'tcx> Visitor<'tcx> for CanConstProp { | MutatingUse(MutatingUseContext::Borrow) | MutatingUse(MutatingUseContext::AddressOf) => { trace!("local {:?} can't be propagaged because it's used: {:?}", local, context); - self.can_const_prop[local] = ConstPropMode::OnlyPropagateInto; + self.can_const_prop[local] = ConstPropMode::NoPropagation; } } } @@ -858,19 +871,22 @@ impl<'mir, 'tcx> MutVisitor<'tcx> for ConstPropagator<'mir, 'tcx> { } } } - if can_const_prop == ConstPropMode::OnlyInsideOwnBlock { - trace!( - "found local restricted to its block. Will remove it from const-prop after block is finished. Local: {:?}", - place.local - ); - self.locals_of_current_block.insert(place.local); - } - - if can_const_prop == ConstPropMode::OnlyPropagateInto { - trace!("can't propagate into {:?}", place); - if place.local != RETURN_PLACE { - Self::remove_const(&mut self.ecx, place.local); + match can_const_prop { + ConstPropMode::OnlyInsideOwnBlock => { + trace!( + "found local restricted to its block. \ + Will remove it from const-prop after block is finished. Local: {:?}", + place.local + ); + self.locals_of_current_block.insert(place.local); } + ConstPropMode::OnlyPropagateInto | ConstPropMode::NoPropagation => { + trace!("can't propagate into {:?}", place); + if place.local != RETURN_PLACE { + Self::remove_const(&mut self.ecx, place.local); + } + } + ConstPropMode::FullConstProp => {} } } else { // Const prop failed, so erase the destination, ensuring that whatever happens @@ -890,6 +906,12 @@ impl<'mir, 'tcx> MutVisitor<'tcx> for ConstPropagator<'mir, 'tcx> { ); Self::remove_const(&mut self.ecx, place.local); } + } else { + trace!( + "cannot propagate into {:?}, because the type of the local is generic.", + place, + ); + Self::remove_const(&mut self.ecx, place.local); } } else { match statement.kind { diff --git a/src/test/mir-opt/const_prop/bad_op_unsafe_oob_for_slices/32bit/rustc.main.ConstProp.diff b/src/test/mir-opt/const_prop/bad_op_unsafe_oob_for_slices/32bit/rustc.main.ConstProp.diff index 7071f31dbf1..7ceec94d81e 100644 --- a/src/test/mir-opt/const_prop/bad_op_unsafe_oob_for_slices/32bit/rustc.main.ConstProp.diff +++ b/src/test/mir-opt/const_prop/bad_op_unsafe_oob_for_slices/32bit/rustc.main.ConstProp.diff @@ -46,22 +46,8 @@ // mir::Constant // + span: $DIR/bad_op_unsafe_oob_for_slices.rs:7:23: 7:24 // + literal: Const { ty: usize, val: Value(Scalar(0x00000003)) } -- _7 = Len((*_1)); // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:7:18: 7:25 -- _8 = Lt(_6, _7); // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:7:18: 7:25 -+ _7 = const 3usize; // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:7:18: 7:25 -+ // ty::Const -+ // + ty: usize -+ // + val: Value(Scalar(0x00000003)) -+ // mir::Constant -+ // + span: $DIR/bad_op_unsafe_oob_for_slices.rs:7:18: 7:25 -+ // + literal: Const { ty: usize, val: Value(Scalar(0x00000003)) } -+ _8 = const false; // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:7:18: 7:25 -+ // ty::Const -+ // + ty: bool -+ // + val: Value(Scalar(0x00)) -+ // mir::Constant -+ // + span: $DIR/bad_op_unsafe_oob_for_slices.rs:7:18: 7:25 -+ // + literal: Const { ty: bool, val: Value(Scalar(0x00)) } + _7 = Len((*_1)); // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:7:18: 7:25 + _8 = Lt(_6, _7); // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:7:18: 7:25 assert(move _8, "index out of bounds: the len is {} but the index is {}", move _7, _6) -> bb1; // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:7:18: 7:25 } diff --git a/src/test/mir-opt/const_prop/bad_op_unsafe_oob_for_slices/64bit/rustc.main.ConstProp.diff b/src/test/mir-opt/const_prop/bad_op_unsafe_oob_for_slices/64bit/rustc.main.ConstProp.diff index 15995ab0700..483a6f232ef 100644 --- a/src/test/mir-opt/const_prop/bad_op_unsafe_oob_for_slices/64bit/rustc.main.ConstProp.diff +++ b/src/test/mir-opt/const_prop/bad_op_unsafe_oob_for_slices/64bit/rustc.main.ConstProp.diff @@ -46,22 +46,8 @@ // mir::Constant // + span: $DIR/bad_op_unsafe_oob_for_slices.rs:7:23: 7:24 // + literal: Const { ty: usize, val: Value(Scalar(0x0000000000000003)) } -- _7 = Len((*_1)); // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:7:18: 7:25 -- _8 = Lt(_6, _7); // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:7:18: 7:25 -+ _7 = const 3usize; // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:7:18: 7:25 -+ // ty::Const -+ // + ty: usize -+ // + val: Value(Scalar(0x0000000000000003)) -+ // mir::Constant -+ // + span: $DIR/bad_op_unsafe_oob_for_slices.rs:7:18: 7:25 -+ // + literal: Const { ty: usize, val: Value(Scalar(0x0000000000000003)) } -+ _8 = const false; // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:7:18: 7:25 -+ // ty::Const -+ // + ty: bool -+ // + val: Value(Scalar(0x00)) -+ // mir::Constant -+ // + span: $DIR/bad_op_unsafe_oob_for_slices.rs:7:18: 7:25 -+ // + literal: Const { ty: bool, val: Value(Scalar(0x00)) } + _7 = Len((*_1)); // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:7:18: 7:25 + _8 = Lt(_6, _7); // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:7:18: 7:25 assert(move _8, "index out of bounds: the len is {} but the index is {}", move _7, _6) -> bb1; // scope 2 at $DIR/bad_op_unsafe_oob_for_slices.rs:7:18: 7:25 } diff --git a/src/test/mir-opt/const_prop_miscompile.rs b/src/test/mir-opt/const_prop_miscompile.rs new file mode 100644 index 00000000000..043b22870f4 --- /dev/null +++ b/src/test/mir-opt/const_prop_miscompile.rs @@ -0,0 +1,22 @@ +#![feature(raw_ref_op)] + +// EMIT_MIR rustc.foo.ConstProp.diff +fn foo() { + let mut u = (1,); + *&mut u.0 = 5; + let y = { u.0 } == 5; +} + +// EMIT_MIR rustc.bar.ConstProp.diff +fn bar() { + let mut v = (1,); + unsafe { + *&raw mut v.0 = 5; + } + let y = { v.0 } == 5; +} + +fn main() { + foo(); + bar(); +} diff --git a/src/test/mir-opt/const_prop_miscompile/rustc.bar.ConstProp.diff b/src/test/mir-opt/const_prop_miscompile/rustc.bar.ConstProp.diff new file mode 100644 index 00000000000..c87f67bf9f5 --- /dev/null +++ b/src/test/mir-opt/const_prop_miscompile/rustc.bar.ConstProp.diff @@ -0,0 +1,75 @@ +- // MIR for `bar` before ConstProp ++ // MIR for `bar` after ConstProp + + fn bar() -> () { + let mut _0: (); // return place in scope 0 at $DIR/const_prop_miscompile.rs:11:10: 11:10 + let mut _1: (i32,); // in scope 0 at $DIR/const_prop_miscompile.rs:12:9: 12:14 + let _2: (); // in scope 0 at $DIR/const_prop_miscompile.rs:13:5: 15:6 + let mut _3: *mut i32; // in scope 0 at $DIR/const_prop_miscompile.rs:14:10: 14:22 + let mut _5: i32; // in scope 0 at $DIR/const_prop_miscompile.rs:16:13: 16:20 + scope 1 { + debug v => _1; // in scope 1 at $DIR/const_prop_miscompile.rs:12:9: 12:14 + let _4: bool; // in scope 1 at $DIR/const_prop_miscompile.rs:16:9: 16:10 + scope 2 { + } + scope 3 { + debug y => _4; // in scope 3 at $DIR/const_prop_miscompile.rs:16:9: 16:10 + } + } + + bb0: { + StorageLive(_1); // scope 0 at $DIR/const_prop_miscompile.rs:12:9: 12:14 +- _1 = (const 1i32,); // scope 0 at $DIR/const_prop_miscompile.rs:12:17: 12:21 ++ _1 = const (1i32,); // scope 0 at $DIR/const_prop_miscompile.rs:12:17: 12:21 + // ty::Const +- // + ty: i32 ++ // + ty: (i32,) + // + val: Value(Scalar(0x00000001)) + // mir::Constant +- // + span: $DIR/const_prop_miscompile.rs:12:18: 12:19 +- // + literal: Const { ty: i32, val: Value(Scalar(0x00000001)) } ++ // + span: $DIR/const_prop_miscompile.rs:12:17: 12:21 ++ // + literal: Const { ty: (i32,), val: Value(Scalar(0x00000001)) } + StorageLive(_2); // scope 1 at $DIR/const_prop_miscompile.rs:13:5: 15:6 + StorageLive(_3); // scope 2 at $DIR/const_prop_miscompile.rs:14:10: 14:22 + _3 = &raw mut (_1.0: i32); // scope 2 at $DIR/const_prop_miscompile.rs:14:10: 14:22 + (*_3) = const 5i32; // scope 2 at $DIR/const_prop_miscompile.rs:14:9: 14:26 + // ty::Const + // + ty: i32 + // + val: Value(Scalar(0x00000005)) + // mir::Constant + // + span: $DIR/const_prop_miscompile.rs:14:25: 14:26 + // + literal: Const { ty: i32, val: Value(Scalar(0x00000005)) } + StorageDead(_3); // scope 2 at $DIR/const_prop_miscompile.rs:14:26: 14:27 + _2 = const (); // scope 2 at $DIR/const_prop_miscompile.rs:13:5: 15:6 + // ty::Const + // + ty: () + // + val: Value(Scalar(<ZST>)) + // mir::Constant + // + span: $DIR/const_prop_miscompile.rs:13:5: 15:6 + // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) } + StorageDead(_2); // scope 1 at $DIR/const_prop_miscompile.rs:15:5: 15:6 + StorageLive(_4); // scope 1 at $DIR/const_prop_miscompile.rs:16:9: 16:10 + StorageLive(_5); // scope 1 at $DIR/const_prop_miscompile.rs:16:13: 16:20 + _5 = (_1.0: i32); // scope 1 at $DIR/const_prop_miscompile.rs:16:15: 16:18 + _4 = Eq(move _5, const 5i32); // scope 1 at $DIR/const_prop_miscompile.rs:16:13: 16:25 + // ty::Const + // + ty: i32 + // + val: Value(Scalar(0x00000005)) + // mir::Constant + // + span: $DIR/const_prop_miscompile.rs:16:24: 16:25 + // + literal: Const { ty: i32, val: Value(Scalar(0x00000005)) } + StorageDead(_5); // scope 1 at $DIR/const_prop_miscompile.rs:16:24: 16:25 + _0 = const (); // scope 0 at $DIR/const_prop_miscompile.rs:11:10: 17:2 + // ty::Const + // + ty: () + // + val: Value(Scalar(<ZST>)) + // mir::Constant + // + span: $DIR/const_prop_miscompile.rs:11:10: 17:2 + // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) } + StorageDead(_4); // scope 1 at $DIR/const_prop_miscompile.rs:17:1: 17:2 + StorageDead(_1); // scope 0 at $DIR/const_prop_miscompile.rs:17:1: 17:2 + return; // scope 0 at $DIR/const_prop_miscompile.rs:17:2: 17:2 + } + } + diff --git a/src/test/mir-opt/const_prop_miscompile/rustc.foo.ConstProp.diff b/src/test/mir-opt/const_prop_miscompile/rustc.foo.ConstProp.diff new file mode 100644 index 00000000000..8a6850d2fe3 --- /dev/null +++ b/src/test/mir-opt/const_prop_miscompile/rustc.foo.ConstProp.diff @@ -0,0 +1,63 @@ +- // MIR for `foo` before ConstProp ++ // MIR for `foo` after ConstProp + + fn foo() -> () { + let mut _0: (); // return place in scope 0 at $DIR/const_prop_miscompile.rs:4:10: 4:10 + let mut _1: (i32,); // in scope 0 at $DIR/const_prop_miscompile.rs:5:9: 5:14 + let mut _2: &mut i32; // in scope 0 at $DIR/const_prop_miscompile.rs:6:6: 6:14 + let mut _4: i32; // in scope 0 at $DIR/const_prop_miscompile.rs:7:13: 7:20 + scope 1 { + debug u => _1; // in scope 1 at $DIR/const_prop_miscompile.rs:5:9: 5:14 + let _3: bool; // in scope 1 at $DIR/const_prop_miscompile.rs:7:9: 7:10 + scope 2 { + debug y => _3; // in scope 2 at $DIR/const_prop_miscompile.rs:7:9: 7:10 + } + } + + bb0: { + StorageLive(_1); // scope 0 at $DIR/const_prop_miscompile.rs:5:9: 5:14 +- _1 = (const 1i32,); // scope 0 at $DIR/const_prop_miscompile.rs:5:17: 5:21 ++ _1 = const (1i32,); // scope 0 at $DIR/const_prop_miscompile.rs:5:17: 5:21 + // ty::Const +- // + ty: i32 ++ // + ty: (i32,) + // + val: Value(Scalar(0x00000001)) + // mir::Constant +- // + span: $DIR/const_prop_miscompile.rs:5:18: 5:19 +- // + literal: Const { ty: i32, val: Value(Scalar(0x00000001)) } ++ // + span: $DIR/const_prop_miscompile.rs:5:17: 5:21 ++ // + literal: Const { ty: (i32,), val: Value(Scalar(0x00000001)) } + StorageLive(_2); // scope 1 at $DIR/const_prop_miscompile.rs:6:6: 6:14 + _2 = &mut (_1.0: i32); // scope 1 at $DIR/const_prop_miscompile.rs:6:6: 6:14 + (*_2) = const 5i32; // scope 1 at $DIR/const_prop_miscompile.rs:6:5: 6:18 + // ty::Const + // + ty: i32 + // + val: Value(Scalar(0x00000005)) + // mir::Constant + // + span: $DIR/const_prop_miscompile.rs:6:17: 6:18 + // + literal: Const { ty: i32, val: Value(Scalar(0x00000005)) } + StorageDead(_2); // scope 1 at $DIR/const_prop_miscompile.rs:6:18: 6:19 + StorageLive(_3); // scope 1 at $DIR/const_prop_miscompile.rs:7:9: 7:10 + StorageLive(_4); // scope 1 at $DIR/const_prop_miscompile.rs:7:13: 7:20 + _4 = (_1.0: i32); // scope 1 at $DIR/const_prop_miscompile.rs:7:15: 7:18 + _3 = Eq(move _4, const 5i32); // scope 1 at $DIR/const_prop_miscompile.rs:7:13: 7:25 + // ty::Const + // + ty: i32 + // + val: Value(Scalar(0x00000005)) + // mir::Constant + // + span: $DIR/const_prop_miscompile.rs:7:24: 7:25 + // + literal: Const { ty: i32, val: Value(Scalar(0x00000005)) } + StorageDead(_4); // scope 1 at $DIR/const_prop_miscompile.rs:7:24: 7:25 + _0 = const (); // scope 0 at $DIR/const_prop_miscompile.rs:4:10: 8:2 + // ty::Const + // + ty: () + // + val: Value(Scalar(<ZST>)) + // mir::Constant + // + span: $DIR/const_prop_miscompile.rs:4:10: 8:2 + // + literal: Const { ty: (), val: Value(Scalar(<ZST>)) } + StorageDead(_3); // scope 1 at $DIR/const_prop_miscompile.rs:8:1: 8:2 + StorageDead(_1); // scope 0 at $DIR/const_prop_miscompile.rs:8:1: 8:2 + return; // scope 0 at $DIR/const_prop_miscompile.rs:8:2: 8:2 + } + } + diff --git a/src/test/ui/mir/mir_detects_invalid_ops.rs b/src/test/ui/mir/mir_detects_invalid_ops.rs index 0940dbe6a5e..136c03cd9f1 100644 --- a/src/test/ui/mir/mir_detects_invalid_ops.rs +++ b/src/test/ui/mir/mir_detects_invalid_ops.rs @@ -19,6 +19,6 @@ fn mod_by_zero() { fn oob_error_for_slices() { let a: *const [_] = &[1, 2, 3]; unsafe { - let _b = (*a)[3]; //~ ERROR this operation will panic at runtime [unconditional_panic] + let _b = (*a)[3]; } } diff --git a/src/test/ui/mir/mir_detects_invalid_ops.stderr b/src/test/ui/mir/mir_detects_invalid_ops.stderr index 41f03789f23..0b6dbfd7c3d 100644 --- a/src/test/ui/mir/mir_detects_invalid_ops.stderr +++ b/src/test/ui/mir/mir_detects_invalid_ops.stderr @@ -12,11 +12,5 @@ error: this operation will panic at runtime LL | let _z = 1 % y; | ^^^^^ attempt to calculate the remainder with a divisor of zero -error: this operation will panic at runtime - --> $DIR/mir_detects_invalid_ops.rs:22:18 - | -LL | let _b = (*a)[3]; - | ^^^^^^^ index out of bounds: the len is 3 but the index is 3 - -error: aborting due to 3 previous errors +error: aborting due to 2 previous errors |