diff --git a/src/librustc_mir/transform/const_prop.rs b/src/librustc_mir/transform/const_prop.rs index 7926bf535b3b7..4dd7c0330530c 100644 --- a/src/librustc_mir/transform/const_prop.rs +++ b/src/librustc_mir/transform/const_prop.rs @@ -349,8 +349,8 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> { } } - fn get_const(&self, local: Local) -> Option> { - let op = self.ecx.access_local(self.ecx.frame(), local, None).ok(); + fn get_const(&self, place: Place<'tcx>) -> Option> { + let op = self.ecx.eval_place_to_op(place, None).ok(); // Try to read the local as an immediate so that if it is representable as a scalar, we can // handle it as such, but otherwise, just return the value as is. @@ -772,13 +772,25 @@ impl<'tcx> Visitor<'tcx> for CanConstProp { fn visit_local(&mut self, &local: &Local, context: PlaceContext, _: Location) { use rustc_middle::mir::visit::PlaceContext::*; match context { - // Constants must have at most one write - // FIXME(oli-obk): we could be more powerful here, if the multiple writes - // only occur in independent execution paths - MutatingUse(MutatingUseContext::Store) => { + // Projections are fine, because `&mut foo.x` will be caught by + // `MutatingUseContext::Borrow` elsewhere. + MutatingUse(MutatingUseContext::Projection) + | MutatingUse(MutatingUseContext::Store) => { if !self.found_assignment.insert(local) { - trace!("local {:?} can't be propagated because of multiple assignments", local); - self.can_const_prop[local] = ConstPropMode::NoPropagation; + match &mut self.can_const_prop[local] { + // If the local can only get propagated in its own block, then we don't have + // to worry about multiple assignments, as we'll nuke the const state at the + // end of the block anyway, and inside the block we overwrite previous + // states as applicable. + ConstPropMode::OnlyInsideOwnBlock => {} + other => { + trace!( + "local {:?} can't be propagated because of multiple assignments", + local, + ); + *other = ConstPropMode::NoPropagation; + } + } } } // Reading constants is allowed an arbitrary number of times @@ -787,12 +799,6 @@ impl<'tcx> Visitor<'tcx> for CanConstProp { | NonMutatingUse(NonMutatingUseContext::Inspect) | NonMutatingUse(NonMutatingUseContext::Projection) | NonUse(_) => {} - // FIXME(felix91gr): explain the reasoning behind this - MutatingUse(MutatingUseContext::Projection) => { - if self.local_kinds[local] != LocalKind::Temp { - self.can_const_prop[local] = ConstPropMode::NoPropagation; - } - } _ => { trace!("local {:?} can't be propagaged because it's used: {:?}", local, context); self.can_const_prop[local] = ConstPropMode::NoPropagation; @@ -826,40 +832,50 @@ impl<'mir, 'tcx> MutVisitor<'tcx> for ConstPropagator<'mir, 'tcx> { if let StatementKind::Assign(box (place, ref mut rval)) = statement.kind { let place_ty: Ty<'tcx> = place.ty(&self.local_decls, self.tcx).ty; if let Ok(place_layout) = self.tcx.layout_of(self.param_env.and(place_ty)) { - if let Some(local) = place.as_local() { - let can_const_prop = self.can_const_prop[local]; - if let Some(()) = self.const_prop(rval, place_layout, source_info, place) { - if can_const_prop != ConstPropMode::NoPropagation { - // This will return None for Locals that are from other blocks, - // so it should be okay to propagate from here on down. - if let Some(value) = self.get_const(local) { - if self.should_const_prop(value) { - trace!("replacing {:?} with {:?}", rval, value); - self.replace_with_const(rval, value, statement.source_info); - if can_const_prop == ConstPropMode::FullConstProp - || can_const_prop == ConstPropMode::OnlyInsideOwnBlock - { - trace!("propagated into {:?}", local); - } - } - if can_const_prop == ConstPropMode::OnlyInsideOwnBlock { - trace!( - "found local restricted to its block. Will remove it from const-prop after block is finished. Local: {:?}", - local - ); - self.locals_of_current_block.insert(local); + let can_const_prop = self.can_const_prop[place.local]; + if let Some(()) = self.const_prop(rval, place_layout, source_info, place) { + if can_const_prop != ConstPropMode::NoPropagation { + // This will return None for variables that are from other blocks, + // so it should be okay to propagate from here on down. + if let Some(value) = self.get_const(place) { + if self.should_const_prop(value) { + trace!("replacing {:?} with {:?}", rval, value); + self.replace_with_const(rval, value, statement.source_info); + if can_const_prop == ConstPropMode::FullConstProp + || can_const_prop == ConstPropMode::OnlyInsideOwnBlock + { + trace!("propagated into {:?}", place); } } + 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 self.can_const_prop[local] == ConstPropMode::OnlyPropagateInto - || self.can_const_prop[local] == ConstPropMode::NoPropagation + if can_const_prop == ConstPropMode::OnlyPropagateInto + || can_const_prop == ConstPropMode::NoPropagation { - trace!("can't propagate into {:?}", local); - if local != RETURN_PLACE { - Self::remove_const(&mut self.ecx, local); + trace!("can't propagate into {:?}", place); + if place.local != RETURN_PLACE { + Self::remove_const(&mut self.ecx, place.local); } } + } else { + // Const prop failed, so erase the destination, ensuring that whatever happens + // from here on, does not know about the previous value. + // This is important in case we have + // ```rust + // let mut x = 42; + // x = SOME_MUTABLE_STATIC; + // // x must now be undefined + // ``` + // FIXME: we overzealously erase the entire local, because that's easier to + // implement. + Self::remove_const(&mut self.ecx, place.local); } } } else { @@ -993,7 +1009,7 @@ impl<'mir, 'tcx> MutVisitor<'tcx> for ConstPropagator<'mir, 'tcx> { arguments are of the variant `Operand::Copy`. This allows us to simplify our handling of `Operands` in this case. */ - if let Some(l) = opr.place().and_then(|p| p.as_local()) { + if let Some(l) = opr.place() { if let Some(value) = self.get_const(l) { if self.should_const_prop(value) { // FIXME(felix91gr): this code only handles `Scalar` cases. diff --git a/src/test/mir-opt/const_prop/mutable_variable.rs b/src/test/mir-opt/const_prop/mutable_variable.rs new file mode 100644 index 0000000000000..b3a2d80fa950a --- /dev/null +++ b/src/test/mir-opt/const_prop/mutable_variable.rs @@ -0,0 +1,8 @@ +// compile-flags: -O + +// EMIT_MIR rustc.main.ConstProp.diff +fn main() { + let mut x = 42; + x = 99; + let y = x; +} diff --git a/src/test/mir-opt/const_prop/mutable_variable/rustc.main.ConstProp.diff b/src/test/mir-opt/const_prop/mutable_variable/rustc.main.ConstProp.diff new file mode 100644 index 0000000000000..c6c5b0cf72635 --- /dev/null +++ b/src/test/mir-opt/const_prop/mutable_variable/rustc.main.ConstProp.diff @@ -0,0 +1,53 @@ +- // MIR for `main` before ConstProp ++ // MIR for `main` after ConstProp + + fn main() -> () { + let mut _0: (); // return place in scope 0 at $DIR/mutable_variable.rs:4:11: 4:11 + let mut _1: i32; // in scope 0 at $DIR/mutable_variable.rs:5:9: 5:14 + scope 1 { + debug x => _1; // in scope 1 at $DIR/mutable_variable.rs:5:9: 5:14 + let _2: i32; // in scope 1 at $DIR/mutable_variable.rs:7:9: 7:10 + scope 2 { + debug y => _2; // in scope 2 at $DIR/mutable_variable.rs:7:9: 7:10 + } + } + + bb0: { + StorageLive(_1); // scope 0 at $DIR/mutable_variable.rs:5:9: 5:14 + _1 = const 42i32; // scope 0 at $DIR/mutable_variable.rs:5:17: 5:19 + // ty::Const + // + ty: i32 + // + val: Value(Scalar(0x0000002a)) + // mir::Constant + // + span: $DIR/mutable_variable.rs:5:17: 5:19 + // + literal: Const { ty: i32, val: Value(Scalar(0x0000002a)) } + _1 = const 99i32; // scope 1 at $DIR/mutable_variable.rs:6:5: 6:11 + // ty::Const + // + ty: i32 + // + val: Value(Scalar(0x00000063)) + // mir::Constant +- // + span: $DIR/mutable_variable.rs:6:9: 6:11 ++ // + span: $DIR/mutable_variable.rs:6:5: 6:11 + // + literal: Const { ty: i32, val: Value(Scalar(0x00000063)) } + StorageLive(_2); // scope 1 at $DIR/mutable_variable.rs:7:9: 7:10 +- _2 = _1; // scope 1 at $DIR/mutable_variable.rs:7:13: 7:14 ++ _2 = const 99i32; // scope 1 at $DIR/mutable_variable.rs:7:13: 7:14 ++ // ty::Const ++ // + ty: i32 ++ // + val: Value(Scalar(0x00000063)) ++ // mir::Constant ++ // + span: $DIR/mutable_variable.rs:7:13: 7:14 ++ // + literal: Const { ty: i32, val: Value(Scalar(0x00000063)) } + _0 = const (); // scope 0 at $DIR/mutable_variable.rs:4:11: 8:2 + // ty::Const + // + ty: () + // + val: Value(Scalar()) + // mir::Constant + // + span: $DIR/mutable_variable.rs:4:11: 8:2 + // + literal: Const { ty: (), val: Value(Scalar()) } + StorageDead(_2); // scope 1 at $DIR/mutable_variable.rs:8:1: 8:2 + StorageDead(_1); // scope 0 at $DIR/mutable_variable.rs:8:1: 8:2 + return; // scope 0 at $DIR/mutable_variable.rs:8:2: 8:2 + } + } + diff --git a/src/test/mir-opt/const_prop/mutable_variable_aggregate.rs b/src/test/mir-opt/const_prop/mutable_variable_aggregate.rs new file mode 100644 index 0000000000000..3c5fb4574b61f --- /dev/null +++ b/src/test/mir-opt/const_prop/mutable_variable_aggregate.rs @@ -0,0 +1,8 @@ +// compile-flags: -O + +// EMIT_MIR rustc.main.ConstProp.diff +fn main() { + let mut x = (42, 43); + x.1 = 99; + let y = x; +} diff --git a/src/test/mir-opt/const_prop/mutable_variable_aggregate/rustc.main.ConstProp.diff b/src/test/mir-opt/const_prop/mutable_variable_aggregate/rustc.main.ConstProp.diff new file mode 100644 index 0000000000000..26f0250d94c0b --- /dev/null +++ b/src/test/mir-opt/const_prop/mutable_variable_aggregate/rustc.main.ConstProp.diff @@ -0,0 +1,67 @@ +- // MIR for `main` before ConstProp ++ // MIR for `main` after ConstProp + + fn main() -> () { + let mut _0: (); // return place in scope 0 at $DIR/mutable_variable_aggregate.rs:4:11: 4:11 + let mut _1: (i32, i32); // in scope 0 at $DIR/mutable_variable_aggregate.rs:5:9: 5:14 + scope 1 { + debug x => _1; // in scope 1 at $DIR/mutable_variable_aggregate.rs:5:9: 5:14 + let _2: (i32, i32); // in scope 1 at $DIR/mutable_variable_aggregate.rs:7:9: 7:10 + scope 2 { + debug y => _2; // in scope 2 at $DIR/mutable_variable_aggregate.rs:7:9: 7:10 + } + } + + bb0: { + StorageLive(_1); // scope 0 at $DIR/mutable_variable_aggregate.rs:5:9: 5:14 + _1 = (const 42i32, const 43i32); // scope 0 at $DIR/mutable_variable_aggregate.rs:5:17: 5:25 + // ty::Const + // + ty: i32 + // + val: Value(Scalar(0x0000002a)) + // mir::Constant +- // + span: $DIR/mutable_variable_aggregate.rs:5:18: 5:20 ++ // + span: $DIR/mutable_variable_aggregate.rs:5:17: 5:25 + // + literal: Const { ty: i32, val: Value(Scalar(0x0000002a)) } + // ty::Const + // + ty: i32 + // + val: Value(Scalar(0x0000002b)) + // mir::Constant +- // + span: $DIR/mutable_variable_aggregate.rs:5:22: 5:24 ++ // + span: $DIR/mutable_variable_aggregate.rs:5:17: 5:25 + // + literal: Const { ty: i32, val: Value(Scalar(0x0000002b)) } + (_1.1: i32) = const 99i32; // scope 1 at $DIR/mutable_variable_aggregate.rs:6:5: 6:13 + // ty::Const + // + ty: i32 + // + val: Value(Scalar(0x00000063)) + // mir::Constant +- // + span: $DIR/mutable_variable_aggregate.rs:6:11: 6:13 ++ // + span: $DIR/mutable_variable_aggregate.rs:6:5: 6:13 + // + literal: Const { ty: i32, val: Value(Scalar(0x00000063)) } + StorageLive(_2); // scope 1 at $DIR/mutable_variable_aggregate.rs:7:9: 7:10 +- _2 = _1; // scope 1 at $DIR/mutable_variable_aggregate.rs:7:13: 7:14 ++ _2 = (const 42i32, const 99i32); // scope 1 at $DIR/mutable_variable_aggregate.rs:7:13: 7:14 ++ // ty::Const ++ // + ty: i32 ++ // + val: Value(Scalar(0x0000002a)) ++ // mir::Constant ++ // + span: $DIR/mutable_variable_aggregate.rs:7:13: 7:14 ++ // + literal: Const { ty: i32, val: Value(Scalar(0x0000002a)) } ++ // ty::Const ++ // + ty: i32 ++ // + val: Value(Scalar(0x00000063)) ++ // mir::Constant ++ // + span: $DIR/mutable_variable_aggregate.rs:7:13: 7:14 ++ // + literal: Const { ty: i32, val: Value(Scalar(0x00000063)) } + _0 = const (); // scope 0 at $DIR/mutable_variable_aggregate.rs:4:11: 8:2 + // ty::Const + // + ty: () + // + val: Value(Scalar()) + // mir::Constant + // + span: $DIR/mutable_variable_aggregate.rs:4:11: 8:2 + // + literal: Const { ty: (), val: Value(Scalar()) } + StorageDead(_2); // scope 1 at $DIR/mutable_variable_aggregate.rs:8:1: 8:2 + StorageDead(_1); // scope 0 at $DIR/mutable_variable_aggregate.rs:8:1: 8:2 + return; // scope 0 at $DIR/mutable_variable_aggregate.rs:8:2: 8:2 + } + } + diff --git a/src/test/mir-opt/const_prop/mutable_variable_aggregate_mut_ref.rs b/src/test/mir-opt/const_prop/mutable_variable_aggregate_mut_ref.rs new file mode 100644 index 0000000000000..fc13cbf2abd56 --- /dev/null +++ b/src/test/mir-opt/const_prop/mutable_variable_aggregate_mut_ref.rs @@ -0,0 +1,9 @@ +// compile-flags: -O + +// EMIT_MIR rustc.main.ConstProp.diff +fn main() { + let mut x = (42, 43); + let z = &mut x; + z.1 = 99; + let y = x; +} diff --git a/src/test/mir-opt/const_prop/mutable_variable_aggregate_mut_ref/rustc.main.ConstProp.diff b/src/test/mir-opt/const_prop/mutable_variable_aggregate_mut_ref/rustc.main.ConstProp.diff new file mode 100644 index 0000000000000..44203ac327ab1 --- /dev/null +++ b/src/test/mir-opt/const_prop/mutable_variable_aggregate_mut_ref/rustc.main.ConstProp.diff @@ -0,0 +1,58 @@ +- // MIR for `main` before ConstProp ++ // MIR for `main` after ConstProp + + fn main() -> () { + let mut _0: (); // return place in scope 0 at $DIR/mutable_variable_aggregate_mut_ref.rs:4:11: 4:11 + let mut _1: (i32, i32); // in scope 0 at $DIR/mutable_variable_aggregate_mut_ref.rs:5:9: 5:14 + scope 1 { + debug x => _1; // in scope 1 at $DIR/mutable_variable_aggregate_mut_ref.rs:5:9: 5:14 + let _2: &mut (i32, i32); // in scope 1 at $DIR/mutable_variable_aggregate_mut_ref.rs:6:9: 6:10 + scope 2 { + debug z => _2; // in scope 2 at $DIR/mutable_variable_aggregate_mut_ref.rs:6:9: 6:10 + let _3: (i32, i32); // in scope 2 at $DIR/mutable_variable_aggregate_mut_ref.rs:8:9: 8:10 + scope 3 { + debug y => _3; // in scope 3 at $DIR/mutable_variable_aggregate_mut_ref.rs:8:9: 8:10 + } + } + } + + bb0: { + StorageLive(_1); // scope 0 at $DIR/mutable_variable_aggregate_mut_ref.rs:5:9: 5:14 + _1 = (const 42i32, const 43i32); // scope 0 at $DIR/mutable_variable_aggregate_mut_ref.rs:5:17: 5:25 + // ty::Const + // + ty: i32 + // + val: Value(Scalar(0x0000002a)) + // mir::Constant + // + span: $DIR/mutable_variable_aggregate_mut_ref.rs:5:18: 5:20 + // + literal: Const { ty: i32, val: Value(Scalar(0x0000002a)) } + // ty::Const + // + ty: i32 + // + val: Value(Scalar(0x0000002b)) + // mir::Constant + // + span: $DIR/mutable_variable_aggregate_mut_ref.rs:5:22: 5:24 + // + literal: Const { ty: i32, val: Value(Scalar(0x0000002b)) } + StorageLive(_2); // scope 1 at $DIR/mutable_variable_aggregate_mut_ref.rs:6:9: 6:10 + _2 = &mut _1; // scope 1 at $DIR/mutable_variable_aggregate_mut_ref.rs:6:13: 6:19 + ((*_2).1: i32) = const 99i32; // scope 2 at $DIR/mutable_variable_aggregate_mut_ref.rs:7:5: 7:13 + // ty::Const + // + ty: i32 + // + val: Value(Scalar(0x00000063)) + // mir::Constant + // + span: $DIR/mutable_variable_aggregate_mut_ref.rs:7:11: 7:13 + // + literal: Const { ty: i32, val: Value(Scalar(0x00000063)) } + StorageLive(_3); // scope 2 at $DIR/mutable_variable_aggregate_mut_ref.rs:8:9: 8:10 + _3 = _1; // scope 2 at $DIR/mutable_variable_aggregate_mut_ref.rs:8:13: 8:14 + _0 = const (); // scope 0 at $DIR/mutable_variable_aggregate_mut_ref.rs:4:11: 9:2 + // ty::Const + // + ty: () + // + val: Value(Scalar()) + // mir::Constant + // + span: $DIR/mutable_variable_aggregate_mut_ref.rs:4:11: 9:2 + // + literal: Const { ty: (), val: Value(Scalar()) } + StorageDead(_3); // scope 2 at $DIR/mutable_variable_aggregate_mut_ref.rs:9:1: 9:2 + StorageDead(_2); // scope 1 at $DIR/mutable_variable_aggregate_mut_ref.rs:9:1: 9:2 + StorageDead(_1); // scope 0 at $DIR/mutable_variable_aggregate_mut_ref.rs:9:1: 9:2 + return; // scope 0 at $DIR/mutable_variable_aggregate_mut_ref.rs:9:2: 9:2 + } + } + diff --git a/src/test/mir-opt/const_prop/mutable_variable_no_prop.rs b/src/test/mir-opt/const_prop/mutable_variable_no_prop.rs new file mode 100644 index 0000000000000..8c9cd00509622 --- /dev/null +++ b/src/test/mir-opt/const_prop/mutable_variable_no_prop.rs @@ -0,0 +1,12 @@ +// compile-flags: -O + +static mut STATIC: u32 = 42; + +// EMIT_MIR rustc.main.ConstProp.diff +fn main() { + let mut x = 42; + unsafe { + x = STATIC; + } + let y = x; +} diff --git a/src/test/mir-opt/const_prop/mutable_variable_no_prop/rustc.main.ConstProp.diff b/src/test/mir-opt/const_prop/mutable_variable_no_prop/rustc.main.ConstProp.diff new file mode 100644 index 0000000000000..1e9cbe6024c9b --- /dev/null +++ b/src/test/mir-opt/const_prop/mutable_variable_no_prop/rustc.main.ConstProp.diff @@ -0,0 +1,69 @@ +- // MIR for `main` before ConstProp ++ // MIR for `main` after ConstProp + + fn main() -> () { + let mut _0: (); // return place in scope 0 at $DIR/mutable_variable_no_prop.rs:6:11: 6:11 + let mut _1: u32; // in scope 0 at $DIR/mutable_variable_no_prop.rs:7:9: 7:14 + let _2: (); // in scope 0 at $DIR/mutable_variable_no_prop.rs:8:5: 10:6 + let mut _3: u32; // in scope 0 at $DIR/mutable_variable_no_prop.rs:9:13: 9:19 + let mut _4: *mut u32; // in scope 0 at $DIR/mutable_variable_no_prop.rs:9:13: 9:19 + scope 1 { + debug x => _1; // in scope 1 at $DIR/mutable_variable_no_prop.rs:7:9: 7:14 + let _5: u32; // in scope 1 at $DIR/mutable_variable_no_prop.rs:11:9: 11:10 + scope 2 { + } + scope 3 { + debug y => _5; // in scope 3 at $DIR/mutable_variable_no_prop.rs:11:9: 11:10 + } + } + + bb0: { + StorageLive(_1); // scope 0 at $DIR/mutable_variable_no_prop.rs:7:9: 7:14 + _1 = const 42u32; // scope 0 at $DIR/mutable_variable_no_prop.rs:7:17: 7:19 + // ty::Const + // + ty: u32 + // + val: Value(Scalar(0x0000002a)) + // mir::Constant + // + span: $DIR/mutable_variable_no_prop.rs:7:17: 7:19 + // + literal: Const { ty: u32, val: Value(Scalar(0x0000002a)) } + StorageLive(_2); // scope 1 at $DIR/mutable_variable_no_prop.rs:8:5: 10:6 + StorageLive(_3); // scope 2 at $DIR/mutable_variable_no_prop.rs:9:13: 9:19 + StorageLive(_4); // scope 2 at $DIR/mutable_variable_no_prop.rs:9:13: 9:19 + _4 = const {alloc0+0x0: *mut u32}; // scope 2 at $DIR/mutable_variable_no_prop.rs:9:13: 9:19 + // ty::Const + // + ty: *mut u32 + // + val: Value(Scalar(alloc0+0x0)) + // mir::Constant + // + span: $DIR/mutable_variable_no_prop.rs:9:13: 9:19 + // + literal: Const { ty: *mut u32, val: Value(Scalar(alloc0+0x0)) } + _3 = (*_4); // scope 2 at $DIR/mutable_variable_no_prop.rs:9:13: 9:19 + _1 = move _3; // scope 2 at $DIR/mutable_variable_no_prop.rs:9:9: 9:19 + StorageDead(_3); // scope 2 at $DIR/mutable_variable_no_prop.rs:9:18: 9:19 + StorageDead(_4); // scope 2 at $DIR/mutable_variable_no_prop.rs:9:19: 9:20 + _2 = const (); // scope 2 at $DIR/mutable_variable_no_prop.rs:8:5: 10:6 + // ty::Const + // + ty: () + // + val: Value(Scalar()) + // mir::Constant + // + span: $DIR/mutable_variable_no_prop.rs:8:5: 10:6 + // + literal: Const { ty: (), val: Value(Scalar()) } + StorageDead(_2); // scope 1 at $DIR/mutable_variable_no_prop.rs:10:5: 10:6 + StorageLive(_5); // scope 1 at $DIR/mutable_variable_no_prop.rs:11:9: 11:10 + _5 = _1; // scope 1 at $DIR/mutable_variable_no_prop.rs:11:13: 11:14 + _0 = const (); // scope 0 at $DIR/mutable_variable_no_prop.rs:6:11: 12:2 + // ty::Const + // + ty: () + // + val: Value(Scalar()) + // mir::Constant + // + span: $DIR/mutable_variable_no_prop.rs:6:11: 12:2 + // + literal: Const { ty: (), val: Value(Scalar()) } + StorageDead(_5); // scope 1 at $DIR/mutable_variable_no_prop.rs:12:1: 12:2 + StorageDead(_1); // scope 0 at $DIR/mutable_variable_no_prop.rs:12:1: 12:2 + return; // scope 0 at $DIR/mutable_variable_no_prop.rs:12:2: 12:2 + } + } + + alloc0 (static: STATIC, size: 4, align: 4) { + 2a 00 00 00 │ *... + } +