diff options
16 files changed, 92 insertions, 15 deletions
diff --git a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs index f6f2e3f2a3a..f8755874014 100644 --- a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs +++ b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs @@ -1,5 +1,5 @@ use itertools::Itertools as _; -use rustc_abi::{self as abi, FIRST_VARIANT}; +use rustc_abi::{self as abi, BackendRepr, FIRST_VARIANT}; use rustc_middle::ty::adjustment::PointerCoercion; use rustc_middle::ty::layout::{HasTyCtxt, HasTypingEnv, LayoutOf, TyAndLayout}; use rustc_middle::ty::{self, Instance, Ty, TyCtxt}; @@ -25,6 +25,15 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { match *rvalue { mir::Rvalue::Use(ref operand) => { let cg_operand = self.codegen_operand(bx, operand); + // Crucially, we do *not* use `OperandValue::Ref` for types with + // `BackendRepr::Scalar | BackendRepr::ScalarPair`. This ensures we match the MIR + // semantics regarding when assignment operators allow overlap of LHS and RHS. + if matches!( + cg_operand.layout.backend_repr, + BackendRepr::Scalar(..) | BackendRepr::ScalarPair(..), + ) { + debug_assert!(!matches!(cg_operand.val, OperandValue::Ref(..))); + } // FIXME: consider not copying constants through stack. (Fixable by codegen'ing // constants into `OperandValue::Ref`; why don’t we do that yet if we don’t?) cg_operand.val.store(bx, dest); diff --git a/compiler/rustc_const_eval/src/interpret/place.rs b/compiler/rustc_const_eval/src/interpret/place.rs index a86fdf80f60..cd34892f029 100644 --- a/compiler/rustc_const_eval/src/interpret/place.rs +++ b/compiler/rustc_const_eval/src/interpret/place.rs @@ -858,7 +858,7 @@ where /// Also, if you use this you are responsible for validating that things get copied at the /// right type. #[instrument(skip(self), level = "trace")] - fn copy_op_no_validate( + pub(super) fn copy_op_no_validate( &mut self, src: &impl Projectable<'tcx, M::Provenance>, dest: &impl Writeable<'tcx, M::Provenance>, diff --git a/compiler/rustc_const_eval/src/interpret/step.rs b/compiler/rustc_const_eval/src/interpret/step.rs index 23d362de308..46950d60f8c 100644 --- a/compiler/rustc_const_eval/src/interpret/step.rs +++ b/compiler/rustc_const_eval/src/interpret/step.rs @@ -310,7 +310,6 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { operands: &IndexSlice<FieldIdx, mir::Operand<'tcx>>, dest: &PlaceTy<'tcx, M::Provenance>, ) -> InterpResult<'tcx> { - self.write_uninit(dest)?; // make sure all the padding ends up as uninit let (variant_index, variant_dest, active_field_index) = match *kind { mir::AggregateKind::Adt(_, variant_index, _, _, active_field_index) => { let variant_dest = self.project_downcast(dest, variant_index)?; @@ -346,9 +345,20 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { let field_index = active_field_index.unwrap_or(field_index); let field_dest = self.project_field(&variant_dest, field_index)?; let op = self.eval_operand(operand, Some(field_dest.layout))?; - self.copy_op(&op, &field_dest)?; + // We validate manually below so we don't have to do it here. + self.copy_op_no_validate(&op, &field_dest, /*allow_transmute*/ false)?; } - self.write_discriminant(variant_index, dest) + self.write_discriminant(variant_index, dest)?; + // Validate that the entire thing is valid, and reset padding that might be in between the + // fields. + if M::enforce_validity(self, dest.layout()) { + self.validate_operand( + dest, + M::enforce_validity_recursively(self, dest.layout()), + /*reset_provenance_and_padding*/ true, + )?; + } + interp_ok(()) } /// Repeats `operand` into the destination. `dest` must have array type, and that type diff --git a/compiler/rustc_middle/src/mir/syntax.rs b/compiler/rustc_middle/src/mir/syntax.rs index 3b8def67f92..d402ea4b04f 100644 --- a/compiler/rustc_middle/src/mir/syntax.rs +++ b/compiler/rustc_middle/src/mir/syntax.rs @@ -327,9 +327,11 @@ pub enum StatementKind<'tcx> { /// interesting for optimizations? Do we want to allow such optimizations? /// /// **Needs clarification**: We currently require that the LHS place not overlap with any place - /// read as part of computation of the RHS for some rvalues (generally those not producing - /// primitives). This requirement is under discussion in [#68364]. As a part of this discussion, - /// it is also unclear in what order the components are evaluated. + /// read as part of computation of the RHS for some rvalues. This requirement is under + /// discussion in [#68364]. Specifically, overlap is permitted only for assignments of a type + /// with `BackendRepr::Scalar | BackendRepr::ScalarPair` where all the scalar fields are + /// [`Scalar::Initialized`][rustc_abi::Scalar::Initialized]. As a part of this discussion, it is + /// also unclear in what order the components are evaluated. /// /// [#68364]: https://github.com/rust-lang/rust/issues/68364 /// diff --git a/src/tools/miri/tests/fail/both_borrows/issue-miri-1050-1.rs b/src/tools/miri/tests/fail/both_borrows/issue-miri-1050-1.rs index dd7dae9cecf..d907c5de797 100644 --- a/src/tools/miri/tests/fail/both_borrows/issue-miri-1050-1.rs +++ b/src/tools/miri/tests/fail/both_borrows/issue-miri-1050-1.rs @@ -1,4 +1,6 @@ //@revisions: stack tree +// Ensure this even hits the aliasing model +//@compile-flags: -Zmiri-disable-validation //@[tree]compile-flags: -Zmiri-tree-borrows //@error-in-other-file: pointer not dereferenceable diff --git a/src/tools/miri/tests/fail/both_borrows/issue-miri-1050-2.rs b/src/tools/miri/tests/fail/both_borrows/issue-miri-1050-2.rs index 5c947e64142..b54f27bb8b2 100644 --- a/src/tools/miri/tests/fail/both_borrows/issue-miri-1050-2.rs +++ b/src/tools/miri/tests/fail/both_borrows/issue-miri-1050-2.rs @@ -1,4 +1,6 @@ //@revisions: stack tree +// Ensure this even hits the aliasing model +//@compile-flags: -Zmiri-disable-validation //@[tree]compile-flags: -Zmiri-tree-borrows //@error-in-other-file: is a dangling pointer use std::ptr::NonNull; diff --git a/src/tools/miri/tests/fail/both_borrows/return_invalid_shr.stack.stderr b/src/tools/miri/tests/fail/both_borrows/return_invalid_shr.stack.stderr index d52143500c4..7c4fe748701 100644 --- a/src/tools/miri/tests/fail/both_borrows/return_invalid_shr.stack.stderr +++ b/src/tools/miri/tests/fail/both_borrows/return_invalid_shr.stack.stderr @@ -11,7 +11,7 @@ help: <TAG> was created by a SharedReadOnly retag at offsets [0x4..0x8] | LL | let ret = unsafe { &(*xraw).1 }; | ^^^^^^^^^^ -help: <TAG> was later invalidated at offsets [0x0..0x8] by a write access +help: <TAG> was later invalidated at offsets [0x4..0x8] by a write access --> tests/fail/both_borrows/return_invalid_shr.rs:LL:CC | LL | unsafe { *xraw = (42, 23) }; // unfreeze diff --git a/src/tools/miri/tests/fail/both_borrows/return_invalid_shr.tree.stderr b/src/tools/miri/tests/fail/both_borrows/return_invalid_shr.tree.stderr index ee0f313d980..a8e3553aae2 100644 --- a/src/tools/miri/tests/fail/both_borrows/return_invalid_shr.tree.stderr +++ b/src/tools/miri/tests/fail/both_borrows/return_invalid_shr.tree.stderr @@ -12,7 +12,7 @@ help: the accessed tag <TAG> was created here, in the initial state Frozen | LL | let ret = unsafe { &(*xraw).1 }; | ^^^^^^^^^^ -help: the accessed tag <TAG> later transitioned to Disabled due to a foreign write access at offsets [0x0..0x8] +help: the accessed tag <TAG> later transitioned to Disabled due to a foreign write access at offsets [0x4..0x8] --> tests/fail/both_borrows/return_invalid_shr.rs:LL:CC | LL | unsafe { *xraw = (42, 23) }; // unfreeze diff --git a/src/tools/miri/tests/fail/both_borrows/return_invalid_shr_option.stack.stderr b/src/tools/miri/tests/fail/both_borrows/return_invalid_shr_option.stack.stderr index d66c8eeb1af..8411437ea4c 100644 --- a/src/tools/miri/tests/fail/both_borrows/return_invalid_shr_option.stack.stderr +++ b/src/tools/miri/tests/fail/both_borrows/return_invalid_shr_option.stack.stderr @@ -14,7 +14,7 @@ help: <TAG> was created by a SharedReadOnly retag at offsets [0x4..0x8] | LL | let ret = Some(unsafe { &(*xraw).1 }); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ -help: <TAG> was later invalidated at offsets [0x0..0x8] by a write access +help: <TAG> was later invalidated at offsets [0x4..0x8] by a write access --> tests/fail/both_borrows/return_invalid_shr_option.rs:LL:CC | LL | unsafe { *xraw = (42, 23) }; // unfreeze diff --git a/src/tools/miri/tests/fail/both_borrows/return_invalid_shr_option.tree.stderr b/src/tools/miri/tests/fail/both_borrows/return_invalid_shr_option.tree.stderr index 16110e5b062..39da45ad6db 100644 --- a/src/tools/miri/tests/fail/both_borrows/return_invalid_shr_option.tree.stderr +++ b/src/tools/miri/tests/fail/both_borrows/return_invalid_shr_option.tree.stderr @@ -12,7 +12,7 @@ help: the accessed tag <TAG> was created here, in the initial state Frozen | LL | let ret = Some(unsafe { &(*xraw).1 }); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ -help: the accessed tag <TAG> later transitioned to Disabled due to a foreign write access at offsets [0x0..0x8] +help: the accessed tag <TAG> later transitioned to Disabled due to a foreign write access at offsets [0x4..0x8] --> tests/fail/both_borrows/return_invalid_shr_option.rs:LL:CC | LL | unsafe { *xraw = (42, 23) }; // unfreeze diff --git a/src/tools/miri/tests/fail/both_borrows/return_invalid_shr_tuple.stack.stderr b/src/tools/miri/tests/fail/both_borrows/return_invalid_shr_tuple.stack.stderr index 727b52ec729..a7c422aa73f 100644 --- a/src/tools/miri/tests/fail/both_borrows/return_invalid_shr_tuple.stack.stderr +++ b/src/tools/miri/tests/fail/both_borrows/return_invalid_shr_tuple.stack.stderr @@ -14,7 +14,7 @@ help: <TAG> was created by a SharedReadOnly retag at offsets [0x4..0x8] | LL | let ret = (unsafe { &(*xraw).1 },); | ^^^^^^^^^^^^^^^^^^^^^^^^ -help: <TAG> was later invalidated at offsets [0x0..0x8] by a write access +help: <TAG> was later invalidated at offsets [0x4..0x8] by a write access --> tests/fail/both_borrows/return_invalid_shr_tuple.rs:LL:CC | LL | unsafe { *xraw = (42, 23) }; // unfreeze diff --git a/src/tools/miri/tests/fail/both_borrows/return_invalid_shr_tuple.tree.stderr b/src/tools/miri/tests/fail/both_borrows/return_invalid_shr_tuple.tree.stderr index f93698f570e..66b03e57905 100644 --- a/src/tools/miri/tests/fail/both_borrows/return_invalid_shr_tuple.tree.stderr +++ b/src/tools/miri/tests/fail/both_borrows/return_invalid_shr_tuple.tree.stderr @@ -12,7 +12,7 @@ help: the accessed tag <TAG> was created here, in the initial state Frozen | LL | let ret = (unsafe { &(*xraw).1 },); | ^^^^^^^^^^^^^^^^^^^^^^^^ -help: the accessed tag <TAG> later transitioned to Disabled due to a foreign write access at offsets [0x0..0x8] +help: the accessed tag <TAG> later transitioned to Disabled due to a foreign write access at offsets [0x4..0x8] --> tests/fail/both_borrows/return_invalid_shr_tuple.rs:LL:CC | LL | unsafe { *xraw = (42, 23) }; // unfreeze diff --git a/src/tools/miri/tests/fail/overlapping_assignment_aggregate.rs b/src/tools/miri/tests/fail/overlapping_assignment_aggregate.rs new file mode 100644 index 00000000000..8d7b1946242 --- /dev/null +++ b/src/tools/miri/tests/fail/overlapping_assignment_aggregate.rs @@ -0,0 +1,18 @@ +//! This is like `pass/overlapping_assignment_aggregate_scalar.rs` but with a non-scalar +//! type, and that makes it definite UB. +#![feature(custom_mir, core_intrinsics)] +#![allow(internal_features)] + +use std::intrinsics::mir::*; + +#[custom_mir(dialect = "runtime")] +fn main() { + mir! { + let _1: ([u8; 1],); + { + _1.0 = [0_u8; 1]; + _1 = (_1.0, ); //~ERROR: overlapping ranges + Return() + } + } +} diff --git a/src/tools/miri/tests/fail/overlapping_assignment_aggregate.stderr b/src/tools/miri/tests/fail/overlapping_assignment_aggregate.stderr new file mode 100644 index 00000000000..f2a6d326b71 --- /dev/null +++ b/src/tools/miri/tests/fail/overlapping_assignment_aggregate.stderr @@ -0,0 +1,15 @@ +error: Undefined Behavior: `copy_nonoverlapping` called on overlapping ranges + --> tests/fail/overlapping_assignment_aggregate.rs:LL:CC + | +LL | _1 = (_1.0, ); + | ^^^^^^^^^^^^^ Undefined Behavior occurred here + | + = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior + = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information + = note: BACKTRACE: + = note: inside `main` at tests/fail/overlapping_assignment_aggregate.rs:LL:CC + +note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace + +error: aborting due to 1 previous error + diff --git a/src/tools/miri/tests/fail/validity/nonzero.stderr b/src/tools/miri/tests/fail/validity/nonzero.stderr index 0c3a35d6b9f..7be3ef46639 100644 --- a/src/tools/miri/tests/fail/validity/nonzero.stderr +++ b/src/tools/miri/tests/fail/validity/nonzero.stderr @@ -2,7 +2,7 @@ error: Undefined Behavior: constructing invalid value: encountered 0, but expect --> tests/fail/validity/nonzero.rs:LL:CC | LL | let _x = Some(unsafe { NonZero(0) }); - | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ Undefined Behavior occurred here + | ^^^^^^^^^^ Undefined Behavior occurred here | = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information diff --git a/src/tools/miri/tests/pass/overlapping_assignment_aggregate_scalar.rs b/src/tools/miri/tests/pass/overlapping_assignment_aggregate_scalar.rs new file mode 100644 index 00000000000..0cb2f764242 --- /dev/null +++ b/src/tools/miri/tests/pass/overlapping_assignment_aggregate_scalar.rs @@ -0,0 +1,19 @@ +#![feature(custom_mir, core_intrinsics)] +#![allow(internal_features)] + +use std::intrinsics::mir::*; + +#[custom_mir(dialect = "runtime")] +fn main() { + mir! { + let _1: (u8,); + { + _1.0 = 0_u8; + // This is a scalar type, so overlap is (for now) not UB. + // However, we used to treat such overlapping assignments incorrectly + // (see <https://github.com/rust-lang/rust/issues/146383#issuecomment-3273224645>). + _1 = (_1.0, ); + Return() + } + } +} |