diff options
| -rw-r--r-- | compiler/rustc_const_eval/src/interpret/eval_context.rs | 8 | ||||
| -rw-r--r-- | compiler/rustc_const_eval/src/interpret/machine.rs | 22 | ||||
| -rw-r--r-- | src/tools/miri/src/machine.rs | 45 | ||||
| -rw-r--r-- | src/tools/miri/tests/pass/const-addrs.rs | 20 |
4 files changed, 10 insertions, 85 deletions
diff --git a/compiler/rustc_const_eval/src/interpret/eval_context.rs b/compiler/rustc_const_eval/src/interpret/eval_context.rs index 11e7706fe60..0c888694e49 100644 --- a/compiler/rustc_const_eval/src/interpret/eval_context.rs +++ b/compiler/rustc_const_eval/src/interpret/eval_context.rs @@ -582,8 +582,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { span: Span, layout: Option<TyAndLayout<'tcx>>, ) -> InterpResult<'tcx, OpTy<'tcx, M::Provenance>> { - M::eval_mir_constant(self, *val, span, layout, |ecx, val, span, layout| { - let const_val = val.eval(*ecx.tcx, ecx.typing_env, span).map_err(|err| { + let const_val = val.eval(*self.tcx, self.typing_env, span).map_err(|err| { if M::ALL_CONSTS_ARE_PRECHECKED { match err { ErrorHandled::TooGeneric(..) => {}, @@ -599,11 +598,10 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { } } } - err.emit_note(*ecx.tcx); + err.emit_note(*self.tcx); err })?; - ecx.const_val_to_op(const_val, val.ty(), layout) - }) + self.const_val_to_op(const_val, val.ty(), layout) } #[must_use] diff --git a/compiler/rustc_const_eval/src/interpret/machine.rs b/compiler/rustc_const_eval/src/interpret/machine.rs index e981f3973ae..e22629993fb 100644 --- a/compiler/rustc_const_eval/src/interpret/machine.rs +++ b/compiler/rustc_const_eval/src/interpret/machine.rs @@ -12,7 +12,6 @@ use rustc_middle::query::TyCtxtAt; use rustc_middle::ty::Ty; use rustc_middle::ty::layout::TyAndLayout; use rustc_middle::{mir, ty}; -use rustc_span::Span; use rustc_span::def_id::DefId; use rustc_target::callconv::FnAbi; @@ -587,27 +586,6 @@ pub trait Machine<'tcx>: Sized { interp_ok(()) } - /// Evaluate the given constant. The `eval` function will do all the required evaluation, - /// but this hook has the chance to do some pre/postprocessing. - #[inline(always)] - fn eval_mir_constant<F>( - ecx: &InterpCx<'tcx, Self>, - val: mir::Const<'tcx>, - span: Span, - layout: Option<TyAndLayout<'tcx>>, - eval: F, - ) -> InterpResult<'tcx, OpTy<'tcx, Self::Provenance>> - where - F: Fn( - &InterpCx<'tcx, Self>, - mir::Const<'tcx>, - Span, - Option<TyAndLayout<'tcx>>, - ) -> InterpResult<'tcx, OpTy<'tcx, Self::Provenance>>, - { - eval(ecx, val, span, layout) - } - /// Returns the salt to be used for a deduplicated global alloation. /// If the allocation is for a function, the instance is provided as well /// (this lets Miri ensure unique addresses for some functions). diff --git a/src/tools/miri/src/machine.rs b/src/tools/miri/src/machine.rs index ce33c870b4b..7271d3f619c 100644 --- a/src/tools/miri/src/machine.rs +++ b/src/tools/miri/src/machine.rs @@ -4,7 +4,6 @@ use std::any::Any; use std::borrow::Cow; use std::cell::{Cell, RefCell}; -use std::collections::hash_map::Entry; use std::path::Path; use std::rc::Rc; use std::{fmt, process}; @@ -70,12 +69,6 @@ pub struct FrameExtra<'tcx> { /// This is used by `MiriMachine::current_span` and `MiriMachine::caller_span` pub is_user_relevant: bool, - /// We have a cache for the mapping from [`mir::Const`] to resulting [`AllocId`]. - /// However, we don't want all frames to always get the same result, so we insert - /// an additional bit of "salt" into the cache key. This salt is fixed per-frame - /// so that within a call, a const will have a stable address. - salt: usize, - /// Data race detector per-frame data. pub data_race: Option<data_race::FrameState>, } @@ -88,14 +81,12 @@ impl<'tcx> std::fmt::Debug for FrameExtra<'tcx> { catch_unwind, timing: _, is_user_relevant, - salt, data_race, } = self; f.debug_struct("FrameData") .field("borrow_tracker", borrow_tracker) .field("catch_unwind", catch_unwind) .field("is_user_relevant", is_user_relevant) - .field("salt", salt) .field("data_race", data_race) .finish() } @@ -108,7 +99,6 @@ impl VisitProvenance for FrameExtra<'_> { borrow_tracker, timing: _, is_user_relevant: _, - salt: _, data_race: _, } = self; @@ -578,11 +568,6 @@ pub struct MiriMachine<'tcx> { /// diagnostics. pub(crate) allocation_spans: RefCell<FxHashMap<AllocId, (Span, Option<Span>)>>, - /// Maps MIR consts to their evaluated result. We combine the const with a "salt" (`usize`) - /// that is fixed per stack frame; this lets us have sometimes different results for the - /// same const while ensuring consistent results within a single call. - const_cache: RefCell<FxHashMap<(mir::Const<'tcx>, usize), OpTy<'tcx>>>, - /// For each allocation, an offset inside that allocation that was deemed aligned even for /// symbolic alignment checks. This cannot be stored in `AllocExtra` since it needs to be /// tracked for vtables and function allocations as well as regular allocations. @@ -764,7 +749,6 @@ impl<'tcx> MiriMachine<'tcx> { stack_size, collect_leak_backtraces: config.collect_leak_backtraces, allocation_spans: RefCell::new(FxHashMap::default()), - const_cache: RefCell::new(FxHashMap::default()), symbolic_alignment: RefCell::new(FxHashMap::default()), union_data_ranges: FxHashMap::default(), pthread_mutex_sanity: Cell::new(false), @@ -941,7 +925,6 @@ impl VisitProvenance for MiriMachine<'_> { stack_size: _, collect_leak_backtraces: _, allocation_spans: _, - const_cache: _, symbolic_alignment: _, union_data_ranges: _, pthread_mutex_sanity: _, @@ -1578,7 +1561,6 @@ impl<'tcx> Machine<'tcx> for MiriMachine<'tcx> { catch_unwind: None, timing, is_user_relevant: ecx.machine.is_user_relevant(&frame), - salt: ecx.machine.rng.borrow_mut().random_range(0..ADDRS_PER_ANON_GLOBAL), data_race: ecx .machine .data_race @@ -1737,33 +1719,6 @@ impl<'tcx> Machine<'tcx> for MiriMachine<'tcx> { interp_ok(()) } - fn eval_mir_constant<F>( - ecx: &InterpCx<'tcx, Self>, - val: mir::Const<'tcx>, - span: Span, - layout: Option<TyAndLayout<'tcx>>, - eval: F, - ) -> InterpResult<'tcx, OpTy<'tcx>> - where - F: Fn( - &InterpCx<'tcx, Self>, - mir::Const<'tcx>, - Span, - Option<TyAndLayout<'tcx>>, - ) -> InterpResult<'tcx, OpTy<'tcx>>, - { - let frame = ecx.active_thread_stack().last().unwrap(); - let mut cache = ecx.machine.const_cache.borrow_mut(); - match cache.entry((val, frame.extra.salt)) { - Entry::Vacant(ve) => { - let op = eval(ecx, val, span, layout)?; - ve.insert(op.clone()); - interp_ok(op) - } - Entry::Occupied(oe) => interp_ok(oe.get().clone()), - } - } - fn get_global_alloc_salt( ecx: &InterpCx<'tcx, Self>, instance: Option<ty::Instance<'tcx>>, diff --git a/src/tools/miri/tests/pass/const-addrs.rs b/src/tools/miri/tests/pass/const-addrs.rs index af68b28b2b8..0d1531c73cd 100644 --- a/src/tools/miri/tests/pass/const-addrs.rs +++ b/src/tools/miri/tests/pass/const-addrs.rs @@ -1,14 +1,10 @@ -// The const fn interpreter creates a new AllocId every time it evaluates any const. -// If we do that in Miri, repeatedly evaluating a const causes unbounded memory use -// we need to keep track of the base address for that AllocId, and the allocation is never -// deallocated. -// In Miri we explicitly store previously-assigned AllocIds for each const and ensure -// that we only hand out a finite number of AllocIds per const. -// MIR inlining will put every evaluation of the const we're repeatedly evaluating into the same -// stack frame, breaking this test. +// The interpreter used to create a new AllocId every time it evaluates any const. +// This caused unbounded memory use in Miri. +// This test verifies that we only create a bounded amount of addresses for any given const. +// In practice, the interpreter always returns the same address, but we *do not guarantee* that. //@compile-flags: -Zinline-mir=no -const EVALS: usize = 256; +const EVALS: usize = 64; use std::collections::HashSet; fn main() { @@ -16,10 +12,8 @@ fn main() { for _ in 0..EVALS { addrs.insert(const_addr()); } - // Check that the const allocation has multiple base addresses - assert!(addrs.len() > 1); - // But also that we get a limited number of unique base addresses - assert!(addrs.len() < EVALS); + // Check that we always return the same base address for the const allocation. + assert_eq!(addrs.len(), 1); // Check that within a call we always produce the same address let mut prev = 0; |