From bc4366b099e7a4d115650dcfec4aeeb62bfc3c54 Mon Sep 17 00:00:00 2001 From: Ralf Jung Date: Sat, 12 Oct 2024 12:14:28 +0200 Subject: [PATCH] miri: avoid cloning AllocExtra --- .../src/const_eval/machine.rs | 2 +- .../rustc_const_eval/src/interpret/memory.rs | 31 +++++++++++-------- src/tools/miri/src/diagnostics.rs | 4 +-- src/tools/miri/src/eval.rs | 2 +- src/tools/miri/src/machine.rs | 10 +++++- 5 files changed, 31 insertions(+), 18 deletions(-) diff --git a/compiler/rustc_const_eval/src/const_eval/machine.rs b/compiler/rustc_const_eval/src/const_eval/machine.rs index 4aec74595bc86..2db43a0f787eb 100644 --- a/compiler/rustc_const_eval/src/const_eval/machine.rs +++ b/compiler/rustc_const_eval/src/const_eval/machine.rs @@ -140,7 +140,7 @@ impl interpret::AllocMap for FxIndexMap { #[inline(always)] fn filter_map_collect(&self, mut f: impl FnMut(&K, &V) -> Option) -> Vec { - self.iter().filter_map(move |(k, v)| f(k, &*v)).collect() + self.iter().filter_map(move |(k, v)| f(k, v)).collect() } #[inline(always)] diff --git a/compiler/rustc_const_eval/src/interpret/memory.rs b/compiler/rustc_const_eval/src/interpret/memory.rs index e6ab8ca12a886..7700eb792effb 100644 --- a/compiler/rustc_const_eval/src/interpret/memory.rs +++ b/compiler/rustc_const_eval/src/interpret/memory.rs @@ -993,11 +993,14 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { bytes } - /// Find leaked allocations. Allocations reachable from `static_roots` or a `Global` allocation - /// are not considered leaked, as well as leaks whose kind's `may_leak()` returns true. - pub fn find_leaked_allocations( - &self, - static_roots: &[AllocId], + /// Find leaked allocations, remove them from memory and return them. Allocations reachable from + /// `static_roots` or a `Global` allocation are not considered leaked, as well as leaks whose + /// kind's `may_leak()` returns true. + /// + /// This is highly destructive, no more execution can happen after this! + pub fn take_leaked_allocations( + &mut self, + static_roots: impl FnOnce(&Self) -> &[AllocId], ) -> Vec<(AllocId, MemoryKind, Allocation)> { // Collect the set of allocations that are *reachable* from `Global` allocations. @@ -1008,7 +1011,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { self.memory.alloc_map.filter_map_collect(move |&id, &(kind, _)| { if Some(kind) == global_kind { Some(id) } else { None } }); - todo.extend(static_roots); + todo.extend(static_roots(self)); while let Some(id) = todo.pop() { if reachable.insert(id) { // This is a new allocation, add the allocation it points to `todo`. @@ -1023,13 +1026,15 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> { }; // All allocations that are *not* `reachable` and *not* `may_leak` are considered leaking. - self.memory.alloc_map.filter_map_collect(|id, (kind, alloc)| { - if kind.may_leak() || reachable.contains(id) { - None - } else { - Some((*id, *kind, alloc.clone())) - } - }) + let leaked: Vec<_> = self.memory.alloc_map.filter_map_collect(|&id, &(kind, _)| { + if kind.may_leak() || reachable.contains(&id) { None } else { Some(id) } + }); + let mut result = Vec::new(); + for &id in leaked.iter() { + let (kind, alloc) = self.memory.alloc_map.remove(&id).unwrap(); + result.push((id, kind, alloc)); + } + result } /// Runs the closure in "validation" mode, which means the machine's memory read hooks will be diff --git a/src/tools/miri/src/diagnostics.rs b/src/tools/miri/src/diagnostics.rs index 5b1bad28c07c7..475139a3b5192 100644 --- a/src/tools/miri/src/diagnostics.rs +++ b/src/tools/miri/src/diagnostics.rs @@ -473,14 +473,14 @@ pub fn report_leaks<'tcx>( leaks: Vec<(AllocId, MemoryKind, Allocation, MiriAllocBytes>)>, ) { let mut any_pruned = false; - for (id, kind, mut alloc) in leaks { + for (id, kind, alloc) in leaks { let mut title = format!( "memory leaked: {id:?} ({}, size: {:?}, align: {:?})", kind, alloc.size().bytes(), alloc.align.bytes() ); - let Some(backtrace) = alloc.extra.backtrace.take() else { + let Some(backtrace) = alloc.extra.backtrace else { ecx.tcx.dcx().err(title); continue; }; diff --git a/src/tools/miri/src/eval.rs b/src/tools/miri/src/eval.rs index ece76e581f248..57b226de28cb7 100644 --- a/src/tools/miri/src/eval.rs +++ b/src/tools/miri/src/eval.rs @@ -476,7 +476,7 @@ pub fn eval_entry<'tcx>( } // Check for memory leaks. info!("Additional static roots: {:?}", ecx.machine.static_roots); - let leaks = ecx.find_leaked_allocations(&ecx.machine.static_roots); + let leaks = ecx.take_leaked_allocations(|ecx| &ecx.machine.static_roots); if !leaks.is_empty() { report_leaks(&ecx, leaks); tcx.dcx().note("set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check"); diff --git a/src/tools/miri/src/machine.rs b/src/tools/miri/src/machine.rs index b9cebcfe9cd82..d346cd7b03ec9 100644 --- a/src/tools/miri/src/machine.rs +++ b/src/tools/miri/src/machine.rs @@ -321,7 +321,7 @@ impl ProvenanceExtra { } /// Extra per-allocation data -#[derive(Debug, Clone)] +#[derive(Debug)] pub struct AllocExtra<'tcx> { /// Global state of the borrow tracker, if enabled. pub borrow_tracker: Option, @@ -338,6 +338,14 @@ pub struct AllocExtra<'tcx> { pub backtrace: Option>>, } +// We need a `Clone` impl because the machine passes `Allocation` through `Cow`... +// but that should never end up actually cloning our `AllocExtra`. +impl<'tcx> Clone for AllocExtra<'tcx> { + fn clone(&self) -> Self { + panic!("our allocations should never be cloned"); + } +} + impl VisitProvenance for AllocExtra<'_> { fn visit_provenance(&self, visit: &mut VisitWith<'_>) { let AllocExtra { borrow_tracker, data_race, weak_memory, backtrace: _ } = self;