Auto merge of #3338 - RalfJung:more-tracking-and-threads, r=RalfJung

print thread name in miri error backtraces; add option to track read/write accesses

This came up while debugging rust-lang/rust#121626. It didn't end up being useful there but still seems like good tools to have around.

Author: bors

src/tools/miri/src/bin/miri.rs

@@ -534,6 +534,8 @@ fn main() {
                     ),
             };
             miri_config.tracked_alloc_ids.extend(ids);
+        } else if arg == "-Zmiri-track-alloc-accesses" {
+            miri_config.track_alloc_accesses = true;
         } else if let Some(param) = arg.strip_prefix("-Zmiri-compare-exchange-weak-failure-rate=") {
             let rate = match param.parse::<f64>() {
                 Ok(rate) if rate >= 0.0 && rate <= 1.0 => rate,

src/tools/miri/src/borrow_tracker/mod.rs

@@ -122,13 +122,6 @@ impl VisitProvenance for GlobalStateInner {
 /// We need interior mutable access to the global state.
 pub type GlobalState = RefCell<GlobalStateInner>;
 
-/// Indicates which kind of access is being performed.
-#[derive(Copy, Clone, Hash, PartialEq, Eq, Debug)]
-pub enum AccessKind {
-    Read,
-    Write,
-}
-
 impl fmt::Display for AccessKind {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {

src/tools/miri/src/borrow_tracker/stacked_borrows/diagnostics.rs

@@ -5,7 +5,7 @@ use rustc_data_structures::fx::FxHashSet;
 use rustc_span::{Span, SpanData};
 use rustc_target::abi::Size;
 
-use crate::borrow_tracker::{AccessKind, GlobalStateInner, ProtectorKind};
+use crate::borrow_tracker::{GlobalStateInner, ProtectorKind};
 use crate::*;
 
 /// Error reporting

src/tools/miri/src/borrow_tracker/stacked_borrows/mod.rs

@@ -16,7 +16,7 @@ use rustc_target::abi::{Abi, Size};
 
 use crate::borrow_tracker::{
     stacked_borrows::diagnostics::{AllocHistory, DiagnosticCx, DiagnosticCxBuilder},
-    AccessKind, GlobalStateInner, ProtectorKind,
+    GlobalStateInner, ProtectorKind,
 };
 use crate::*;
 

src/tools/miri/src/borrow_tracker/tree_borrows/diagnostics.rs

@@ -9,7 +9,7 @@ use crate::borrow_tracker::tree_borrows::{
     tree::LocationState,
     unimap::UniIndex,
 };
-use crate::borrow_tracker::{AccessKind, ProtectorKind};
+use crate::borrow_tracker::ProtectorKind;
 use crate::*;
 
 /// Cause of an access: either a real access or one

src/tools/miri/src/borrow_tracker/tree_borrows/mod.rs

@@ -1,6 +1,6 @@
 use rustc_target::abi::{Abi, Size};
 
-use crate::borrow_tracker::{AccessKind, GlobalState, GlobalStateInner, ProtectorKind};
+use crate::borrow_tracker::{GlobalState, GlobalStateInner, ProtectorKind};
 use rustc_middle::{
     mir::{Mutability, RetagKind},
     ty::{

src/tools/miri/src/borrow_tracker/tree_borrows/perms.rs

@@ -3,7 +3,7 @@ use std::fmt;
 
 use crate::borrow_tracker::tree_borrows::diagnostics::TransitionError;
 use crate::borrow_tracker::tree_borrows::tree::AccessRelatedness;
-use crate::borrow_tracker::AccessKind;
+use crate::AccessKind;
 
 /// The activation states of a pointer.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]

src/tools/miri/src/borrow_tracker/tree_borrows/tree.rs

@@ -24,7 +24,7 @@ use crate::borrow_tracker::tree_borrows::{
     unimap::{UniEntry, UniIndex, UniKeyMap, UniValMap},
     Permission,
 };
-use crate::borrow_tracker::{AccessKind, GlobalState, ProtectorKind};
+use crate::borrow_tracker::{GlobalState, ProtectorKind};
 use crate::*;
 
 mod tests;

src/tools/miri/src/concurrency/data_race.rs

@@ -1673,8 +1673,8 @@ impl GlobalState {
         vector: VectorIdx,
     ) -> String {
         let thread = self.vector_info.borrow()[vector];
-        let thread_name = thread_mgr.get_thread_name(thread);
-        format!("thread `{}`", String::from_utf8_lossy(thread_name))
+        let thread_name = thread_mgr.get_thread_display_name(thread);
+        format!("thread `{thread_name}`")
     }
 
     /// Acquire a lock, express that the previous call of

src/tools/miri/src/concurrency/thread.rs

@@ -160,9 +160,18 @@ pub type StackEmptyCallback<'mir, 'tcx> =
     Box<dyn FnMut(&mut MiriInterpCx<'mir, 'tcx>) -> InterpResult<'tcx, Poll<()>>>;
 
 impl<'mir, 'tcx> Thread<'mir, 'tcx> {
-    /// Get the name of the current thread, or `<unnamed>` if it was not set.
-    fn thread_name(&self) -> &[u8] {
-        if let Some(ref thread_name) = self.thread_name { thread_name } else { b"<unnamed>" }
+    /// Get the name of the current thread if it was set.
+    fn thread_name(&self) -> Option<&[u8]> {
+        self.thread_name.as_deref()
+    }
+
+    /// Get the name of the current thread for display purposes; will include thread ID if not set.
+    fn thread_display_name(&self, id: ThreadId) -> String {
+        if let Some(ref thread_name) = self.thread_name {
+            String::from_utf8_lossy(thread_name).into_owned()
+        } else {
+            format!("unnamed-{}", id.index())
+        }
     }
 
     /// Return the top user-relevant frame, if there is one.
@@ -205,7 +214,7 @@ impl<'mir, 'tcx> std::fmt::Debug for Thread<'mir, 'tcx> {
         write!(
             f,
             "{}({:?}, {:?})",
-            String::from_utf8_lossy(self.thread_name()),
+            String::from_utf8_lossy(self.thread_name().unwrap_or(b"<unnamed>")),
             self.state,
             self.join_status
         )
@@ -572,10 +581,14 @@ impl<'mir, 'tcx: 'mir> ThreadManager<'mir, 'tcx> {
     }
 
     /// Get the name of the given thread.
-    pub fn get_thread_name(&self, thread: ThreadId) -> &[u8] {
+    pub fn get_thread_name(&self, thread: ThreadId) -> Option<&[u8]> {
         self.threads[thread].thread_name()
     }
 
+    pub fn get_thread_display_name(&self, thread: ThreadId) -> String {
+        self.threads[thread].thread_display_name(thread)
+    }
+
     /// Put the thread into the blocked state.
     fn block_thread(&mut self, thread: ThreadId) {
         let state = &mut self.threads[thread].state;
@@ -980,7 +993,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
     }
 
     #[inline]
-    fn get_thread_name<'c>(&'c self, thread: ThreadId) -> &'c [u8]
+    fn get_thread_name<'c>(&'c self, thread: ThreadId) -> Option<&[u8]>
     where
         'mir: 'c,
     {