Auto merge of #1202 - RalfJung:symbols, r=RalfJung

switch extern_statics map to symbols, and use FxHashMap everywhere

Cc @eddyb

Author: bors

src/intptrcast.rs

@@ -1,9 +1,10 @@
 use std::cell::RefCell;
 use std::cmp::max;
-use std::collections::{hash_map::Entry, HashMap};
+use std::collections::hash_map::Entry;
 
 use rand::Rng;
 
+use rustc_data_structures::fx::FxHashMap;
 use rustc::ty::layout::HasDataLayout;
 use rustc_mir::interpret::{AllocCheck, AllocId, InterpResult, Memory, Machine, Pointer, PointerArithmetic};
 use rustc_target::abi::Size;
@@ -21,7 +22,7 @@ pub struct GlobalState {
     /// `AllocExtra` because function pointers also have a base address, and
     /// they do not have an `AllocExtra`.
     /// This is the inverse of `int_to_ptr_map`.
-    pub base_addr: HashMap<AllocId, u64>,
+    pub base_addr: FxHashMap<AllocId, u64>,
     /// This is used as a memory address when a new pointer is casted to an integer. It
     /// is always larger than any address that was previously made part of a block.
     pub next_base_addr: u64,
@@ -31,7 +32,7 @@ impl Default for GlobalState {
     fn default() -> Self {
         GlobalState {
             int_to_ptr_map: Vec::default(),
-            base_addr: HashMap::default(),
+            base_addr: FxHashMap::default(),
             next_base_addr: STACK_ADDR,
         }
     }

src/machine.rs

@@ -3,20 +3,20 @@
 
 use std::borrow::Cow;
 use std::cell::RefCell;
-use std::collections::HashMap;
 use std::num::NonZeroU64;
 use std::rc::Rc;
 
 use rand::rngs::StdRng;
 
+use rustc_data_structures::fx::FxHashMap;
 use rustc::mir;
 use rustc::ty::{
     self,
     layout::{LayoutOf, Size},
     Ty,
 };
 use rustc_ast::attr;
-use rustc_span::{source_map::Span, symbol::sym};
+use rustc_span::{source_map::Span, symbol::{sym, Symbol}};
 
 use crate::*;
 
@@ -75,7 +75,7 @@ pub struct MemoryExtra {
     pub intptrcast: intptrcast::MemoryExtra,
 
     /// Mapping extern static names to their canonical allocation.
-    pub(crate) extern_statics: HashMap<&'static str, AllocId>,
+    pub(crate) extern_statics: FxHashMap<Symbol, AllocId>,
 
     /// The random number generator used for resolving non-determinism.
     /// Needs to be queried by ptr_to_int, hence needs interior mutability.
@@ -92,7 +92,7 @@ impl MemoryExtra {
         MemoryExtra {
             stacked_borrows,
             intptrcast: Default::default(),
-            extern_statics: HashMap::default(),
+            extern_statics: FxHashMap::default(),
             rng: RefCell::new(rng),
         }
     }
@@ -111,7 +111,7 @@ impl MemoryExtra {
                 this.memory
                     .extra
                     .extern_statics
-                    .insert("__cxa_thread_atexit_impl", place.ptr.assert_ptr().alloc_id)
+                    .insert(Symbol::intern("__cxa_thread_atexit_impl"), place.ptr.assert_ptr().alloc_id)
                     .unwrap_none();
             }
             _ => {} // No "extern statics" supported on this platform
@@ -310,11 +310,11 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for Evaluator<'tcx> {
         };
         let attrs = tcx.get_attrs(def_id);
         let link_name = match attr::first_attr_value_str_by_name(&attrs, sym::link_name) {
-            Some(name) => name.as_str(),
-            None => tcx.item_name(def_id).as_str(),
+            Some(name) => name,
+            None => tcx.item_name(def_id),
         };
         // Check if we know this one.
-        if let Some(canonical_id) = mem.extra.extern_statics.get(&*link_name) {
+        if let Some(canonical_id) = mem.extra.extern_statics.get(&link_name) {
             trace!("canonical_alloc_id: {:?} ({}) -> {:?}", id, link_name, canonical_id);
             *canonical_id
         } else {

src/mono_hash_map.rs

@@ -1,6 +1,6 @@
-//! This is a "monotonic `HashMap`": A `HashMap` that, when shared, can be pushed to but not
+//! This is a "monotonic `FxHashMap`": A `FxHashMap` that, when shared, can be pushed to but not
 //! otherwise mutated. We also box items in the map. This means we can safely provide
-//! shared references into existing items in the `HashMap`, because they will not be dropped
+//! shared references into existing items in the `FxHashMap`, because they will not be dropped
 //! (from being removed) or moved (because they are boxed).
 //! The API is is completely tailored to what `memory.rs` needs. It is still in
 //! a separate file to minimize the amount of code that has to care about the unsafety.
@@ -21,8 +21,8 @@ impl<K: Hash + Eq, V> MonoHashMap<K, V> {
     /// This function exists for priroda to be able to iterate over all evaluator memory.
     ///
     /// The function is somewhat roundabout with the closure argument because internally the
-    /// `MonoHashMap` uses a `RefCell`. When iterating over the `HashMap` inside the `RefCell`,
-    /// we need to keep a borrow to the `HashMap` inside the iterator. The borrow is only alive
+    /// `MonoHashMap` uses a `RefCell`. When iterating over the `FxHashMap` inside the `RefCell`,
+    /// we need to keep a borrow to the `FxHashMap` inside the iterator. The borrow is only alive
     /// as long as the `Ref` returned by `RefCell::borrow()` is alive. So we can't return the
     /// iterator, as that would drop the `Ref`. We can't return both, as it's not possible in Rust
     /// to have a struct/tuple with a field that refers to another field.

src/shims/env.rs

@@ -1,18 +1,18 @@
-use std::collections::HashMap;
 use std::ffi::{OsString, OsStr};
 use std::env;
 
 use crate::stacked_borrows::Tag;
 use crate::*;
 
+use rustc_data_structures::fx::FxHashMap;
 use rustc::ty::layout::Size;
 use rustc_mir::interpret::Pointer;
 
 #[derive(Default)]
 pub struct EnvVars {
     /// Stores pointers to the environment variables. These variables must be stored as
     /// null-terminated C strings with the `"{name}={value}"` format.
-    map: HashMap<OsString, Pointer<Tag>>,
+    map: FxHashMap<OsString, Pointer<Tag>>,
 }
 
 impl EnvVars {

src/shims/fs.rs

@@ -1,11 +1,11 @@
 use std::collections::BTreeMap;
-use std::collections::HashMap;
 use std::convert::{TryFrom, TryInto};
 use std::fs::{read_dir, remove_dir, remove_file, rename, DirBuilder, File, FileType, OpenOptions, ReadDir};
 use std::io::{Read, Seek, SeekFrom, Write};
 use std::path::PathBuf;
 use std::time::SystemTime;
 
+use rustc_data_structures::fx::FxHashMap;
 use rustc::ty::layout::{Align, LayoutOf, Size};
 
 use crate::stacked_borrows::Tag;
@@ -212,10 +212,10 @@ pub struct DirHandler {
     /// When opendir is called, a directory iterator is created on the host for the target
     /// directory, and an entry is stored in this hash map, indexed by an ID which represents
     /// the directory stream. When readdir is called, the directory stream ID is used to look up
-    /// the corresponding ReadDir iterator from this HashMap, and information from the next
+    /// the corresponding ReadDir iterator from this map, and information from the next
     /// directory entry is returned. When closedir is called, the ReadDir iterator is removed from
-    /// this HashMap.
-    streams: HashMap<u64, ReadDir>,
+    /// the map.
+    streams: FxHashMap<u64, ReadDir>,
     /// ID number to be used by the next call to opendir
     next_id: u64,
 }
@@ -232,7 +232,7 @@ impl DirHandler {
 impl Default for DirHandler {
     fn default() -> DirHandler {
         DirHandler {
-            streams: HashMap::new(),
+            streams: FxHashMap::default(),
             // Skip 0 as an ID, because it looks like a null pointer to libc
             next_id: 1,
         }

src/stacked_borrows.rs

@@ -2,11 +2,11 @@
 //! for further information.
 
 use std::cell::RefCell;
-use std::collections::{HashMap, HashSet};
 use std::fmt;
 use std::num::NonZeroU64;
 use std::rc::Rc;
 
+use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc::mir::RetagKind;
 use rustc::ty::{self, layout::Size};
 use rustc_hir::Mutability;
@@ -96,11 +96,11 @@ pub struct GlobalState {
     /// Table storing the "base" tag for each allocation.
     /// The base tag is the one used for the initial pointer.
     /// We need this in a separate table to handle cyclic statics.
-    base_ptr_ids: HashMap<AllocId, Tag>,
+    base_ptr_ids: FxHashMap<AllocId, Tag>,
     /// Next unused call ID (for protectors).
     next_call_id: CallId,
     /// Those call IDs corresponding to functions that are still running.
-    active_calls: HashSet<CallId>,
+    active_calls: FxHashSet<CallId>,
     /// The id to trace in this execution run
     tracked_pointer_tag: Option<PtrId>,
 }
@@ -153,9 +153,9 @@ impl GlobalState {
     pub fn new(tracked_pointer_tag: Option<PtrId>) -> Self {
         GlobalState {
             next_ptr_id: NonZeroU64::new(1).unwrap(),
-            base_ptr_ids: HashMap::default(),
+            base_ptr_ids: FxHashMap::default(),
             next_call_id: NonZeroU64::new(1).unwrap(),
-            active_calls: HashSet::default(),
+            active_calls: FxHashSet::default(),
             tracked_pointer_tag,
         }
     }