Pass WorkProductMap to build_dep_graph instead of FxIndexMap

Constructing an FxIndexMap is useless work as the iteration order never
matters.

compiler/rustc_incremental/src/persist/load.rs

@@ -3,7 +3,7 @@
 use crate::errors;
 use rustc_data_structures::memmap::Mmap;
 use rustc_data_structures::unord::UnordMap;
-use rustc_middle::dep_graph::{SerializedDepGraph, WorkProduct, WorkProductId};
+use rustc_middle::dep_graph::{SerializedDepGraph, WorkProductMap};
 use rustc_middle::query::on_disk_cache::OnDiskCache;
 use rustc_serialize::opaque::MemDecoder;
 use rustc_serialize::Decodable;
@@ -16,8 +16,6 @@
 use super::fs::*;
 use super::work_product;
 
-type WorkProductMap = UnordMap<WorkProductId, WorkProduct>;
-
 #[derive(Debug)]
 /// Represents the result of an attempt to load incremental compilation data.
 pub enum LoadResult<T> {

compiler/rustc_incremental/src/persist/save.rs

 use crate::errors;
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::sync::join;
-use rustc_middle::dep_graph::{DepGraph, SerializedDepGraph, WorkProduct, WorkProductId};
+use rustc_middle::dep_graph::{
+    DepGraph, SerializedDepGraph, WorkProduct, WorkProductId, WorkProductMap,
+};
 use rustc_middle::ty::TyCtxt;
 use rustc_serialize::opaque::{FileEncodeResult, FileEncoder};
 use rustc_serialize::Encodable as RustcEncodable;
@@ -101,7 +103,7 @@ pub fn save_work_product_index(
     // deleted during invalidation. Some object files don't change their
     // content, they are just not needed anymore.
     let previous_work_products = dep_graph.previous_work_products();
-    for (id, wp) in previous_work_products.iter() {
+    for (id, wp) in previous_work_products.to_sorted_stable_ord().iter() {
         if !new_work_products.contains_key(id) {
             work_product::delete_workproduct_files(sess, wp);
             debug_assert!(
@@ -146,7 +148,7 @@ fn encode_query_cache(tcx: TyCtxt<'_>, encoder: FileEncoder) -> FileEncodeResult
 pub fn build_dep_graph(
     sess: &Session,
     prev_graph: SerializedDepGraph,
-    prev_work_products: FxIndexMap<WorkProductId, WorkProduct>,
+    prev_work_products: WorkProductMap,
 ) -> Option<DepGraph> {
     if sess.opts.incremental.is_none() {
         // No incremental compilation.

compiler/rustc_interface/src/queries.rs

@@ -5,7 +5,6 @@
 use rustc_ast as ast;
 use rustc_codegen_ssa::traits::CodegenBackend;
 use rustc_codegen_ssa::CodegenResults;
-use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::steal::Steal;
 use rustc_data_structures::svh::Svh;
 use rustc_data_structures::sync::{AppendOnlyIndexVec, Lrc, OnceCell, RwLock, WorkerLocal};
@@ -162,15 +161,8 @@ fn dep_graph(&self, dep_graph_future: Option<DepGraphFuture>) -> DepGraph {
         dep_graph_future
             .and_then(|future| {
                 let sess = self.session();
-                let (prev_graph, mut prev_work_products) =
+                let (prev_graph, prev_work_products) =
                     sess.time("blocked_on_dep_graph_loading", || future.open().open(sess));
-                // Convert from UnordMap to FxIndexMap by sorting
-                let prev_work_product_ids =
-                    prev_work_products.items().map(|x| *x.0).into_sorted_stable_ord();
-                let prev_work_products = prev_work_product_ids
-                    .into_iter()
-                    .map(|x| (x, prev_work_products.remove(&x).unwrap()))
-                    .collect::<FxIndexMap<_, _>>();
                 rustc_incremental::build_dep_graph(sess, prev_graph, prev_work_products)
             })
             .unwrap_or_else(DepGraph::new_disabled)

compiler/rustc_middle/src/dep_graph/mod.rs

@@ -8,7 +8,7 @@
 
 pub use rustc_query_system::dep_graph::{
     debug::DepNodeFilter, hash_result, DepContext, DepNodeColor, DepNodeIndex,
-    SerializedDepNodeIndex, WorkProduct, WorkProductId,
+    SerializedDepNodeIndex, WorkProduct, WorkProductId, WorkProductMap,
 };
 
 pub use dep_node::{label_strs, DepKind, DepNode, DepNodeExt};

compiler/rustc_query_system/src/dep_graph/graph.rs

 use rustc_data_structures::fingerprint::Fingerprint;
-use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
+use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::profiling::{EventId, QueryInvocationId, SelfProfilerRef};
 use rustc_data_structures::sharded::{self, Sharded};
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
@@ -93,7 +93,7 @@ pub struct DepGraphData<K: DepKind> {
     /// things available to us. If we find that they are not dirty, we
     /// load the path to the file storing those work-products here into
     /// this map. We can later look for and extract that data.
-    previous_work_products: FxIndexMap<WorkProductId, WorkProduct>,
+    previous_work_products: WorkProductMap,
 
     dep_node_debug: Lock<FxHashMap<DepNode<K>, String>>,
 
@@ -116,7 +116,7 @@ impl<K: DepKind> DepGraph<K> {
     pub fn new(
         profiler: &SelfProfilerRef,
         prev_graph: SerializedDepGraph<K>,
-        prev_work_products: FxIndexMap<WorkProductId, WorkProduct>,
+        prev_work_products: WorkProductMap,
         encoder: FileEncoder,
         record_graph: bool,
         record_stats: bool,
@@ -688,7 +688,7 @@ pub fn previous_work_product(&self, v: &WorkProductId) -> Option<WorkProduct> {
 
     /// Access the map of work-products created during the cached run. Only
     /// used during saving of the dep-graph.
-    pub fn previous_work_products(&self) -> &FxIndexMap<WorkProductId, WorkProduct> {
+    pub fn previous_work_products(&self) -> &WorkProductMap {
         &self.data.as_ref().unwrap().previous_work_products
     }
 
@@ -1051,6 +1051,8 @@ pub struct WorkProduct {
     pub saved_files: UnordMap<String, String>,
 }
 
+pub type WorkProductMap = UnordMap<WorkProductId, WorkProduct>;
+
 // Index type for `DepNodeData`'s edges.
 rustc_index::newtype_index! {
     struct EdgeIndex {}

compiler/rustc_query_system/src/dep_graph/mod.rs

@@ -7,7 +7,7 @@
 pub use dep_node::{DepKindStruct, DepNode, DepNodeParams, WorkProductId};
 pub use graph::{
     hash_result, DepGraph, DepGraphData, DepNodeColor, DepNodeIndex, TaskDeps, TaskDepsRef,
-    WorkProduct,
+    WorkProduct, WorkProductMap,
 };
 pub use query::DepGraphQuery;
 pub use serialized::{SerializedDepGraph, SerializedDepNodeIndex};