Get basic (de)serialization working

Author: Radbuglet

src/rustc/src/analyzer/mod.rs

@@ -23,8 +23,6 @@ mod sym;
 mod template;
 mod trace;
 
-// TODO: Double-check the short-circuits in the analysis routine to make sure we're not ignoring
-//  important items.
 pub fn analyze(tcx: TyCtxt<'_>) {
     // Fetch the MIR for each local definition to populate the `MirBuiltStasher`.
     for local_def in iter_all_local_def_ids(tcx) {
@@ -34,8 +32,6 @@ pub fn analyze(tcx: TyCtxt<'_>) {
     }
 
     // Generate borrow-checking templates for each local function.
-    //
-    // TODO: Serialize these across crates.
     assert!(!tcx.untracked().definitions.is_frozen());
 
     let mut templates = FxHashMap::default();

src/rustc/src/util/meta.rs

@@ -1,4 +1,5 @@
-use rustc_incremental::in_incr_comp_dir_sess;
+use std::path::Path;
+
 use rustc_middle::ty::TyCtxt;
 use rustc_serialize::{Decodable, Encodable};
 
@@ -7,25 +8,21 @@ pub use self::adapted_encoding::{CacheDecoder, CacheEncoder};
 // Adapted from: compiler/rustc_incremental/src/persist/save.rs:27
 pub fn save_to_file<'tcx>(
     tcx: TyCtxt<'tcx>,
-    file_name: &str,
     name: &str,
+    path: &Path,
     item: &impl for<'a> Encodable<CacheEncoder<'a, 'tcx>>,
 ) {
-    let path = in_incr_comp_dir_sess(tcx.sess, file_name);
-
-    adapted_io::save_in(tcx.sess, path, name, |e| {
+    adapted_io::save_in(tcx.sess, path.to_path_buf(), name, |e| {
         adapted_encoding::save_to_encoder(tcx, e, item)
     });
 }
 
 // Adapted from: compiler/rustc_incremental/src/persist/load.rs:176
-pub fn try_load_from_file<'tcx, D>(tcx: TyCtxt<'tcx>, file_name: &str, name: &str) -> Option<D>
+pub fn try_load_from_file<'tcx, D>(tcx: TyCtxt<'tcx>, name: &str, path: &Path) -> Option<D>
 where
     D: for<'a> Decodable<CacheDecoder<'a, 'tcx>>,
 {
-    let path = in_incr_comp_dir_sess(tcx.sess, file_name);
-
-    match adapted_io::read_file(&path) {
+    match adapted_io::read_file(path) {
         Ok(Some((mmap, start_pos))) => {
             Some(adapted_encoding::load_from_decoder(tcx, mmap, start_pos))
         }
@@ -54,19 +51,7 @@ mod adapted_io {
     };
     use rustc_session::Session;
 
-    /// The first few bytes of files generated by incremental compilation.
-    const FILE_MAGIC: &[u8] = b"AUTOKEN-v1";
-
-    /// Change this if the header format changes.
-    const HEADER_FORMAT_VERSION: u16 = 0;
-
-    fn write_file_header(stream: &mut FileEncoder) {
-        stream.emit_raw_bytes(FILE_MAGIC);
-        stream.emit_raw_bytes(&[
-            (HEADER_FORMAT_VERSION) as u8,
-            (HEADER_FORMAT_VERSION >> 8) as u8,
-        ]);
-    }
+    const FILE_MAGIC: &[u8] = b"autoken-1";
 
     pub fn save_in<F>(sess: &Session, path_buf: PathBuf, name: &str, encode: F)
     where
@@ -90,7 +75,7 @@ mod adapted_io {
             }
         };
 
-        write_file_header(&mut encoder);
+        encoder.emit_raw_bytes(FILE_MAGIC);
 
         match encode(encoder) {
             Ok(_) => {}
@@ -100,27 +85,14 @@ mod adapted_io {
         }
     }
 
-    /// Reads the contents of a file with a file header as defined in this module.
-    ///
-    /// - Returns `Ok(Some(data, pos))` if the file existed and was generated by a
-    ///   compatible compiler version. `data` is the entire contents of the file
-    ///   and `pos` points to the first byte after the header.
-    /// - Returns `Ok(None)` if the file did not exist or was generated by an
-    ///   incompatible version of the compiler.
-    /// - Returns `Err(..)` if some kind of IO error occurred while reading the
-    ///   file.
     pub fn read_file(path: &Path) -> io::Result<Option<(Mmap, usize)>> {
+        // Open file
         let file = match fs::File::open(path) {
             Ok(file) => file,
             Err(err) if err.kind() == io::ErrorKind::NotFound => return Ok(None),
             Err(err) => return Err(err),
         };
-        // SAFETY: This process must not modify nor remove the backing file while the memory map lives.
-        // For the dep-graph and the work product index, it is as soon as the decoding is done.
-        // For the query result cache, the memory map is dropped in save_dep_graph before calling
-        // save_in and trying to remove the backing file.
-        //
-        // There is no way to prevent another process from modifying this file.
+
         let mmap = unsafe { Mmap::map(file) }?;
 
         let mut file = io::Cursor::new(&*mmap);
@@ -315,7 +287,7 @@ mod adapted_encoding {
         };
 
         // Adapted from compiler/rustc_middle/src/query/on_disk_cache.rs:156
-        let pos = AbsoluteBytePos(0);
+        let pos = AbsoluteBytePos(start_pos as u64);
 
         let alloc_decoding_session = AllocDecodingState::new(footer.interpret_alloc_index);