Shorten names of some compiler generated artifacts.

src/librustc/mir/mono.rs

@@ -12,9 +12,11 @@
 use syntax::symbol::InternedString;
 use ty::Instance;
 use util::nodemap::FxHashMap;
+use rustc_data_structures::base_n;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasherResult,
                                            StableHasher};
 use ich::{Fingerprint, StableHashingContext, NodeIdHashingMode};
+use std::hash::Hash;
 
 #[derive(PartialEq, Eq, Clone, Copy, Debug, Hash)]
 pub enum MonoItem<'tcx> {
@@ -119,6 +121,16 @@ pub fn items_mut(&mut self)
     {
         &mut self.items
     }
+
+    pub fn mangle_name(human_readable_name: &str) -> String {
+        // We generate a 80 bit hash from the name. This should be enough to
+        // avoid collisions and is still reasonably short for filenames.
+        let mut hasher = StableHasher::new();
+        human_readable_name.hash(&mut hasher);
+        let hash: u128 = hasher.finish();
+        let hash = hash & ((1u128 << 80) - 1);
+        base_n::encode(hash, base_n::CASE_INSENSITIVE)
+    }
 }
 
 impl<'tcx> HashStable<StableHashingContext<'tcx>> for CodegenUnit<'tcx> {

src/librustc/session/config.rs

@@ -1236,6 +1236,8 @@ fn parse_optimization_fuel(slot: &mut Option<(String, u64)>, v: Option<&str>) ->
         "rewrite operators on i128 and u128 into lang item calls (typically provided \
          by compiler-builtins) so translation doesn't need to support them,
          overriding the default for the current target"),
+    human_readable_cgu_names: bool = (false, parse_bool, [TRACKED],
+        "generate human-readable, predictable names for codegen units"),
 }
 
 pub fn default_lib_output() -> CrateType {

src/librustc_data_structures/base_n.rs

@@ -13,18 +13,21 @@
 
 use std::str;
 
-pub const MAX_BASE: u64 = 64;
-pub const ALPHANUMERIC_ONLY: u64 = 62;
+pub const MAX_BASE: usize = 64;
+pub const ALPHANUMERIC_ONLY: usize = 62;
+pub const CASE_INSENSITIVE: usize = 36;
 
 const BASE_64: &'static [u8; MAX_BASE as usize] =
     b"0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ@$";
 
 #[inline]
-pub fn push_str(mut n: u64, base: u64, output: &mut String) {
+pub fn push_str(mut n: u128, base: usize, output: &mut String) {
     debug_assert!(base >= 2 && base <= MAX_BASE);
-    let mut s = [0u8; 64];
+    let mut s = [0u8; 128];
     let mut index = 0;
 
+    let base = base as u128;
+
     loop {
         s[index] = BASE_64[(n % base) as usize];
         index += 1;
@@ -39,16 +42,16 @@ pub fn push_str(mut n: u64, base: u64, output: &mut String) {
 }
 
 #[inline]
-pub fn encode(n: u64, base: u64) -> String {
-    let mut s = String::with_capacity(13);
+pub fn encode(n: u128, base: usize) -> String {
+    let mut s = String::new();
     push_str(n, base, &mut s);
     s
 }
 
 #[test]
 fn test_encode() {
-    fn test(n: u64, base: u64) {
-        assert_eq!(Ok(n), u64::from_str_radix(&encode(n, base), base as u32));
+    fn test(n: u128, base: usize) {
+        assert_eq!(Ok(n), u128::from_str_radix(&encode(n, base), base as u32));
     }
 
     for base in 2..37 {
@@ -57,7 +60,8 @@ fn test(n: u64, base: u64) {
         test(35, base);
         test(36, base);
         test(37, base);
-        test(u64::max_value(), base);
+        test(u64::max_value() as u128, base);
+        test(u128::max_value(), base);
 
         for i in 0 .. 1_000 {
             test(i * 983, base);

src/librustc_incremental/persist/fs.rs

@@ -137,7 +137,7 @@
 // or hexadecimal numbers (we want short file and directory names). Since these
 // numbers will be used in file names, we choose an encoding that is not
 // case-sensitive (as opposed to base64, for example).
-const INT_ENCODE_BASE: u64 = 36;
+const INT_ENCODE_BASE: usize = base_n::CASE_INSENSITIVE;
 
 pub fn dep_graph_path(sess: &Session) -> PathBuf {
     in_incr_comp_dir_sess(sess, DEP_GRAPH_FILENAME)
@@ -357,7 +357,7 @@ pub fn finalize_session_directory(sess: &Session, svh: Svh) {
     let mut new_sub_dir_name = String::from(&old_sub_dir_name[.. dash_indices[2] + 1]);
 
     // Append the svh
-    base_n::push_str(svh.as_u64(), INT_ENCODE_BASE, &mut new_sub_dir_name);
+    base_n::push_str(svh.as_u64() as u128, INT_ENCODE_BASE, &mut new_sub_dir_name);
 
     // Create the full path
     let new_path = incr_comp_session_dir.parent().unwrap().join(new_sub_dir_name);
@@ -465,7 +465,7 @@ fn generate_session_dir_path(crate_dir: &Path) -> PathBuf {
 
     let directory_name = format!("s-{}-{}-working",
                                   timestamp,
-                                  base_n::encode(random_number as u64,
+                                  base_n::encode(random_number as u128,
                                                  INT_ENCODE_BASE));
     debug!("generate_session_dir_path: directory_name = {}", directory_name);
     let directory_path = crate_dir.join(directory_name);
@@ -599,7 +599,7 @@ fn timestamp_to_string(timestamp: SystemTime) -> String {
     let duration = timestamp.duration_since(UNIX_EPOCH).unwrap();
     let micros = duration.as_secs() * 1_000_000 +
                 (duration.subsec_nanos() as u64) / 1000;
-    base_n::encode(micros, INT_ENCODE_BASE)
+    base_n::encode(micros as u128, INT_ENCODE_BASE)
 }
 
 fn string_to_timestamp(s: &str) -> Result<SystemTime, ()> {
@@ -626,7 +626,8 @@ fn crate_path(sess: &Session,
     // The full crate disambiguator is really long. 64 bits of it should be
     // sufficient.
     let crate_disambiguator = crate_disambiguator.to_fingerprint().to_smaller_hash();
-    let crate_disambiguator = base_n::encode(crate_disambiguator, INT_ENCODE_BASE);
+    let crate_disambiguator = base_n::encode(crate_disambiguator as u128,
+                                             INT_ENCODE_BASE);
 
     let crate_name = format!("{}-{}", crate_name, crate_disambiguator);
     incr_dir.join(crate_name)

src/librustc_incremental/persist/work_product.rs

@@ -35,9 +35,9 @@ pub fn save_trans_partition(sess: &Session,
                  let extension = match kind {
                      WorkProductFileKind::Object => "o",
                      WorkProductFileKind::Bytecode => "bc",
-                     WorkProductFileKind::BytecodeCompressed => "bc-compressed",
+                     WorkProductFileKind::BytecodeCompressed => "bc.z",
                  };
-                 let file_name = format!("cgu-{}.{}", cgu_name, extension);
+                 let file_name = format!("{}.{}", cgu_name, extension);
                  let path_in_incr_dir = in_incr_comp_dir_sess(sess, &file_name);
                  match link_or_copy(path, &path_in_incr_dir) {
                      Ok(_) => Some((kind, file_name)),

src/librustc_mir/monomorphize/partitioning.rs

@@ -200,7 +200,16 @@ fn as_codegen_unit(&self) -> &CodegenUnit<'tcx> {
 }
 
 // Anything we can't find a proper codegen unit for goes into this.
-const FALLBACK_CODEGEN_UNIT: &'static str = "__rustc_fallback_codegen_unit";
+fn fallback_cgu_name(tcx: TyCtxt) -> InternedString {
+    const FALLBACK_CODEGEN_UNIT: &'static str = "__rustc_fallback_codegen_unit";
+
+    if tcx.sess.opts.debugging_opts.human_readable_cgu_names {
+        Symbol::intern(FALLBACK_CODEGEN_UNIT).as_str()
+    } else {
+        Symbol::intern(&CodegenUnit::mangle_name(FALLBACK_CODEGEN_UNIT)).as_str()
+    }
+}
+
 
 pub fn partition<'a, 'tcx, I>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                               trans_items: I,
@@ -297,7 +306,7 @@ fn place_root_translation_items<'a, 'tcx, I>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 
         let codegen_unit_name = match characteristic_def_id {
             Some(def_id) => compute_codegen_unit_name(tcx, def_id, is_volatile),
-            None => Symbol::intern(FALLBACK_CODEGEN_UNIT).as_str(),
+            None => fallback_cgu_name(tcx),
         };
 
         let make_codegen_unit = || {
@@ -381,7 +390,7 @@ fn place_root_translation_items<'a, 'tcx, I>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     // always ensure we have at least one CGU; otherwise, if we have a
     // crate with just types (for example), we could wind up with no CGU
     if codegen_units.is_empty() {
-        let codegen_unit_name = Symbol::intern(FALLBACK_CODEGEN_UNIT).as_str();
+        let codegen_unit_name = fallback_cgu_name(tcx);
         codegen_units.insert(codegen_unit_name.clone(),
                              CodegenUnit::new(codegen_unit_name.clone()));
     }
@@ -630,10 +639,10 @@ fn compute_codegen_unit_name<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     // Unfortunately we cannot just use the `ty::item_path` infrastructure here
     // because we need paths to modules and the DefIds of those are not
     // available anymore for external items.
-    let mut mod_path = String::with_capacity(64);
+    let mut cgu_name = String::with_capacity(64);
 
     let def_path = tcx.def_path(def_id);
-    mod_path.push_str(&tcx.crate_name(def_path.krate).as_str());
+    cgu_name.push_str(&tcx.crate_name(def_path.krate).as_str());
 
     for part in tcx.def_path(def_id)
                    .data
@@ -644,15 +653,21 @@ fn compute_codegen_unit_name<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                             _ => false,
                         }
                     }) {
-        mod_path.push_str("-");
-        mod_path.push_str(&part.data.as_interned_str());
+        cgu_name.push_str("-");
+        cgu_name.push_str(&part.data.as_interned_str());
     }
 
     if volatile {
-        mod_path.push_str(".volatile");
+        cgu_name.push_str(".volatile");
     }
 
-    return Symbol::intern(&mod_path[..]).as_str();
+    let cgu_name = if tcx.sess.opts.debugging_opts.human_readable_cgu_names {
+        cgu_name
+    } else {
+        CodegenUnit::mangle_name(&cgu_name)
+    };
+
+    Symbol::intern(&cgu_name[..]).as_str()
 }
 
 fn numbered_codegen_unit_name(crate_name: &str, index: usize) -> InternedString {

src/librustc_trans/assert_module_sources.rs

@@ -28,8 +28,10 @@
 //! perturb the reuse results.
 
 use rustc::dep_graph::{DepNode, DepConstructor};
+use rustc::mir::mono::CodegenUnit;
 use rustc::ty::TyCtxt;
 use syntax::ast;
+use syntax_pos::symbol::Symbol;
 use rustc::ich::{ATTR_PARTITION_REUSED, ATTR_PARTITION_TRANSLATED};
 
 const MODULE: &'static str = "module";
@@ -71,9 +73,11 @@ fn check_attr(&self, attr: &ast::Attribute) {
         }
 
         let mname = self.field(attr, MODULE);
+        let mangled_cgu_name = CodegenUnit::mangle_name(&mname.as_str());
+        let mangled_cgu_name = Symbol::intern(&mangled_cgu_name).as_str();
 
         let dep_node = DepNode::new(self.tcx,
-                                    DepConstructor::CompileCodegenUnit(mname.as_str()));
+                                    DepConstructor::CompileCodegenUnit(mangled_cgu_name));
 
         if let Some(loaded_from_cache) = self.tcx.dep_graph.was_loaded_from_cache(&dep_node) {
             match (disposition, loaded_from_cache) {

src/librustc_trans/back/bytecode.rs

@@ -47,7 +47,7 @@
 // The version number this compiler will write to bytecode objects in rlibs
 pub const RLIB_BYTECODE_OBJECT_VERSION: u8 = 2;
 
-pub const RLIB_BYTECODE_EXTENSION: &str = "bytecode.encoded";
+pub const RLIB_BYTECODE_EXTENSION: &str = "bc.z";
 
 pub fn encode(identifier: &str, bytecode: &[u8]) -> Vec<u8> {
     let mut encoded = Vec::new();

src/librustc_trans/context.rs

@@ -572,7 +572,7 @@ pub fn generate_local_symbol_name(&self, prefix: &str) -> String {
         let mut name = String::with_capacity(prefix.len() + 6);
         name.push_str(prefix);
         name.push_str(".");
-        base_n::push_str(idx as u64, base_n::ALPHANUMERIC_ONLY, &mut name);
+        base_n::push_str(idx as u128, base_n::ALPHANUMERIC_ONLY, &mut name);
         name
     }
 

src/tools/compiletest/src/runtest.rs

@@ -1520,6 +1520,10 @@ fn make_compile_args(&self, input_file: &Path, output_file: TargetLocation) -> C
             rustc.args(&["-Z", "incremental-queries"]);
         }
 
+        if self.config.mode == CodegenUnits {
+            rustc.args(&["-Z", "human_readable_cgu_names"]);
+        }
+
         match self.config.mode {
             CompileFail | ParseFail | Incremental => {
                 // If we are extracting and matching errors in the new