Remove rustc_llvm dependency from rustc_metadata

Move the code for loading metadata from rlibs and dylibs from
rustc_metadata into rustc_trans, and introduce a trait to avoid
introducing a direct dependency on rustc_trans.

This means rustc_metadata is no longer rebuilt when LLVM changes.

Author: Robin Kruppe

src/Cargo.lock

@@ -13,6 +13,7 @@ arena = { path = "../libarena" }
 fmt_macros = { path = "../libfmt_macros" }
 graphviz = { path = "../libgraphviz" }
 log = "0.3"
+owning_ref = "0.3.3"
 rustc_back = { path = "../librustc_back" }
 rustc_bitflags = { path = "../librustc_bitflags" }
 rustc_const_math = { path = "../librustc_const_math" }

src/librustc/Cargo.toml

@@ -54,6 +54,7 @@ extern crate fmt_macros;
 extern crate getopts;
 extern crate graphviz;
 extern crate libc;
+extern crate owning_ref;
 extern crate rustc_llvm as llvm;
 extern crate rustc_back;
 extern crate rustc_data_structures;

src/librustc/lib.rs

@@ -36,8 +36,9 @@ use session::search_paths::PathKind;
 use util::nodemap::{NodeSet, DefIdMap};
 
 use std::any::Any;
-use std::path::PathBuf;
+use std::path::{Path, PathBuf};
 use std::rc::Rc;
+use owning_ref::ErasedBoxRef;
 use syntax::ast;
 use syntax::ext::base::SyntaxExtension;
 use syntax::symbol::Symbol;
@@ -201,11 +202,33 @@ impl EncodedMetadataHashes {
     }
 }
 
+/// The backend's way to give the crate store access to the metadata in a library.
+/// Note that it returns the raw metadata bytes stored in the library file, whether
+/// it is compressed, uncompressed, some weird mix, etc.
+/// rmeta files are backend independent and not handled here.
+///
+/// At the time of this writing, there is only one backend and one way to store
+/// metadata in library -- this trait just serves to decouple rustc_metadata from
+/// the archive reader, which depends on LLVM.
+pub trait MetadataLoader {
+    fn get_rlib_metadata(&self,
+                         target: &Target,
+                         filename: &Path)
+                         -> Result<ErasedBoxRef<[u8]>, String>;
+    fn get_dylib_metadata(&self,
+                          target: &Target,
+                          filename: &Path)
+                          -> Result<ErasedBoxRef<[u8]>, String>;
+}
+
 /// A store of Rust crates, through with their metadata
 /// can be accessed.
 pub trait CrateStore {
     fn crate_data_as_rc_any(&self, krate: CrateNum) -> Rc<Any>;
 
+    // access to the metadata loader
+    fn metadata_loader(&self) -> &MetadataLoader;
+
     // item info
     fn visibility(&self, def: DefId) -> ty::Visibility;
     fn visible_parent_map<'a>(&'a self) -> ::std::cell::Ref<'a, DefIdMap<DefId>>;
@@ -275,8 +298,6 @@ pub trait CrateStore {
     fn used_link_args(&self) -> Vec<String>;
 
     // utility functions
-    fn metadata_filename(&self) -> &str;
-    fn metadata_section_name(&self, target: &Target) -> &str;
     fn used_crates(&self, prefer: LinkagePreference) -> Vec<(CrateNum, LibSource)>;
     fn used_crate_source(&self, cnum: CrateNum) -> CrateSource;
     fn extern_mod_stmt_cnum(&self, emod_id: ast::NodeId) -> Option<CrateNum>;
@@ -413,8 +434,6 @@ impl CrateStore for DummyCrateStore {
     fn used_link_args(&self) -> Vec<String> { vec![] }
 
     // utility functions
-    fn metadata_filename(&self) -> &str { bug!("metadata_filename") }
-    fn metadata_section_name(&self, target: &Target) -> &str { bug!("metadata_section_name") }
     fn used_crates(&self, prefer: LinkagePreference) -> Vec<(CrateNum, LibSource)>
         { vec![] }
     fn used_crate_source(&self, cnum: CrateNum) -> CrateSource { bug!("used_crate_source") }
@@ -427,6 +446,9 @@ impl CrateStore for DummyCrateStore {
         bug!("encode_metadata")
     }
     fn metadata_encoding_version(&self) -> &[u8] { bug!("metadata_encoding_version") }
+
+    // access to the metadata loader
+    fn metadata_loader(&self) -> &MetadataLoader { bug!("metadata_loader") }
 }
 
 pub trait CrateLoader {

src/librustc/middle/cstore.rs

@@ -204,7 +204,7 @@ pub fn run_compiler<'a>(args: &[String],
     };
 
     let dep_graph = DepGraph::new(sopts.build_dep_graph());
-    let cstore = Rc::new(CStore::new(&dep_graph));
+    let cstore = Rc::new(CStore::new(&dep_graph, box rustc_trans::LlvmMetadataLoader));
 
     let loader = file_loader.unwrap_or(box RealFileLoader);
     let codemap = Rc::new(CodeMap::with_file_loader(loader, sopts.file_path_mapping()));
@@ -409,7 +409,7 @@ impl<'a> CompilerCalls<'a> for RustcDefaultCalls {
                     return None;
                 }
                 let dep_graph = DepGraph::new(sopts.build_dep_graph());
-                let cstore = Rc::new(CStore::new(&dep_graph));
+                let cstore = Rc::new(CStore::new(&dep_graph, box rustc_trans::LlvmMetadataLoader));
                 let mut sess = build_session(sopts.clone(),
                     &dep_graph,
                     None,
@@ -558,7 +558,11 @@ impl RustcDefaultCalls {
                 &Input::File(ref ifile) => {
                     let path = &(*ifile);
                     let mut v = Vec::new();
-                    locator::list_file_metadata(&sess.target.target, path, &mut v).unwrap();
+                    locator::list_file_metadata(&sess.target.target,
+                                                path,
+                                                sess.cstore.metadata_loader(),
+                                                &mut v)
+                            .unwrap();
                     println!("{}", String::from_utf8(v).unwrap());
                 }
                 &Input::Str { .. } => {

src/librustc_driver/lib.rs

@@ -14,6 +14,7 @@ use driver;
 use rustc::dep_graph::DepGraph;
 use rustc_lint;
 use rustc_resolve::MakeGlobMap;
+use rustc_trans;
 use rustc::middle::lang_items;
 use rustc::middle::free_region::FreeRegionMap;
 use rustc::middle::region::{CodeExtent, RegionMaps};
@@ -104,7 +105,7 @@ fn test_env<F>(source_string: &str,
 
     let dep_graph = DepGraph::new(false);
     let _ignore = dep_graph.in_ignore();
-    let cstore = Rc::new(CStore::new(&dep_graph));
+    let cstore = Rc::new(CStore::new(&dep_graph, box rustc_trans::LlvmMetadataLoader));
     let sess = session::build_session_(options,
                                        &dep_graph,
                                        None,

src/librustc_driver/test.rs

@@ -11,13 +11,13 @@ crate-type = ["dylib"]
 [dependencies]
 flate = { path = "../libflate" }
 log = "0.3"
+owning_ref = "0.3.3"
 proc_macro = { path = "../libproc_macro" }
 rustc = { path = "../librustc" }
 rustc_back = { path = "../librustc_back" }
 rustc_const_math = { path = "../librustc_const_math" }
 rustc_data_structures = { path = "../librustc_data_structures" }
 rustc_errors = { path = "../librustc_errors" }
-rustc_llvm = { path = "../librustc_llvm" }
 serialize = { path = "../libserialize" }
 syntax = { path = "../libsyntax" }
 syntax_ext = { path = "../libsyntax_ext" }

src/librustc_metadata/Cargo.toml

@@ -393,6 +393,7 @@ impl<'a> CrateLoader<'a> {
                 rejected_via_filename: vec![],
                 should_match_name: true,
                 is_proc_macro: Some(false),
+                metadata_loader: &*self.cstore.metadata_loader,
             };
 
             self.load(&mut locate_ctxt).or_else(|| {
@@ -554,6 +555,7 @@ impl<'a> CrateLoader<'a> {
             rejected_via_filename: vec![],
             should_match_name: true,
             is_proc_macro: None,
+            metadata_loader: &*self.cstore.metadata_loader,
         };
         let library = self.load(&mut locate_ctxt).or_else(|| {
             if !is_cross {

src/librustc_metadata/creader.rs

@@ -11,21 +11,20 @@
 // The crate store - a central repo for information collected about external
 // crates and libraries
 
-use locator;
 use schema::{self, Tracked};
 
 use rustc::dep_graph::{DepGraph, DepNode, GlobalMetaDataKind};
 use rustc::hir::def_id::{CRATE_DEF_INDEX, LOCAL_CRATE, CrateNum, DefIndex, DefId};
 use rustc::hir::map::definitions::DefPathTable;
 use rustc::hir::svh::Svh;
-use rustc::middle::cstore::{DepKind, ExternCrate};
+use rustc::middle::cstore::{DepKind, ExternCrate, MetadataLoader};
 use rustc_back::PanicStrategy;
 use rustc_data_structures::indexed_vec::IndexVec;
 use rustc::util::nodemap::{FxHashMap, FxHashSet, NodeMap, DefIdMap};
 
 use std::cell::{RefCell, Cell};
 use std::rc::Rc;
-use flate::Bytes;
+use owning_ref::ErasedBoxRef;
 use syntax::{ast, attr};
 use syntax::ext::base::SyntaxExtension;
 use syntax::symbol::Symbol;
@@ -43,11 +42,7 @@ pub use cstore_impl::provide;
 // own crate numbers.
 pub type CrateNumMap = IndexVec<CrateNum, CrateNum>;
 
-pub enum MetadataBlob {
-    Inflated(Bytes),
-    Archive(locator::ArchiveMetadata),
-    Raw(Vec<u8>),
-}
+pub struct MetadataBlob(pub ErasedBoxRef<[u8]>);
 
 /// Holds information about a syntax_pos::FileMap imported from another crate.
 /// See `imported_filemaps()` for more information.
@@ -103,10 +98,11 @@ pub struct CStore {
     statically_included_foreign_items: RefCell<FxHashSet<DefIndex>>,
     pub dllimport_foreign_items: RefCell<FxHashSet<DefIndex>>,
     pub visible_parent_map: RefCell<DefIdMap<DefId>>,
+    pub metadata_loader: Box<MetadataLoader>,
 }
 
 impl CStore {
-    pub fn new(dep_graph: &DepGraph) -> CStore {
+    pub fn new(dep_graph: &DepGraph, metadata_loader: Box<MetadataLoader>) -> CStore {
         CStore {
             dep_graph: dep_graph.clone(),
             metas: RefCell::new(FxHashMap()),
@@ -116,6 +112,7 @@ impl CStore {
             statically_included_foreign_items: RefCell::new(FxHashSet()),
             dllimport_foreign_items: RefCell::new(FxHashSet()),
             visible_parent_map: RefCell::new(FxHashMap()),
+            metadata_loader: metadata_loader,
         }
     }
 

src/librustc_metadata/cstore.rs

@@ -10,12 +10,11 @@
 
 use cstore;
 use encoder;
-use locator;
 use schema;
 
 use rustc::dep_graph::DepTrackingMapConfig;
 use rustc::middle::cstore::{CrateStore, CrateSource, LibSource, DepKind,
-                            ExternCrate, NativeLibrary, LinkMeta,
+                            ExternCrate, NativeLibrary, MetadataLoader, LinkMeta,
                             LinkagePreference, LoadedMacro, EncodedMetadata};
 use rustc::hir::def;
 use rustc::middle::lang_items;
@@ -38,7 +37,6 @@ use syntax::parse::filemap_to_stream;
 use syntax::symbol::Symbol;
 use syntax_pos::{Span, NO_EXPANSION};
 use rustc::hir::svh::Svh;
-use rustc_back::target::Target;
 use rustc::hir;
 
 macro_rules! provide {
@@ -135,6 +133,10 @@ impl CrateStore for cstore::CStore {
         self.get_crate_data(krate)
     }
 
+    fn metadata_loader(&self) -> &MetadataLoader {
+        &*self.metadata_loader
+    }
+
     fn visibility(&self, def: DefId) -> ty::Visibility {
         self.dep_graph.read(DepNode::MetaData(def));
         self.get_crate_data(def.krate).get_visibility(def.index)
@@ -420,17 +422,6 @@ impl CrateStore for cstore::CStore {
     {
         self.get_used_link_args().borrow().clone()
     }
-
-    fn metadata_filename(&self) -> &str
-    {
-        locator::METADATA_FILENAME
-    }
-
-    fn metadata_section_name(&self, target: &Target) -> &str
-    {
-        locator::meta_section_name(target)
-    }
-
     fn used_crates(&self, prefer: LinkagePreference) -> Vec<(CrateNum, LibSource)>
     {
         self.do_get_used_crates(prefer)
@@ -522,4 +513,4 @@ impl CrateStore for cstore::CStore {
         drop(visible_parent_map);
         self.visible_parent_map.borrow()
     }
-}
+}

src/librustc_metadata/cstore_impl.rs

@@ -77,11 +77,7 @@ pub trait Metadata<'a, 'tcx>: Copy {
 
 impl<'a, 'tcx> Metadata<'a, 'tcx> for &'a MetadataBlob {
     fn raw_bytes(self) -> &'a [u8] {
-        match *self {
-            MetadataBlob::Inflated(ref vec) => vec,
-            MetadataBlob::Archive(ref ar) => ar.as_slice(),
-            MetadataBlob::Raw(ref vec) => vec,
-        }
+        &self.0
     }
 }
 

src/librustc_metadata/decoder.rs

@@ -37,6 +37,7 @@ extern crate syntax;
 extern crate syntax_pos;
 extern crate flate;
 extern crate serialize as rustc_serialize; // used by deriving
+extern crate owning_ref;
 extern crate rustc_errors as errors;
 extern crate syntax_ext;
 extern crate proc_macro;
@@ -46,7 +47,6 @@ extern crate rustc;
 extern crate rustc_back;
 extern crate rustc_const_math;
 extern crate rustc_data_structures;
-extern crate rustc_llvm;
 
 mod diagnostics;