Implement debuginfo path remapping.

This commit adds the -Zdebug-prefix-map-from/-Zdebug-prefix-map-to
commandline option pair. This feature allows to replace prefixes
of any file paths that are emitted into debuginfo.

Author: michaelwoerister

src/grammar/verify.rs

@@ -296,7 +296,7 @@ fn main() {
                                          syntax::errors::registry::Registry::new(&[]),
                                          Rc::new(DummyCrateStore));
     let filemap = session.parse_sess.codemap()
-                         .new_filemap("<n/a>".to_string(), None, code);
+                         .new_filemap("<n/a>".to_string(), code);
     let mut lexer = lexer::StringReader::new(session.diagnostic(), filemap);
     let cm = session.codemap();
 

src/librustc/middle/cstore.rs

@@ -237,6 +237,15 @@ pub trait CrateStore {
     fn exported_symbols(&self, cnum: CrateNum) -> Vec<DefId>;
     fn is_no_builtins(&self, cnum: CrateNum) -> bool;
 
+    /// Gives the directory the compiler has been executed in when compiling
+    /// crate `cnum`. This is used by debuginfo generation.
+    fn compiler_working_dir(&self, cnum: CrateNum) -> String;
+
+    /// Gives the prefix map as specified via `-Zdebug-prefix-map-*`. We keep
+    /// using the original prefix-mapping for a crate, not the mapping specified
+    /// for the current one.
+    fn debug_prefix_map(&self, cnum: CrateNum) -> Vec<(String, String)>;
+
     // resolve
     fn retrace_path(&self,
                     cnum: CrateNum,
@@ -380,6 +389,12 @@ impl CrateStore for DummyCrateStore {
         { bug!("native_libraries") }
     fn exported_symbols(&self, cnum: CrateNum) -> Vec<DefId> { bug!("exported_symbols") }
     fn is_no_builtins(&self, cnum: CrateNum) -> bool { bug!("is_no_builtins") }
+    fn compiler_working_dir(&self, cnum: CrateNum) -> String {
+        bug!("compiler_working_dir")
+    }
+    fn debug_prefix_map(&self, cnum: CrateNum) -> Vec<(String, String)> {
+        bug!("debug_prefix_map")
+    }
 
     // resolve
     fn retrace_path(&self,

src/librustc/session/config.rs

@@ -1012,6 +1012,10 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
         "Set the optimization fuel quota for a crate."),
     print_fuel: Option<String> = (None, parse_opt_string, [TRACKED],
         "Make Rustc print the total optimization fuel used by a crate."),
+    debug_prefix_map_from: Vec<String> = (vec![], parse_string_push, [TRACKED],
+        "push a debuginfo path remapping source"),
+    debug_prefix_map_to: Vec<String> = (vec![], parse_string_push, [TRACKED],
+        "push a debuginfo path remapping target"),
 }
 
 pub fn default_lib_output() -> CrateType {
@@ -1430,6 +1434,23 @@ pub fn build_session_options_and_crate_config(matches: &getopts::Matches)
         output_types.insert(OutputType::Exe, None);
     }
 
+    let debug_prefix_map_sources = debugging_opts.debug_prefix_map_from.len();
+    let debug_prefix_map_targets = debugging_opts.debug_prefix_map_from.len();
+
+    if debug_prefix_map_targets < debug_prefix_map_sources {
+        for source in &debugging_opts.debug_prefix_map_from[debug_prefix_map_targets..] {
+            early_error(error_format,
+                &format!("option `-Zdebug_prefix_map_from='{}'` does not have \
+                         a corresponding `-Zdebug_prefix_map_to`", source))
+        }
+    } else if debug_prefix_map_targets > debug_prefix_map_sources {
+        for target in &debugging_opts.debug_prefix_map_to[debug_prefix_map_sources..] {
+            early_error(error_format,
+                &format!("option `-Zdebug_prefix_map_to='{}'` does not have \
+                          a corresponding `-Zdebug_prefix_map_from`", target))
+        }
+    }
+
     let mut cg = build_codegen_options(matches, error_format);
 
     // Issue #30063: if user requests llvm-related output to one

src/librustc/session/mod.rs

@@ -631,15 +631,6 @@ pub fn build_session_(sopts: config::Options,
         None => Some(filesearch::get_or_default_sysroot())
     };
 
-    // Make the path absolute, if necessary
-    let local_crate_source_file = local_crate_source_file.map(|path|
-        if path.is_absolute() {
-            path.clone()
-        } else {
-            env::current_dir().unwrap().join(&path)
-        }
-    );
-
     let optimization_fuel_crate = sopts.debugging_opts.fuel.as_ref().map(|i| i.0.clone());
     let optimization_fuel_limit = Cell::new(sopts.debugging_opts.fuel.as_ref()
         .map(|i| i.1).unwrap_or(0));

src/librustc_metadata/cstore_impl.rs

@@ -340,6 +340,14 @@ impl CrateStore for cstore::CStore {
         self.get_crate_data(cnum).is_no_builtins()
     }
 
+    fn compiler_working_dir(&self, cnum: CrateNum) -> String {
+        self.get_crate_data(cnum).compiler_working_dir()
+    }
+
+    fn debug_prefix_map(&self, cnum: CrateNum) -> Vec<(String, String)> {
+        self.get_crate_data(cnum).debug_prefix_map()
+    }
+
     fn retrace_path(&self,
                     cnum: CrateNum,
                     path: &[DisambiguatedDefPathData])
@@ -399,7 +407,7 @@ impl CrateStore for cstore::CStore {
         let (name, def) = data.get_macro(id.index);
         let source_name = format!("<{} macros>", name);
 
-        let filemap = sess.parse_sess.codemap().new_filemap(source_name, None, def.body);
+        let filemap = sess.parse_sess.codemap().new_filemap(source_name, def.body);
         let local_span = Span { lo: filemap.start_pos, hi: filemap.end_pos, ctxt: NO_EXPANSION };
         let body = filemap_to_stream(&sess.parse_sess, filemap);
 

src/librustc_metadata/decoder.rs

@@ -646,6 +646,14 @@ impl<'a, 'tcx> CrateMetadata {
         self.root.lang_items.decode(self).collect()
     }
 
+    pub fn compiler_working_dir(&self) -> String {
+        self.root.compiler_working_dir.clone()
+    }
+
+    pub fn debug_prefix_map(&self) -> Vec<(String, String)> {
+        self.root.debug_prefix_map.decode(self).collect()
+    }
+
     /// Iterates over each child of the given item.
     pub fn each_child_of_item<F>(&self, id: DefIndex, mut callback: F)
         where F: FnMut(def::Export)
@@ -1120,7 +1128,6 @@ impl<'a, 'tcx> CrateMetadata {
                         // We can't reuse an existing FileMap, so allocate a new one
                         // containing the information we need.
                         let syntax_pos::FileMap { name,
-                                                  abs_path,
                                                   start_pos,
                                                   end_pos,
                                                   lines,
@@ -1144,7 +1151,6 @@ impl<'a, 'tcx> CrateMetadata {
                         }
 
                         let local_version = local_codemap.new_imported_filemap(name,
-                                                                               abs_path,
                                                                                source_length,
                                                                                lines,
                                                                                multibyte_chars);

src/librustc_metadata/encoder.rs

@@ -1342,6 +1342,25 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         self.lazy_seq(exported_symbols.iter().map(|&id| tcx.hir.local_def_id(id).index))
     }
 
+    fn encode_debug_prefix_map(&mut self) -> LazySeq<(String, String)> {
+        let tcx = self.tcx;
+
+        let debug_prefix_map = tcx.sess
+                                  .opts
+                                  .debugging_opts
+                                  .debug_prefix_map_from
+                                  .iter()
+                                  .cloned()
+                                  .zip(tcx.sess
+                                          .opts
+                                          .debugging_opts
+                                          .debug_prefix_map_from
+                                          .iter()
+                                          .cloned())
+                                  .collect::<Vec<(String, String)>>();
+        self.lazy_seq(debug_prefix_map.into_iter())
+    }
+
     fn encode_dylib_dependency_formats(&mut self) -> LazySeq<Option<LinkagePreference>> {
         match self.tcx.sess.dependency_formats.borrow().get(&config::CrateTypeDylib) {
             Some(arr) => {
@@ -1397,6 +1416,10 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
         let exported_symbols = self.encode_exported_symbols();
         let exported_symbols_bytes = self.position() - i;
 
+        i = self.position();
+        let debug_prefix_map = self.encode_debug_prefix_map();
+        let debug_prefix_map_bytes = self.position() - i;
+
         // Encode and index the items.
         i = self.position();
         let items = self.encode_info_for_items();
@@ -1435,6 +1458,8 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
             def_path_table: def_path_table,
             impls: impls,
             exported_symbols: exported_symbols,
+            compiler_working_dir: tcx.sess.working_dir.to_string_lossy().into_owned(),
+            debug_prefix_map: debug_prefix_map,
             index: index,
         });
 
@@ -1455,6 +1480,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
             println!("         codemap bytes: {}", codemap_bytes);
             println!("            impl bytes: {}", impl_bytes);
             println!("    exp. symbols bytes: {}", exported_symbols_bytes);
+            println!("debug prefix map bytes: {}", debug_prefix_map_bytes);
             println!("  def-path table bytes: {}", def_path_table_bytes);
             println!("            item bytes: {}", item_bytes);
             println!("           index bytes: {}", index_bytes);

src/librustc_metadata/schema.rs

@@ -205,6 +205,8 @@ pub struct CrateRoot {
     pub def_path_table: Lazy<hir::map::definitions::DefPathTable>,
     pub impls: LazySeq<TraitImpls>,
     pub exported_symbols: LazySeq<DefIndex>,
+    pub compiler_working_dir: String,
+    pub debug_prefix_map: LazySeq<(String, String)>,
     pub index: LazySeq<index::Index>,
 }
 

src/librustc_trans/context.rs

@@ -452,7 +452,7 @@ impl<'tcx> LocalCrateContext<'tcx> {
                                                           &llmod_id[..]);
 
             let dbg_cx = if shared.tcx.sess.opts.debuginfo != NoDebugInfo {
-                let dctx = debuginfo::CrateDebugContext::new(llmod);
+                let dctx = debuginfo::CrateDebugContext::new(shared.sess(), llmod);
                 debuginfo::metadata::compile_unit_metadata(shared, &dctx, shared.tcx.sess);
                 Some(dctx)
             } else {

src/librustc_trans/debuginfo/create_scope_map.rs

@@ -8,12 +8,12 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use super::FunctionDebugContext;
+use super::{FunctionDebugContext, FunctionDebugContextData};
 use super::metadata::file_metadata;
 use super::utils::{DIB, span_start};
 
 use llvm;
-use llvm::debuginfo::{DIScope, DISubprogram};
+use llvm::debuginfo::DIScope;
 use common::CrateContext;
 use rustc::mir::{Mir, VisibilityScope};
 
@@ -53,8 +53,8 @@ pub fn create_mir_scopes(ccx: &CrateContext, mir: &Mir, debug_context: &Function
     };
     let mut scopes = IndexVec::from_elem(null_scope, &mir.visibility_scopes);
 
-    let fn_metadata = match *debug_context {
-        FunctionDebugContext::RegularContext(ref data) => data.fn_metadata,
+    let debug_context = match *debug_context {
+        FunctionDebugContext::RegularContext(ref data) => data,
         FunctionDebugContext::DebugInfoDisabled |
         FunctionDebugContext::FunctionWithoutDebugInfo => {
             return scopes;
@@ -71,7 +71,12 @@ pub fn create_mir_scopes(ccx: &CrateContext, mir: &Mir, debug_context: &Function
     // Instantiate all scopes.
     for idx in 0..mir.visibility_scopes.len() {
         let scope = VisibilityScope::new(idx);
-        make_mir_scope(ccx, &mir, &has_variables, fn_metadata, scope, &mut scopes);
+        make_mir_scope(ccx,
+                       &mir,
+                       &has_variables,
+                       debug_context,
+                       scope,
+                       &mut scopes);
     }
 
     scopes
@@ -80,7 +85,7 @@ pub fn create_mir_scopes(ccx: &CrateContext, mir: &Mir, debug_context: &Function
 fn make_mir_scope(ccx: &CrateContext,
                   mir: &Mir,
                   has_variables: &BitVector,
-                  fn_metadata: DISubprogram,
+                  debug_context: &FunctionDebugContextData,
                   scope: VisibilityScope,
                   scopes: &mut IndexVec<VisibilityScope, MirDebugScope>) {
     if scopes[scope].is_valid() {
@@ -89,13 +94,13 @@ fn make_mir_scope(ccx: &CrateContext,
 
     let scope_data = &mir.visibility_scopes[scope];
     let parent_scope = if let Some(parent) = scope_data.parent_scope {
-        make_mir_scope(ccx, mir, has_variables, fn_metadata, parent, scopes);
+        make_mir_scope(ccx, mir, has_variables, debug_context, parent, scopes);
         scopes[parent]
     } else {
         // The root is the function itself.
         let loc = span_start(ccx, mir.span);
         scopes[scope] = MirDebugScope {
-            scope_metadata: fn_metadata,
+            scope_metadata: debug_context.fn_metadata,
             file_start_pos: loc.file.start_pos,
             file_end_pos: loc.file.end_pos,
         };
@@ -109,14 +114,14 @@ fn make_mir_scope(ccx: &CrateContext,
         // However, we don't skip creating a nested scope if
         // our parent is the root, because we might want to
         // put arguments in the root and not have shadowing.
-        if parent_scope.scope_metadata != fn_metadata {
+        if parent_scope.scope_metadata != debug_context.fn_metadata {
             scopes[scope] = parent_scope;
             return;
         }
     }
 
     let loc = span_start(ccx, scope_data.span);
-    let file_metadata = file_metadata(ccx, &loc.file.name, &loc.file.abs_path);
+    let file_metadata = file_metadata(ccx, &loc.file.name, debug_context.defining_crate);
     let scope_metadata = unsafe {
         llvm::LLVMRustDIBuilderCreateLexicalBlock(
             DIB(ccx),