Apply path remapping to DW_AT_GNU_dwo_name when producing split DWARF

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -205,8 +205,11 @@ pub fn target_machine_factory(
     let use_init_array =
         !sess.opts.debugging_opts.use_ctors_section.unwrap_or(sess.target.use_ctors_section);
 
+    let path_mapping = sess.source_map().path_mapping().clone();
+
     Arc::new(move |config: TargetMachineFactoryConfig| {
-        let split_dwarf_file = config.split_dwarf_file.unwrap_or_default();
+        let split_dwarf_file =
+            path_mapping.map_prefix(config.split_dwarf_file.unwrap_or_default()).0;
         let split_dwarf_file = CString::new(split_dwarf_file.to_str().unwrap()).unwrap();
 
         let tm = unsafe {
@@ -901,17 +904,14 @@ pub(crate) unsafe fn codegen(
                     .generic_activity_with_arg("LLVM_module_codegen_emit_obj", &module.name[..]);
 
                 let dwo_out = cgcx.output_filenames.temp_path_dwo(module_name);
-                let dwo_out = match cgcx.split_debuginfo {
-                    // Don't change how DWARF is emitted in single mode (or when disabled).
-                    SplitDebuginfo::Off | SplitDebuginfo::Packed => None,
+                let dwo_out = if cgcx.target_can_use_split_dwarf
+                    && cgcx.split_debuginfo != SplitDebuginfo::Off
+                {
                     // Emit (a subset of the) DWARF into a separate file in split mode.
-                    SplitDebuginfo::Unpacked => {
-                        if cgcx.target_can_use_split_dwarf {
-                            Some(dwo_out.as_path())
-                        } else {
-                            None
-                        }
-                    }
+                    Some(dwo_out.as_path())
+                } else {
+                    // Don't change how DWARF is emitted in single mode (or when disabled).
+                    None
                 };
 
                 with_codegen(tm, llmod, config.no_builtins, |cpm| {
@@ -948,7 +948,7 @@ pub(crate) unsafe fn codegen(
 
     Ok(module.into_compiled_module(
         config.emit_obj != EmitObj::None,
-        cgcx.target_can_use_split_dwarf && cgcx.split_debuginfo == SplitDebuginfo::Unpacked,
+        cgcx.target_can_use_split_dwarf && cgcx.split_debuginfo != SplitDebuginfo::Off,
         config.emit_bc,
         &cgcx.output_filenames,
     ))

compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs

@@ -1055,11 +1055,11 @@ pub fn compile_unit_metadata(
     let work_dir = tcx.sess.opts.working_dir.to_string_lossy(FileNameDisplayPreference::Remapped);
     let flags = "\0";
     let output_filenames = tcx.output_filenames(());
-    let out_dir = &output_filenames.out_directory;
     let split_name = if tcx.sess.target_can_use_split_dwarf() {
         output_filenames
             .split_dwarf_path(tcx.sess.split_debuginfo(), Some(codegen_unit_name))
-            .map(|f| out_dir.join(f))
+            // We get a path relative to the working directory from split_dwarf_path
+            .map(|f| tcx.sess.source_map().path_mapping().map_prefix(f).0)
     } else {
         None
     }

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -35,7 +35,7 @@ use object::{Architecture, BinaryFormat, Endianness, FileFlags, SectionFlags, Se
 use regex::Regex;
 use tempfile::Builder as TempFileBuilder;
 
-use std::ffi::OsString;
+use std::ffi::{OsStr, OsString};
 use std::lazy::OnceCell;
 use std::path::{Path, PathBuf};
 use std::process::{ExitStatus, Output, Stdio};
@@ -639,15 +639,17 @@ const LLVM_DWP_EXECUTABLE: &'static str = "rust-llvm-dwp";
 
 /// Invoke `llvm-dwp` (shipped alongside rustc) to link `dwo` files from Split DWARF into a `dwp`
 /// file.
-fn link_dwarf_object<'a>(sess: &'a Session, executable_out_filename: &Path) {
+fn link_dwarf_object<'a, I>(sess: &'a Session, executable_out_filename: &Path, dwo_files: I)
+where
+    I: IntoIterator<Item: AsRef<OsStr>>,
+{
     info!("preparing dwp to {}.dwp", executable_out_filename.to_str().unwrap());
 
     let dwp_out_filename = executable_out_filename.with_extension("dwp");
     let mut cmd = Command::new(LLVM_DWP_EXECUTABLE);
-    cmd.arg("-e");
-    cmd.arg(executable_out_filename);
     cmd.arg("-o");
     cmd.arg(&dwp_out_filename);
+    cmd.args(dwo_files);
 
     let mut new_path = sess.get_tools_search_paths(false);
     if let Some(path) = env::var_os("PATH") {
@@ -1031,7 +1033,14 @@ fn link_natively<'a, B: ArchiveBuilder<'a>>(
         SplitDebuginfo::Packed if sess.target.is_like_msvc => {}
 
         // ... and otherwise we're processing a `*.dwp` packed dwarf file.
-        SplitDebuginfo::Packed => link_dwarf_object(sess, &out_filename),
+        // We cannot rely on the .dwo paths in the exectuable because they may have been
+        // remapped by --remap-path-prefix and therefore invalid. So we need to provide
+        // the .dwo paths explicitly
+        SplitDebuginfo::Packed => link_dwarf_object(
+            sess,
+            &out_filename,
+            codegen_results.modules.iter().filter_map(|m| m.dwarf_object.as_ref()),
+        ),
     }
 
     let strip = strip_value(sess);

src/test/run-make-fulldeps/split-dwarf/Makefile

@@ -2,7 +2,16 @@
 
 # only-linux
 
-all:
+all: packed remapped
+
+remapped:
+	$(RUSTC) -Z unstable-options -C split-debuginfo=packed -C debuginfo=2 --remap-path-prefix $(TMPDIR)=/a foo.rs -g
+	objdump -Wi $(TMPDIR)/foo | grep DW_AT_GNU_dwo_name | (! grep $(TMPDIR)) || exit 1
+
+	$(RUSTC) -Z unstable-options -C split-debuginfo=unpacked -C debuginfo=2 --remap-path-prefix $(TMPDIR)=/a foo.rs -g
+	objdump -Wi $(TMPDIR)/foo | grep DW_AT_GNU_dwo_name | (! grep $(TMPDIR)) || exit 1
+
+packed:
 	$(RUSTC) -Z unstable-options -C split-debuginfo=packed -C debuginfo=2 foo.rs -g
 	rm $(TMPDIR)/foo.dwp
 	rm $(TMPDIR)/$(call BIN,foo)