Support file hashes in .debug_line

src/debuginfo/line_info.rs

@@ -3,12 +3,12 @@ use std::path::{Component, Path};
 
 use crate::prelude::*;
 
-use rustc_span::{FileName, SourceFileAndLine, Pos};
+use rustc_span::{FileName, SourceFile, SourceFileAndLine, Pos, SourceFileHash, SourceFileHashAlgorithm};
 
 use cranelift_codegen::binemit::CodeOffset;
 
 use gimli::write::{
-    Address, AttributeValue, FileId, LineProgram, LineString, LineStringTable, UnitEntryId,
+    Address, AttributeValue, FileId, LineProgram, LineString, FileInfo, LineStringTable, UnitEntryId,
 };
 
 // OPTIMIZATION: It is cheaper to do this in one pass than using `.parent()` and `.file_name()`.
@@ -35,12 +35,28 @@ fn osstr_as_utf8_bytes(path: &OsStr) -> &[u8] {
     }
 }
 
+pub(crate) const MD5_LEN: usize = 16;
+
+pub fn make_file_info(hash: SourceFileHash) -> Option<FileInfo> {
+    if hash.kind == SourceFileHashAlgorithm::Md5 {
+        let mut buf = [0u8; MD5_LEN];
+        buf.copy_from_slice(hash.hash_bytes());
+        Some(FileInfo {
+            timestamp: 0,
+            size: 0,
+            md5: buf,
+        })
+    } else {
+        None
+    }
+}
+
 fn line_program_add_file(
     line_program: &mut LineProgram,
     line_strings: &mut LineStringTable,
-    file: &FileName,
+    file: &SourceFile,
 ) -> FileId {
-    match file {
+    match &file.name {
         FileName::Real(path) => {
             let (dir_path, file_name) = split_path_dir_and_file(path);
             let dir_name = osstr_as_utf8_bytes(dir_path.as_os_str());
@@ -57,13 +73,17 @@ fn line_program_add_file(
                 line_program.encoding(),
                 line_strings,
             );
-            line_program.add_file(file_name, dir_id, None)
+
+            let info = make_file_info(file.src_hash);
+
+            line_program.file_has_md5 &= info.is_some();
+            line_program.add_file(file_name, dir_id, info)
         }
         // FIXME give more appropriate file names
-        _ => {
+        filename => {
             let dir_id = line_program.default_directory();
             let dummy_file_name = LineString::new(
-                file.to_string().into_bytes(),
+                filename.to_string().into_bytes(),
                 line_program.encoding(),
                 line_strings,
             );
@@ -79,7 +99,7 @@ impl<'tcx> DebugContext<'tcx> {
         let file_id = line_program_add_file(
             &mut self.dwarf.unit.line_program,
             &mut self.dwarf.line_strings,
-            &loc.file.name,
+            &loc.file,
         );
 
         let entry = self.dwarf.unit.get_mut(entry_id);
@@ -167,7 +187,7 @@ impl<'a, 'tcx> FunctionDebugContext<'a, 'tcx> {
                 true
             };
             if current_file_changed {
-                let file_id = line_program_add_file(line_program, line_strings, &file.name);
+                let file_id = line_program_add_file(line_program, line_strings, &file);
                 line_program.row().file = file_id;
                 last_file = Some(file.clone());
             }

src/debuginfo/mod.rs

@@ -3,6 +3,8 @@ mod line_info;
 
 use crate::prelude::*;
 
+use rustc_span::FileName;
+
 use cranelift_codegen::ir::{StackSlots, ValueLabel, ValueLoc};
 use cranelift_codegen::isa::TargetIsa;
 use cranelift_codegen::ValueLocRange;
@@ -42,7 +44,14 @@ impl<'tcx> DebugContext<'tcx> {
             format: Format::Dwarf32,
             // TODO: this should be configurable
             // macOS doesn't seem to support DWARF > 3
-            version: 3,
+            // 5 version is required for md5 file hash
+            version: if tcx.sess.target.target.options.is_like_osx {
+                3
+            } else {
+                // FIXME change to version 5 once the gdb and lldb shipping with the latest debian
+                // support it.
+                4
+            },
             address_size,
         };
 
@@ -52,18 +61,28 @@ impl<'tcx> DebugContext<'tcx> {
         // Normally this would use option_env!("CFG_VERSION").
         let producer = format!("cg_clif (rustc {})", "unknown version");
         let comp_dir = tcx.sess.working_dir.0.to_string_lossy().into_owned();
-        let name = match tcx.sess.local_crate_source_file {
-            Some(ref path) => path.to_string_lossy().into_owned(),
-            None => tcx.crate_name(LOCAL_CRATE).to_string(),
+        let (name, file_info) = match tcx.sess.local_crate_source_file.clone() {
+            Some(path) => {
+                let name = path.to_string_lossy().into_owned();
+                let info = tcx.sess
+                    .source_map()
+                    .get_source_file(&FileName::Real(path))
+                    .map(|f| f.src_hash)
+                    .and_then(line_info::make_file_info);
+                (name, info)
+            },
+            None => (tcx.crate_name(LOCAL_CRATE).to_string(), None),
         };
 
-        let line_program = LineProgram::new(
+        let mut line_program = LineProgram::new(
             encoding,
             LineEncoding::default(),
             LineString::new(comp_dir.as_bytes(), encoding, &mut dwarf.line_strings),
             LineString::new(name.as_bytes(), encoding, &mut dwarf.line_strings),
-            None,
+            file_info,
         );
+        line_program.file_has_md5 = file_info.is_some();
+
         dwarf.unit.line_program = line_program;
 
         {