cg_llvm: implement split dwarf support

This commit implements Split DWARF support, wiring up the flag (added in
earlier commits) to the modified FFI wrapper (also from earlier
commits).

Signed-off-by: David Wood <david@davidtw.co>

1 files changed, 27 insertions, 1 deletions

diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index b5354513dc2..b3d4c6e3ec7 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -550,6 +550,7 @@ impl_stable_hash_via_hash!(OutputFilenames);
 
 pub const RLINK_EXT: &str = "rlink";
 pub const RUST_CGU_EXT: &str = "rcgu";
+pub const DWARF_OBJECT_EXT: &str = "dwo";
 
 impl OutputFilenames {
     pub fn new(
@@ -583,7 +584,12 @@ impl OutputFilenames {
         self.temp_path_ext(extension, codegen_unit_name)
     }
 
-    /// Like temp_path, but also supports things where there is no corresponding
+    /// Like `temp_path`, but specifically for dwarf objects.
+    pub fn temp_path_dwo(&self, codegen_unit_name: Option<&str>) -> PathBuf {
+        self.temp_path_ext(DWARF_OBJECT_EXT, codegen_unit_name)
+    }
+
+    /// Like `temp_path`, but also supports things where there is no corresponding
     /// OutputType, like noopt-bitcode or lto-bitcode.
     pub fn temp_path_ext(&self, ext: &str, codegen_unit_name: Option<&str>) -> PathBuf {
         let mut extension = String::new();
@@ -610,6 +616,26 @@ impl OutputFilenames {
         path.set_extension(extension);
         path
     }
+
+    /// Returns the path for the Split DWARF file - this can differ depending on which Split DWARF
+    /// mode is being used, which is the logic that this function is intended to encapsulate.
+    pub fn split_dwarf_file(
+        &self,
+        split_dwarf_kind: SplitDwarfKind,
+        cgu_name: Option<&str>,
+    ) -> Option<PathBuf> {
+        let obj_out = self.temp_path(OutputType::Object, cgu_name);
+        let dwo_out = self.temp_path_dwo(cgu_name);
+        match split_dwarf_kind {
+            SplitDwarfKind::None => None,
+            // Single mode doesn't change how DWARF is emitted, but does add Split DWARF attributes
+            // (pointing at the path which is being determined here). Use the path to the current
+            // object file.
+            SplitDwarfKind::Single => Some(obj_out),
+            // Split mode emits the DWARF into a different file, use that path.
+            SplitDwarfKind::Split => Some(dwo_out),
+        }
+    }
 }
 
 pub fn host_triple() -> &'static str {