refactor: Make fetching of source info platform-specific (#1593)

Issue #1538

Author: davidlattimore

libwild/src/dwarf_address_info.rs

@@ -8,6 +8,8 @@ use crate::platform::ObjectFile as _;
 use crate::platform::Platform;
 use crate::platform::Relocation;
 use crate::platform::RelocationSequence as _;
+use crate::platform::SourceInfo;
+use crate::platform::SourceInfoDetails;
 use anyhow::Context;
 use object::LittleEndian;
 use object::read::elf::Crel;
@@ -19,14 +21,6 @@ use std::os::unix::ffi::OsStrExt;
 use std::path::Path;
 use std::path::PathBuf;
 
-pub(crate) struct SourceInfo(Option<SourceInfoDetails>);
-
-#[derive(Debug)]
-pub(crate) struct SourceInfoDetails {
-    path: PathBuf,
-    line: u64,
-}
-
 /// The address at which we'll pretend that we loaded the section we're interested in. This value is
 /// arbitrary, but should be larger than the largest input section we expect to encounter and small
 /// enough to fit comfortably in a u32.

libwild/src/elf_aarch64.rs

@@ -290,6 +290,20 @@ impl<'data> crate::platform::Platform<'data> for ElfAArch64 {
             .symbol(symbol_index)
             .is_ok_and(|sym| (sym.st_other & object::elf::STO_AARCH64_VARIANT_PCS) != 0)
     }
+
+    fn get_source_info(
+        object: &Self::File,
+        relocations: &<Self::File as crate::platform::ObjectFile<'data>>::RelocationSections,
+        section: &<Self::File as crate::platform::ObjectFile<'data>>::SectionHeader,
+        offset_in_section: u64,
+    ) -> Result<crate::platform::SourceInfo> {
+        crate::dwarf_address_info::get_source_info::<Self>(
+            object,
+            relocations,
+            section,
+            offset_in_section,
+        )
+    }
 }
 
 #[derive(Debug, Clone)]

libwild/src/elf_loongarch64.rs

@@ -154,6 +154,20 @@ impl<'data> crate::platform::Platform<'data> for ElfLoongArch64 {
 
         None
     }
+
+    fn get_source_info(
+        object: &Self::File,
+        relocations: &<Self::File as crate::platform::ObjectFile<'data>>::RelocationSections,
+        section: &<Self::File as crate::platform::ObjectFile<'data>>::SectionHeader,
+        offset_in_section: u64,
+    ) -> Result<crate::platform::SourceInfo> {
+        crate::dwarf_address_info::get_source_info::<Self>(
+            object,
+            relocations,
+            section,
+            offset_in_section,
+        )
+    }
 }
 
 #[derive(Debug, Clone)]

libwild/src/elf_riscv64.rs

@@ -258,6 +258,20 @@ impl<'data> crate::platform::Platform<'data> for ElfRiscV64 {
             ),
         }
     }
+
+    fn get_source_info(
+        object: &Self::File,
+        relocations: &<Self::File as crate::platform::ObjectFile<'data>>::RelocationSections,
+        section: &<Self::File as crate::platform::ObjectFile<'data>>::SectionHeader,
+        offset_in_section: u64,
+    ) -> Result<crate::platform::SourceInfo> {
+        crate::dwarf_address_info::get_source_info::<Self>(
+            object,
+            relocations,
+            section,
+            offset_in_section,
+        )
+    }
 }
 
 #[derive(Debug, Clone)]

libwild/src/elf_x86_64.rs

@@ -398,6 +398,20 @@ impl<'data> crate::platform::Platform<'data> for ElfX86_64 {
         };
         None
     }
+
+    fn get_source_info(
+        object: &Self::File,
+        relocations: &<Self::File as crate::platform::ObjectFile<'data>>::RelocationSections,
+        section: &<Self::File as crate::platform::ObjectFile<'data>>::SectionHeader,
+        offset_in_section: u64,
+    ) -> Result<crate::platform::SourceInfo> {
+        crate::dwarf_address_info::get_source_info::<Self>(
+            object,
+            relocations,
+            section,
+            offset_in_section,
+        )
+    }
 }
 
 #[derive(Debug, Clone)]

libwild/src/layout.rs

@@ -2838,7 +2838,7 @@ fn process_relocation<
     P: Platform<'data, File = crate::elf::File<'data>>,
     R: Relocation,
 >(
-    object: &ObjectLayoutState,
+    object: &ObjectLayoutState<'data>,
     common: &mut CommonGroupState,
     rel: &R,
     section: &object::elf::SectionHeader64<LittleEndian>,
@@ -2970,13 +2970,9 @@ fn process_relocation<
                 symbol_db.output_kind,
             ) {
                 let symbol_name = symbol_db.symbol_name_for_display(symbol_id);
-                let source_info = crate::dwarf_address_info::get_source_info::<P>(
-                    object.object,
-                    &object.relocations,
-                    section,
-                    rel_offset,
-                )
-                .context("Failed to get source info")?;
+                let source_info =
+                    P::get_source_info(object.object, &object.relocations, section, rel_offset)
+                        .context("Failed to get source info")?;
 
                 if args.error_unresolved_symbols {
                     resources.report_error(error!(

libwild/src/platform.rs

@@ -20,6 +20,7 @@ use linker_utils::relaxation::RelocationModifier;
 use linker_utils::relaxation::SectionRelaxDeltas;
 use std::borrow::Cow;
 use std::ops::Range;
+use std::path::PathBuf;
 
 /// Represents a supported object file format + architecture combination.
 pub(crate) trait Platform<'data>: 'data {
@@ -69,6 +70,15 @@ pub(crate) trait Platform<'data>: 'data {
         false
     }
 
+    /// Uses debug info, if available, to get information about where in the source code a
+    /// particular offset in a particular section came from.
+    fn get_source_info(
+        object: &Self::File,
+        relocations: &<Self::File as ObjectFile<'data>>::RelocationSections,
+        section: &<Self::File as ObjectFile<'data>>::SectionHeader,
+        offset_in_section: u64,
+    ) -> Result<SourceInfo>;
+
     fn collect_relaxation_deltas(
         _section_output_address: u64,
         _section_bytes: &[u8],
@@ -480,3 +490,11 @@ pub(crate) trait SectionAttributes: std::fmt::Debug + Send + Sync + 'static {
 
     fn apply(&self, output_sections: &mut OutputSections, section_id: OutputSectionId);
 }
+
+pub(crate) struct SourceInfo(pub(crate) Option<SourceInfoDetails>);
+
+#[derive(Debug)]
+pub(crate) struct SourceInfoDetails {
+    pub(crate) path: PathBuf,
+    pub(crate) line: u64,
+}