diff options
Diffstat (limited to 'compiler/rustc_codegen_ssa/src/back/metadata.rs')
| -rw-r--r-- | compiler/rustc_codegen_ssa/src/back/metadata.rs | 82 |
1 files changed, 43 insertions, 39 deletions
diff --git a/compiler/rustc_codegen_ssa/src/back/metadata.rs b/compiler/rustc_codegen_ssa/src/back/metadata.rs index 99ddd1764..51c5c375d 100644 --- a/compiler/rustc_codegen_ssa/src/back/metadata.rs +++ b/compiler/rustc_codegen_ssa/src/back/metadata.rs @@ -60,7 +60,7 @@ impl MetadataLoader for DefaultMetadataLoader { let data = entry .data(data) .map_err(|e| format!("failed to parse rlib '{}': {}", path.display(), e))?; - return search_for_metadata(path, data, ".rmeta"); + return search_for_section(path, data, ".rmeta"); } } @@ -69,11 +69,11 @@ impl MetadataLoader for DefaultMetadataLoader { } fn get_dylib_metadata(&self, _target: &Target, path: &Path) -> Result<MetadataRef, String> { - load_metadata_with(path, |data| search_for_metadata(path, data, ".rustc")) + load_metadata_with(path, |data| search_for_section(path, data, ".rustc")) } } -fn search_for_metadata<'a>( +pub(super) fn search_for_section<'a>( path: &Path, bytes: &'a [u8], section: &str, @@ -191,39 +191,43 @@ pub enum MetadataPosition { Last, } -// For rlibs we "pack" rustc metadata into a dummy object file. -// -// Historically it was needed because rustc linked rlibs as whole-archive in some cases. -// In that case linkers try to include all files located in an archive, so if metadata is stored -// in an archive then it needs to be of a form that the linker is able to process. -// Now it's not clear whether metadata still needs to be wrapped into an object file or not. -// -// Note, though, that we don't actually want this metadata to show up in any -// final output of the compiler. Instead this is purely for rustc's own -// metadata tracking purposes. -// -// With the above in mind, each "flavor" of object format gets special -// handling here depending on the target: -// -// * MachO - macos-like targets will insert the metadata into a section that -// is sort of fake dwarf debug info. Inspecting the source of the macos -// linker this causes these sections to be skipped automatically because -// it's not in an allowlist of otherwise well known dwarf section names to -// go into the final artifact. -// -// * WebAssembly - we actually don't have any container format for this -// target. WebAssembly doesn't support the `dylib` crate type anyway so -// there's no need for us to support this at this time. Consequently the -// metadata bytes are simply stored as-is into an rlib. -// -// * COFF - Windows-like targets create an object with a section that has -// the `IMAGE_SCN_LNK_REMOVE` flag set which ensures that if the linker -// ever sees the section it doesn't process it and it's removed. -// -// * ELF - All other targets are similar to Windows in that there's a -// `SHF_EXCLUDE` flag we can set on sections in an object file to get -// automatically removed from the final output. -pub fn create_rmeta_file(sess: &Session, metadata: &[u8]) -> (Vec<u8>, MetadataPosition) { +/// For rlibs we "pack" rustc metadata into a dummy object file. +/// +/// Historically it was needed because rustc linked rlibs as whole-archive in some cases. +/// In that case linkers try to include all files located in an archive, so if metadata is stored +/// in an archive then it needs to be of a form that the linker is able to process. +/// Now it's not clear whether metadata still needs to be wrapped into an object file or not. +/// +/// Note, though, that we don't actually want this metadata to show up in any +/// final output of the compiler. Instead this is purely for rustc's own +/// metadata tracking purposes. +/// +/// With the above in mind, each "flavor" of object format gets special +/// handling here depending on the target: +/// +/// * MachO - macos-like targets will insert the metadata into a section that +/// is sort of fake dwarf debug info. Inspecting the source of the macos +/// linker this causes these sections to be skipped automatically because +/// it's not in an allowlist of otherwise well known dwarf section names to +/// go into the final artifact. +/// +/// * WebAssembly - we actually don't have any container format for this +/// target. WebAssembly doesn't support the `dylib` crate type anyway so +/// there's no need for us to support this at this time. Consequently the +/// metadata bytes are simply stored as-is into an rlib. +/// +/// * COFF - Windows-like targets create an object with a section that has +/// the `IMAGE_SCN_LNK_REMOVE` flag set which ensures that if the linker +/// ever sees the section it doesn't process it and it's removed. +/// +/// * ELF - All other targets are similar to Windows in that there's a +/// `SHF_EXCLUDE` flag we can set on sections in an object file to get +/// automatically removed from the final output. +pub fn create_wrapper_file( + sess: &Session, + section_name: Vec<u8>, + data: &[u8], +) -> (Vec<u8>, MetadataPosition) { let Some(mut file) = create_object_file(sess) else { // This is used to handle all "other" targets. This includes targets // in two categories: @@ -241,11 +245,11 @@ pub fn create_rmeta_file(sess: &Session, metadata: &[u8]) -> (Vec<u8>, MetadataP // WebAssembly and for targets not supported by the `object` crate // yet it means that work will need to be done in the `object` crate // to add a case above. - return (metadata.to_vec(), MetadataPosition::Last); + return (data.to_vec(), MetadataPosition::Last); }; let section = file.add_section( file.segment_name(StandardSegment::Debug).to_vec(), - b".rmeta".to_vec(), + section_name, SectionKind::Debug, ); match file.format() { @@ -259,7 +263,7 @@ pub fn create_rmeta_file(sess: &Session, metadata: &[u8]) -> (Vec<u8>, MetadataP } _ => {} }; - file.append_section_data(section, metadata, 1); + file.append_section_data(section, data, 1); (file.write().unwrap(), MetadataPosition::First) } |