diff options
| -rw-r--r-- | Cargo.lock | 11 | ||||
| -rw-r--r-- | compiler/rustc_codegen_ssa/Cargo.toml | 2 | ||||
| -rw-r--r-- | compiler/rustc_codegen_ssa/src/back/metadata.rs | 88 | ||||
| -rw-r--r-- | src/tools/tidy/src/deps.rs | 17 |
4 files changed, 97 insertions, 21 deletions
diff --git a/Cargo.lock b/Cargo.lock index 61f9c130e38..848c826f940 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -2627,6 +2627,7 @@ dependencies = [ "rustc-std-workspace-alloc", "rustc-std-workspace-core", "ruzstd", + "wasmparser", ] [[package]] @@ -6129,6 +6130,16 @@ source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "4f186bd2dcf04330886ce82d6f33dd75a7bfcf69ecf5763b89fcde53b6ac9838" [[package]] +name = "wasmparser" +version = "0.118.2" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "77f1154f1ab868e2a01d9834a805faca7bf8b50d041b4ca714d005d0dab1c50c" +dependencies = [ + "indexmap", + "semver", +] + +[[package]] name = "web-sys" version = "0.3.68" source = "registry+https://github.com/rust-lang/crates.io-index" diff --git a/compiler/rustc_codegen_ssa/Cargo.toml b/compiler/rustc_codegen_ssa/Cargo.toml index e144b1dc1bd..781c54bdef8 100644 --- a/compiler/rustc_codegen_ssa/Cargo.toml +++ b/compiler/rustc_codegen_ssa/Cargo.toml @@ -48,7 +48,7 @@ libc = "0.2.50" [dependencies.object] version = "0.32.1" default-features = false -features = ["read_core", "elf", "macho", "pe", "xcoff", "unaligned", "archive", "write"] +features = ["read_core", "elf", "macho", "pe", "xcoff", "unaligned", "archive", "write", "wasm"] [target.'cfg(windows)'.dependencies.windows] version = "0.52.0" diff --git a/compiler/rustc_codegen_ssa/src/back/metadata.rs b/compiler/rustc_codegen_ssa/src/back/metadata.rs index b683e1b45a8..8e76e47cfef 100644 --- a/compiler/rustc_codegen_ssa/src/back/metadata.rs +++ b/compiler/rustc_codegen_ssa/src/back/metadata.rs @@ -15,6 +15,7 @@ use rustc_data_structures::owned_slice::{try_slice_owned, OwnedSlice}; use rustc_metadata::creader::MetadataLoader; use rustc_metadata::fs::METADATA_FILENAME; use rustc_metadata::EncodedMetadata; +use rustc_serialize::leb128; use rustc_session::Session; use rustc_span::sym; use rustc_target::abi::Endian; @@ -420,10 +421,9 @@ pub enum MetadataPosition { /// 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. +/// * WebAssembly - this uses wasm files themselves as the object file format +/// so an empty file with no linking metadata but a single custom section is +/// created holding our metadata. /// /// * 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 @@ -438,22 +438,13 @@ pub fn create_wrapper_file( 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: - // - // * Some targets don't have support in the `object` crate just yet - // to write an object file. These targets are likely to get filled - // out over time. - // - // * Targets like WebAssembly don't support dylibs, so the purpose - // of putting metadata in object files, to support linking rlibs - // into dylibs, is moot. - // - // In both of these cases it means that linking into dylibs will - // not be supported by rustc. This doesn't matter for targets like - // 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. + if sess.target.is_like_wasm { + return (create_metadata_file_for_wasm(data, §ion_name), MetadataPosition::First); + } + + // Targets using this branch don't have support implemented here yet or + // they're not yet implemented in the `object` crate and will likely + // fill out this module over time. return (data.to_vec(), MetadataPosition::Last); }; let section = if file.format() == BinaryFormat::Xcoff { @@ -532,6 +523,9 @@ pub fn create_compressed_metadata_file( packed_metadata.extend(metadata.raw_data()); let Some(mut file) = create_object_file(sess) else { + if sess.target.is_like_wasm { + return create_metadata_file_for_wasm(&packed_metadata, b".rustc"); + } return packed_metadata.to_vec(); }; if file.format() == BinaryFormat::Xcoff { @@ -624,3 +618,57 @@ pub fn create_compressed_metadata_file_for_xcoff( file.append_section_data(section, data, 1); file.write().unwrap() } + +/// Creates a simple WebAssembly object file, which is itself a wasm module, +/// that contains a custom section of the name `section_name` with contents +/// `data`. +/// +/// NB: the `object` crate does not yet have support for writing the the wasm +/// object file format. The format is simple enough that for now an extra crate +/// from crates.io (such as `wasm-encoder`). The file format is: +/// +/// * 4-byte header "\0asm" +/// * 4-byte version number - 1u32 in little-endian format +/// * concatenated sections, which for this object is always "custom sections" +/// +/// Custom sections are then defined by: +/// * 1-byte section identifier - 0 for a custom section +/// * leb-encoded section length (size of the contents beneath this bullet) +/// * leb-encoded custom section name length +/// * custom section name +/// * section contents +/// +/// One custom section, `linking`, is added here in accordance with +/// <https://github.com/WebAssembly/tool-conventions/blob/main/Linking.md> +/// which is required to inform LLD that this is an object file but it should +/// otherwise basically ignore it if it otherwise looks at it. The linking +/// section currently is defined by a single version byte (2) and then further +/// sections, but we have no more sections, so it's just the byte "2". +/// +/// The next custom section is the one we're interested in. +pub fn create_metadata_file_for_wasm(data: &[u8], section_name: &[u8]) -> Vec<u8> { + let mut bytes = b"\0asm\x01\0\0\0".to_vec(); + + let mut append_custom_section = |section_name: &[u8], data: &[u8]| { + let mut section_name_len = [0; leb128::max_leb128_len::<usize>()]; + let off = leb128::write_usize_leb128(&mut section_name_len, section_name.len()); + let section_name_len = §ion_name_len[..off]; + + let mut section_len = [0; leb128::max_leb128_len::<usize>()]; + let off = leb128::write_usize_leb128( + &mut section_len, + data.len() + section_name_len.len() + section_name.len(), + ); + let section_len = §ion_len[..off]; + + bytes.push(0u8); + bytes.extend_from_slice(section_len); + bytes.extend_from_slice(section_name_len); + bytes.extend_from_slice(section_name); + bytes.extend_from_slice(data); + }; + + append_custom_section(b"linking", &[2]); + append_custom_section(section_name, data); + bytes +} diff --git a/src/tools/tidy/src/deps.rs b/src/tools/tidy/src/deps.rs index b36b6da308e..cff219285dc 100644 --- a/src/tools/tidy/src/deps.rs +++ b/src/tools/tidy/src/deps.rs @@ -92,6 +92,7 @@ const EXCEPTIONS: ExceptionList = &[ ("ryu", "Apache-2.0 OR BSL-1.0"), // BSL is not acceptble, but we use it under Apache-2.0 // cargo/... (because of serde) ("self_cell", "Apache-2.0"), // rustc (fluent translations) ("snap", "BSD-3-Clause"), // rustc + ("wasmparser", "Apache-2.0 WITH LLVM-exception"), // rustc // tidy-alphabetical-end ]; @@ -379,6 +380,7 @@ const PERMITTED_RUSTC_DEPENDENCIES: &[&str] = &[ "valuable", "version_check", "wasi", + "wasmparser", "winapi", "winapi-i686-pc-windows-gnu", "winapi-util", @@ -564,6 +566,21 @@ fn check_runtime_license_exceptions( if pkg.name == "fortanix-sgx-abi" && pkg.license.as_deref() == Some("MPL-2.0") { continue; } + + // This exception is due to the fact that the feature set of the + // `object` crate is different between rustc and libstd. In the + // standard library only a conservative set of features are enabled + // which notably does not include the `wasm` feature which pulls in + // this dependency. In the compiler, however, the `wasm` feature is + // enabled. This exception is intended to be here so long as the + // `EXCEPTIONS` above contains `wasmparser`, but once that goes away + // this can be removed. + if pkg.name == "wasmparser" + && pkg.license.as_deref() == Some("Apache-2.0 WITH LLVM-exception") + { + continue; + } + tidy_error!(bad, "invalid license `{}` in `{}`", license, pkg.id); } } |