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Use the object crate for metadata reading

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This commit is contained in:
bjorn3 2021-03-29 11:39:13 +02:00
parent e5f83d24ae
commit 267d55d44a
8 changed files with 79 additions and 156 deletions
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9
Cargo.lock
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@ -2348,8 +2348,10 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "8d3b63360ec3cb337817c2dbd47ab4a0f170d285d8e5a2064600f3def1402397"
dependencies = [
"compiler_builtins",
"flate2",
"rustc-std-workspace-alloc",
"rustc-std-workspace-core",
"wasmparser",
]
[[package]]
@ -3700,6 +3702,7 @@ dependencies = [
"itertools 0.9.0",
"jobserver",
"libc",
"object",
"pathdiff",
"rustc_apfloat",
"rustc_ast",
@ -5618,6 +5621,12 @@ dependencies = [
"rustc-std-workspace-core",
]
[[package]]
name = "wasmparser"
version = "0.57.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "32fddd575d477c6e9702484139cf9f23dcd554b06d185ed0f56c857dd3a47aa6"
[[package]]
name = "winapi"
version = "0.2.8"

2
compiler/rustc_codegen_cranelift/src/lib.rs
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@ -165,7 +165,7 @@ fn init(&self, sess: &Session) {
}
fn metadata_loader(&self) -> Box<dyn MetadataLoader + Sync> {
Box::new(crate::metadata::CraneliftMetadataLoader)
Box::new(rustc_codegen_ssa::back::metadata::DefaultMetadataLoader)
}
fn provide(&self, _providers: &mut Providers) {}

66
compiler/rustc_codegen_cranelift/src/metadata.rs
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@ -1,73 +1,9 @@
//! Reading and writing of the rustc metadata for rlibs and dylibs
//! Writing of the rustc metadata for dylibs
use std::fs::File;
use std::path::Path;
use rustc_codegen_ssa::METADATA_FILENAME;
use rustc_data_structures::memmap::Mmap;
use rustc_data_structures::owning_ref::OwningRef;
use rustc_data_structures::rustc_erase_owner;
use rustc_data_structures::sync::MetadataRef;
use rustc_middle::middle::cstore::MetadataLoader;
use rustc_middle::ty::TyCtxt;
use rustc_target::spec::Target;
use crate::backend::WriteMetadata;
/// The metadata loader used by cg_clif.
///
/// The metadata is stored in the same format as cg_llvm.
///
/// # Metadata location
///
/// <dl>
/// <dt>rlib</dt>
/// <dd>The metadata can be found in the `lib.rmeta` file inside of the ar archive.</dd>
/// <dt>dylib</dt>
/// <dd>The metadata can be found in the `.rustc` section of the shared library.</dd>
/// </dl>
pub(crate) struct CraneliftMetadataLoader;
fn load_metadata_with(
path: &Path,
f: impl for<'a> FnOnce(&'a [u8]) -> Result<&'a [u8], String>,
) -> Result<MetadataRef, String> {
let file = File::open(path).map_err(|e| format!("{:?}", e))?;
let data = unsafe { Mmap::map(file) }.map_err(|e| format!("{:?}", e))?;
let metadata = OwningRef::new(data).try_map(f)?;
return Ok(rustc_erase_owner!(metadata.map_owner_box()));
}
impl MetadataLoader for CraneliftMetadataLoader {
fn get_rlib_metadata(&self, _target: &Target, path: &Path) -> Result<MetadataRef, String> {
load_metadata_with(path, |data| {
let archive = object::read::archive::ArchiveFile::parse(&*data)
.map_err(|e| format!("{:?}", e))?;
for entry_result in archive.members() {
let entry = entry_result.map_err(|e| format!("{:?}", e))?;
if entry.name() == METADATA_FILENAME.as_bytes() {
return Ok(entry.data());
}
}
Err("couldn't find metadata entry".to_string())
})
}
fn get_dylib_metadata(&self, _target: &Target, path: &Path) -> Result<MetadataRef, String> {
use object::{Object, ObjectSection};
load_metadata_with(path, |data| {
let file = object::File::parse(&data).map_err(|e| format!("parse: {:?}", e))?;
file.section_by_name(".rustc")
.ok_or("no .rustc section")?
.data()
.map_err(|e| format!("failed to read .rustc section: {:?}", e))
})
}
}
// Adapted from https://github.com/rust-lang/rust/blob/da573206f87b5510de4b0ee1a9c044127e409bd3/src/librustc_codegen_llvm/base.rs#L47-L112
pub(crate) fn write_metadata<O: WriteMetadata>(tcx: TyCtxt<'_>, object: &mut O) {
use snap::write::FrameEncoder;

2
compiler/rustc_codegen_llvm/src/lib.rs
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@ -250,7 +250,7 @@ fn target_features(&self, sess: &Session) -> Vec<Symbol> {
}
fn metadata_loader(&self) -> Box<MetadataLoaderDyn> {
Box::new(metadata::LlvmMetadataLoader)
Box::new(rustc_codegen_ssa::back::metadata::DefaultMetadataLoader)
}
fn provide(&self, providers: &mut ty::query::Providers) {

89
compiler/rustc_codegen_llvm/src/metadata.rs
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@ -1,94 +1,9 @@
use crate::llvm;
use crate::llvm::archive_ro::ArchiveRO;
use crate::llvm::{mk_section_iter, False, ObjectFile};
use rustc_middle::middle::cstore::MetadataLoader;
use rustc_target::spec::Target;
use rustc_codegen_ssa::METADATA_FILENAME;
use rustc_data_structures::owning_ref::OwningRef;
use rustc_data_structures::rustc_erase_owner;
use tracing::debug;
use rustc_fs_util::path_to_c_string;
use std::path::Path;
use std::slice;
pub use rustc_data_structures::sync::MetadataRef;
pub struct LlvmMetadataLoader;
impl MetadataLoader for LlvmMetadataLoader {
fn get_rlib_metadata(&self, _: &Target, filename: &Path) -> Result<MetadataRef, String> {
// Use ArchiveRO for speed here, it's backed by LLVM and uses mmap
// internally to read the file. We also avoid even using a memcpy by
// just keeping the archive along while the metadata is in use.
let archive =
ArchiveRO::open(filename).map(|ar| OwningRef::new(Box::new(ar))).map_err(|e| {
debug!("llvm didn't like `{}`: {}", filename.display(), e);
format!("failed to read rlib metadata in '{}': {}", filename.display(), e)
})?;
let buf: OwningRef<_, [u8]> = archive.try_map(|ar| {
ar.iter()
.filter_map(|s| s.ok())
.find(|sect| sect.name() == Some(METADATA_FILENAME))
.map(|s| s.data())
.ok_or_else(|| {
debug!("didn't find '{}' in the archive", METADATA_FILENAME);
format!("failed to read rlib metadata: '{}'", filename.display())
})
})?;
Ok(rustc_erase_owner!(buf))
}
fn get_dylib_metadata(&self, target: &Target, filename: &Path) -> Result<MetadataRef, String> {
unsafe {
let buf = path_to_c_string(filename);
let mb = llvm::LLVMRustCreateMemoryBufferWithContentsOfFile(buf.as_ptr())
.ok_or_else(|| format!("error reading library: '{}'", filename.display()))?;
let of =
ObjectFile::new(mb).map(|of| OwningRef::new(Box::new(of))).ok_or_else(|| {
format!("provided path not an object file: '{}'", filename.display())
})?;
let buf = of.try_map(|of| search_meta_section(of, target, filename))?;
Ok(rustc_erase_owner!(buf))
}
}
}
fn search_meta_section<'a>(
of: &'a ObjectFile,
target: &Target,
filename: &Path,
) -> Result<&'a [u8], String> {
unsafe {
let si = mk_section_iter(of.llof);
while llvm::LLVMIsSectionIteratorAtEnd(of.llof, si.llsi) == False {
let mut name_buf = None;
let name_len = llvm::LLVMRustGetSectionName(si.llsi, &mut name_buf);
let name = name_buf.map_or_else(
String::new, // We got a null ptr, ignore `name_len`.
|buf| {
String::from_utf8(
slice::from_raw_parts(buf.as_ptr() as *const u8, name_len as usize)
.to_vec(),
)
.unwrap()
},
);
debug!("get_metadata_section: name {}", name);
if read_metadata_section_name(target) == name {
let cbuf = llvm::LLVMGetSectionContents(si.llsi);
let csz = llvm::LLVMGetSectionSize(si.llsi) as usize;
// The buffer is valid while the object file is around
let buf: &'a [u8] = slice::from_raw_parts(cbuf as *const u8, csz);
return Ok(buf);
}
llvm::LLVMMoveToNextSection(si.llsi);
}
}
Err(format!("metadata not found: '{}'", filename.display()))
}
pub fn metadata_section_name(target: &Target) -> &'static str {
// Historical note:
//
@ -106,7 +21,3 @@ pub fn metadata_section_name(target: &Target) -> &'static str {
if target.is_like_osx { "__DATA,.rustc" } else { ".rustc" }
}
fn read_metadata_section_name(_target: &Target) -> &'static str {
".rustc"
}

1
compiler/rustc_codegen_ssa/Cargo.toml
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@ -16,6 +16,7 @@ libc = "0.2.50"
jobserver = "0.1.22"
tempfile = "3.2"
pathdiff = "0.2.0"
object = "0.22.0"
rustc_serialize = { path = "../rustc_serialize" }
rustc_ast = { path = "../rustc_ast" }

65
compiler/rustc_codegen_ssa/src/back/metadata.rs Normal file
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@ -0,0 +1,65 @@
//! Reading of the rustc metadata for rlibs and dylibs
use std::fs::File;
use std::path::Path;
use rustc_data_structures::memmap::Mmap;
use rustc_data_structures::owning_ref::OwningRef;
use rustc_data_structures::rustc_erase_owner;
use rustc_data_structures::sync::MetadataRef;
use rustc_middle::middle::cstore::MetadataLoader;
use rustc_target::spec::Target;
use crate::METADATA_FILENAME;
/// The default metadata loader. This is used by cg_llvm and cg_clif.
///
/// # Metadata location
///
/// <dl>
/// <dt>rlib</dt>
/// <dd>The metadata can be found in the `lib.rmeta` file inside of the ar archive.</dd>
/// <dt>dylib</dt>
/// <dd>The metadata can be found in the `.rustc` section of the shared library.</dd>
/// </dl>
pub struct DefaultMetadataLoader;
fn load_metadata_with(
path: &Path,
f: impl for<'a> FnOnce(&'a [u8]) -> Result<&'a [u8], String>,
) -> Result<MetadataRef, String> {
let file = File::open(path).map_err(|e| format!("{:?}", e))?;
let data = unsafe { Mmap::map(file) }.map_err(|e| format!("{:?}", e))?;
let metadata = OwningRef::new(data).try_map(f)?;
return Ok(rustc_erase_owner!(metadata.map_owner_box()));
}
impl MetadataLoader for DefaultMetadataLoader {
fn get_rlib_metadata(&self, _target: &Target, path: &Path) -> Result<MetadataRef, String> {
load_metadata_with(path, |data| {
let archive = object::read::archive::ArchiveFile::parse(&*data)
.map_err(|e| format!("{:?}", e))?;
for entry_result in archive.members() {
let entry = entry_result.map_err(|e| format!("{:?}", e))?;
if entry.name() == METADATA_FILENAME.as_bytes() {
return Ok(entry.data());
}
}
Err("couldn't find metadata entry".to_string())
})
}
fn get_dylib_metadata(&self, _target: &Target, path: &Path) -> Result<MetadataRef, String> {
use object::{Object, ObjectSection};
load_metadata_with(path, |data| {
let file = object::File::parse(&data).map_err(|e| format!("parse: {:?}", e))?;
file.section_by_name(".rustc")
.ok_or("no .rustc section")?
.data()
.map_err(|e| format!("failed to read .rustc section: {:?}", e))
})
}
}

1
compiler/rustc_codegen_ssa/src/back/mod.rs
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@ -3,6 +3,7 @@
pub mod link;
pub mod linker;
pub mod lto;
pub mod metadata;
pub mod rpath;
pub mod symbol_export;
pub mod write;