rust/src/driver/aot.rs

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//! The AOT driver uses [`cranelift_object`] to write object files suitable for linking into a
//! standalone executable.
use std::path::PathBuf;
use rustc_codegen_ssa::back::linker::LinkerInfo;
use rustc_codegen_ssa::{CodegenResults, CompiledModule, CrateInfo, ModuleKind};
use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
use rustc_middle::middle::cstore::EncodedMetadata;
use rustc_middle::mir::mono::{CodegenUnit, MonoItem};
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use rustc_session::cgu_reuse_tracker::CguReuse;
use rustc_session::config::{DebugInfo, OutputType};
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use cranelift_object::{ObjectModule, ObjectProduct};
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use crate::prelude::*;
use crate::backend::AddConstructor;
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fn new_module(tcx: TyCtxt<'_>, name: String) -> ObjectModule {
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let module = crate::backend::make_module(tcx.sess, name);
assert_eq!(pointer_ty(tcx), module.target_config().pointer_type());
module
}
struct ModuleCodegenResult(CompiledModule, Option<(WorkProductId, WorkProduct)>);
impl<HCX> HashStable<HCX> for ModuleCodegenResult {
fn hash_stable(&self, _: &mut HCX, _: &mut StableHasher) {
// do nothing
}
}
fn emit_module(
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tcx: TyCtxt<'_>,
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name: String,
kind: ModuleKind,
module: ObjectModule,
debug: Option<DebugContext<'_>>,
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unwind_context: UnwindContext<'_>,
map_product: impl FnOnce(ObjectProduct) -> ObjectProduct,
) -> ModuleCodegenResult {
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let mut product = module.finish();
if let Some(mut debug) = debug {
debug.emit(&mut product);
}
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unwind_context.emit(&mut product);
let product = map_product(product);
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let tmp_file = tcx
.output_filenames(LOCAL_CRATE)
.temp_path(OutputType::Object, Some(&name));
let obj = product.object.write().unwrap();
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if let Err(err) = std::fs::write(&tmp_file, obj) {
tcx.sess
.fatal(&format!("error writing object file: {}", err));
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}
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let work_product = if std::env::var("CG_CLIF_INCR_CACHE_DISABLED").is_ok() {
None
} else {
rustc_incremental::copy_cgu_workproduct_to_incr_comp_cache_dir(
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tcx.sess,
&name,
&Some(tmp_file.clone()),
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)
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};
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ModuleCodegenResult(
CompiledModule {
name,
kind,
object: Some(tmp_file),
dwarf_object: None,
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bytecode: None,
},
work_product,
)
}
fn reuse_workproduct_for_cgu(
tcx: TyCtxt<'_>,
cgu: &CodegenUnit<'_>,
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work_products: &mut FxHashMap<WorkProductId, WorkProduct>,
) -> CompiledModule {
let incr_comp_session_dir = tcx.sess.incr_comp_session_dir();
let mut object = None;
let work_product = cgu.work_product(tcx);
if let Some(saved_file) = &work_product.saved_file {
let obj_out = tcx
.output_filenames(LOCAL_CRATE)
.temp_path(OutputType::Object, Some(&cgu.name().as_str()));
object = Some(obj_out.clone());
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let source_file = rustc_incremental::in_incr_comp_dir(&incr_comp_session_dir, &saved_file);
if let Err(err) = rustc_fs_util::link_or_copy(&source_file, &obj_out) {
tcx.sess.err(&format!(
"unable to copy {} to {}: {}",
source_file.display(),
obj_out.display(),
err
));
}
}
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work_products.insert(cgu.work_product_id(), work_product);
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CompiledModule {
name: cgu.name().to_string(),
kind: ModuleKind::Regular,
object,
dwarf_object: None,
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bytecode: None,
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}
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}
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fn module_codegen(tcx: TyCtxt<'_>, cgu_name: rustc_span::Symbol) -> ModuleCodegenResult {
let cgu = tcx.codegen_unit(cgu_name);
let mono_items = cgu.items_in_deterministic_order(tcx);
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let mut module = new_module(tcx, cgu_name.as_str().to_string());
// Initialize the global atomic mutex using a constructor for proc-macros.
// FIXME implement atomic instructions in Cranelift.
let mut init_atomics_mutex_from_constructor = None;
if tcx
.sess
.crate_types()
.contains(&rustc_session::config::CrateType::ProcMacro)
{
if mono_items.iter().any(|(mono_item, _)| match mono_item {
rustc_middle::mir::mono::MonoItem::Static(def_id) => tcx
.symbol_name(Instance::mono(tcx, *def_id))
.name
.contains("__rustc_proc_macro_decls_"),
_ => false,
}) {
init_atomics_mutex_from_constructor =
Some(crate::atomic_shim::init_global_lock_constructor(
&mut module,
&format!("{}_init_atomics_mutex", cgu_name.as_str()),
));
}
}
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let mut cx = crate::CodegenCx::new(
tcx,
module,
tcx.sess.opts.debuginfo != DebugInfo::None,
true,
);
super::predefine_mono_items(&mut cx, &mono_items);
for (mono_item, (linkage, visibility)) in mono_items {
let linkage = crate::linkage::get_clif_linkage(mono_item, linkage, visibility);
match mono_item {
MonoItem::Fn(inst) => {
cx.tcx.sess.time("codegen fn", || {
crate::base::codegen_fn(&mut cx, inst, linkage)
});
}
MonoItem::Static(def_id) => {
crate::constant::codegen_static(&mut cx.constants_cx, def_id)
}
MonoItem::GlobalAsm(hir_id) => {
let item = cx.tcx.hir().expect_item(hir_id);
if let rustc_hir::ItemKind::GlobalAsm(rustc_hir::GlobalAsm { asm }) = item.kind {
cx.global_asm.push_str(&*asm.as_str());
cx.global_asm.push_str("\n\n");
} else {
bug!("Expected GlobalAsm found {:?}", item);
}
}
}
}
let (mut module, global_asm, debug, mut unwind_context) =
tcx.sess.time("finalize CodegenCx", || cx.finalize());
crate::main_shim::maybe_create_entry_wrapper(tcx, &mut module, &mut unwind_context, false);
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let codegen_result = emit_module(
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tcx,
cgu.name().as_str().to_string(),
ModuleKind::Regular,
module,
debug,
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unwind_context,
|mut product| {
if let Some(func_id) = init_atomics_mutex_from_constructor {
product.add_constructor(func_id);
}
product
},
);
codegen_global_asm(tcx, &cgu.name().as_str(), &global_asm);
codegen_result
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}
pub(super) fn run_aot(
tcx: TyCtxt<'_>,
metadata: EncodedMetadata,
need_metadata_module: bool,
) -> Box<(CodegenResults, FxHashMap<WorkProductId, WorkProduct>)> {
let mut work_products = FxHashMap::default();
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let cgus = if tcx.sess.opts.output_types.should_codegen() {
tcx.collect_and_partition_mono_items(LOCAL_CRATE).1
} else {
// If only `--emit metadata` is used, we shouldn't perform any codegen.
// Also `tcx.collect_and_partition_mono_items` may panic in that case.
&[]
};
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if tcx.dep_graph.is_fully_enabled() {
for cgu in &*cgus {
tcx.ensure().codegen_unit(cgu.name());
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}
}
let modules = super::time(tcx, "codegen mono items", || {
cgus.iter()
.map(|cgu| {
let cgu_reuse = determine_cgu_reuse(tcx, cgu);
tcx.sess
.cgu_reuse_tracker
.set_actual_reuse(&cgu.name().as_str(), cgu_reuse);
match cgu_reuse {
_ if std::env::var("CG_CLIF_INCR_CACHE_DISABLED").is_ok() => {}
CguReuse::No => {}
CguReuse::PreLto => {
return reuse_workproduct_for_cgu(tcx, &*cgu, &mut work_products);
}
CguReuse::PostLto => unreachable!(),
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}
let dep_node = cgu.codegen_dep_node(tcx);
let (ModuleCodegenResult(module, work_product), _) = tcx.dep_graph.with_task(
dep_node,
tcx,
cgu.name(),
module_codegen,
rustc_middle::dep_graph::hash_result,
);
if let Some((id, product)) = work_product {
work_products.insert(id, product);
}
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module
})
.collect::<Vec<_>>()
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});
tcx.sess.abort_if_errors();
let mut allocator_module = new_module(tcx, "allocator_shim".to_string());
let mut allocator_unwind_context = UnwindContext::new(tcx, allocator_module.isa(), true);
let created_alloc_shim =
crate::allocator::codegen(tcx, &mut allocator_module, &mut allocator_unwind_context);
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let allocator_module = if created_alloc_shim {
let ModuleCodegenResult(module, work_product) = emit_module(
tcx,
"allocator_shim".to_string(),
ModuleKind::Allocator,
allocator_module,
None,
allocator_unwind_context,
|product| product,
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);
if let Some((id, product)) = work_product {
work_products.insert(id, product);
}
Some(module)
} else {
None
};
let metadata_module = if need_metadata_module {
let _timer = tcx.prof.generic_activity("codegen crate metadata");
let (metadata_cgu_name, tmp_file) = tcx.sess.time("write compressed metadata", || {
use rustc_middle::mir::mono::CodegenUnitNameBuilder;
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let cgu_name_builder = &mut CodegenUnitNameBuilder::new(tcx);
let metadata_cgu_name = cgu_name_builder
.build_cgu_name(LOCAL_CRATE, &["crate"], Some("metadata"))
.as_str()
.to_string();
let tmp_file = tcx
.output_filenames(LOCAL_CRATE)
.temp_path(OutputType::Metadata, Some(&metadata_cgu_name));
let obj = crate::backend::with_object(tcx.sess, &metadata_cgu_name, |object| {
crate::metadata::write_metadata(tcx, object);
});
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if let Err(err) = std::fs::write(&tmp_file, obj) {
tcx.sess
.fatal(&format!("error writing metadata object file: {}", err));
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}
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(metadata_cgu_name, tmp_file)
});
Some(CompiledModule {
name: metadata_cgu_name,
kind: ModuleKind::Metadata,
object: Some(tmp_file),
dwarf_object: None,
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bytecode: None,
})
} else {
None
};
Box::new((
CodegenResults {
crate_name: tcx.crate_name(LOCAL_CRATE),
modules,
allocator_module,
metadata_module,
metadata,
windows_subsystem: None, // Windows is not yet supported
linker_info: LinkerInfo::new(tcx),
crate_info: CrateInfo::new(tcx),
},
work_products,
))
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}
fn codegen_global_asm(tcx: TyCtxt<'_>, cgu_name: &str, global_asm: &str) {
use std::io::Write;
use std::process::{Command, Stdio};
if global_asm.is_empty() {
return;
}
if cfg!(not(feature = "inline_asm"))
|| tcx.sess.target.is_like_osx
|| tcx.sess.target.is_like_windows
{
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if global_asm.contains("__rust_probestack") {
return;
}
// FIXME fix linker error on macOS
if cfg!(not(feature = "inline_asm")) {
tcx.sess.fatal(
"asm! and global_asm! support is disabled while compiling rustc_codegen_cranelift",
);
} else {
tcx.sess
.fatal("asm! and global_asm! are not yet supported on macOS and Windows");
}
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}
let assembler = crate::toolchain::get_toolchain_binary(tcx.sess, "as");
let linker = crate::toolchain::get_toolchain_binary(tcx.sess, "ld");
// Remove all LLVM style comments
let global_asm = global_asm
.lines()
.map(|line| {
if let Some(index) = line.find("//") {
&line[0..index]
} else {
line
}
})
.collect::<Vec<_>>()
.join("\n");
let output_object_file = tcx
.output_filenames(LOCAL_CRATE)
.temp_path(OutputType::Object, Some(cgu_name));
// Assemble `global_asm`
let global_asm_object_file = add_file_stem_postfix(output_object_file.clone(), ".asm");
let mut child = Command::new(assembler)
.arg("-o")
.arg(&global_asm_object_file)
.stdin(Stdio::piped())
.spawn()
.expect("Failed to spawn `as`.");
child
.stdin
.take()
.unwrap()
.write_all(global_asm.as_bytes())
.unwrap();
let status = child.wait().expect("Failed to wait for `as`.");
if !status.success() {
tcx.sess
.fatal(&format!("Failed to assemble `{}`", global_asm));
}
// Link the global asm and main object file together
let main_object_file = add_file_stem_postfix(output_object_file.clone(), ".main");
std::fs::rename(&output_object_file, &main_object_file).unwrap();
let status = Command::new(linker)
.arg("-r") // Create a new object file
.arg("-o")
.arg(output_object_file)
.arg(&main_object_file)
.arg(&global_asm_object_file)
.status()
.unwrap();
if !status.success() {
tcx.sess.fatal(&format!(
"Failed to link `{}` and `{}` together",
main_object_file.display(),
global_asm_object_file.display(),
));
}
std::fs::remove_file(global_asm_object_file).unwrap();
std::fs::remove_file(main_object_file).unwrap();
}
fn add_file_stem_postfix(mut path: PathBuf, postfix: &str) -> PathBuf {
let mut new_filename = path.file_stem().unwrap().to_owned();
new_filename.push(postfix);
if let Some(extension) = path.extension() {
new_filename.push(".");
new_filename.push(extension);
}
path.set_file_name(new_filename);
path
}
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// Adapted from https://github.com/rust-lang/rust/blob/303d8aff6092709edd4dbd35b1c88e9aa40bf6d8/src/librustc_codegen_ssa/base.rs#L922-L953
fn determine_cgu_reuse<'tcx>(tcx: TyCtxt<'tcx>, cgu: &CodegenUnit<'tcx>) -> CguReuse {
if !tcx.dep_graph.is_fully_enabled() {
return CguReuse::No;
}
let work_product_id = &cgu.work_product_id();
if tcx
.dep_graph
.previous_work_product(work_product_id)
.is_none()
{
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// We don't have anything cached for this CGU. This can happen
// if the CGU did not exist in the previous session.
return CguReuse::No;
}
// Try to mark the CGU as green. If it we can do so, it means that nothing
// affecting the LLVM module has changed and we can re-use a cached version.
// If we compile with any kind of LTO, this means we can re-use the bitcode
// of the Pre-LTO stage (possibly also the Post-LTO version but we'll only
// know that later). If we are not doing LTO, there is only one optimized
// version of each module, so we re-use that.
let dep_node = cgu.codegen_dep_node(tcx);
assert!(
!tcx.dep_graph.dep_node_exists(&dep_node),
"CompileCodegenUnit dep-node for CGU `{}` already exists before marking.",
cgu.name()
);
if tcx.dep_graph.try_mark_green(tcx, &dep_node).is_some() {
CguReuse::PreLto
} else {
CguReuse::No
}
}