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Special case allocator module submission to avoid special casing it elsewhere

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A lot of places had special handling just in case they would get an
allocator module even though most of these places could never get one or
would have a trivial implementation for the allocator module. Moving all
handling of the allocator module to a single place simplifies things a
fair bit.
This commit is contained in:
bjorn3
2025-08-28 10:26:29 +00:00
parent eea81b5d75
commit 319fe230f0
6 changed files with 79 additions and 146 deletions
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22
compiler/rustc_codegen_llvm/src/back/lto.rs
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@@ -11,7 +11,7 @@ use object::{Object, ObjectSection};
use rustc_codegen_ssa::back::lto::{SerializedModule, ThinModule, ThinShared};
use rustc_codegen_ssa::back::write::{CodegenContext, FatLtoInput};
use rustc_codegen_ssa::traits::*;
use rustc_codegen_ssa::{ModuleCodegen, ModuleKind, looks_like_rust_object_file};
use rustc_codegen_ssa::{ModuleCodegen, looks_like_rust_object_file};
use rustc_data_structures::fx::FxHashMap;
use rustc_data_structures::memmap::Mmap;
use rustc_errors::DiagCtxtHandle;
@@ -43,9 +43,7 @@ fn prepare_lto(
.map(|symbol| CString::new(symbol.to_owned()).unwrap())
.collect::<Vec<CString>>();
if cgcx.regular_module_config.instrument_coverage
|| cgcx.regular_module_config.pgo_gen.enabled()
{
if cgcx.module_config.instrument_coverage || cgcx.module_config.pgo_gen.enabled() {
// These are weak symbols that point to the profile version and the
// profile name, which need to be treated as exported so LTO doesn't nix
// them.
@@ -55,15 +53,15 @@ fn prepare_lto(
symbols_below_threshold.extend(PROFILER_WEAK_SYMBOLS.iter().map(|&sym| sym.to_owned()));
}
if cgcx.regular_module_config.sanitizer.contains(SanitizerSet::MEMORY) {
if cgcx.module_config.sanitizer.contains(SanitizerSet::MEMORY) {
let mut msan_weak_symbols = Vec::new();
// Similar to profiling, preserve weak msan symbol during LTO.
if cgcx.regular_module_config.sanitizer_recover.contains(SanitizerSet::MEMORY) {
if cgcx.module_config.sanitizer_recover.contains(SanitizerSet::MEMORY) {
msan_weak_symbols.push(c"__msan_keep_going");
}
if cgcx.regular_module_config.sanitizer_memory_track_origins != 0 {
if cgcx.module_config.sanitizer_memory_track_origins != 0 {
msan_weak_symbols.push(c"__msan_track_origins");
}
@@ -227,15 +225,9 @@ fn fat_lto(
// All the other modules will be serialized and reparsed into the new
// context, so this hopefully avoids serializing and parsing the largest
// codegen unit.
//
// Additionally use a regular module as the base here to ensure that various
// file copy operations in the backend work correctly. The only other kind
// of module here should be an allocator one, and if your crate is smaller
// than the allocator module then the size doesn't really matter anyway.
let costliest_module = in_memory
.iter()
.enumerate()
.filter(|&(_, module)| module.kind == ModuleKind::Regular)
.map(|(i, module)| {
let cost = unsafe { llvm::LLVMRustModuleCost(module.module_llvm.llmod()) };
(cost, i)
@@ -583,7 +575,7 @@ pub(crate) fn run_pass_manager(
thin: bool,
) {
let _timer = cgcx.prof.generic_activity_with_arg("LLVM_lto_optimize", &*module.name);
let config = cgcx.config(module.kind);
let config = &cgcx.module_config;
// Now we have one massive module inside of llmod. Time to run the
// LTO-specific optimization passes that LLVM provides.
@@ -745,7 +737,7 @@ pub(crate) fn optimize_thin_module(
let module_llvm = ModuleLlvm::parse(cgcx, module_name, thin_module.data(), dcx);
let mut module = ModuleCodegen::new_regular(thin_module.name(), module_llvm);
// Given that the newly created module lacks a thinlto buffer for embedding, we need to re-add it here.
if cgcx.config(ModuleKind::Regular).embed_bitcode() {
if cgcx.module_config.embed_bitcode() {
module.thin_lto_buffer = Some(thin_module.data().to_vec());
}
{