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Ensure AArch64 LSE object files have distinct names in an archive

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This is needed by libtool which rejects archives that contain object
files with the same name multiple times.

Fixes #443
This commit is contained in:
Amanieu d'Antras 2021-11-28 12:50:21 +00:00
parent a01a61bd36
commit c750277268
1 changed files with 28 additions and 23 deletions
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51
library/compiler-builtins/build.rs
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@ -95,6 +95,8 @@ mod c {
use std::collections::{BTreeMap, HashSet};
use std::env;
use std::fs::File;
use std::io::Write;
use std::path::{Path, PathBuf};
struct Sources {
@ -523,20 +525,13 @@ mod c {
cfg.compile("libcompiler-rt.a");
}
fn build_aarch64_out_of_line_atomics_libraries(builtins_dir: &Path, cfg: &cc::Build) {
// NOTE: because we're recompiling the same source file in N different ways, building
// serially is necessary. If we want to lift this restriction, we can either:
// - create symlinks to lse.S and build those_(though we'd still need to pass special
// #define-like flags to each of these), or
// - synthesizing tiny .S files in out/ with the proper #defines, which ultimately #include
// lse.S.
// That said, it's unclear how useful this added complexity will be, so just do the simple
// thing for now.
fn build_aarch64_out_of_line_atomics_libraries(builtins_dir: &Path, cfg: &mut cc::Build) {
let out_dir = PathBuf::from(env::var("OUT_DIR").unwrap());
let outlined_atomics_file = builtins_dir.join("aarch64/lse.S");
println!("cargo:rerun-if-changed={}", outlined_atomics_file.display());
// Ideally, this would be a Vec of object files, but cc doesn't make it *entirely*
// trivial to build an individual object.
cfg.include(&builtins_dir);
for instruction_type in &["cas", "swp", "ldadd", "ldclr", "ldeor", "ldset"] {
for size in &[1, 2, 4, 8, 16] {
if *size == 16 && *instruction_type != "cas" {
@ -546,20 +541,30 @@ mod c {
for (model_number, model_name) in
&[(1, "relax"), (2, "acq"), (3, "rel"), (4, "acq_rel")]
{
let library_name = format!(
"liboutline_atomic_helper_{}{}_{}.a",
instruction_type, size, model_name
// The original compiler-rt build system compiles the same
// source file multiple times with different compiler
// options. Here we do something slightly different: we
// create multiple .S files with the proper #defines and
// then include the original file.
//
// This is needed because the cc crate doesn't allow us to
// override the name of object files and libtool requires
// all objects in an archive to have unique names.
let path =
out_dir.join(format!("lse_{}{}_{}.S", instruction_type, size, model_name));
let mut file = File::create(&path).unwrap();
writeln!(file, "#define L_{}", instruction_type).unwrap();
writeln!(file, "#define SIZE {}", size).unwrap();
writeln!(file, "#define MODEL {}", model_number).unwrap();
writeln!(
file,
"#include \"{}\"",
outlined_atomics_file.canonicalize().unwrap().display()
);
drop(file);
cfg.file(path);
let sym = format!("__aarch64_{}{}_{}", instruction_type, size, model_name);
let mut cfg = cfg.clone();
cfg.include(&builtins_dir)
.define(&format!("L_{}", instruction_type), None)
.define("SIZE", size.to_string().as_str())
.define("MODEL", model_number.to_string().as_str())
.file(&outlined_atomics_file);
cfg.compile(&library_name);
println!("cargo:rustc-cfg={}=\"optimized-c\"", sym);
}
}