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exclude #![no_builtins] crates from LTO

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this prevents intrinsics like `memcpy` from being mis-optimized to
infinite recursive calls when LTO is used.

fixes #31544
closes #35540
This commit is contained in:
Jorge Aparicio 2016-08-12 21:15:42 -05:00
parent 8787a12334
commit db16909ae3
2 changed files with 28 additions and 11 deletions
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28
src/librustc_trans/back/link.rs
View file

@ -42,7 +42,7 @@ use std::process::Command;
use std::str;
use flate;
use syntax::ast;
use syntax::attr::AttrMetaMethods;
use syntax::attr::{self, AttrMetaMethods};
use syntax_pos::Span;
// RLIB LLVM-BYTECODE OBJECT LAYOUT
@ -938,8 +938,10 @@ fn add_upstream_rust_crates(cmd: &mut Linker,
Linkage::NotLinked |
Linkage::IncludedFromDylib => {}
Linkage::Static => {
let is_a_no_builtins_crate =
attr::contains_name(&sess.cstore.crate_attrs(cnum), "no_builtins");
add_static_crate(cmd, sess, tmpdir, crate_type,
&src.rlib.unwrap().0)
&src.rlib.unwrap().0, is_a_no_builtins_crate)
}
Linkage::Dynamic => {
add_dynamic_crate(cmd, sess, &src.dylib.unwrap().0)
@ -963,12 +965,16 @@ fn add_upstream_rust_crates(cmd: &mut Linker,
// * For LTO, we remove upstream object files.
// * For dylibs we remove metadata and bytecode from upstream rlibs
//
// When performing LTO, all of the bytecode from the upstream libraries has
// already been included in our object file output. As a result we need to
// remove the object files in the upstream libraries so the linker doesn't
// try to include them twice (or whine about duplicate symbols). We must
// continue to include the rest of the rlib, however, as it may contain
// static native libraries which must be linked in.
// When performing LTO, almost(*) all of the bytecode from the upstream
// libraries has already been included in our object file output. As a
// result we need to remove the object files in the upstream libraries so
// the linker doesn't try to include them twice (or whine about duplicate
// symbols). We must continue to include the rest of the rlib, however, as
// it may contain static native libraries which must be linked in.
//
// (*) Crates marked with `#![no_builtins]` don't participate in LTO and
// their bytecode wasn't included. The object files in those libraries must
// still be passed to the linker.
//
// When making a dynamic library, linkers by default don't include any
// object files in an archive if they're not necessary to resolve the link.
@ -988,7 +994,8 @@ fn add_upstream_rust_crates(cmd: &mut Linker,
sess: &Session,
tmpdir: &Path,
crate_type: config::CrateType,
cratepath: &Path) {
cratepath: &Path,
is_a_no_builtins_crate: bool) {
if !sess.lto() && crate_type != config::CrateTypeDylib {
cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath));
return
@ -1012,7 +1019,8 @@ fn add_upstream_rust_crates(cmd: &mut Linker,
}
let canonical = f.replace("-", "_");
let canonical_name = name.replace("-", "_");
if sess.lto() && canonical.starts_with(&canonical_name) &&
if sess.lto() && !is_a_no_builtins_crate &&
canonical.starts_with(&canonical_name) &&
canonical.ends_with(".o") {
let num = &f[name.len()..f.len() - 2];
if num.len() > 0 && num[1..].parse::<u32>().is_ok() {

11
src/librustc_trans/back/lto.rs
View file

@ -17,6 +17,7 @@ use llvm::{ModuleRef, TargetMachineRef, True, False};
use rustc::util::common::time;
use rustc::util::common::path2cstr;
use back::write::{ModuleConfig, with_llvm_pmb};
use syntax::attr;
use libc;
use flate;
@ -52,7 +53,15 @@ pub fn run(sess: &session::Session, llmod: ModuleRef,
// For each of our upstream dependencies, find the corresponding rlib and
// load the bitcode from the archive. Then merge it into the current LLVM
// module that we've got.
link::each_linked_rlib(sess, &mut |_, path| {
link::each_linked_rlib(sess, &mut |cnum, path| {
let is_a_no_builtins_crate =
attr::contains_name(&sess.cstore.crate_attrs(cnum), "no_builtins");
// `#![no_builtins]` crates don't participate in LTO.
if is_a_no_builtins_crate {
return;
}
let archive = ArchiveRO::open(&path).expect("wanted an rlib");
let bytecodes = archive.iter().filter_map(|child| {
child.ok().and_then(|c| c.name().map(|name| (name, c)))