rust/src/librustc/back/lto.rs
2013-12-25 21:50:36 -07:00

103 lines
3.8 KiB
Rust

// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use back::archive::ArchiveRO;
use back::link;
use driver::session;
use lib::llvm::{ModuleRef, TargetMachineRef, llvm, True, False};
use metadata::cstore;
use util::common::time;
use std::libc;
pub fn run(sess: session::Session, llmod: ModuleRef,
tm: TargetMachineRef, reachable: &[~str]) {
// Make sure we actually can run LTO
for output in sess.outputs.iter() {
match *output {
session::OutputExecutable | session::OutputStaticlib => {}
_ => {
sess.fatal("lto can only be run for executables and \
static library outputs");
}
}
}
// 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.
let crates = sess.cstore.get_used_crates(cstore::RequireStatic);
for (cnum, path) in crates.move_iter() {
let name = sess.cstore.get_crate_data(cnum).name;
let path = match path {
Some(p) => p,
None => {
sess.fatal(format!("could not find rlib for: `{}`", name));
}
};
let archive = ArchiveRO::open(&path).expect("wanted an rlib");
debug!("reading {}", name);
let bc = time(sess.time_passes(), format!("read {}.bc", name), (), |_|
archive.read(format!("{}.bc", name)));
let bc = bc.expect("missing bytecode in archive!");
let ptr = bc.as_ptr();
debug!("linking {}", name);
time(sess.time_passes(), format!("ll link {}", name), (), |()| unsafe {
if !llvm::LLVMRustLinkInExternalBitcode(llmod,
ptr as *libc::c_char,
bc.len() as libc::size_t) {
link::llvm_err(sess, format!("failed to load bc of `{}`", name));
}
});
}
// Internalize everything but the reachable symbols of the current module
let cstrs = reachable.map(|s| s.to_c_str());
let arr = cstrs.map(|c| c.with_ref(|p| p));
let ptr = arr.as_ptr();
unsafe {
llvm::LLVMRustRunRestrictionPass(llmod, ptr as **libc::c_char,
arr.len() as libc::size_t);
}
if sess.no_landing_pads() {
unsafe {
llvm::LLVMRustMarkAllFunctionsNounwind(llmod);
}
}
// Now we have one massive module inside of llmod. Time to run the
// LTO-specific optimization passes that LLVM provides.
//
// This code is based off the code found in llvm's LTO code generator:
// tools/lto/LTOCodeGenerator.cpp
debug!("running the pass manager");
unsafe {
let pm = llvm::LLVMCreatePassManager();
llvm::LLVMRustAddAnalysisPasses(tm, pm, llmod);
"verify".with_c_str(|s| llvm::LLVMRustAddPass(pm, s));
let builder = llvm::LLVMPassManagerBuilderCreate();
llvm::LLVMPassManagerBuilderPopulateLTOPassManager(builder, pm,
/* Internalize = */ False,
/* RunInliner = */ True);
llvm::LLVMPassManagerBuilderDispose(builder);
"verify".with_c_str(|s| llvm::LLVMRustAddPass(pm, s));
time(sess.time_passes(), "LTO pases", (), |()|
llvm::LLVMRunPassManager(pm, llmod));
llvm::LLVMDisposePassManager(pm);
}
debug!("lto done");
}