1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135

// 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 driver::config;
use lib::llvm::{ModuleRef, TargetMachineRef, llvm, True, False};
use metadata::cstore;
use util::common::time;

use libc;
use flate;

pub fn run(sess: &session::Session, llmod: ModuleRef,
           tm: TargetMachineRef, reachable: &[String]) {
    if sess.opts.cg.prefer_dynamic {
        sess.err("cannot prefer dynamic linking when performing LTO");
        sess.note("only 'staticlib' and 'bin' outputs are supported with LTO");
        sess.abort_if_errors();
    }

    // Make sure we actually can run LTO
    for crate_type in sess.crate_types.borrow().iter() {
        match *crate_type {
            config::CrateTypeExecutable | config::CrateTypeStaticlib => {}
            _ => {
                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.clone();
        let path = match path {
            Some(p) => p,
            None => {
                sess.fatal(format!("could not find rlib for: `{}`",
                                   name).as_slice());
            }
        };

        let archive = ArchiveRO::open(&path).expect("wanted an rlib");
        debug!("reading {}", name);
        let bc = time(sess.time_passes(),
                      format!("read {}.bytecode.deflate", name).as_slice(),
                      (),
                      |_| {
                          archive.read(format!("{}.bytecode.deflate",
                                               name).as_slice())
                      });
        let bc = bc.expect("missing compressed bytecode in archive!");
        let bc = time(sess.time_passes(),
                      format!("inflate {}.bc", name).as_slice(),
                      (),
                      |_| {
                          match flate::inflate_bytes(bc) {
                              Some(bc) => bc,
                              None => {
                                  sess.fatal(format!("failed to decompress \
                                                      bc of `{}`",
                                                     name).as_slice())
                              }
                          }
                      });
        let ptr = bc.as_slice().as_ptr();
        debug!("linking {}", name);
        time(sess.time_passes(),
             format!("ll link {}", name).as_slice(),
             (),
             |()| 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.as_slice()));
            }
        });
    }

    // Internalize everything but the reachable symbols of the current module
    let cstrs: Vec<::std::c_str::CString> =
        reachable.iter().map(|s| s.as_slice().to_c_str()).collect();
    let arr: Vec<*i8> = cstrs.iter().map(|c| c.with_ref(|p| p)).collect();
    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");
}