13 src/librustc/session/config.rs
View file
@@ -1545,19 +1545,6 @@ pub fn build_session_options_and_crate_config(matches: &getopts::Matches)
early_error(error_format, "Value for codegen units must be a positive nonzero integer");
}

// It's possible that we have `codegen_units > 1` but only one item in
// `trans.modules`. We could theoretically proceed and do LTO in that
// case, but it would be confusing to have the validity of
// `-Z lto -C codegen-units=2` depend on details of the crate being
// compiled, so we complain regardless.
if cg.lto && cg.codegen_units > 1 {
// This case is impossible to handle because LTO expects to be able
// to combine the entire crate and all its dependencies into a
// single compilation unit, but each codegen unit is in a separate
// LLVM context, so they can't easily be combined.
early_error(error_format, "can't perform LTO when using multiple codegen units");
}

if cg.lto && debugging_opts.incremental.is_some() {
early_error(error_format, "can't perform LTO when compiling incrementally");
}
7 src/librustc_llvm/ffi.rs
View file
@@ -478,6 +478,7 @@ pub mod debuginfo {
}
}

pub enum ModuleBuffer {}

// Link to our native llvm bindings (things that we need to use the C++ api
// for) and because llvm is written in C++ we need to link against libstdc++
@@ -1609,6 +1610,7 @@ extern "C" {
pub fn LLVMRustSetNormalizedTarget(M: ModuleRef, triple: *const c_char);
pub fn LLVMRustAddAlwaysInlinePass(P: PassManagerBuilderRef, AddLifetimes: bool);
pub fn LLVMRustLinkInExternalBitcode(M: ModuleRef, bc: *const c_char, len: size_t) -> bool;
pub fn LLVMRustLinkInParsedExternalBitcode(M: ModuleRef, M: ModuleRef) -> bool;
pub fn LLVMRustRunRestrictionPass(M: ModuleRef, syms: *const *const c_char, len: size_t);
pub fn LLVMRustMarkAllFunctionsNounwind(M: ModuleRef);

@@ -1678,4 +1680,9 @@ extern "C" {
pub fn LLVMRustSetComdat(M: ModuleRef, V: ValueRef, Name: *const c_char);
pub fn LLVMRustUnsetComdat(V: ValueRef);
pub fn LLVMRustSetModulePIELevel(M: ModuleRef);
pub fn LLVMRustModuleBufferCreate(M: ModuleRef) -> *mut ModuleBuffer;
pub fn LLVMRustModuleBufferPtr(p: *const ModuleBuffer) -> *const u8;
pub fn LLVMRustModuleBufferLen(p: *const ModuleBuffer) -> usize;
pub fn LLVMRustModuleBufferFree(p: *mut ModuleBuffer);
pub fn LLVMRustModuleCost(M: ModuleRef) -> u64;
}
8 src/librustc_trans/back/archive.rs
View file
@@ -17,6 +17,7 @@ use std::path::{Path, PathBuf};
use std::ptr;
use std::str;

use back::bytecode::RLIB_BYTECODE_EXTENSION;
use libc;
use llvm::archive_ro::{ArchiveRO, Child};
use llvm::{self, ArchiveKind};
@@ -154,12 +155,9 @@ impl<'a> ArchiveBuilder<'a> {
// might be also an extra name suffix
let obj_start = format!("{}", name);

// Ignoring all bytecode files, no matter of
// name
let bc_ext = ".bytecode.deflate";

self.add_archive(rlib, move |fname: &str| {
if fname.ends_with(bc_ext) || fname == METADATA_FILENAME {
// Ignore bytecode/metadata files, no matter the name.
if fname.ends_with(RLIB_BYTECODE_EXTENSION) || fname == METADATA_FILENAME {
return true
}

160 src/librustc_trans/back/bytecode.rs
View file
@@ -0,0 +1,160 @@
// Copyright 2017 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.

//! Management of the encoding of LLVM bytecode into rlibs
//!
//! This module contains the management of encoding LLVM bytecode into rlibs,
//! primarily for the usage in LTO situations. Currently the compiler will
//! unconditionally encode LLVM-IR into rlibs regardless of what's happening
//! elsewhere, so we currently compress the bytecode via deflate to avoid taking
//! up too much space on disk.
//!
//! After compressing the bytecode we then have the rest of the format to
//! basically deal with various bugs in various archive implementations. The
//! format currently is:
//!
//! RLIB LLVM-BYTECODE OBJECT LAYOUT
//! Version 2
//! Bytes Data
//! 0..10 "RUST_OBJECT" encoded in ASCII
//! 11..14 format version as little-endian u32
//! 15..19 the length of the module identifier string
//! 20..n the module identifier string
//! n..n+8 size in bytes of deflate compressed LLVM bitcode as
//! little-endian u64
//! n+9.. compressed LLVM bitcode
//! ? maybe a byte to make this whole thing even length

use std::io::{Read, Write};
use std::ptr;
use std::str;

use flate2::Compression;
use flate2::read::DeflateDecoder;
use flate2::write::DeflateEncoder;

// This is the "magic number" expected at the beginning of a LLVM bytecode
// object in an rlib.
pub const RLIB_BYTECODE_OBJECT_MAGIC: &'static [u8] = b"RUST_OBJECT";

// The version number this compiler will write to bytecode objects in rlibs
pub const RLIB_BYTECODE_OBJECT_VERSION: u8 = 2;

pub const RLIB_BYTECODE_EXTENSION: &str = "bytecode.encoded";

pub fn encode(identifier: &str, bytecode: &[u8]) -> Vec<u8> {
let mut encoded = Vec::new();

// Start off with the magic string
encoded.extend_from_slice(RLIB_BYTECODE_OBJECT_MAGIC);

// Next up is the version
encoded.extend_from_slice(&[RLIB_BYTECODE_OBJECT_VERSION, 0, 0, 0]);

// Next is the LLVM module identifier length + contents
let identifier_len = identifier.len();
encoded.extend_from_slice(&[
(identifier_len >> 0) as u8,
(identifier_len >> 8) as u8,
(identifier_len >> 16) as u8,
(identifier_len >> 24) as u8,
]);
encoded.extend_from_slice(identifier.as_bytes());

// Next is the LLVM module deflate compressed, prefixed with its length. We
// don't know its length yet, so fill in 0s
let deflated_size_pos = encoded.len();
encoded.extend_from_slice(&[0, 0, 0, 0, 0, 0, 0, 0]);

let before = encoded.len();
DeflateEncoder::new(&mut encoded, Compression::Fast)
.write_all(bytecode)
.unwrap();
let after = encoded.len();

// Fill in the length we reserved space for before
let bytecode_len = (after - before) as u64;
encoded[deflated_size_pos + 0] = (bytecode_len >> 0) as u8;
encoded[deflated_size_pos + 1] = (bytecode_len >> 8) as u8;
encoded[deflated_size_pos + 2] = (bytecode_len >> 16) as u8;
encoded[deflated_size_pos + 3] = (bytecode_len >> 24) as u8;
encoded[deflated_size_pos + 4] = (bytecode_len >> 32) as u8;
encoded[deflated_size_pos + 5] = (bytecode_len >> 40) as u8;
encoded[deflated_size_pos + 6] = (bytecode_len >> 48) as u8;
encoded[deflated_size_pos + 7] = (bytecode_len >> 56) as u8;

// If the number of bytes written to the object so far is odd, add a
// padding byte to make it even. This works around a crash bug in LLDB
// (see issue #15950)
if encoded.len() % 2 == 1 {
encoded.push(0);
}

return encoded
}

pub struct DecodedBytecode<'a> {
identifier: &'a str,
encoded_bytecode: &'a [u8],
}

impl<'a> DecodedBytecode<'a> {
pub fn new(data: &'a [u8]) -> Result<DecodedBytecode<'a>, String> {
if !data.starts_with(RLIB_BYTECODE_OBJECT_MAGIC) {
return Err(format!("magic bytecode prefix not found"))
}
let data = &data[RLIB_BYTECODE_OBJECT_MAGIC.len()..];
if !data.starts_with(&[RLIB_BYTECODE_OBJECT_VERSION, 0, 0, 0]) {
return Err(format!("wrong version prefix found in bytecode"))
}
let data = &data[4..];
if data.len() < 4 {
return Err(format!("bytecode corrupted"))
}
let identifier_len = unsafe {
u32::from_le(ptr::read_unaligned(data.as_ptr() as *const u32)) as usize
};
let data = &data[4..];
if data.len() < identifier_len {
return Err(format!("bytecode corrupted"))
}
let identifier = match str::from_utf8(&data[..identifier_len]) {
Ok(s) => s,
Err(_) => return Err(format!("bytecode corrupted"))
};
let data = &data[identifier_len..];
if data.len() < 8 {
return Err(format!("bytecode corrupted"))
}
let bytecode_len = unsafe {
u64::from_le(ptr::read_unaligned(data.as_ptr() as *const u64)) as usize
};
let data = &data[8..];
if data.len() < bytecode_len {
return Err(format!("bytecode corrupted"))
}
let encoded_bytecode = &data[..bytecode_len];

Ok(DecodedBytecode {
identifier,
encoded_bytecode,
})
}

pub fn bytecode(&self) -> Vec<u8> {
let mut data = Vec::new();
DeflateDecoder::new(self.encoded_bytecode).read_to_end(&mut data).unwrap();
return data
}

pub fn identifier(&self) -> &'a str {
self.identifier
}
}