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bors 7aa407958b auto merge of #15998 : luqmana/rust/nmnnbd, r=thestinger
LLVM recently added a new attribute, dereferenceable: http://reviews.llvm.org/D4449

>This patch adds a dereferencable attribute. In some sense, this is a companion to the nonnull attribute, but specifies that the pointer is known to be dereferencable in the same sense as a pointer generated by alloca is known to be dereferencable.

With rust, everywhere that we previously marked `nonnull` we can actually mark as `dereferenceable` (which implies nonnull) since we know the size. That is, except for one case: when generating calls for TyVisitor. It seems like we haven't substituted the self type (so we have `ty_param`) and just treat it as an opaque pointer so I just left that bit as nonnull.

With this, LLVM can for example hoist a load out of a loop where it previously couldn't:

```Rust
pub fn baz(c: &uint, n: uint) -> uint {
    let mut res = 0;
    for i in range(0, n) {
        if i > 0 {
            res += *c * i;
        }
    }
    res
}
```

Before:
```llvm
define i64 @baz(i64* noalias nocapture nonnull readonly, i64) unnamed_addr #0 {
entry-block:
  br label %for_loopback.outer

for_loopback.outer:                               ; preds = %then-block-33-, %entry-block
  %.ph = phi i64 [ %.lcssa, %then-block-33- ], [ 0, %entry-block ]
  %res.0.ph = phi i64 [ %8, %then-block-33- ], [ 0, %entry-block ]
  br label %for_loopback

for_exit:                                         ; preds = %for_loopback
  %res.0.ph.lcssa = phi i64 [ %res.0.ph, %for_loopback ]
  ret i64 %res.0.ph.lcssa

for_loopback:                                     ; preds = %for_loopback.outer, %for_body
  %2 = phi i64 [ %4, %for_body ], [ %.ph, %for_loopback.outer ]
  %3 = icmp ult i64 %2, %1
  br i1 %3, label %for_body, label %for_exit

for_body:                                         ; preds = %for_loopback
  %4 = add i64 %2, 1
  %5 = icmp eq i64 %2, 0
  br i1 %5, label %for_loopback, label %then-block-33-

then-block-33-:                                   ; preds = %for_body
  %.lcssa = phi i64 [ %4, %for_body ]
  %.lcssa15 = phi i64 [ %2, %for_body ]
  %6 = load i64* %0, align 8                     ; <------- this load
  %7 = mul i64 %6, %.lcssa15
  %8 = add i64 %7, %res.0.ph
  br label %for_loopback.outer
}
```

After:
```llvm
define i64 @baz(i64* noalias nocapture readonly dereferenceable(8), i64) unnamed_addr #0 {
entry-block:
  %2 = load i64* %0, align 8                    ; <------- load once instead
  br label %for_loopback.outer

for_loopback.outer:                               ; preds = %then-block-33-, %entry-block
  %.ph = phi i64 [ %.lcssa, %then-block-33- ], [ 0, %entry-block ]
  %res.0.ph = phi i64 [ %8, %then-block-33- ], [ 0, %entry-block ]
  br label %for_loopback

for_exit:                                         ; preds = %for_loopback
  %res.0.ph.lcssa = phi i64 [ %res.0.ph, %for_loopback ]
  ret i64 %res.0.ph.lcssa

for_loopback:                                     ; preds = %for_loopback.outer, %for_body
  %3 = phi i64 [ %5, %for_body ], [ %.ph, %for_loopback.outer ]
  %4 = icmp ult i64 %3, %1
  br i1 %4, label %for_body, label %for_exit

for_body:                                         ; preds = %for_loopback
  %5 = add i64 %3, 1
  %6 = icmp eq i64 %3, 0
  br i1 %6, label %for_loopback, label %then-block-33-

then-block-33-:                                   ; preds = %for_body
  %.lcssa = phi i64 [ %5, %for_body ]
  %.lcssa15 = phi i64 [ %3, %for_body ]
  %7 = mul i64 %2, %.lcssa15
  %8 = add i64 %7, %res.0.ph
  br label %for_loopback.outer
}
```
2014-07-26 15:46:18 +00:00
man rustc.1: fix typo 2014-07-16 08:01:59 +02:00
mk mk: Print grammar info message like others 2014-07-25 14:32:34 -07:00
src auto merge of #15998 : luqmana/rust/nmnnbd, r=thestinger 2014-07-26 15:46:18 +00:00
.gitattributes webfonts: proper fix 2014-07-08 20:29:36 +02:00
.gitignore Move llvm bindings to their own crate 2014-07-14 12:27:07 -07:00
.gitmodules add back jemalloc to the tree 2014-05-10 19:58:17 -04:00
.mailmap .mailmap: tolerate different names, emails in shortlog 2013-06-05 23:26:00 +05:30
.travis.yml travis: Move from travis_wait to time-passes 2014-07-01 20:21:16 -07:00
AUTHORS.txt Updated release notes for 0.11.0 2014-06-30 07:25:58 -07:00
configure configure: Add --enable-dist-host-only flag 2014-07-23 12:04:27 -07:00
CONTRIBUTING.md Update repo location 2014-06-16 18:16:36 -07:00
COPYRIGHT Update some copyright dates 2014-01-08 18:04:43 -08:00
LICENSE-APACHE Update license, add license boilerplate to most files. Remainder will follow. 2012-12-03 17:12:14 -08:00
LICENSE-MIT Change the licence holder to The Rust Project Developers 2014-05-03 23:59:24 +02:00
Makefile.in Shuffle around check-lexer conditions 2014-07-21 18:38:40 -07:00
README.md fix typo in readme 2014-06-30 11:17:25 +02:00
RELEASES.txt Update RELEASES.txt 2014-07-05 00:22:59 -04:00

The Rust Programming Language

This is a compiler for Rust, including standard libraries, tools and documentation.

Quick Start

  1. Download a binary installer for your platform.
  2. Read the tutorial.
  3. Enjoy!

Note: Windows users can read the detailed getting started notes on the wiki.

Building from Source

  1. Make sure you have installed the dependencies:

    • g++ 4.7 or clang++ 3.x
    • python 2.6 or later (but not 3.x)
    • perl 5.0 or later
    • GNU make 3.81 or later
    • curl
    • git
  2. Download and build Rust:

    You can either download a tarball or build directly from the repo.

    To build from the tarball do:

     $ curl -O http://static.rust-lang.org/dist/rust-nightly.tar.gz
     $ tar -xzf rust-nightly.tar.gz
     $ cd rust-nightly
    

    Or to build from the repo do:

     $ git clone https://github.com/rust-lang/rust.git
     $ cd rust
    

    Now that you have Rust's source code, you can configure and build it:

     $ ./configure
     $ make && make install
    

    Note: You may need to use sudo make install if you do not normally have permission to modify the destination directory. The install locations can be adjusted by passing a --prefix argument to configure. Various other options are also supported, pass --help for more information on them.

    When complete, make install will place several programs into /usr/local/bin: rustc, the Rust compiler, and rustdoc, the API-documentation tool.

  3. Read the tutorial.

  4. Enjoy!

Building on Windows

To easily build on windows we can use MSYS2:

  1. Grab the latest MSYS2 installer and go through the installer.

  2. Now from the MSYS2 terminal we want to install the mingw64 toolchain and the other tools we need.

     $ pacman -S mingw-w64-i686-toolchain
     $ pacman -S base-devel
    
  3. With that now start mingw32_shell.bat from where you installed MSYS2 (i.e. C:\msys).

  4. From there just navigate to where you have Rust's source code, configure and build it:

     $ ./configure --build=i686-pc-mingw32
     $ make && make install
    

Notes

Since the Rust compiler is written in Rust, it must be built by a precompiled "snapshot" version of itself (made in an earlier state of development). As such, source builds require a connection to the Internet, to fetch snapshots, and an OS that can execute the available snapshot binaries.

Snapshot binaries are currently built and tested on several platforms:

  • Windows (7, 8, Server 2008 R2), x86 only
  • Linux (2.6.18 or later, various distributions), x86 and x86-64
  • OSX 10.7 (Lion) or greater, x86 and x86-64

You may find that other platforms work, but these are our officially supported build environments that are most likely to work.

Rust currently needs about 1.5 GiB of RAM to build without swapping; if it hits swap, it will take a very long time to build.

There is a lot more documentation in the wiki.

License

Rust is primarily distributed under the terms of both the MIT license and the Apache License (Version 2.0), with portions covered by various BSD-like licenses.

See LICENSE-APACHE, LICENSE-MIT, and COPYRIGHT for details.