Turns out for OSX our data layout was subtly wrong and the LLVM update must have
exposed this. Instead of fixing this I've removed all data layouts from the
compiler to just use the defaults that LLVM provides for all targets. All data
layouts (and a number of dead modules) are removed from the compiler here.
Custom target specifications can still provide a custom data layout, but it is
now an optional key as the default will be used if one isn't specified.
Updates our LLVM bindings to be able to write out multiple kinds of archives.
This commit also enables using LLVM instead of the system ar on all current
targets.
We have previously always relied upon an external tool, `ar`, to modify archives
that the compiler produces (staticlibs, rlibs, etc). This approach, however, has
a number of downsides:
* Spawning a process is relatively expensive for small compilations
* Encoding arguments across process boundaries often incurs unnecessary overhead
or lossiness. For example `ar` has a tough time dealing with files that have
the same name in archives, and the compiler copies many files around to ensure
they can be passed to `ar` in a reasonable fashion.
* Most `ar` programs found do **not** have the ability to target arbitrary
platforms, so this is an extra tool which needs to be found/specified when
cross compiling.
The LLVM project has had a tool called `llvm-ar` for quite some time now, but it
wasn't available in the standard LLVM libraries (it was just a standalone
program). Recently, however, in LLVM 3.7, this functionality has been moved to a
library and is now accessible by consumers of LLVM via the `writeArchive`
function.
This commit migrates our archive bindings to no longer invoke `ar` by default
but instead make a library call to LLVM to do various operations. This solves
all of the downsides listed above:
* Archive management is now much faster, for example creating a "hello world"
staticlib is now 6x faster (50ms => 8ms). Linking dynamic libraries also
recently started requiring modification of rlibs, and linking a hello world
dynamic library is now 2x faster.
* The compiler is now one step closer to "hassle free" cross compilation because
no external tool is needed for managing archives, LLVM does the right thing!
This commit does not remove support for calling a system `ar` utility currently.
We will continue to maintain compatibility with LLVM 3.5 and 3.6 looking forward
(so the system LLVM can be used wherever possible), and in these cases we must
shell out to a system utility. All nightly builds of Rust, however, will stop
needing a system `ar`.
The first one in particular results in Rust not being able to build itself
if it is installed. The latter two shouldn't be necessary, and should only
be included if they are actually going to be used.
Special thanks to @retep998 for the [excellent writeup](https://github.com/rust-lang/rfcs/issues/1061) of tasks to be done and @ricky26 for initially blazing the trail here!
# MSVC Support
This goal of this series of commits is to add MSVC support to the Rust compiler
and build system, allowing it more easily interoperate with Visual Studio
installations and native libraries compiled outside of MinGW.
The tl;dr; of this change is that there is a new target of the compiler,
`x86_64-pc-windows-msvc`, which will not interact with the MinGW toolchain at
all and will instead use `link.exe` to assemble output artifacts.
## Why try to use MSVC?
With today's Rust distribution, when you install a compiler on Windows you also
install `gcc.exe` and a number of supporting libraries by default (this can be
opted out of). This allows installations to remain independent of MinGW
installations, but it still generally requires native code to be linked with
MinGW instead of MSVC. Some more background can also be found in #1768 about the
incompatibilities between MinGW and MSVC.
Overall the current installation strategy is quite nice so long as you don't
interact with native code, but once you do the usage of a MinGW-based `gcc.exe`
starts to get quite painful.
Relying on a nonstandard Windows toolchain has also been a long-standing "code
smell" of Rust and has been slated for remedy for quite some time now. Using a
standard toolchain is a great motivational factor for improving the
interoperability of Rust code with the native system.
## What does it mean to use MSVC?
"Using MSVC" can be a bit of a nebulous concept, but this PR defines it as:
* The build system for Rust will build as much code as possible with the MSVC
compiler, `cl.exe`.
* The build system will use native MSVC tools for managing archives.
* The compiler will link all output with `link.exe` instead of `gcc.exe`.
None of these are currently implemented today, but all are required for the
compiler to fluently interoperate with MSVC.
## How does this all work?
At the highest level, this PR adds a new target triple to the Rust compiler:
x86_64-pc-windows-msvc
All logic for using MSVC or not is scoped within this triple and code can
conditionally build for MSVC or MinGW via:
#[cfg(target_env = "msvc")]
It is expected that auto builders will be set up for MSVC-based compiles in
addition to the existing MinGW-based compiles, and we will likely soon start
shipping MSVC nightlies where `x86_64-pc-windows-msvc` is the host target triple
of the compiler.
# Summary of changes
Here I'll explain at a high level what many of the changes made were targeted
at, but many more details can be found in the commits themselves. Many thanks to
@retep998 for the excellent writeup in rust-lang/rfcs#1061 and @rick26 for a lot
of the initial proof-of-concept work!
## Build system changes
As is probably expected, a large chunk of this PR is changes to Rust's build
system to build with MSVC. At a high level **it is an explicit non goal** to
enable building outside of a MinGW shell, instead all Makefile infrastructure we
have today is retrofitted with support to use MSVC instead of the standard MSVC
toolchain. Some of the high-level changes are:
* The configure script now detects when MSVC is being targeted and adds a number
of additional requirements about the build environment:
* The `--msvc-root` option must be specified or `cl.exe` must be in PATH to
discover where MSVC is installed. The compiler in use is also required to
target x86_64.
* Once the MSVC root is known, the INCLUDE/LIB environment variables are
scraped so they can be reexported by the build system.
* CMake is required to build LLVM with MSVC (and LLVM is also configured with
CMake instead of the normal configure script).
* jemalloc is currently unconditionally disabled for MSVC targets as jemalloc
isn't a hard requirement and I don't know how to build it with MSVC.
* Invocations of a C and/or C++ compiler are now abstracted behind macros to
appropriately call the underlying compiler with the correct format of
arguments, for example there is now a macro for "assemble an archive from
objects" instead of hard-coded invocations of `$(AR) crus liboutput.a ...`
* The output filenames for standard libraries such as morestack/compiler-rt are
now "more correct" on windows as they are shipped as `foo.lib` instead of
`libfoo.a`.
* Rust targets can now depend on native tools provided by LLVM, and as you'll
see in the commits the entire MSVC target depends on `llvm-ar.exe`.
* Support for custom arbitrary makefile dependencies of Rust targets has been
added. The MSVC target for `rustc_llvm` currently requires a custom `.DEF`
file to be passed to the linker to get further linkages to complete.
## Compiler changes
The modifications made to the compiler have so far largely been minor tweaks
here and there, mostly just adding a layer of abstraction over whether MSVC or a
GNU-like linker is being used. At a high-level these changes are:
* The section name for metadata storage in dynamic libraries is called `.rustc`
for MSVC-based platorms as section names cannot contain more than 8
characters.
* The implementation of `rustc_back::Archive` was refactored, but the
functionality has remained the same.
* Targets can now specify the default `ar` utility to use, and for MSVC this
defaults to `llvm-ar.exe`
* The building of the linker command in `rustc_trans:🔙:link` has been
abstracted behind a trait for the same code path to be used between GNU and
MSVC linkers.
## Standard library changes
Only a few small changes were required to the stadnard library itself, and only
for minor differences between the C runtime of msvcrt.dll and MinGW's libc.a
* Some function names for floating point functions have leading underscores, and
some are not present at all.
* Linkage to the `advapi32` library for crypto-related functions is now
explicit.
* Some small bits of C code here and there were fixed for compatibility with
MSVC's cl.exe compiler.
# Future Work
This commit is not yet a 100% complete port to using MSVC as there are still
some key components missing as well as some unimplemented optimizations. This PR
is already getting large enough that I wanted to draw the line here, but here's
a list of what is not implemented in this PR, on purpose:
## Unwinding
The revision of our LLVM submodule [does not seem to implement][llvm] does not
support lowering SEH exception handling on the Windows MSVC targets, so
unwinding support is not currently implemented for the standard library (it's
lowered to an abort).
[llvm]: https://github.com/rust-lang/llvm/blob/rust-llvm-2015-02-19/lib/CodeGen/Passes.cpp#L454-L461
It looks like, however, that upstream LLVM has quite a bit more support for SEH
unwinding and landing pads than the current revision we have, so adding support
will likely just involve updating LLVM and then adding some shims of our own
here and there.
## dllimport and dllexport
An interesting part of Windows which MSVC forces our hand on (and apparently
MinGW didn't) is the usage of `dllimport` and `dllexport` attributes in LLVM IR
as well as native dependencies (in C these correspond to
`__declspec(dllimport)`).
Whenever a dynamic library is built by MSVC it must have its public interface
specified by functions tagged with `dllexport` or otherwise they're not
available to be linked against. This poses a few problems for the compiler, some
of which are somewhat fundamental, but this commit alters the compiler to attach
the `dllexport` attribute to all LLVM functions that are reachable (e.g. they're
already tagged with external linkage). This is suboptimal for a few reasons:
* If an object file will never be included in a dynamic library, there's no need
to attach the dllexport attribute. Most object files in Rust are not destined
to become part of a dll as binaries are statically linked by default.
* If the compiler is emitting both an rlib and a dylib, the same source object
file is currently used but with MSVC this may be less feasible. The compiler
may be able to get around this, but it may involve some invasive changes to
deal with this.
The flipside of this situation is that whenever you link to a dll and you import
a function from it, the import should be tagged with `dllimport`. At this time,
however, the compiler does not emit `dllimport` for any declarations other than
constants (where it is required), which is again suboptimal for even more
reasons!
* Calling a function imported from another dll without using `dllimport` causes
the linker/compiler to have extra overhead (one `jmp` instruction on x86) when
calling the function.
* The same object file may be used in different circumstances, so a function may
be imported from a dll if the object is linked into a dll, but it may be
just linked against if linked into an rlib.
* The compiler has no knowledge about whether native functions should be tagged
dllimport or not.
For now the compiler takes the perf hit (I do not have any numbers to this
effect) by marking very little as `dllimport` and praying the linker will take
care of everything. Fixing this problem will likely require adding a few
attributes to Rust itself (feature gated at the start) and then strongly
recommending static linkage on Windows! This may also involve shipping a
statically linked compiler on Windows instead of a dynamically linked compiler,
but these sorts of changes are pretty invasive and aren't part of this PR.
## CI integration
Thankfully we don't need to set up a new snapshot bot for the changes made here as our snapshots are freestanding already, we should be able to use the same snapshot to bootstrap both MinGW and MSVC compilers (once a new snapshot is made from these changes).
I plan on setting up a new suite of auto bots which are testing MSVC configurations for now as well, for now they'll just be bootstrapping and not running tests, but once unwinding is implemented they'll start running all tests as well and we'll eventually start gating on them as well.
---
I'd love as many eyes on this as we've got as this was one of my first interactions with MSVC and Visual Studio, so there may be glaring holes that I'm missing here and there!
cc @retep998, @ricky26, @vadimcn, @klutzy
r? @brson
This is OK to do given:
- PIE is supported on Android starting with API 16.
- The bots are running API 18.
- API < 16 now has a 12.5% market share[0] as of 2015-04-29.
Unfortunately, this breaks backtrace support. See #17520.
Closes#17437.
[0] https://developer.android.com/about/dashboards/index.html
This commit adds support for x86_64-unknown-linux-musl as a target of the
compiler. There's some comments in the commit about some of the more flavorful
flags passed to the linker as it's not quite as trivial as the normal specs.
This adds a new `#[cfg]` matcher against the `target_env` property of the
destination target triple. For example all windows triples today end with `-gnu`
but we will also hopefully support non-`gnu` targets for Windows, at which point
we'll need to differentiate between the two. This new `target_env` matches is
provided and filled in with the target's environment name.
Currently the only non-empty value of this name is `gnu`, but `musl` will be
shortly added for the linux triples.
This commit stabilizes a few remaining bits of the `io::Error` type:
* The `Error::new` method is now stable. The last `detail` parameter was removed
and the second `desc` parameter was generalized to `E: Into<Box<Error>>` to
allow creating an I/O error from any form of error. Currently there is no form
of downcasting, but this will be added in time.
* An implementation of `From<&str> for Box<Error>` was added to liballoc to
allow construction of errors from raw strings.
* The `Error::raw_os_error` method was stabilized as-is.
* Trait impls for `Clone`, `Eq`, and `PartialEq` were removed from `Error` as it
is not possible to use them with trait objects.
This is a breaking change due to the modification of the `new` method as well as
the removal of the trait implementations for the `Error` type.
[breaking-change]
This commit:
* Introduces `std::convert`, providing an implementation of
RFC 529.
* Deprecates the `AsPath`, `AsOsStr`, and `IntoBytes` traits, all
in favor of the corresponding generic conversion traits.
Consequently, various IO APIs now take `AsRef<Path>` rather than
`AsPath`, and so on. Since the types provided by `std` implement both
traits, this should cause relatively little breakage.
* Deprecates many `from_foo` constructors in favor of `from`.
* Changes `PathBuf::new` to take no argument (creating an empty buffer,
as per convention). The previous behavior is now available as
`PathBuf::from`.
* De-stabilizes `IntoCow`. It's not clear whether we need this separate trait.
Closes#22751Closes#14433
[breaking-change]
This module is now superseded by the `std::process` module. This module still
has some room to expand to get quite back up to parity with the `old_io`
version, and there is a [tracking issue][issue] for feature requests as well as
known room for expansion.
[issue]: https://github.com/rust-lang/rfcs/issues/941
[breaking-change]
This commit deprecates the majority of std::old_io::fs in favor of std::fs and
its new functionality. Some functions remain non-deprecated but are now behind a
feature gate called `old_fs`. These functions will be deprecated once
suitable replacements have been implemented.
The compiler has been migrated to new `std::fs` and `std::path` APIs where
appropriate as part of this change.
This commit moves `std::env` away from the `std::old_io` error type as well as
the `std::old_path` module. Methods returning an error now return `io::Error`
and methods consuming or returning paths use `std::path` instead of
`std::old_path`. This commit does not yet mark these APIs as `#[stable]`.
This commit also migrates `std::old_io::TempDir` to `std::fs::TempDir` with
essentially the exact same API. This type was added to interoperate with the new
path API and has its own `tempdir` feature.
Finally, this commit reverts the deprecation of `std::os` APIs returning the old
path API types. This deprecation can come back once the entire `std::old_path`
module is deprecated.
[breaking-change]
This commit moves `std::env` away from the `std::old_io` error type as well as
the `std::old_path` module. Methods returning an error now return `io::Error`
and methods consuming or returning paths use `std::path` instead of
`std::old_path`. This commit does not yet mark these APIs as `#[stable]`.
This commit also migrates `std::old_io::TempDir` to `std::fs::TempDir` with
essentially the exact same API. This type was added to interoperate with the new
path API and has its own `tempdir` feature.
Finally, this commit reverts the deprecation of `std::os` APIs returning the old
path API types. This deprecation can come back once the entire `std::old_path`
module is deprecated.
[breaking-change]
This aligns json target specification to match terminology used elsewhere in the code base.
[breaking-change] for custom target json users. Change all appearances of target-word-size
to target-pointer-width.
- Now "make check-stage2-T-aarch64-linux-android-H-x86_64-unknown-linux-gnu" works (#21773)
- Fix & enable debuginfo tests for android (#10381)
- Fix & enable more tests for android (both for arm/aarch64)
- Enable many already-pass tests on android (both for arm/aarch64)
This PR replaces uses of `os::getenv` with newly introduced `env::var{,_os}`.
Mostly did this as a background activity to procrastinate from procrastinating.
Tests appear to build and run fine. This includes benchmarks from test/bench directory.
This commit tweaks the interface of the `std::env` module to make it more
ergonomic for common usage:
* `env::var` was renamed to `env::var_os`
* `env::var_string` was renamed to `env::var`
* `env::args` was renamed to `env::args_os`
* `env::args` was re-added as a panicking iterator over string values
* `env::vars` was renamed to `env::vars_os`
* `env::vars` was re-added as a panicking iterator over string values.
This should make common usage (e.g. unicode values everywhere) more ergonomic
as well as "the default". This is also a breaking change due to the differences
of what's yielded from each of these functions, but migration should be fairly
easy as the defaults operate over `String` which is a common type to use.
[breaking-change]
This aligns json target specification to match terminology used elsewhere in the code base.
[breaking-change] for custom target json users. Change all appearances of target-word-size
to target-pointer-width.
As part of [RFC 474](https://github.com/rust-lang/rfcs/pull/474), this
commit renames `std::path` to `std::old_path`, leaving the existing path
API in place to ease migration to the new one. Updating should be as
simple as adjusting imports, and the prelude still maps to the old path
APIs for now.
[breaking-change]
This is an implementation of [RFC 578][rfc] which adds a new `std::env` module
to replace most of the functionality in the current `std::os` module. More
details can be found in the RFC itself, but as a summary the following methods
have all been deprecated:
[rfc]: https://github.com/rust-lang/rfcs/pull/578
* `os::args_as_bytes` => `env::args`
* `os::args` => `env::args`
* `os::consts` => `env::consts`
* `os::dll_filename` => no replacement, use `env::consts` directly
* `os::page_size` => `env::page_size`
* `os::make_absolute` => use `env::current_dir` + `join` instead
* `os::getcwd` => `env::current_dir`
* `os::change_dir` => `env::set_current_dir`
* `os::homedir` => `env::home_dir`
* `os::tmpdir` => `env::temp_dir`
* `os::join_paths` => `env::join_paths`
* `os::split_paths` => `env::split_paths`
* `os::self_exe_name` => `env::current_exe`
* `os::self_exe_path` => use `env::current_exe` + `pop`
* `os::set_exit_status` => `env::set_exit_status`
* `os::get_exit_status` => `env::get_exit_status`
* `os::env` => `env::vars`
* `os::env_as_bytes` => `env::vars`
* `os::getenv` => `env::var` or `env::var_string`
* `os::getenv_as_bytes` => `env::var`
* `os::setenv` => `env::set_var`
* `os::unsetenv` => `env::remove_var`
Many function signatures have also been tweaked for various purposes, but the
main changes were:
* `Vec`-returning APIs now all return iterators instead
* All APIs are now centered around `OsString` instead of `Vec<u8>` or `String`.
There is currently on convenience API, `env::var_string`, which can be used to
get the value of an environment variable as a unicode `String`.
All old APIs are `#[deprecated]` in-place and will remain for some time to allow
for migrations. The semantics of the APIs have been tweaked slightly with regard
to dealing with invalid unicode (panic instead of replacement).
The new `std::env` module is all contained within the `env` feature, so crates
must add the following to access the new APIs:
#![feature(env)]
[breaking-change]
