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merged 1 commit into from
May 27, 2015

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SimonSapin
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This test would fail with Option. Should we also assert that?

    assert!(match Some(zero) {
        Some(_) => false,
        None => true  // Not really expected, but demonstrates the issue.
     });

bluss added a commit that referenced this pull request May 27, 2015
Add a test for #[repr] as used in arrayvec
@bluss bluss merged commit e57f69f into bluss:doc-enum-repr May 27, 2015
bluss pushed a commit that referenced this pull request Aug 2, 2015
bluss pushed a commit that referenced this pull request Dec 6, 2015
…hange

Change verbiage in Stack & Heap page
bluss pushed a commit that referenced this pull request Feb 6, 2016
update tests emitter.rs
bluss added a commit that referenced this pull request Feb 26, 2016
Change import a trait suggestion from:

   help: candidate #1: use `std::io::Write`

to

   help: candidate #1: `use std::io::Write`

so that the code can be copied directly.
bluss pushed a commit that referenced this pull request Mar 4, 2016
suggest: Put the `use` in suggested code inside the quotes

Change import a trait suggestion from:

       help: candidate #1: use `std::io::Write`

to

       help: candidate #1: `use std::io::Write`

so that the code can be copied directly.

Fixes rust-lang#31864
bluss pushed a commit that referenced this pull request Jun 14, 2016
bluss pushed a commit that referenced this pull request Aug 21, 2016
rustc_trans: don't Assert(Overflow(Neg)) when overflow checks are off.

Generic functions using `Neg` on primitive types would panic even in release mode, with MIR trans.
The solution is a bit hacky, as I'm checking the message, since there's no dedicated `CheckedUnOp`.

Blocks Servo rustup ([failure #1](http://build.servo.org/builders/linux-rel/builds/2477/steps/test_3/logs/stdio), [failure #2](http://build.servo.org/builders/mac-rel-css/builds/2364/steps/test/logs/stdio)) - this should be the last hurdle, it affects only one test.
bluss pushed a commit that referenced this pull request Oct 25, 2017
…crichton

Allow atomic operations up to 32 bits

The ARMv5te platform does not have instruction-level support for atomics, however the kernel provides [user space helpers] which can be used to perform atomic operations. When linked with `libgcc`, the atomic symbols needed by Rust will be provided, rather than CPU level intrinsics.

[user space helpers]: https://www.kernel.org/doc/Documentation/arm/kernel_user_helpers.txt

32-bit versions of these kernel level helpers were introduced in Linux Kernel 2.6.12, and 64-bit version of these kernel level helpers were introduced in Linux Kernel 3.1. I have selected 32 bit versions as std currently only requires Linux version 2.6.18 and above as far as I am aware.

As this target is specifically linux and gnueabi, it is reasonable to assume the Linux Kernel and libc will be available for the target. There is a large performance penalty, as we are not using CPU level intrinsics, however this penalty is likely preferable to not having the target at all.

I have used this change in a custom target (along with xargo) to build std, as well as a number of higher level crates.

## Additional information

For reference, here is what a a code snippet decompiles to:

```rust
use std::sync::atomic::{AtomicIsize, Ordering};

#[no_mangle]
pub extern fn foo(a: &AtomicIsize) -> isize {

    a.fetch_add(1, Ordering::SeqCst)
}
```

```
Disassembly of section .text.foo:

00000000 <foo>:
   0:	e92d4800 	push	{fp, lr}
   4:	e3a01001 	mov	r1, #1
   8:	ebfffffe 	bl	0 <__sync_fetch_and_add_4>
   c:	e8bd8800 	pop	{fp, pc}
```

Which in turn is provided by `libgcc.a`, which has code which looks like this:

```
Disassembly of section .text:

00000000 <__sync_fetch_and_add_4>:
       0:	e92d40f8 	push	{r3, r4, r5, r6, r7, lr}
       4:	e1a05000 	mov	r5, r0
       8:	e1a07001 	mov	r7, r1
       c:	e59f6028 	ldr	r6, [pc, rust-lang#40]	; 3c <__sync_fetch_and_add_4+0x3c>
      10:	e5954000 	ldr	r4, [r5]
      14:	e1a02005 	mov	r2, r5
      18:	e1a00004 	mov	r0, r4
      1c:	e0841007 	add	r1, r4, r7
      20:	e1a0e00f 	mov	lr, pc
      24:	e12fff16 	bx	r6
      28:	e3500000 	cmp	r0, #0
      2c:	1afffff7 	bne	10 <__sync_fetch_and_add_4+0x10>
      30:	e1a00004 	mov	r0, r4
      34:	e8bd40f8 	pop	{r3, r4, r5, r6, r7, lr}
      38:	e12fff1e 	bx	lr
      3c:	ffff0fc0 	.word	0xffff0fc0
```

Where you can see the reference to `0xffff0fc0`, which is provided by the [user space helpers].
bluss pushed a commit that referenced this pull request Jan 13, 2019
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2 participants