Add variant to newtype_index! allowing a debug name #1
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Nashenas88
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…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].
Nashenas88
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Jul 22, 2019
Nashenas88
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Aug 16, 2019
Merge recent changes into master
Nashenas88
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Jun 4, 2020
…ing opaque return type
Go from
```
error[E0495]: cannot infer an appropriate lifetime due to conflicting requirements
--> file8.rs:22:5
|
22 | / move || {
23 | | *dest = g.get();
24 | | }
| |_____^
|
note: first, the lifetime cannot outlive the anonymous lifetime #1 defined on the function body at 18:1...
--> file8.rs:18:1
|
18 | / fn bat<'a, G: 'a, T>(g: G, dest: &mut T) -> impl FnOnce() + '_ + 'a
19 | | where
20 | | G: Get<T>
21 | | {
... |
24 | | }
25 | | }
| |_^
note: ...so that the types are compatible
--> file8.rs:22:5
|
22 | / move || { //~ ERROR cannot infer an appropriate lifetime
23 | | *dest = g.get();
24 | | }
| |_____^
= note: expected `&mut T`
found `&mut T`
note: but, the lifetime must be valid for the lifetime `'a` as defined on the function body at 18:8...
--> file8.rs:18:8
|
18 | fn bat<'a, G: 'a, T>(g: G, dest: &mut T) -> impl FnOnce() + '_ + 'a
| ^^
note: ...so that return value is valid for the call
--> file8.rs:18:45
|
18 | fn bat<'a, G: 'a, T>(g: G, dest: &mut T) -> impl FnOnce() + '_ + 'a
| ^^^^^^^^^^^^^^^^^^^^^^^
```
to
```
error[E0621]: explicit lifetime required in the type of `dest`
--> file8.rs:18:45
|
18 | fn bat<'a, G: 'a, T>(g: G, dest: &mut T) -> impl FnOnce() + '_ + 'a
| ------ ^^^^^^^^^^^^^^^^^^^^^^^ lifetime `'a` required
| |
| help: add explicit lifetime `'a` to the type of `dest`: `&'a mut T`
```
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This restores the 'short names' of the various MIR constructs. This fixes the failing tests in rust-lang#44878.