Currently the test passes with the LLVM backend as the codegen unit
partitioning logic happens to place both the global_asm!() and the
function which calls the function defined by the global_asm!() in the
same CGU. With the Cranelift backend it breaks however as it will place
all assembly in separate codegen units to be passed to an external
linker.
Relax ordering rules for `asm!` operands
The `asm!` and `global_asm!` macros require their operands to appear strictly in the following order:
- Template strings
- Positional operands
- Named operands
- Explicit register operands
- `clobber_abi`
- `options`
This is overly strict and can be inconvienent when building complex `asm!` statements with macros. This PR relaxes the ordering requirements as follows:
- Template strings must still come before all other operands.
- Positional operands must still come before named and explicit register operands.
- Named and explicit register operands can be freely mixed.
- `options` and `clobber_abi` can appear in any position after the template strings.
r? ```````@joshtriplett```````
Stabilize `#![feature(target_feature_11)]`
## Stabilization report
### Summary
Allows for safe functions to be marked with `#[target_feature]` attributes.
Functions marked with `#[target_feature]` are generally considered as unsafe functions: they are unsafe to call, cannot be assigned to safe function pointers, and don't implement the `Fn*` traits.
However, calling them from other `#[target_feature]` functions with a superset of features is safe.
```rust
// Demonstration function
#[target_feature(enable = "avx2")]
fn avx2() {}
fn foo() {
// Calling `avx2` here is unsafe, as we must ensure
// that AVX is available first.
unsafe {
avx2();
}
}
#[target_feature(enable = "avx2")]
fn bar() {
// Calling `avx2` here is safe.
avx2();
}
```
### Test cases
Tests for this feature can be found in [`src/test/ui/rfcs/rfc-2396-target_feature-11/`](b67ba9ba20/src/test/ui/rfcs/rfc-2396-target_feature-11/).
### Edge cases
- https://github.com/rust-lang/rust/issues/73631
Closures defined inside functions marked with `#[target_feature]` inherit the target features of their parent function. They can still be assigned to safe function pointers and implement the appropriate `Fn*` traits.
```rust
#[target_feature(enable = "avx2")]
fn qux() {
let my_closure = || avx2(); // this call to `avx2` is safe
let f: fn() = my_closure;
}
```
This means that in order to call a function with `#[target_feature]`, you must show that the target-feature is available while the function executes *and* for as long as whatever may escape from that function lives.
### Documentation
- Reference: https://github.com/rust-lang/reference/pull/1181
---
cc tracking issue #69098
r? `@ghost`
Most tests involving save-analysis were removed, but I kept a few where
the `-Zsave-analysis` was an add-on to the main thing being tested,
rather than the main thing being tested.
For `x.py install`, the `rust-analysis` target has been removed.
For `x.py dist`, the `rust-analysis` target has been kept in a
degenerate form: it just produces a single file `reduced.json`
indicating that save-analysis has been removed. This is necessary for
rustup to keep working.
Closes#43606.
The `asm!` and `global_asm!` macros require their operands to appear
strictly in the following order:
- Template strings
- Positional operands
- Named operands
- Explicit register operands
- `clobber_abi`
- `options`
This is overly strict and can be inconvienent when building complex
`asm!` statements with macros. This PR relaxes the ordering requirements
as follows:
- Template strings must still come before all other operands.
- Positional operands must still come before named and explicit register
operands.
- Named and explicit register operands can be freely mixed.
- `options` and `clobber_abi` can appear in any position.
