mirror of
https://github.com/rust-lang/rust
synced 2024-11-05 20:45:15 +00:00
ac24299636
The `mir!` macro has multiple parts:
- An optional return type annotation.
- A sequence of zero or more local declarations.
- A mandatory starting anonymous basic block, which is brace-delimited.
- A sequence of zero of more additional named basic blocks.
Some `mir!` invocations use braces with a "block" style, like so:
```
mir! {
let _unit: ();
{
let non_copy = S(42);
let ptr = std::ptr::addr_of_mut!(non_copy);
// Inside `callee`, the first argument and `*ptr` are basically
// aliasing places!
Call(_unit = callee(Move(*ptr), ptr), ReturnTo(after_call), UnwindContinue())
}
after_call = {
Return()
}
}
```
Some invocations use parens with a "block" style, like so:
```
mir!(
let x: [i32; 2];
let one: i32;
{
x = [42, 43];
one = 1;
x = [one, 2];
RET = Move(x);
Return()
}
)
```
And some invocations uses parens with a "tighter" style, like so:
```
mir!({
SetDiscriminant(*b, 0);
Return()
})
```
This last style is generally used for cases where just the mandatory
starting basic block is present. Its braces are placed next to the
parens.
This commit changes all `mir!` invocations to use braces with a "block"
style. Why?
- Consistency is good.
- The contents of the invocation is a block of code, so it's odd to use
parens. They are more normally used for function-like macros.
- Most importantly, the next commit will enable rustfmt for
`tests/mir-opt/`. rustfmt is more aggressive about formatting macros
that use parens than macros that use braces. Without this commit's
changes, rustfmt would break a couple of `mir!` macro invocations that
use braces within `tests/mir-opt` by inserting an extraneous comma.
E.g.:
```
mir!(type RET = (i32, bool);, { // extraneous comma after ';'
RET.0 = 1;
RET.1 = true;
Return()
})
```
Switching those `mir!` invocations to use braces avoids that problem,
resulting in this, which is nicer to read as well as being valid
syntax:
```
mir! {
type RET = (i32, bool);
{
RET.0 = 1;
RET.1 = true;
Return()
}
}
```
78 lines
1.6 KiB
Rust
78 lines
1.6 KiB
Rust
// `SetDiscriminant` does not actually write anything if the chosen variant is the untagged variant
|
|
// of a niche encoding. Verify that we do not thread over this case.
|
|
//@ test-mir-pass: JumpThreading
|
|
|
|
#![feature(custom_mir)]
|
|
#![feature(core_intrinsics)]
|
|
|
|
use std::intrinsics::mir::*;
|
|
|
|
enum E<T> {
|
|
A,
|
|
B(T),
|
|
}
|
|
|
|
// EMIT_MIR set_no_discriminant.f.JumpThreading.diff
|
|
#[custom_mir(dialect = "runtime")]
|
|
pub fn f() -> usize {
|
|
// CHECK-LABEL: fn f(
|
|
// CHECK-NOT: goto
|
|
// CHECK: switchInt(
|
|
// CHECK-NOT: goto
|
|
mir! {
|
|
let a: isize;
|
|
let e: E<char>;
|
|
{
|
|
e = E::A;
|
|
SetDiscriminant(e, 1);
|
|
a = Discriminant(e);
|
|
match a {
|
|
0 => bb0,
|
|
_ => bb1,
|
|
}
|
|
}
|
|
bb0 = {
|
|
RET = 0;
|
|
Return()
|
|
}
|
|
bb1 = {
|
|
RET = 1;
|
|
Return()
|
|
}
|
|
}
|
|
}
|
|
|
|
// EMIT_MIR set_no_discriminant.generic.JumpThreading.diff
|
|
#[custom_mir(dialect = "runtime")]
|
|
pub fn generic<T>() -> usize {
|
|
// CHECK-LABEL: fn generic(
|
|
// CHECK-NOT: goto
|
|
// CHECK: switchInt(
|
|
// CHECK-NOT: goto
|
|
mir! {
|
|
let a: isize;
|
|
let e: E<T>;
|
|
{
|
|
e = E::A;
|
|
SetDiscriminant(e, 1);
|
|
a = Discriminant(e);
|
|
match a {
|
|
0 => bb0,
|
|
_ => bb1,
|
|
}
|
|
}
|
|
bb0 = {
|
|
RET = 0;
|
|
Return()
|
|
}
|
|
bb1 = {
|
|
RET = 1;
|
|
Return()
|
|
}
|
|
}
|
|
}
|
|
|
|
fn main() {
|
|
assert_eq!(f(), 0);
|
|
assert_eq!(generic::<char>(), 0);
|
|
}
|