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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()
}
}
```
47 lines
1.2 KiB
Rust
47 lines
1.2 KiB
Rust
// This example is interesting because the non-transitive version of `MaybeLiveLocals` would
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// report that *all* of these stores are live.
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//
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//@ needs-unwind
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//@ test-mir-pass: DeadStoreElimination-initial
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#![feature(core_intrinsics, custom_mir)]
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use std::intrinsics::mir::*;
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#[inline(never)]
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fn cond() -> bool {
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false
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}
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// EMIT_MIR cycle.cycle.DeadStoreElimination-initial.diff
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#[custom_mir(dialect = "runtime", phase = "post-cleanup")]
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fn cycle(mut x: i32, mut y: i32, mut z: i32) {
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// CHECK-LABEL: fn cycle(
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// CHECK-NOT: {{_.*}} = {{_.*}};
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// CHECK-NOT: {{_.*}} = move {{_.*}};
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// We use custom MIR to avoid generating debuginfo, that would force to preserve writes.
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mir! {
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let condition: bool;
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{
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Call(condition = cond(), ReturnTo(bb1), UnwindContinue())
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}
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bb1 = {
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match condition { true => bb2, _ => ret }
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}
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bb2 = {
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let temp = z;
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z = y;
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y = x;
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x = temp;
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Call(condition = cond(), ReturnTo(bb1), UnwindContinue())
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}
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ret = {
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Return()
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}
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}
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}
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fn main() {
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cycle(1, 2, 3);
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}
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