mirror of
https://github.com/rust-lang/rust
synced 2024-07-20 18:05:58 +00:00
72800d3b89
Except for `simd-intrinsic/`, which has a lot of files containing multiple types like `u8x64` which really are better when hand-formatted. There is a surprising amount of two-space indenting in this directory. Non-trivial changes: - `rustfmt::skip` needed in `debug-column.rs` to preserve meaning of the test. - `rustfmt::skip` used in a few places where hand-formatting read more nicely: `enum/enum-match.rs` - Line number adjustments needed for the expected output of `debug-column.rs` and `coroutine-debug.rs`.
91 lines
3 KiB
Rust
91 lines
3 KiB
Rust
//@ compile-flags: -O
|
||
//@ only-x86_64
|
||
|
||
#![crate_type = "lib"]
|
||
|
||
use std::mem::swap;
|
||
use std::ptr::{copy_nonoverlapping, read, write};
|
||
|
||
type KeccakBuffer = [[u64; 5]; 5];
|
||
|
||
// A basic read+copy+write swap implementation ends up copying one of the values
|
||
// to stack for large types, which is completely unnecessary as the lack of
|
||
// overlap means we can just do whatever fits in registers at a time.
|
||
|
||
// CHECK-LABEL: @swap_basic
|
||
#[no_mangle]
|
||
pub fn swap_basic(x: &mut KeccakBuffer, y: &mut KeccakBuffer) {
|
||
// CHECK: alloca [200 x i8]
|
||
|
||
// SAFETY: exclusive references are always valid to read/write,
|
||
// are non-overlapping, and nothing here panics so it's drop-safe.
|
||
unsafe {
|
||
let z = read(x);
|
||
copy_nonoverlapping(y, x, 1);
|
||
write(y, z);
|
||
}
|
||
}
|
||
|
||
// This test verifies that the library does something smarter, and thus
|
||
// doesn't need any scratch space on the stack.
|
||
|
||
// CHECK-LABEL: @swap_std
|
||
#[no_mangle]
|
||
pub fn swap_std(x: &mut KeccakBuffer, y: &mut KeccakBuffer) {
|
||
// CHECK-NOT: alloca
|
||
// CHECK: load <{{[0-9]+}} x i64>
|
||
// CHECK: store <{{[0-9]+}} x i64>
|
||
swap(x, y)
|
||
}
|
||
|
||
// Verify that types with usize alignment are swapped via vectored usizes,
|
||
// not falling back to byte-level code.
|
||
|
||
// CHECK-LABEL: @swap_slice
|
||
#[no_mangle]
|
||
pub fn swap_slice(x: &mut [KeccakBuffer], y: &mut [KeccakBuffer]) {
|
||
// CHECK-NOT: alloca
|
||
// CHECK: load <{{[0-9]+}} x i64>
|
||
// CHECK: store <{{[0-9]+}} x i64>
|
||
if x.len() == y.len() {
|
||
x.swap_with_slice(y);
|
||
}
|
||
}
|
||
|
||
// But for a large align-1 type, vectorized byte copying is what we want.
|
||
|
||
type OneKilobyteBuffer = [u8; 1024];
|
||
|
||
// CHECK-LABEL: @swap_1kb_slices
|
||
#[no_mangle]
|
||
pub fn swap_1kb_slices(x: &mut [OneKilobyteBuffer], y: &mut [OneKilobyteBuffer]) {
|
||
// CHECK-NOT: alloca
|
||
// CHECK: load <{{[0-9]+}} x i8>
|
||
// CHECK: store <{{[0-9]+}} x i8>
|
||
if x.len() == y.len() {
|
||
x.swap_with_slice(y);
|
||
}
|
||
}
|
||
|
||
// This verifies that the 2×read + 2×write optimizes to just 3 memcpys
|
||
// for an unusual type like this. It's not clear whether we should do anything
|
||
// smarter in Rust for these, so for now it's fine to leave these up to the backend.
|
||
// That's not as bad as it might seem, as for example, LLVM will lower the
|
||
// memcpys below to VMOVAPS on YMMs if one enables the AVX target feature.
|
||
// Eventually we'll be able to pass `align_of::<T>` to a const generic and
|
||
// thus pick a smarter chunk size ourselves without huge code duplication.
|
||
|
||
#[repr(align(64))]
|
||
pub struct BigButHighlyAligned([u8; 64 * 3]);
|
||
|
||
// CHECK-LABEL: @swap_big_aligned
|
||
#[no_mangle]
|
||
pub fn swap_big_aligned(x: &mut BigButHighlyAligned, y: &mut BigButHighlyAligned) {
|
||
// CHECK-NOT: call void @llvm.memcpy
|
||
// CHECK: call void @llvm.memcpy.{{.+}}(ptr noundef nonnull align 64 dereferenceable(192)
|
||
// CHECK: call void @llvm.memcpy.{{.+}}(ptr noundef nonnull align 64 dereferenceable(192)
|
||
// CHECK: call void @llvm.memcpy.{{.+}}(ptr noundef nonnull align 64 dereferenceable(192)
|
||
// CHECK-NOT: call void @llvm.memcpy
|
||
swap(x, y)
|
||
}
|