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Auto merge of #121225 - RalfJung:simd-extract-insert-const-idx, r=oli-obk,Amanieu

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require simd_insert, simd_extract indices to be constants

As discussed in https://github.com/rust-lang/rust/issues/77477 (see in particular [here](https://github.com/rust-lang/rust/issues/77477#issuecomment-703149102)). This PR doesn't touch codegen yet -- the first step is to ensure that the indices are always constants; the second step is to then make use of this fact in backends.

Blocked on https://github.com/rust-lang/stdarch/pull/1530 propagating to the rustc repo.
This commit is contained in:
bors 2024-02-22 09:59:41 +00:00
commit 52dba5ffe7
8 changed files with 37 additions and 89 deletions
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8
compiler/rustc_borrowck/messages.ftl
View File

@ -163,7 +163,13 @@ borrowck_returned_lifetime_wrong =
borrowck_returned_ref_escaped =
returns a reference to a captured variable which escapes the closure body
borrowck_simd_shuffle_last_const = last argument of `simd_shuffle` is required to be a `const` item
borrowck_simd_intrinsic_arg_const =
{$arg ->
[1] 1st
[2] 2nd
[3] 3rd
*[other] {$arg}th
} argument of `{$intrinsic}` is required to be a `const` item
borrowck_suggest_create_freash_reborrow =
consider reborrowing the `Pin` instead of moving it

6
compiler/rustc_borrowck/src/session_diagnostics.rs
View File

@ -454,8 +454,10 @@ pub(crate) enum TypeNoCopy<'a, 'tcx> {
}
#[derive(Diagnostic)]
#[diag(borrowck_simd_shuffle_last_const)]
pub(crate) struct SimdShuffleLastConst {
#[diag(borrowck_simd_intrinsic_arg_const)]
pub(crate) struct SimdIntrinsicArgConst {
#[primary_span]
pub span: Span,
pub arg: usize,
pub intrinsic: String,
}

21
compiler/rustc_borrowck/src/type_check/mod.rs
View File

@ -49,7 +49,7 @@
use rustc_mir_dataflow::move_paths::MoveData;
use rustc_mir_dataflow::ResultsCursor;
use crate::session_diagnostics::{MoveUnsized, SimdShuffleLastConst};
use crate::session_diagnostics::{MoveUnsized, SimdIntrinsicArgConst};
use crate::{
borrow_set::BorrowSet,
constraints::{OutlivesConstraint, OutlivesConstraintSet},
@ -1664,9 +1664,22 @@ fn check_call_inputs(
let func_ty = func.ty(body, self.infcx.tcx);
if let ty::FnDef(def_id, _) = *func_ty.kind() {
if let Some(sym::simd_shuffle) = self.tcx().intrinsic(def_id) {
if !matches!(args[2], Spanned { node: Operand::Constant(_), .. }) {
self.tcx().dcx().emit_err(SimdShuffleLastConst { span: term.source_info.span });
// Some of the SIMD intrinsics are special: they need a particular argument to be a constant.
// (Eventually this should use const-generics, but those are not up for the task yet:
// https://github.com/rust-lang/rust/issues/85229.)
if let Some(name @ (sym::simd_shuffle | sym::simd_insert | sym::simd_extract)) =
self.tcx().intrinsic(def_id)
{
let idx = match name {
sym::simd_shuffle => 2,
_ => 1,
};
if !matches!(args[idx], Spanned { node: Operand::Constant(_), .. }) {
self.tcx().dcx().emit_err(SimdIntrinsicArgConst {
span: term.source_info.span,
arg: idx + 1,
intrinsic: name.to_string(),
});
}
}
}

3
compiler/rustc_codegen_ssa/src/mir/block.rs
View File

@ -864,8 +864,7 @@ fn codegen_call_terminator(
.map(|(i, arg)| {
// The indices passed to simd_shuffle in the
// third argument must be constant. This is
// checked by const-qualification, which also
// promotes any complex rvalues to constants.
// checked by the type-checker.
if i == 2 && intrinsic == sym::simd_shuffle {
if let mir::Operand::Constant(constant) = &arg.node {
let (llval, ty) = self.simd_shuffle_indices(bx, constant);

47
tests/codegen/simd-intrinsic/simd-intrinsic-generic-extract-insert.rs
View File

@ -1,47 +0,0 @@
// compile-flags: -C no-prepopulate-passes
#![crate_type = "lib"]
#![feature(repr_simd, platform_intrinsics, min_const_generics)]
#![allow(non_camel_case_types)]
#[repr(simd)]
#[derive(Copy, Clone)]
pub struct M(pub f32, pub f32, pub f32, pub f32);
#[repr(simd)]
#[derive(Copy, Clone)]
pub struct S<const N: usize>([f32; N]);
extern "platform-intrinsic" {
fn simd_extract<T, U>(x: T, idx: u32) -> U;
fn simd_insert<T, U>(x: T, idx: u32, b: U) -> T;
}
// CHECK-LABEL: @extract_m
#[no_mangle]
pub unsafe fn extract_m(v: M, i: u32) -> f32 {
// CHECK: extractelement <4 x float> %{{v|1|2}}, i32 %i
simd_extract(v, i)
}
// CHECK-LABEL: @extract_s
#[no_mangle]
pub unsafe fn extract_s(v: S<4>, i: u32) -> f32 {
// CHECK: extractelement <4 x float> %{{v|1|2}}, i32 %i
simd_extract(v, i)
}
// CHECK-LABEL: @insert_m
#[no_mangle]
pub unsafe fn insert_m(v: M, i: u32, j: f32) -> M {
// CHECK: insertelement <4 x float> %{{v|0|1}}, float %j, i32 %i
simd_insert(v, i, j)
}
// CHECK-LABEL: @insert_s
#[no_mangle]
pub unsafe fn insert_s(v: S<4>, i: u32, j: f32) -> S<4> {
// CHECK: insertelement <4 x float> %{{v|0|1}}, float %j, i32 %i
simd_insert(v, i, j)
}

9
tests/ui/simd/array-trait.rs
View File

@ -33,12 +33,7 @@ impl Simd for i32x4 {
pub fn main() {
let mut t = T::<i32x4>([0; 4]);
unsafe {
for i in 0_i32..4 {
t = simd_insert(t, i as u32, i);
}
for i in 0_i32..4 {
assert_eq!(i, simd_extract(t, i as u32));
//~^ ERROR: use of moved value: `t`
}
t = simd_insert(t, 3, 3);
assert_eq!(3, simd_extract(t, 3));
}
}

16
tests/ui/simd/array-trait.stderr
View File

@ -23,18 +23,6 @@ LL | pub struct T<S: Simd>([S::Lane; S::SIZE]);
= help: try adding a `where` bound using this expression: `where [(); S::SIZE]:`
= note: this error originates in the derive macro `Clone` (in Nightly builds, run with -Z macro-backtrace for more info)
error[E0382]: use of moved value: `t`
--> $DIR/array-trait.rs:40:40
|
LL | let mut t = T::<i32x4>([0; 4]);
| ----- move occurs because `t` has type `T<i32x4>`, which does not implement the `Copy` trait
...
LL | for i in 0_i32..4 {
| ----------------- inside of this loop
LL | assert_eq!(i, simd_extract(t, i as u32));
| ^ value moved here, in previous iteration of loop
error: aborting due to 3 previous errors
error: aborting due to 4 previous errors
Some errors have detailed explanations: E0077, E0382.
For more information about an error, try `rustc --explain E0077`.
For more information about this error, try `rustc --explain E0077`.

16
tests/ui/simd/array-type.rs
View File

@ -22,21 +22,13 @@ pub fn main() {
let mut s = S([0; 4]);
unsafe {
for i in 0_i32..4 {
s = simd_insert(s, i as u32, i);
}
for i in 0_i32..4 {
assert_eq!(i, simd_extract(s, i as u32));
}
s = simd_insert(s, 3, 3);
assert_eq!(3, simd_extract(s, 3));
}
let mut t = T::<4>([0; 4]);
unsafe {
for i in 0_i32..4 {
t = simd_insert(t, i as u32, i);
}
for i in 0_i32..4 {
assert_eq!(i, simd_extract(t, i as u32));
}
t = simd_insert(t, 3, 3);
assert_eq!(3, simd_extract(t, 3));
}
}