Make some helpers const

Author: sayantn

crates/core_arch/src/lib.rs

@@ -34,7 +34,10 @@
     f16,
     aarch64_unstable_target_feature,
     bigint_helper_methods,
-    funnel_shifts
+    funnel_shifts,
+    const_trait_impl,
+    const_cmp,
+    const_convert
 )]
 #![cfg_attr(test, feature(test, abi_vectorcall, stdarch_internal))]
 #![deny(clippy::missing_inline_in_public_items)]

crates/core_arch/src/simd.rs

@@ -23,7 +23,8 @@ macro_rules! simd_ty {
             }
             // FIXME: Workaround rust@60637
             #[inline(always)]
-            pub(crate) fn splat(value: $elem_type) -> Self {
+            #[rustc_const_unstable(feature = "stdarch_const_intrinsics", issue = "none")]
+            pub(crate) const fn splat(value: $elem_type) -> Self {
                 #[derive(Copy, Clone)]
                 #[repr(simd)]
                 struct JustOne([$elem_type; 1]);
@@ -38,12 +39,12 @@ macro_rules! simd_ty {
             /// Use for testing only.
             // FIXME: Workaround rust@60637
             #[inline(always)]
-            pub(crate) fn extract(&self, index: usize) -> $elem_type {
+            pub(crate) const fn extract(&self, index: usize) -> $elem_type {
                 self.as_array()[index]
             }
 
             #[inline]
-            pub(crate) fn as_array(&self) -> &[$elem_type; $len] {
+            pub(crate) const fn as_array(&self) -> &[$elem_type; $len] {
                 let simd_ptr: *const Self = self;
                 let array_ptr: *const [$elem_type; $len] = simd_ptr.cast();
                 // SAFETY: We can always read the prefix of a simd type as an array.
@@ -89,7 +90,8 @@ macro_rules! simd_m_ty {
 
             // FIXME: Workaround rust@60637
             #[inline(always)]
-            pub(crate) fn splat(value: bool) -> Self {
+            #[rustc_const_unstable(feature = "stdarch_const_intrinsics", issue = "none")]
+            pub(crate) const fn splat(value: bool) -> Self {
                 #[derive(Copy, Clone)]
                 #[repr(simd)]
                 struct JustOne([$elem_type; 1]);
@@ -100,7 +102,7 @@ macro_rules! simd_m_ty {
             }
 
             #[inline]
-            pub(crate) fn as_array(&self) -> &[$elem_type; $len] {
+            pub(crate) const fn as_array(&self) -> &[$elem_type; $len] {
                 let simd_ptr: *const Self = self;
                 let array_ptr: *const [$elem_type; $len] = simd_ptr.cast();
                 // SAFETY: We can always read the prefix of a simd type as an array.

crates/core_arch/src/x86/mod.rs

@@ -520,14 +520,14 @@ macro_rules! as_transmute {
     ($from:ty => $as_from:ident, $($as_to:ident -> $to:ident),* $(,)?) => {
         impl $from {$(
             #[inline]
-            pub(crate) fn $as_to(self) -> crate::core_arch::simd::$to {
+            pub(crate) const fn $as_to(self) -> crate::core_arch::simd::$to {
                 unsafe { transmute(self) }
             }
         )*}
         $(
             impl crate::core_arch::simd::$to {
                 #[inline]
-                pub(crate) fn $as_from(self) -> $from {
+                pub(crate) const fn $as_from(self) -> $from {
                     unsafe { transmute(self) }
                 }
             }

crates/core_arch/src/x86/test.rs

@@ -48,7 +48,8 @@ pub unsafe fn assert_eq_m128h(a: __m128h, b: __m128h) {
 // not actually an intrinsic but useful in various tests as we proted from
 // `i64x2::new` which is backwards from `_mm_set_epi64x`
 #[target_feature(enable = "sse2")]
-pub unsafe fn _mm_setr_epi64x(a: i64, b: i64) -> __m128i {
+#[rustc_const_unstable(feature = "stdarch_const_intrinsics", issue = "none")]
+pub const unsafe fn _mm_setr_epi64x(a: i64, b: i64) -> __m128i {
     _mm_set_epi64x(b, a)
 }
 
@@ -118,14 +119,14 @@ mod x86_polyfill {
     use crate::intrinsics::simd::*;
 
     #[rustc_legacy_const_generics(2)]
-    pub unsafe fn _mm_insert_epi64<const INDEX: i32>(a: __m128i, val: i64) -> __m128i {
+    pub const unsafe fn _mm_insert_epi64<const INDEX: i32>(a: __m128i, val: i64) -> __m128i {
         static_assert_uimm_bits!(INDEX, 1);
         transmute(simd_insert!(a.as_i64x2(), INDEX as u32, val))
     }
 
     #[target_feature(enable = "avx2")]
     #[rustc_legacy_const_generics(2)]
-    pub unsafe fn _mm256_insert_epi64<const INDEX: i32>(a: __m256i, val: i64) -> __m256i {
+    pub const unsafe fn _mm256_insert_epi64<const INDEX: i32>(a: __m256i, val: i64) -> __m256i {
         static_assert_uimm_bits!(INDEX, 2);
         transmute(simd_insert!(a.as_i64x4(), INDEX as u32, val))
     }