From fb90ac598144a469f0f19c45864b63ced86134bf Mon Sep 17 00:00:00 2001
From: "Kurt Heiritz (pseudo)" <saarthkarkera@gmail.com>
Date: Mon, 8 Dec 2025 18:44:49 +0800
Subject: [PATCH] Add support for f16

---
 .../crates/core_simd/src/alias.rs              | 10 ++++++++++
 .../portable-simd/crates/core_simd/src/cast.rs |  5 +++++
 .../portable-simd/crates/core_simd/src/iter.rs |  1 +
 .../portable-simd/crates/core_simd/src/lib.rs  |  1 +
 .../portable-simd/crates/core_simd/src/ops.rs  |  2 +-
 .../crates/core_simd/src/ops/unary.rs          |  2 ++
 .../crates/core_simd/src/simd/cmp/eq.rs        |  2 +-
 .../crates/core_simd/src/simd/cmp/ord.rs       |  2 +-
 .../crates/core_simd/src/simd/num/float.rs     |  2 +-
 .../crates/core_simd/src/to_bytes.rs           |  2 ++
 .../crates/core_simd/src/vector.rs             |  7 +++++++
 .../portable-simd/crates/std_float/src/lib.rs  | 18 ++++++++++++++++++
 12 files changed, 50 insertions(+), 4 deletions(-)

diff --git a/library/portable-simd/crates/core_simd/src/alias.rs b/library/portable-simd/crates/core_simd/src/alias.rs
index 23f121c46197c..6dcfcb660c26a 100644
--- a/library/portable-simd/crates/core_simd/src/alias.rs
+++ b/library/portable-simd/crates/core_simd/src/alias.rs
@@ -153,6 +153,16 @@ alias! {
         usizex64 64
     }
 
+    f16 = {
+        f16x1 1
+        f16x2 2
+        f16x4 4
+        f16x8 8
+        f16x16 16
+        f16x32 32
+        f16x64 64
+    }
+
     f32 = {
         f32x1 1
         f32x2 2
diff --git a/library/portable-simd/crates/core_simd/src/cast.rs b/library/portable-simd/crates/core_simd/src/cast.rs
index 1c3592f807578..46792b2e76fc9 100644
--- a/library/portable-simd/crates/core_simd/src/cast.rs
+++ b/library/portable-simd/crates/core_simd/src/cast.rs
@@ -44,6 +44,11 @@ impl SimdCast for u64 {}
 unsafe impl Sealed for usize {}
 impl SimdCast for usize {}
 // Safety: primitive number types can be cast to other primitive number types
+
+unsafe impl Sealed for f16 {}
+
+impl SimdCast for f16 {}
+// Safety: primitive number types can be cast to other primitive number types
 unsafe impl Sealed for f32 {}
 impl SimdCast for f32 {}
 // Safety: primitive number types can be cast to other primitive number types
diff --git a/library/portable-simd/crates/core_simd/src/iter.rs b/library/portable-simd/crates/core_simd/src/iter.rs
index b3732fd74d5f6..81724ce2da211 100644
--- a/library/portable-simd/crates/core_simd/src/iter.rs
+++ b/library/portable-simd/crates/core_simd/src/iter.rs
@@ -48,6 +48,7 @@ macro_rules! impl_traits {
     }
 }
 
+impl_traits! { f16 }
 impl_traits! { f32 }
 impl_traits! { f64 }
 impl_traits! { u8 }
diff --git a/library/portable-simd/crates/core_simd/src/lib.rs b/library/portable-simd/crates/core_simd/src/lib.rs
index 717b882b64ba1..54ef790d32baa 100644
--- a/library/portable-simd/crates/core_simd/src/lib.rs
+++ b/library/portable-simd/crates/core_simd/src/lib.rs
@@ -4,6 +4,7 @@
     convert_float_to_int,
     core_intrinsics,
     decl_macro,
+    f16_and_f128,
     intra_doc_pointers,
     repr_simd,
     simd_ffi,
diff --git a/library/portable-simd/crates/core_simd/src/ops.rs b/library/portable-simd/crates/core_simd/src/ops.rs
index f36e8d01a73bb..f645c57b69b2e 100644
--- a/library/portable-simd/crates/core_simd/src/ops.rs
+++ b/library/portable-simd/crates/core_simd/src/ops.rs
@@ -248,7 +248,7 @@ for_base_ops! {
 // We don't need any special precautions here:
 // Floats always accept arithmetic ops, but may become NaN.
 for_base_ops! {
-    T = (f32, f64);
+    T = (f16, f32, f64);
     type Lhs = Simd<T, N>;
     type Rhs = Simd<T, N>;
     type Output = Self;
diff --git a/library/portable-simd/crates/core_simd/src/ops/unary.rs b/library/portable-simd/crates/core_simd/src/ops/unary.rs
index 412a5b801171b..82ed9c9160bdb 100644
--- a/library/portable-simd/crates/core_simd/src/ops/unary.rs
+++ b/library/portable-simd/crates/core_simd/src/ops/unary.rs
@@ -20,6 +20,8 @@ macro_rules! neg {
 }
 
 neg! {
+    impl<const N: usize> Neg for Simd<f16, N>
+    
     impl<const N: usize> Neg for Simd<f32, N>
 
     impl<const N: usize> Neg for Simd<f64, N>
diff --git a/library/portable-simd/crates/core_simd/src/simd/cmp/eq.rs b/library/portable-simd/crates/core_simd/src/simd/cmp/eq.rs
index 2312ba401fa78..2d69d57241edc 100644
--- a/library/portable-simd/crates/core_simd/src/simd/cmp/eq.rs
+++ b/library/portable-simd/crates/core_simd/src/simd/cmp/eq.rs
@@ -44,7 +44,7 @@ macro_rules! impl_number {
     }
 }
 
-impl_number! { f32, f64, u8, u16, u32, u64, usize, i8, i16, i32, i64, isize }
+impl_number! { f16, f32, f64, u8, u16, u32, u64, usize, i8, i16, i32, i64, isize }
 
 macro_rules! impl_mask {
     { $($integer:ty),* } => {
diff --git a/library/portable-simd/crates/core_simd/src/simd/cmp/ord.rs b/library/portable-simd/crates/core_simd/src/simd/cmp/ord.rs
index e813e7613032c..115e01b650251 100644
--- a/library/portable-simd/crates/core_simd/src/simd/cmp/ord.rs
+++ b/library/portable-simd/crates/core_simd/src/simd/cmp/ord.rs
@@ -150,7 +150,7 @@ macro_rules! impl_float {
     }
 }
 
-impl_float! { f32, f64 }
+impl_float! { f16, f32, f64 }
 
 macro_rules! impl_mask {
     { $($integer:ty),* } => {
diff --git a/library/portable-simd/crates/core_simd/src/simd/num/float.rs b/library/portable-simd/crates/core_simd/src/simd/num/float.rs
index b5972c47373bb..2c91bd49e4f0e 100644
--- a/library/portable-simd/crates/core_simd/src/simd/num/float.rs
+++ b/library/portable-simd/crates/core_simd/src/simd/num/float.rs
@@ -450,4 +450,4 @@ macro_rules! impl_trait {
     }
 }
 
-impl_trait! { f32 { bits: u32, mask: i32 }, f64 { bits: u64, mask: i64 } }
+impl_trait! { f16 { bits: u16, mask: i16 }, f32 { bits: u32, mask: i32 }, f64 { bits: u64, mask: i64 } }
diff --git a/library/portable-simd/crates/core_simd/src/to_bytes.rs b/library/portable-simd/crates/core_simd/src/to_bytes.rs
index fee2cc06c5b09..51cc968bf9a2a 100644
--- a/library/portable-simd/crates/core_simd/src/to_bytes.rs
+++ b/library/portable-simd/crates/core_simd/src/to_bytes.rs
@@ -46,6 +46,7 @@ pub trait ToBytes: Sealed {
 }
 
 macro_rules! swap_bytes {
+    { f16, $x:expr } => { Simd::from_bits($x.to_bits().swap_bytes()) };
     { f32, $x:expr } => { Simd::from_bits($x.to_bits().swap_bytes()) };
     { f64, $x:expr } => { Simd::from_bits($x.to_bits().swap_bytes()) };
     { $ty:ty, $x:expr } => { $x.swap_bytes() }
@@ -141,5 +142,6 @@ impl_to_bytes! { isize, 4 }
 #[cfg(target_pointer_width = "64")]
 impl_to_bytes! { isize, 8 }
 
+impl_to_bytes! { f16, 2 }
 impl_to_bytes! { f32, 4 }
 impl_to_bytes! { f64, 8 }
diff --git a/library/portable-simd/crates/core_simd/src/vector.rs b/library/portable-simd/crates/core_simd/src/vector.rs
index f40031f8c4da7..0b7d961f7de5f 100644
--- a/library/portable-simd/crates/core_simd/src/vector.rs
+++ b/library/portable-simd/crates/core_simd/src/vector.rs
@@ -1192,6 +1192,13 @@ unsafe impl SimdElement for isize {
     type Mask = isize;
 }
 
+impl Sealed for f16 {}
+
+// Safety: f16 is a valid SIMD element type, and is supported by this API
+unsafe impl SimdElement for f16 {
+    type Mask = i16;
+}
+
 impl Sealed for f32 {}
 
 // Safety: f32 is a valid SIMD element type, and is supported by this API
diff --git a/library/portable-simd/crates/std_float/src/lib.rs b/library/portable-simd/crates/std_float/src/lib.rs
index 148aa5f9f1771..8af7dd98f5ad7 100644
--- a/library/portable-simd/crates/std_float/src/lib.rs
+++ b/library/portable-simd/crates/std_float/src/lib.rs
@@ -140,6 +140,7 @@ pub trait StdFloat: Sealed + Sized {
     fn fract(self) -> Self;
 }
 
+impl<const N: usize> Sealed for Simd<f16, N> where LaneCount<N>: SupportedLaneCount {}
 impl<const N: usize> Sealed for Simd<f32, N> where LaneCount<N>: SupportedLaneCount {}
 impl<const N: usize> Sealed for Simd<f64, N> where LaneCount<N>: SupportedLaneCount {}
 
@@ -147,6 +148,23 @@ macro_rules! impl_float {
     {
         $($fn:ident: $intrinsic:ident,)*
     } => {
+        impl<const N: usize> StdFloat for Simd<f16, N>
+        where
+            LaneCount<N>: SupportedLaneCount,
+        {
+            #[inline]
+            fn fract(self) -> Self {
+                self - self.trunc()
+            }
+
+            $(
+            #[inline]
+            fn $fn(self) -> Self {
+                unsafe { intrinsics::$intrinsic(self) }
+            }
+            )*
+        }
+
         impl<const N: usize> StdFloat for Simd<f32, N>
         where
             LaneCount<N>: SupportedLaneCount,