Replace multiversion by manually implemented macro rules

Author: marmeladema

Cargo.toml

@@ -10,12 +10,12 @@ license = "MIT"
 keywords = ["search", "text", "string", "single", "simd"]
 
 [dependencies]
+cfg-if = "1"
+paste = "1"
 memchr = "2.3"
-multiversion = { version = "0.6", default-features = false }
 seq-macro = "0.3"
 
 [dev-dependencies]
-cfg-if = "1"
 memmap2 = "0.5"
 
 [profile.release]

src/lib.rs

@@ -27,6 +27,9 @@ use memchr::memchr;
 use std::rc::Rc;
 use std::sync::Arc;
 
+#[macro_use]
+mod multiversion;
+
 /// Needle that can be searched for within a haystack. It allows specialized
 /// searcher implementations for needle sizes known at compile time.
 pub trait Needle {
@@ -193,10 +196,7 @@ macro_rules! memcmp {
     };
 }
 
-#[multiversion::multiversion]
-#[clone(target = "[x86|x86_64]+avx2")]
-#[clone(target = "wasm32+simd128")]
-#[clone(target = "aarch64+neon")]
+multiversion! {
 unsafe fn vector_search_in_chunk<N: NeedleWithSize + ?Sized, V: Vector>(
     needle: &N,
     position: usize,
@@ -248,13 +248,9 @@ unsafe fn vector_search_in_chunk<N: NeedleWithSize + ?Sized, V: Vector>(
     }
 
     false
-}
+}}
 
-#[allow(dead_code)]
-#[multiversion::multiversion]
-#[clone(target = "[x86|x86_64]+avx2")]
-#[clone(target = "wasm32+simd128")]
-#[clone(target = "aarch64+neon")]
+multiversion! {
 pub(crate) unsafe fn vector_search_in<N: NeedleWithSize + ?Sized, V: Vector>(
     needle: &N,
     position: usize,
@@ -266,7 +262,7 @@ pub(crate) unsafe fn vector_search_in<N: NeedleWithSize + ?Sized, V: Vector>(
 
     let mut chunks = haystack[..end].chunks_exact(V::LANES);
     for chunk in &mut chunks {
-        if dispatch!(vector_search_in_chunk(
+        if dispatch!(TARGET => vector_search_in_chunk(
             needle,
             position,
             hash,
@@ -282,13 +278,13 @@ pub(crate) unsafe fn vector_search_in<N: NeedleWithSize + ?Sized, V: Vector>(
         let start = haystack.as_ptr().add(end - V::LANES);
         let mask = u32::MAX << (V::LANES - remainder);
 
-        if dispatch!(vector_search_in_chunk(needle, position, hash, start, mask)) {
+        if dispatch!(TARGET => vector_search_in_chunk(needle, position, hash, start, mask)) {
             return true;
         }
     }
 
     false
-}
+}}
 
 trait Searcher<N: NeedleWithSize + ?Sized> {
     fn needle(&self) -> &N;

src/multiversion.rs

@@ -0,0 +1,96 @@
+macro_rules! multiversion {
+    ($vis:vis unsafe fn $name:ident $(<$($gen_name:ident : $gen_ty:ty),+>)? ( $($arg_name:ident : $arg_ty:ty ,)+ ) -> $ret:ty $block:block) => {
+        paste::paste! {
+            #[allow(dead_code)]
+            #[inline(always)]
+            $vis unsafe fn [<$name _ default_version>] $(<$($gen_name : $gen_ty),+>)? ( $($arg_name : $arg_ty),+ ) -> $ret {
+                #[allow(dead_code)]
+                const TARGET: crate::multiversion::Target = crate::multiversion::Target::Default;
+                $block
+            }
+
+            #[cfg(target_arch = "x86_64")]
+            #[target_feature(enable = "avx2")]
+            #[inline]
+            $vis unsafe fn [<$name _ avx2_version>] $(<$($gen_name : $gen_ty),+>)? ( $($arg_name : $arg_ty),+ ) -> $ret {
+                #[allow(dead_code)]
+                const TARGET: crate::multiversion::Target = crate::multiversion::Target::Avx2;
+                $block
+            }
+
+            #[cfg(target_arch = "wasm32")]
+            #[target_feature(enable = "simd128")]
+            #[inline]
+            $vis unsafe fn [<$name _ simd128_version>] $(<$($gen_name : $gen_ty),+>)? ( $($arg_name : $arg_ty),+ ) -> $ret {
+                #[allow(dead_code)]
+                const TARGET: crate::multiversion::Target = crate::multiversion::Target::Simd128;
+                $block
+            }
+
+            #[cfg(target_arch = "aarch64")]
+            #[target_feature(enable = "neon")]
+            #[inline]
+            $vis unsafe fn [<$name _ neon_version>] $(<$($gen_name : $gen_ty),+>)? ( $($arg_name : $arg_ty),+ ) -> $ret {
+                #[allow(dead_code)]
+                const TARGET: crate::multiversion::Target = crate::multiversion::Target::Neon;
+                $block
+            }
+        }
+    };
+}
+
+cfg_if::cfg_if! {
+    if #[cfg(target_arch = "x86_64")] {
+        pub(crate) enum Target {
+            Default,
+            Avx2,
+        }
+
+        macro_rules! dispatch {
+            ($target:ident => $name:ident ( $($arg:expr),+ )) => {
+                match $target {
+                    crate::multiversion::Target::Default => paste::paste! { [<$name _ default_version>] ( $($arg),+ ) },
+                    crate::multiversion::Target::Avx2 => paste::paste! { [<$name _ avx2_version>] ( $($arg),+ ) },
+                }
+            }
+        }
+    } else if #[cfg(target_arch = "wasm32")] {
+        pub(crate) enum Target {
+            Default,
+            Simd128,
+        }
+
+        macro_rules! dispatch {
+            ($target:ident => $name:ident ( $($arg:expr),+ )) => {
+                match $target {
+                    crate::multiversion::Target::Default => paste::paste! { [<$name _ default_version>] ( $($arg),+ ) },
+                    crate::multiversion::Target::Simd128 => paste::paste! { [<$name _ simd128_version>] ( $($arg),+ ) },
+                }
+            }
+        }
+    } else if #[cfg(target_arch = "aarch64")] {
+        pub(crate) enum Target {
+            Default,
+            Neon,
+        }
+
+        macro_rules! dispatch {
+            ($target:ident => $name:ident ( $($arg:expr),+ )) => {
+                match $target {
+                    crate::multiversion::Target::Default => paste::paste! { [<$name _ default_version>] ( $($arg),+ ) },
+                    crate::multiversion::Target::Neon => paste::paste! { [<$name _ neon_version>] ( $($arg),+ ) },
+                }
+            }
+        }
+    } else {
+        pub(crate) enum Target {
+            Default,
+        }
+
+        macro_rules! dispatch {
+            ($target:ident => $name:ident ( $($arg:expr),+ )) => {
+                paste::paste! { [<$name _ default_version>] ( $($arg),+ ) },
+            }
+        }
+    }
+}