Use stable SIMD intrinsics with runtime detection

Cargo.toml

@@ -3,7 +3,7 @@ name = "twoway"
 version = "0.1.8"
 authors = ["bluss"]
 
-description = "Fast substring search for strings and byte strings. Optional SSE4.2 acceleration (requires nightly and cargo feature flag pcmp) using pcmpestri. Memchr is the only mandatory dependency. The two way algorithm is also used by rust's libstd itself, but here it is exposed both for byte strings, using memchr, and optionally using a SSE4.2 accelerated version."
+description = "Fast substring search for strings and byte strings. Optional SSE4.2 acceleration (if detected at runtime) using pcmpestri. Memchr is the only mandatory dependency. The two way algorithm is also used by rust's libstd itself, but here it is exposed both for byte strings, using memchr, and optionally using a SSE4.2 accelerated version."
 
 license = "MIT/Apache-2.0"
 repository = "https://github.com/bluss/twoway"
@@ -14,7 +14,7 @@ categories = ["algorithms", "no-std"]
 
 [dependencies]
 memchr = { version = "2.0", default-features = false }
-unchecked-index = { version = "0.2.2", optional = true }
+unchecked-index = { version = "0.2.2" }
 jetscii = {version = "0.3", features= ["unstable"], optional = true }
 galil-seiferas = { version = "0.1.1", optional = true }
 
@@ -31,14 +31,11 @@ quickcheck = { version = "0.5", default-features = false }
 default = ["use_std"]
 use_std = ["memchr/use_std"]
 
-# pcmpestri, requires nightly
-pcmp = ["unchecked-index"]
-
 # Internal features for testing & benchmarking & development
 pattern = []
 test-set = []
-benchmarks = ["galil-seiferas", "pattern", "unchecked-index"]
-all = ["jetscii", "pcmp", "pattern", "test-set"]
+benchmarks = ["galil-seiferas", "pattern"]
+all = ["jetscii", "pattern", "test-set"]
 
 
 [package.metadata.release]

README.rst

@@ -22,11 +22,9 @@ This is the same code as is included in Rust's libstd to “power” ``str::find
 but here it is exposed with some improvements:
 
 - Available for byte string searches using ``&[u8]``
-- Having an optional SSE4.2 accelerated version which is even faster.
+- Having an optional SSE4.2 accelerated version (if detected at runtime) which is even faster.
 - Using ``memchr`` for the single byte case, which is ultra fast.
 
-Use cargo feature ``pcmp`` to enable SSE4.2 / pcmpestri accelerated version (only the forward search).
-
 - ``twoway::find_bytes(text: &[u8], pattern: &[u8]) -> Option<usize>``
 - ``twoway::rfind_bytes(text: &[u8], pattern: &[u8]) -> Option<usize>``
 - ``twoway::find_str(text: &str, pattern: &str) -> Option<usize>``

benches/pathology.rs

@@ -27,9 +27,11 @@ use test::{Bencher, black_box};
 use twoway::find_str as tw_find;
 use twoway::rfind_str as tw_rfind;
 
+/*
 pub fn is_prefix(text: &str, pattern: &str) -> bool {
     Str(pattern).is_prefix_of(text)
 }
+*/
 
 pub fn memmem(text: &str, pattern: &str) -> bool {
     #[allow(improper_ctypes)]
@@ -162,7 +164,6 @@ macro_rules! bench_contains_vs_tw {
             }
             */
 
-            #[cfg(feature = "pcmp")]
             #[bench]
             pub fn pcmp_find(b: &mut Bencher) {
                 let haystack = black_box($hay);
@@ -535,7 +536,7 @@ pub fn rfind_char_1(b: &mut Bencher) {
         t
     });
     b.bytes = haystack.len() as u64;
-} 
+}
 
 #[cfg(feature = "test-set")]
 fn bench_data() -> Vec<u8> { vec![0u8; 256 * 1024] }

fuzz/Cargo.toml

@@ -13,9 +13,6 @@ path = ".."
 [dependencies.libfuzzer-sys]
 git = "https://github.com/rust-fuzz/libfuzzer-sys.git"
 
-[features]
-pcmp = ["twoway/pcmp"]
-
 # Prevent this from interfering with workspaces
 [workspace]
 members = ["."]

fuzz/run1_pcmp.sh

@@ -2,4 +2,4 @@
 
 DIR=$(dirname "$0")
 V=$(cat "$DIR"/nightly-version)
-cargo +$V fuzz run --features=pcmp -O -a fuzz_target_1 -- -only_ascii=1 -max_len=5000 "$@"
+cargo +$V fuzz run -O -a fuzz_target_1 -- -only_ascii=1 -max_len=5000 "$@"

fuzz/run_substring_pcmp.sh

@@ -2,4 +2,4 @@
 
 DIR=$(dirname "$0")
 V=$(cat "$DIR"/nightly-version)
-cargo +$V fuzz run --features=pcmp -O substring -- -only_ascii=1 -max_len=256 "$@"
+cargo +$V fuzz run -O substring -- -only_ascii=1 -max_len=256 "$@"

src/lib.rs

@@ -1,8 +1,7 @@
-#![cfg_attr(not(test), no_std)]
+#![cfg_attr(not(feature = "use_std"), no_std)]
 #![cfg_attr(feature = "pattern", feature(pattern))]
-#![cfg_attr(feature = "pcmp", feature(asm))]
 
-#[cfg(not(test))]
+#[cfg(not(feature = "use_std"))]
 extern crate core as std;
 
 use std::cmp;
@@ -11,7 +10,7 @@ use std::usize;
 extern crate memchr;
 
 mod tw;
-#[cfg(feature = "pcmp")]
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 pub mod pcmp;
 pub mod bmh;
 #[cfg(feature = "test-set")]
@@ -28,31 +27,28 @@ use std::str::pattern::{
 
 /// `find_str` finds the first ocurrence of `pattern` in the `text`.
 ///
-/// Uses the SSE42 version if it is compiled in.
+/// Uses the SSE42 version if it is available at runtime.
 #[inline]
 pub fn find_str(text: &str, pattern: &str) -> Option<usize> {
     find_bytes(text.as_bytes(), pattern.as_bytes())
 }
 
 /// `find_bytes` finds the first ocurrence of `pattern` in the `text`.
 ///
-/// Uses the SSE42 version if it is compiled in.
-#[cfg(feature = "pcmp")]
-#[inline]
-pub fn find_bytes(text: &[u8], pattern: &[u8]) -> Option<usize> {
-    pcmp::find(text, pattern)
-}
-
-/// `find_bytes` finds the first ocurrence of `pattern` in the `text`.
-///
-/// Uses the SSE42 version if it is compiled in.
-#[cfg(not(feature = "pcmp"))]
+/// Uses the SSE42 version if it is available at runtime.
 pub fn find_bytes(text: &[u8], pattern: &[u8]) -> Option<usize> {
     if pattern.is_empty() {
         Some(0)
+    } else if text.len() < pattern.len() {
+        return None;
     } else if pattern.len() == 1 {
         memchr::memchr(pattern[0], text)
     } else {
+        #[cfg(any(target_arch = "x86", target_arch = "x86_64"))] {
+            if pcmp::is_supported() {
+                return unsafe { pcmp::find_inner(text, pattern) };
+            }
+        }
         let mut searcher = TwoWaySearcher::new(pattern, text.len());
         let is_long = searcher.memory == usize::MAX;
         // write out `true` and `false` cases to encourage the compiler
@@ -492,7 +488,7 @@ impl TwoWaySearcher {
     }
 
     /// Return the zero-based critical position and period of the provided needle.
-    /// 
+    ///
     /// The returned period is incorrect when the actual period is "long." In
     /// that case the approximation must be computed separately.
     #[inline(always)]
@@ -913,7 +909,7 @@ fn test_contains() {
     assert!(contains(h, n));
     assert!(contains_rev(h, n));
 
-    let h = "\u{0}\u{0}\u{0}\u{0}"; 
+    let h = "\u{0}\u{0}\u{0}\u{0}";
     let n = "\u{0}";
     assert!(contains(h, n));
     assert!(contains_rev(h, n));