perf: add a faster skip_until using SIMD memchr (#745)

it was put under the "memchr" feature-flag, as memchr SIMD support is only on x86_64 at the moment (json bench is ~8% faster over baseline there): #737 (comment) once memchr has the Arm SIMD support, this could be perhaps the default implementation. For Aho-Corasick, it'll require more investigation. Co-authored-by: Tomas Tauber <me@tomtau.be>
pest-parser · Dec 2, 2022 · 1e40766 · 1e40766
1 parent ca11433
commit 1e40766
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Showing 8 changed files with 73 additions and 19 deletions.
diff --git a/debugger/Cargo.toml b/debugger/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name = "pest_debugger"
 description = "pest grammar debugger"
-version = "2.5.0"
+version = "2.5.1"
 edition = "2021"
 authors = ["Dragoș Tiselice <dragostiselice@gmail.com>", "Tomas Tauber <me@tomtau.be>"]
 homepage = "https://pest.rs/"
@@ -14,9 +14,9 @@ readme = "_README.md"
 rust-version = "1.56"
 
 [dependencies]
-pest = { path = "../pest", version = "2.5.0" }
-pest_meta = { path = "../meta", version = "2.5.0" }
-pest_vm = { path = "../vm", version = "2.5.0" }
+pest = { path = "../pest", version = "2.5.1" }
+pest_meta = { path = "../meta", version = "2.5.1" }
+pest_vm = { path = "../vm", version = "2.5.1" }
 rustyline = "10"
 thiserror = "1"
 

diff --git a/derive/Cargo.toml b/derive/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name = "pest_derive"
 description = "pest's derive macro"
-version = "2.5.0"
+version = "2.5.1"
 edition = "2021"
 authors = ["Dragoș Tiselice <dragostiselice@gmail.com>"]
 homepage = "https://pest.rs/"
@@ -23,5 +23,5 @@ std = ["pest/std", "pest_generator/std"]
 
 [dependencies]
 # for tests, included transitively anyway
-pest = { path = "../pest", version = "2.5.0", default-features = false }
-pest_generator = { path = "../generator", version = "2.5.0", default-features = false }
+pest = { path = "../pest", version = "2.5.1", default-features = false }
+pest_generator = { path = "../generator", version = "2.5.1", default-features = false }
diff --git a/generator/Cargo.toml b/generator/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name = "pest_generator"
 description = "pest code generator"
-version = "2.5.0"
+version = "2.5.1"
 edition = "2021"
 authors = ["Dragoș Tiselice <dragostiselice@gmail.com>"]
 homepage = "https://pest.rs/"
@@ -18,8 +18,8 @@ default = ["std"]
 std = ["pest/std"]
 
 [dependencies]
-pest = { path = "../pest", version = "2.5.0", default-features = false }
-pest_meta = { path = "../meta", version = "2.5.0" }
+pest = { path = "../pest", version = "2.5.1", default-features = false }
+pest_meta = { path = "../meta", version = "2.5.1" }
 proc-macro2 = "1.0"
 quote = "1.0"
 syn = "1.0"
diff --git a/grammars/Cargo.toml b/grammars/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name = "pest_grammars"
 description = "pest popular grammar implementations"
-version = "2.5.0"
+version = "2.5.1"
 edition = "2021"
 authors = ["Dragoș Tiselice <dragostiselice@gmail.com>"]
 homepage = "https://pest.rs/"
@@ -14,8 +14,8 @@ readme = "_README.md"
 rust-version = "1.56"
 
 [dependencies]
-pest = { path = "../pest", version = "2.5.0" }
-pest_derive = { path = "../derive", version = "2.5.0" }
+pest = { path = "../pest", version = "2.5.1" }
+pest_derive = { path = "../derive", version = "2.5.1" }
 
 [dev-dependencies]
 criterion = "0.3"

diff --git a/meta/Cargo.toml b/meta/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name = "pest_meta"
 description = "pest meta language parser and validator"
-version = "2.5.0"
+version = "2.5.1"
 edition = "2021"
 authors = ["Dragoș Tiselice <dragostiselice@gmail.com>"]
 homepage = "https://pest.rs/"
@@ -16,7 +16,7 @@ include = ["Cargo.toml", "src/**/*", "src/grammar.rs", "_README.md", "LICENSE-*"
 rust-version = "1.56"
 
 [dependencies]
-pest = { path = "../pest", version = "2.5.0" }
+pest = { path = "../pest", version = "2.5.1" }
 once_cell = "1.8.0"
 
 [build-dependencies]

diff --git a/pest/Cargo.toml b/pest/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name = "pest"
 description = "The Elegant Parser"
-version = "2.5.0"
+version = "2.5.1"
 edition = "2021"
 authors = ["Dragoș Tiselice <dragostiselice@gmail.com>"]
 homepage = "https://pest.rs/"

diff --git a/pest/src/position.rs b/pest/src/position.rs
@@ -266,6 +266,60 @@ impl<'i> Position<'i> {
     /// this function will return `false` but its `pos` will *still* be updated.
     #[inline]
     pub(crate) fn skip_until(&mut self, strings: &[&str]) -> bool {
+        #[cfg(not(feature = "memchr"))]
+        {
+            self.skip_until_basic(strings)
+        }
+        #[cfg(feature = "memchr")]
+        {
+            match strings {
+                [] => (),
+                [s1] => {
+                    if let Some(from) =
+                        memchr::memmem::find(&self.input.as_bytes()[self.pos..], s1.as_bytes())
+                    {
+                        self.pos += from;
+                        return true;
+                    }
+                }
+                [s1, s2] if !s1.is_empty() && !s2.is_empty() => {
+                    let b1 = s1.as_bytes()[0];
+                    let b2 = s2.as_bytes()[0];
+                    let miter = memchr::memchr2_iter(b1, b2, &self.input.as_bytes()[self.pos..]);
+                    for from in miter {
+                        let start = &self.input[self.pos + from..];
+                        if start.starts_with(s1) || start.starts_with(s2) {
+                            self.pos += from;
+                            return true;
+                        }
+                    }
+                }
+                [s1, s2, s3] if !s1.is_empty() && !s2.is_empty() && s3.is_empty() => {
+                    let b1 = s1.as_bytes()[0];
+                    let b2 = s2.as_bytes()[0];
+                    let b3 = s2.as_bytes()[0];
+                    let miter =
+                        memchr::memchr3_iter(b1, b2, b3, &self.input.as_bytes()[self.pos..]);
+                    for from in miter {
+                        let start = &self.input[self.pos + from..];
+                        if start.starts_with(s1) || start.starts_with(s2) || start.starts_with(s3) {
+                            self.pos += from;
+                            return true;
+                        }
+                    }
+                }
+                _ => {
+                    return self.skip_until_basic(strings);
+                }
+            }
+            self.pos = self.input.len();
+            false
+        }
+    }
+
+    #[inline]
+    fn skip_until_basic(&mut self, strings: &[&str]) -> bool {
+        // TODO: optimize with Aho-Corasick, e.g. https://crates.io/crates/daachorse?
         for from in self.pos..self.input.len() {
             let bytes = if let Some(string) = self.input.get(from..) {
                 string.as_bytes()

diff --git a/vm/Cargo.toml b/vm/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name = "pest_vm"
 description = "pest grammar virtual machine"
-version = "2.5.0"
+version = "2.5.1"
 edition = "2021"
 authors = ["Dragoș Tiselice <dragostiselice@gmail.com>"]
 homepage = "https://pest.rs/"
@@ -14,5 +14,5 @@ readme = "_README.md"
 rust-version = "1.56"
 
 [dependencies]
-pest = { path = "../pest", version = "2.5.0" }
-pest_meta = { path = "../meta", version = "2.5.0" }
+pest = { path = "../pest", version = "2.5.1" }
+pest_meta = { path = "../meta", version = "2.5.1" }