peepmatic: Represent various id types with u16

These ids end up in the automaton, so making them smaller should give us better
data cache locality and also smaller serialized sizes.

cranelift/peepmatic/crates/runtime/src/integer_interner.rs

@@ -7,11 +7,11 @@
 
 use serde::{Deserialize, Serialize};
 use std::collections::BTreeMap;
-use std::num::NonZeroU32;
+use std::num::{NonZeroU16, NonZeroU32};
 
 /// An identifier for an interned integer.
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)]
-pub struct IntegerId(#[doc(hidden)] pub NonZeroU32);
+pub struct IntegerId(#[doc(hidden)] pub NonZeroU16);
 
 /// An interner for integer values.
 #[derive(Debug, Default, Serialize, Deserialize)]
@@ -40,8 +40,8 @@ impl IntegerInterner {
             return *id;
         }
 
-        assert!((self.values.len() as u64) < (std::u32::MAX as u64));
-        let id = IntegerId(unsafe { NonZeroU32::new_unchecked(self.values.len() as u32 + 1) });
+        assert!((self.values.len() as u64) < (std::u16::MAX as u64));
+        let id = IntegerId(unsafe { NonZeroU16::new_unchecked(self.values.len() as u16 + 1) });
 
         self.values.push(value);
         self.map.insert(value, id);
@@ -65,16 +65,9 @@ impl IntegerInterner {
     }
 }
 
-impl From<IntegerId> for u32 {
-    #[inline]
-    fn from(id: IntegerId) -> u32 {
-        id.0.get()
-    }
-}
-
 impl From<IntegerId> for NonZeroU32 {
     #[inline]
     fn from(id: IntegerId) -> NonZeroU32 {
-        id.0
+        id.0.into()
     }
 }

cranelift/peepmatic/crates/runtime/src/linear.rs

@@ -149,11 +149,11 @@ pub enum MatchOp {
 /// A canonicalized identifier for a left-hand side value that was bound in a
 /// pattern.
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord, Serialize, Deserialize)]
-pub struct LhsId(pub u32);
+pub struct LhsId(pub u16);
 
 /// A canonicalized identifier for a right-hand side value.
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)]
-pub struct RhsId(pub u32);
+pub struct RhsId(pub u16);
 
 /// An action to perform when transitioning between states in the automata.
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)]
@@ -243,18 +243,22 @@ pub enum Action {
 mod tests {
     use super::*;
 
+    // These types all end up in the automaton, so we should take care that they
+    // are small and don't fill up the data cache (or take up too much
+    // serialized size).
+
     #[test]
-    fn match_result_is_4_bytes_in_size() {
+    fn match_result_size() {
         assert_eq!(std::mem::size_of::<MatchResult>(), 4);
     }
 
     #[test]
-    fn match_op_is_12_bytes_in_size() {
-        assert_eq!(std::mem::size_of::<MatchOp>(), 12);
+    fn match_op_size() {
+        assert_eq!(std::mem::size_of::<MatchOp>(), 6);
     }
 
     #[test]
-    fn action_is_20_bytes_in_size() {
-        assert_eq!(std::mem::size_of::<Action>(), 20);
+    fn action_size() {
+        assert_eq!(std::mem::size_of::<Action>(), 16);
     }
 }

cranelift/peepmatic/crates/runtime/src/optimizer.rs

@@ -414,7 +414,7 @@ where
                     Part::Constant(c) => {
                         let x = c.as_int().ok_or(Else)?;
                         let id = self.peep_opt.integers.already_interned(x).ok_or(Else)?;
-                        Ok(id.0)
+                        Ok(id.into())
                     }
                     Part::Instruction(i) => {
                         let c = self
@@ -423,7 +423,7 @@ where
                             .ok_or(Else)?;
                         let x = c.as_int().ok_or(Else)?;
                         let id = self.peep_opt.integers.already_interned(x).ok_or(Else)?;
-                        Ok(id.0)
+                        Ok(id.into())
                     }
                     Part::ConditionCode(_) => unreachable!("IntegerValue on condition code"),
                 }

cranelift/peepmatic/crates/runtime/src/paths.rs

@@ -46,7 +46,7 @@ impl Path<'_> {
 
 /// An identifier for an interned path.
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)]
-pub struct PathId(u32);
+pub struct PathId(u16);
 
 /// An interner and de-duplicator for `Path`s.
 ///
@@ -93,7 +93,7 @@ impl PathInterner {
 
     #[inline(never)]
     fn intern_new<'a>(&mut self, path: Path<'a>) -> PathId {
-        let id: u32 = self
+        let id: u16 = self
             .paths
             .len()
             .try_into()

cranelift/peepmatic/src/dot_fmt.rs

@@ -10,9 +10,9 @@ use peepmatic_runtime::{
     operator::Operator,
     paths::{PathId, PathInterner},
 };
-use std::convert::TryFrom;
+use std::convert::{TryFrom, TryInto};
 use std::io::{self, Write};
-use std::num::NonZeroU32;
+use std::num::NonZeroU16;
 
 #[derive(Debug)]
 pub(crate) struct PeepholeDotFmt<'a>(pub(crate) &'a PathInterner, pub(crate) &'a IntegerInterner);
@@ -39,7 +39,9 @@ impl DotFmt<linear::MatchResult, linear::MatchOp, Vec<linear::Action>> for Peeph
                     write!(w, "{}", cc)
                 }
                 linear::MatchOp::IntegerValue { .. } => {
-                    let x = self.1.lookup(IntegerId(NonZeroU32::new(x).unwrap()));
+                    let x = self
+                        .1
+                        .lookup(IntegerId(NonZeroU16::new(x.try_into().unwrap()).unwrap()));
                     write!(w, "{}", x)
                 }
                 _ => write!(w, "Ok({})", x),

cranelift/peepmatic/src/linearize.rs

@@ -92,6 +92,7 @@ use peepmatic_runtime::{
     paths::{Path, PathId, PathInterner},
 };
 use std::collections::BTreeMap;
+use std::convert::TryInto;
 use std::num::NonZeroU32;
 use wast::Id;
 
@@ -339,7 +340,7 @@ impl<'a> RhsBuilder<'a> {
     ) {
         while let Some(rhs) = self.rhs_post_order.next() {
             actions.push(self.rhs_to_linear_action(integers, lhs_id_to_path, rhs));
-            let id = linear::RhsId(self.rhs_span_to_id.len() as u32);
+            let id = linear::RhsId(self.rhs_span_to_id.len().try_into().unwrap());
             self.rhs_span_to_id.insert(rhs.span(), id);
         }
     }