Share constant_hash code between the meta and codegen crates;

cranelift/codegen/meta/src/constant_hash.rs

@@ -1,55 +0,0 @@
-use std::iter;
-
-pub(crate) fn simple_hash(s: &str) -> usize {
-    let mut h: u32 = 5381;
-    for c in s.chars() {
-        h = (h ^ c as u32).wrapping_add(h.rotate_right(6));
-    }
-    h as usize
-}
-
-/// Compute an open addressed, quadratically probed hash table containing
-/// `items`. The returned table is a list containing the elements of the
-/// iterable `items` and `None` in unused slots.
-pub(crate) fn generate_table<'cont, T, I: iter::Iterator<Item = &'cont T>, H: Fn(&T) -> usize>(
-    items: I,
-    num_items: usize,
-    hash_function: H,
-) -> Vec<Option<&'cont T>> {
-    let size = (1.20 * num_items as f64) as usize;
-    // TODO do we really need the multiply by two here?
-    let size = if size.is_power_of_two() {
-        size * 2
-    } else {
-        size.next_power_of_two()
-    };
-
-    let mut table = vec![None; size];
-
-    for i in items {
-        let mut h = hash_function(&i) % size;
-        let mut s = 0;
-        while table[h].is_some() {
-            s += 1;
-            h = (h + s) % size;
-        }
-        table[h] = Some(i);
-    }
-
-    table
-}
-
-#[test]
-fn test_generate_table() {
-    let v = vec!["Hello".to_string(), "world".to_string()];
-    let table = generate_table(v.iter(), v.len(), |s| simple_hash(&s));
-    assert_eq!(
-        table,
-        vec![
-            None,
-            Some(&"Hello".to_string()),
-            Some(&"world".to_string()),
-            None
-        ]
-    );
-}

cranelift/codegen/meta/src/gen_encodings.rs

@@ -49,6 +49,7 @@ use std::collections::{BTreeMap, HashMap, HashSet};
 use std::convert::TryFrom;
 use std::iter::FromIterator;
 
+use cranelift_codegen_shared::constant_hash::generate_table;
 use cranelift_entity::EntityRef;
 
 use crate::error;
@@ -66,7 +67,6 @@ use crate::cdsl::xform::TransformGroupIndex;
 
 use crate::shared::Definitions as SharedDefinitions;
 
-use crate::constant_hash::generate_table;
 use crate::default_map::MapWithDefault;
 use crate::unique_table::UniqueSeqTable;
 

cranelift/codegen/meta/src/gen_inst.rs

@@ -1,5 +1,6 @@
 use std::fmt;
 
+use cranelift_codegen_shared::constant_hash;
 use cranelift_entity::EntityRef;
 
 use crate::cdsl::camel_case;
@@ -10,7 +11,6 @@ use crate::cdsl::typevar::{TypeSet, TypeVar};
 
 use crate::shared::Definitions as SharedDefinitions;
 
-use crate::constant_hash;
 use crate::error;
 use crate::srcgen::{Formatter, Match};
 use crate::unique_table::{UniqueSeqTable, UniqueTable};

cranelift/codegen/meta/src/gen_settings.rs

@@ -1,12 +1,14 @@
+use std::collections::HashMap;
+
+use cranelift_codegen_shared::constant_hash::{generate_table, simple_hash};
+
 use crate::cdsl::camel_case;
 use crate::cdsl::settings::{
     BoolSetting, Predicate, Preset, Setting, SettingGroup, SpecificSetting,
 };
-use crate::constant_hash::{generate_table, simple_hash};
 use crate::error;
 use crate::srcgen::{Formatter, Match};
 use crate::unique_table::UniqueSeqTable;
-use std::collections::HashMap;
 
 pub enum ParentGroup {
     None,

cranelift/codegen/meta/src/lib.rs

@@ -13,7 +13,6 @@ mod gen_registers;
 mod gen_settings;
 mod gen_types;
 
-mod constant_hash;
 mod default_map;
 mod shared;
 mod unique_table;