Merge pull request #3480 from bjorn3/move_constant_hash_gen_table

Move generate_table from cranelift-codegen-shared to cranelift-codege…

cranelift/codegen/meta/src/constant_hash.rs

@@ -0,0 +1,64 @@
+//! Build support for precomputed constant hash tables.
+//!
+//! This module can generate constant hash tables using open addressing and quadratic probing.
+//!
+//! The hash tables are arrays that are guaranteed to:
+//!
+//! - Have a power-of-two size.
+//! - Contain at least one empty slot.
+
+use std::iter;
+
+/// 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.
+#[allow(clippy::float_arithmetic)]
+pub 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;
+
+    // Probing code's stop condition relies on the table having one vacant entry at least.
+    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
+}
+
+#[cfg(test)]
+mod tests {
+    use super::generate_table;
+    use cranelift_codegen_shared::constant_hash::simple_hash;
+
+    #[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_inst.rs

@@ -553,9 +553,10 @@ fn gen_opcodes(all_inst: &AllInstructions, fmt: &mut Formatter) {
     fmt.empty_line();
 
     // Generate an opcode hash table for looking up opcodes by name.
-    let hash_table = constant_hash::generate_table(all_inst.iter(), all_inst.len(), |inst| {
-        constant_hash::simple_hash(&inst.name)
-    });
+    let hash_table =
+        crate::constant_hash::generate_table(all_inst.iter(), all_inst.len(), |inst| {
+            constant_hash::simple_hash(&inst.name)
+        });
     fmtln!(
         fmt,
         "const OPCODE_HASH_TABLE: [Option<Opcode>; {}] = [",

cranelift/codegen/meta/src/gen_settings.rs

@@ -1,7 +1,8 @@
 //! Generate the ISA-specific settings.
 use std::collections::HashMap;
 
-use cranelift_codegen_shared::constant_hash::{generate_table, simple_hash};
+use crate::constant_hash::generate_table;
+use cranelift_codegen_shared::constant_hash::simple_hash;
 
 use crate::cdsl::camel_case;
 use crate::cdsl::settings::{

cranelift/codegen/meta/src/lib.rs

@@ -11,6 +11,7 @@ mod gen_inst;
 mod gen_settings;
 mod gen_types;
 
+mod constant_hash;
 mod shared;
 mod unique_table;
 

cranelift/codegen/shared/src/constant_hash.rs

@@ -1,16 +1,4 @@
-//! Build support for precomputed constant hash tables.
-//!
-//! This module can generate constant hash tables using open addressing and quadratic probing.
-//!
-//! The hash tables are arrays that are guaranteed to:
-//!
-//! - Have a power-of-two size.
-//! - Contain at least one empty slot.
-//!
-//! This module provides build meta support for lookups in these tables, as well as the shared hash
-//! function used for probing.
-
-use std::iter;
+//! This module provides a primitive hash function.
 
 /// A primitive hash function for matching opcodes.
 pub fn simple_hash(s: &str) -> usize {
@@ -21,61 +9,13 @@ pub fn simple_hash(s: &str) -> usize {
     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.
-#[allow(clippy::float_arithmetic)]
-pub 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;
-
-    // Probing code's stop condition relies on the table having one vacant entry at least.
-    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
-}
-
 #[cfg(test)]
 mod tests {
-    use super::{generate_table, simple_hash};
+    use super::simple_hash;
 
     #[test]
     fn basic() {
         assert_eq!(simple_hash("Hello"), 0x2fa70c01);
         assert_eq!(simple_hash("world"), 0x5b0c31d5);
     }
-
-    #[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
-            ]
-        );
-    }
 }