Rename the 'cretonne' crate to 'cretonne-codegen'.

This fixes the next part of #287.

lib/codegen/src/ir/jumptable.rs

@@ -0,0 +1,180 @@
+//! Jump table representation.
+//!
+//! Jump tables are declared in the preamble and assigned an `ir::entities::JumpTable` reference.
+//! The actual table of destinations is stored in a `JumpTableData` struct defined in this module.
+
+use ir::entities::Ebb;
+use packed_option::PackedOption;
+use std::fmt::{self, Display, Formatter};
+use std::iter;
+use std::slice;
+use std::vec::Vec;
+
+/// Contents of a jump table.
+///
+/// All jump tables use 0-based indexing and are expected to be densely populated. They don't need
+/// to be completely populated, though. Individual entries can be missing.
+#[derive(Clone)]
+pub struct JumpTableData {
+    // Table entries, using `None` as a placeholder for missing entries.
+    table: Vec<PackedOption<Ebb>>,
+
+    // How many `None` holes in table?
+    holes: usize,
+}
+
+impl JumpTableData {
+    /// Create a new empty jump table.
+    pub fn new() -> Self {
+        Self {
+            table: Vec::new(),
+            holes: 0,
+        }
+    }
+
+    /// Create a new empty jump table with the specified capacity.
+    pub fn with_capacity(capacity: usize) -> Self {
+        Self {
+            table: Vec::with_capacity(capacity),
+            holes: 0,
+        }
+    }
+
+    /// Get the number of table entries.
+    pub fn len(&self) -> usize {
+        self.table.len()
+    }
+
+    /// Set a table entry.
+    ///
+    /// The table will grow as needed to fit `idx`.
+    pub fn set_entry(&mut self, idx: usize, dest: Ebb) {
+        // Resize table to fit `idx`.
+        if idx >= self.table.len() {
+            self.holes += idx - self.table.len();
+            self.table.resize(idx + 1, None.into());
+        } else if self.table[idx].is_none() {
+            // We're filling in an existing hole.
+            self.holes -= 1;
+        }
+        self.table[idx] = dest.into();
+    }
+
+    /// Append a table entry.
+    pub fn push_entry(&mut self, dest: Ebb) {
+        self.table.push(dest.into())
+    }
+
+    /// Clear a table entry.
+    ///
+    /// The `br_table` instruction will fall through if given an index corresponding to a cleared
+    /// table entry.
+    pub fn clear_entry(&mut self, idx: usize) {
+        if idx < self.table.len() && self.table[idx].is_some() {
+            self.holes += 1;
+            self.table[idx] = None.into();
+        }
+    }
+
+    /// Get the entry for `idx`, or `None`.
+    pub fn get_entry(&self, idx: usize) -> Option<Ebb> {
+        self.table.get(idx).and_then(|e| e.expand())
+    }
+
+    /// Enumerate over all `(idx, dest)` pairs in the table in order.
+    ///
+    /// This returns an iterator that skips any empty slots in the table.
+    pub fn entries(&self) -> Entries {
+        Entries(self.table.iter().cloned().enumerate())
+    }
+
+    /// Checks if any of the entries branch to `ebb`.
+    pub fn branches_to(&self, ebb: Ebb) -> bool {
+        self.table.iter().any(|target_ebb| {
+            target_ebb.expand() == Some(ebb)
+        })
+    }
+
+    /// Access the whole table as a mutable slice.
+    pub fn as_mut_slice(&mut self) -> &mut [PackedOption<Ebb>] {
+        self.table.as_mut_slice()
+    }
+}
+
+/// Enumerate `(idx, dest)` pairs in order.
+pub struct Entries<'a>(iter::Enumerate<iter::Cloned<slice::Iter<'a, PackedOption<Ebb>>>>);
+
+impl<'a> Iterator for Entries<'a> {
+    type Item = (usize, Ebb);
+
+    fn next(&mut self) -> Option<Self::Item> {
+        loop {
+            if let Some((idx, dest)) = self.0.next() {
+                if let Some(ebb) = dest.expand() {
+                    return Some((idx, ebb));
+                }
+            } else {
+                return None;
+            }
+        }
+    }
+}
+
+impl Display for JumpTableData {
+    fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
+        match self.table.first().and_then(|e| e.expand()) {
+            None => write!(fmt, "jump_table 0")?,
+            Some(first) => write!(fmt, "jump_table {}", first)?,
+        }
+
+        for dest in self.table.iter().skip(1).map(|e| e.expand()) {
+            match dest {
+                None => write!(fmt, ", 0")?,
+                Some(ebb) => write!(fmt, ", {}", ebb)?,
+            }
+        }
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::JumpTableData;
+    use entity::EntityRef;
+    use ir::Ebb;
+    use std::string::ToString;
+    use std::vec::Vec;
+
+    #[test]
+    fn empty() {
+        let jt = JumpTableData::new();
+
+        assert_eq!(jt.get_entry(0), None);
+        assert_eq!(jt.get_entry(10), None);
+
+        assert_eq!(jt.to_string(), "jump_table 0");
+
+        let v: Vec<(usize, Ebb)> = jt.entries().collect();
+        assert_eq!(v, []);
+    }
+
+    #[test]
+    fn insert() {
+        let e1 = Ebb::new(1);
+        let e2 = Ebb::new(2);
+
+        let mut jt = JumpTableData::new();
+
+        jt.set_entry(0, e1);
+        jt.set_entry(0, e2);
+        jt.set_entry(10, e1);
+
+        assert_eq!(
+            jt.to_string(),
+            "jump_table ebb2, 0, 0, 0, 0, 0, 0, 0, 0, 0, ebb1"
+        );
+
+        let v: Vec<(usize, Ebb)> = jt.entries().collect();
+        assert_eq!(v, [(0, e2), (10, e1)]);
+    }
+}