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Use PackedOption<Ebb> to represent jump tables.

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Avoid NO_EBB.
This commit is contained in:
Jakob Stoklund Olesen
2017-01-19 13:41:56 -08:00
parent f004f370c5
commit 5fc222348d
3 changed files with 33 additions and 33 deletions
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51
lib/cretonne/src/ir/jumptable.rs
View File

@@ -3,7 +3,8 @@
//! 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, NO_EBB};
use packed_option::PackedOption;
use ir::entities::Ebb;
use std::iter;
use std::slice;
use std::fmt::{self, Display, Formatter};
@@ -14,10 +15,10 @@ use std::fmt::{self, Display, Formatter};
/// to be completely populated, though. Individual entries can be missing.
#[derive(Clone)]
pub struct JumpTableData {
// Table entries, using NO_EBB as a placeholder for missing entries.
table: Vec<Ebb>,
// Table entries, using `None` as a placeholder for missing entries.
table: Vec<PackedOption<Ebb>>,
// How many `NO_EBB` holes in table?
// How many `None` holes in table?
holes: usize,
}
@@ -34,16 +35,15 @@ impl JumpTableData {
///
/// The table will grow as needed to fit 'idx'.
pub fn set_entry(&mut self, idx: usize, dest: Ebb) {
assert!(dest != NO_EBB);
// Resize table to fit `idx`.
if idx >= self.table.len() {
self.holes += idx - self.table.len();
self.table.resize(idx + 1, NO_EBB);
} else if self.table[idx] == NO_EBB {
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;
self.table[idx] = dest.into();
}
/// Clear a table entry.
@@ -51,19 +51,15 @@ impl JumpTableData {
/// 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] != NO_EBB {
if idx < self.table.len() && self.table[idx].is_some() {
self.holes += 1;
self.table[idx] = NO_EBB;
self.table[idx] = None.into();
}
}
/// Get the entry for `idx`, or `None`.
pub fn get_entry(&self, idx: usize) -> Option<Ebb> {
if idx < self.table.len() && self.table[idx] != NO_EBB {
Some(self.table[idx])
} else {
None
}
self.table.get(idx).and_then(|e| e.expand())
}
/// Enumerate over all `(idx, dest)` pairs in the table in order.
@@ -74,13 +70,13 @@ impl JumpTableData {
}
/// Access the whole table as a mutable slice.
pub fn as_mut_slice(&mut self) -> &mut [Ebb] {
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, Ebb>>>);
pub struct Entries<'a>(iter::Enumerate<iter::Cloned<slice::Iter<'a, PackedOption<Ebb>>>>);
impl<'a> Iterator for Entries<'a> {
type Item = (usize, Ebb);
@@ -88,8 +84,8 @@ impl<'a> Iterator for Entries<'a> {
fn next(&mut self) -> Option<Self::Item> {
loop {
if let Some((idx, dest)) = self.0.next() {
if dest != NO_EBB {
return Some((idx, dest));
if let Some(ebb) = dest.expand() {
return Some((idx, ebb));
}
} else {
return None;
@@ -100,18 +96,15 @@ impl<'a> Iterator for Entries<'a> {
impl Display for JumpTableData {
fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
let first = self.table.first().cloned().unwrap_or_default();
if first == NO_EBB {
try!(write!(fmt, "jump_table 0"));
} else {
try!(write!(fmt, "jump_table {}", first));
match self.table.first().and_then(|e| e.expand()) {
None => try!(write!(fmt, "jump_table 0")),
Some(first) => try!(write!(fmt, "jump_table {}", first)),
}
for dest in self.table.iter().cloned().skip(1) {
if dest == NO_EBB {
try!(write!(fmt, ", 0"));
} else {
try!(write!(fmt, ", {}", dest));
for dest in self.table.iter().skip(1).map(|e| e.expand()) {
match dest {
None => try!(write!(fmt, ", 0")),
Some(ebb) => try!(write!(fmt, ", {}", ebb)),
}
}
Ok(())

5
lib/cretonne/src/packed_option.rs
View File

@@ -25,6 +25,11 @@ impl<T: ReservedValue> PackedOption<T> {
self.0 == T::reserved_value()
}
/// Returns `true` if the packed option is a `Some` value.
pub fn is_some(&self) -> bool {
!self.is_none()
}
/// Expand the packed option into a normal `Option`.
pub fn expand(self) -> Option<T> {
if self.is_none() { None } else { Some(self.0) }

10
lib/reader/src/parser.rs
View File

@@ -13,7 +13,7 @@ use cretonne::ir::{Function, Ebb, Opcode, Value, Type, FunctionName, StackSlotDa
FuncRef};
use cretonne::ir::types::VOID;
use cretonne::ir::immediates::{Imm64, Ieee32, Ieee64};
use cretonne::ir::entities::{AnyEntity, NO_EBB, NO_INST, NO_VALUE};
use cretonne::ir::entities::{AnyEntity, NO_INST, NO_VALUE};
use cretonne::ir::instructions::{InstructionFormat, InstructionData, VariableArgs,
TernaryOverflowData, JumpData, BranchData, CallData,
IndirectCallData, ReturnData};
@@ -204,9 +204,11 @@ impl Context {
// Rewrite EBB references in jump tables.
for jt in self.function.jump_tables.keys() {
let loc = jt.into();
for ebb in self.function.jump_tables[jt].as_mut_slice() {
if *ebb != NO_EBB {
try!(self.map.rewrite_ebb(ebb, loc));
for ebb_ref in self.function.jump_tables[jt].as_mut_slice() {
if let Some(mut ebb) = ebb_ref.expand() {
try!(self.map.rewrite_ebb(&mut ebb, loc));
// Convert back to a packed option.
*ebb_ref = ebb.into();
}
}
}