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pre.rs
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pre.rs
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use std::cell::RefCell;
use std::collections::{BTreeSet, HashMap};
use std::hash::{Hash, Hasher};
use std::iter::FromIterator;
use std::ops::Deref;
use crate::lang::func::{BlockRef, DomTreeListener, Fn, FnRef};
use crate::lang::inst::{BinOp, Inst};
use crate::lang::Program;
use crate::lang::util::{ExtRc, WorkList};
use crate::lang::value::{Const, SymbolGen, SymbolRef, Type, Typed, Value};
use crate::pass::{FnPass, Pass};
use crate::pass::copy::CopyProp;
use crate::pass::gvn::Gvn;
#[derive(Eq, PartialEq, Hash, Clone, Debug)]
enum Expr {
/// Compile time constants
Const(Const),
/// Binary operations
Bin(BinExpr),
/// Pointer operations
Ptr(PtrExpr),
/// Temporaries that store values
Temp(SymbolRef),
}
impl Typed for Expr {
fn get_type(&self) -> Type {
match self {
Expr::Const(c) => c.get_type(),
Expr::Bin(bin) => bin.get_type(),
Expr::Ptr(ptr) => ptr.get_type(),
Expr::Temp(sym) => sym.get_type()
}
}
}
impl Expr {
fn opd(&self) -> Vec<usize> {
match self {
Expr::Bin(BinExpr { op: _, ty: _, fst, snd }) => vec![*fst, *snd],
Expr::Ptr(PtrExpr { ty: _, base, off, idx }) =>
vec![*base, *off, *idx].into_iter().filter(|o| *o != NONE).collect(),
_ => vec![]
}
}
}
#[derive(Eq, Clone, Debug)]
struct BinExpr {
/// Binary operator
op: BinOp,
/// Type of operands, not result
ty: Type,
/// Value number of both operands
fst: usize,
snd: usize,
}
impl Typed for BinExpr {
fn get_type(&self) -> Type { self.op.res_type(&self.ty).unwrap() }
}
impl PartialEq for BinExpr {
fn eq(&self, other: &Self) -> bool {
self.op == other.op && self.fst == other.fst && self.snd == other.snd
}
}
impl Hash for BinExpr {
fn hash<H: Hasher>(&self, state: &mut H) {
self.op.hash(state);
self.fst.hash(state);
self.snd.hash(state);
}
}
const NONE: usize = usize::max_value();
/// Represent pointer operation that in form of base and offset. Indices into aggregate is not
/// considered.
#[derive(Eq, Clone, Debug)]
struct PtrExpr {
/// Type of the pointer
ty: Type,
/// Base pointer
base: usize,
/// Pointer offset
off: usize,
/// Single index
idx: usize,
}
impl Typed for PtrExpr {
fn get_type(&self) -> Type { self.ty.clone() }
}
impl PartialEq for PtrExpr {
fn eq(&self, other: &Self) -> bool {
self.base == other.base && self.off == other.off
}
}
impl Hash for PtrExpr {
fn hash<H: Hasher>(&self, state: &mut H) {
self.base.hash(state);
self.off.hash(state);
self.idx.hash(state);
}
}
#[derive(Debug)]
struct ValueTable {
/// Expression list for each numbered value
tab: Vec<Vec<Expr>>,
/// Map expressions to their corresponding value number.
/// Note that if an expression is `Expr::Result` and the variable it holds is global, it will
/// not be contained in this map, because the mapping is not unique.
num: HashMap<Expr, usize>,
}
impl ValueTable {
fn new(reserved: usize) -> ValueTable {
ValueTable {
tab: vec![vec![]; reserved],
num: Default::default(),
}
}
/// Add expressions that do not have a number. Return allocated number for this expression.
fn add(&mut self, expr: Expr) -> usize {
let num = self.tab.len();
self.tab.push(vec![expr.clone()]);
self.map(expr, num);
num
}
/// Add expression that already has a value, this number must be less than the `reserved`
/// argument passed to the constructor.
fn add_num(&mut self, num: usize, expr: Expr) {
self.tab[num].push(expr.clone());
self.map(expr, num)
}
/// Map `expr` to given number, as long as it is not `Expr::Result` of a global variable.
fn map(&mut self, expr: Expr, num: usize) {
match expr {
Expr::Temp(sym) if sym.is_global_var() => {} // never map global variables
expr => { self.num.insert(expr, num); }
}
}
/// Find value number for given expression. This method also encompass operator commutation and
/// re-association to find expressions that are not obviously available.
fn find(&mut self, expr: &Expr) -> Option<usize> {
self.get_num(expr).or_else(|| match expr.clone() {
// Use operator commutativity to have another try
Expr::Bin(BinExpr { op, ty, fst, snd }) if op.is_comm() => self.get_num(
&Expr::Bin(BinExpr { op, ty, fst: snd, snd: fst })
),
_ => None
}).or_else(|| match expr {
// Try to re-associate binary operations
Expr::Bin(BinExpr { op, ty: _, fst: _, snd: _ }) if op.is_assoc() =>
match expr.clone() {
// Try processing first value
Expr::Bin(BinExpr { op, ty: _, fst, snd })
if self.find_bin(fst).is_some() =>
self.find_bin(fst).and_then(|fst| {
match fst {
BinExpr { op: opl, ty, fst: l_fst, snd: l_snd }
if opl.assoc_with(&op) =>
self.get_num(&Expr::Bin(BinExpr {
op,
ty: ty.clone(),
fst: l_snd,
snd,
})).and_then(
|snd| self.get_num(&Expr::Bin(BinExpr {
op: opl,
ty,
fst: l_fst,
snd,
}))
),
_ => None
}
}),
_ => None
}.or_else(|| match expr.clone() {
// Try processing second value
Expr::Bin(BinExpr { op, ty: _, fst, snd })
if self.find_bin(snd).is_some() =>
self.find_bin(snd).and_then(|snd| {
match snd {
BinExpr { op: opr, ty, fst: r_fst, snd: r_snd }
if op.assoc_with(&opr) =>
self.get_num(&Expr::Bin(BinExpr {
op,
ty: ty.clone(),
fst,
snd: r_fst,
})).and_then(
|fst| self.get_num(&Expr::Bin(BinExpr {
op: opr,
ty,
fst,
snd: r_snd,
}))
),
_ => None
}
}),
_ => None
}),
_ => None,
})
}
/// Look up value number of an expression. This method uses algebraic identities to find
/// expressions that are not obviously available. This is different from `find` that it is more
/// fundamental and does not dive into the structure of operand values.
fn get_num(&mut self, expr: &Expr) -> Option<usize> {
self.num.get(expr).copied().or_else(|| match expr.clone() {
Expr::Bin(BinExpr { op, ref ty, fst, snd }) => {
let fst_cn = self.find_const(fst);
let snd_cn = self.find_const(snd);
if let (Some(l), Some(r)) = (fst_cn, snd_cn) {
return Some(self.find_or_add(Expr::Const(op.eval(l, r))));
}
let zero = Const::zero(ty);
let one = Const::one(ty);
match op {
// 0 + x = x + 0 = x
BinOp::Add => match (fst_cn, snd_cn) {
(Some(l), _) if l == zero => Some(snd),
(_, Some(r)) if r == zero => Some(fst),
_ => None
}
// x - x = 0, x - 0 = x
BinOp::Sub => match (fst_cn, snd_cn) {
(_, Some(r)) if r == zero => Some(fst),
_ if fst == snd => Some(self.find_or_add(Expr::Const(zero.clone()))),
_ => None
}
// 0 * x = x * 0 = 0, 1 * x = x * 1 = x
BinOp::Mul => match (fst_cn, snd_cn) {
(Some(l), _) if l == zero =>
Some(self.find_or_add(Expr::Const(zero.clone()))),
(_, Some(r)) if r == zero =>
Some(self.find_or_add(Expr::Const(zero.clone()))),
(Some(l), _) if l == one => Some(snd),
(_, Some(r)) if r == one => Some(fst),
_ => None
}
// x << 0 = x, x >> 0 = x
BinOp::Shl | BinOp::Shr => match snd_cn {
r if r == Some(zero) => Some(fst),
_ => None
}
_ => None
}
}
Expr::Ptr(PtrExpr { ty: _, base, off, idx }) => match idx {
NONE => match self.find_const(off) {
Some(Const::I64(0)) => Some(base),
_ => None,
}
_ => None
}
_ => None
})
}
/// Find binary expression in the value list of given value number
fn find_const(&self, num: usize) -> Option<Const> {
self.tab.get(num).and_then(|list| list.iter().find(|expr| match expr {
Expr::Const(_) => true,
_ => false
}).and_then(|expr| match expr {
Expr::Const(c) => Some(c.clone()),
_ => unreachable!()
}))
}
/// Find binary expression in the value list of given value number
fn find_bin(&self, num: usize) -> Option<BinExpr> {
self.tab.get(num).and_then(|list| list.iter().find(|expr| match expr {
Expr::Bin(_) => true,
_ => false
}).and_then(|expr| match expr {
Expr::Bin(bin) => Some(bin.clone()),
_ => unreachable!()
}))
}
/// Possibly find indices for expression or create new number for it
fn find_or_add(&mut self, expr: Expr) -> usize {
self.find(&expr).unwrap_or_else(|| self.add(expr))
}
}
/// Implement GVN-PRE proposed by Thomas.
/// See [https://www.cs.purdue.edu/homes/hosking/papers/cc04.pdf].
pub struct PreOpt {
table: ValueTable,
}
impl Pass for PreOpt {
fn run(&mut self, pro: &mut Program) { FnPass::run(self, pro) }
}
impl FnPass for PreOpt {
//noinspection RsTypeCheck
fn run_on_fn(&mut self, func: &FnRef) {
// Make sure the CFG is edge split
func.split_edge();
// Renumber the non-continuous symbols given by GVN
let mut sym_num = Gvn::new().number(func);
let num_set: BTreeSet<usize> = sym_num.values().copied().collect();
let size = num_set.len();
let num_remap: HashMap<usize, usize> = num_set.into_iter()
.enumerate().map(|(new, old)| (old, new)).collect();
sym_num.iter_mut().for_each(|(_, num)| *num = num_remap[num]);
// Build flow sets as well as value table
self.table = ValueTable::new(size);
let mut builder = SetBuilder {
sym_num,
table: &mut self.table,
sets: Default::default(),
};
func.walk_dom(&mut builder);
// Build anticipated set in post-dominator order
let SetBuilder { sym_num: _, table: _, mut sets } = builder;
let mut changed = true;
while changed {
changed = false;
func.post_dom(|ref block| {
// Build anticipated set at exit of the block
let old = sets[block].antic_in.clone();
let mut antic_out: HashMap<usize, Expr> = HashMap::new();
match block.succ.borrow().len() {
// Do nothing for exit block.
0 => {}
// This block has one successor, deal with phis in this block
1 => {
let succ = &block.succ.borrow()[0];
antic_out = self.phi_trans(sets[succ].antic_in.clone(), block.clone(),
succ.clone());
}
// This block has several successors, find intersection of anticipated sets
// of all the successors
_ => {
let all_succ = block.succ.borrow().clone();
let mut work = WorkList::from_iter(all_succ.into_iter());
let first = work.pick().unwrap();
antic_out = sets[&first].antic_in.clone();
while !work.is_empty() {
let succ = work.pick().unwrap();
antic_out.retain(|num, _| {
Self::find_leader(&sets[&succ].antic_in, *num).is_some()
})
}
}
}
// Build anticipated set at entrance of the block
let other = Self::remove_tmp(&antic_out, &sets[block].tmp);
sets.get_mut(block).unwrap().antic_in = Self::remove_tmp(&sets[block].expr,
&sets[block].tmp);
other.iter().for_each(|(num, expr)| {
if Self::find_leader(&sets[block].antic_in, *num).is_none() {
sets.get_mut(block).unwrap().antic_in.insert(*num, expr.clone());
}
});
Self::clean(&mut sets.get_mut(block).unwrap().antic_in);
if old != sets[block].antic_in {
changed = true
}
})
}
// Hoist expressions to earlier points
let mut new_tmp: HashMap<BlockRef, HashMap<usize, SymbolRef>> = HashMap::new();
let mut gen = SymbolGen::new(func.scope.clone(), "t");
let mut inserted = true;
while inserted {
inserted = false;
// Traverse dominator tree
func.iter_dom().for_each(|ref block| {
// Inherit created temporaries from dominator
new_tmp.insert(block.clone(), HashMap::new());
if block.parent().is_none() { return; }
let ref dom = block.parent().unwrap();
new_tmp[dom].clone().into_iter().for_each(|(num, sym)| {
new_tmp.get_mut(block).unwrap().insert(num, sym.clone());
sets.get_mut(block).unwrap().avail_out.insert(num, Expr::Temp(sym));
});
// Insert instructions using work list algorithm
if block.pred.borrow().len() <= 1 { return; } // only insert at merge point
let mut work: WorkList<(usize, Expr)> = sets[block].antic_in.clone().into_iter()
.collect();
while !work.is_empty() {
// Find insertion point
let (num, expr) = work.pick().unwrap();
let expr = if let Expr::Bin(bin) = expr { bin } else { continue; };
if Self::find_leader(&sets[dom].avail_out, num).is_some() { continue; }
let mut avail: HashMap<BlockRef, Expr> = HashMap::new();
let mut by_some = false;
let mut all_same = true;
let mut first_sym = None;
block.pred.borrow().iter().for_each(|pred| {
let (trans_num, trans_expr) =
self.phi_trans_one(num, Expr::Bin(expr.clone()), pred.clone(),
block.clone());
match Self::find_leader(&sets[pred].avail_out, trans_num) {
Some(leader) => {
avail.insert(pred.clone(), Expr::Temp(leader.clone()));
by_some = true;
if first_sym == None {
first_sym = Some(leader)
} else if first_sym != Some(leader) {
all_same = false
}
}
None => {
avail.insert(pred.clone(), trans_expr);
all_same = false;
}
}
});
// Insert expression where it is not available
if all_same || !by_some { continue; }
// Operands in inserted expressions may depend on temporaries that has not yet
// been created. In this case, we just skip inserting phi instruction and wait
// for the next iteration.
let success = block.pred.borrow().iter().all(|pred| {
self.insert_expr(pred, &mut avail, &mut sets, &mut gen)
});
if !success || sets[block].phi.contains_key(&num) { continue; }
let dst_sym = gen.gen(&expr.get_type());
self.table.add_num(num, Expr::Temp(dst_sym.clone()));
sets.get_mut(block).unwrap().avail_out
.insert(num, Expr::Temp(dst_sym.clone()));
let phi_src = block.pred.borrow().clone().into_iter().map(|block| {
let sym = if let Expr::Temp(sym) = avail[&block].clone() {
sym
} else { unreachable!() };
(RefCell::new(block), RefCell::new(Value::Var(sym)))
}).collect();
block.push_front(ExtRc::new(Inst::Phi {
src: phi_src,
dst: RefCell::new(dst_sym.clone()),
}));
sets.get_mut(block).unwrap().phi.insert(num, dst_sym.clone());
new_tmp.get_mut(block).unwrap().insert(num, dst_sym);
inserted = true;
}
});
}
// Eliminate redundant computation
func.iter_dom().for_each(|ref block| {
block.inst.borrow_mut().iter_mut().for_each(|instr| {
match instr.dst() {
Some(dst) if dst.borrow().is_local_var() => {
let dst = dst.borrow().clone();
let num = self.table.find(&Expr::Temp(dst.clone())).unwrap();
let leader = Self::find_leader(&sets[block].avail_out, num).unwrap();
if leader != dst.clone() {
*instr = ExtRc::new(Inst::Mov {
src: RefCell::new(Value::Var(leader)),
dst: RefCell::new(dst),
})
}
}
_ => {}
}
})
});
// Propagate copy
CopyProp::new().run_on_fn(func)
}
}
impl PreOpt {
pub fn new() -> PreOpt {
PreOpt { table: ValueTable::new(0) }
}
/// Insert corresponding instruction at given predecessor. Return whether this instruction
/// has been successfully inserted.
/// Insertion may fail because some operands are not available at this time.
fn insert_expr(&mut self, pred: &BlockRef, avail: &mut HashMap<BlockRef, Expr>,
sets: &mut HashMap<BlockRef, LeaderSet>, gen: &mut SymbolGen) -> bool
{
match avail[pred].clone() {
Expr::Bin(BinExpr { op, ty, fst, snd }) => {
// First operand
let fst_val =
if let Some(fst_val) = self.create_opd(&sets[pred].avail_out, fst) {
fst_val
} else { return false; };
// Second operand
let snd_val =
if let Some(snd_val) = self.create_opd(&sets[pred].avail_out, snd) {
snd_val
} else { return false; };
// Insert instruction
let dst_sym = gen.gen(&op.res_type(&ty).unwrap());
pred.insert_before_ctrl(ExtRc::new(Inst::Bin {
op,
fst: RefCell::new(fst_val),
snd: RefCell::new(snd_val),
dst: RefCell::new(dst_sym.clone()),
}));
// Add to value table and leader sets
let expr_num = self.table.find_or_add(Expr::Bin(
BinExpr { op, ty, fst, snd }
));
self.table.add_num(expr_num, Expr::Temp(dst_sym.clone()));
sets.get_mut(pred).unwrap().avail_out
.insert(expr_num, Expr::Temp(dst_sym.clone()));
avail.insert(pred.clone(), Expr::Temp(dst_sym));
true
}
Expr::Ptr(PtrExpr { ty, base, off, idx }) => {
// Base pointer
let base_val =
if let Some(base_val) = self.create_opd(&sets[pred].avail_out, base) {
base_val
} else { return false; };
// Pointer offset
let off_val = match self.create_opd(&sets[pred].avail_out, off) {
// zero pointer offset can be ignored
Some(Value::Const(Const::I64(0))) => None,
Some(val) => Some(RefCell::new(val)),
None => return false,
};
// Aggregate index
let idx_val = match idx {
NONE => vec![],
idx => if let Some(idx_val) = self.create_opd(&sets[pred].avail_out, idx) {
vec![RefCell::new(idx_val)]
} else { return false; }
};
// Insert instruction
let dst_sym = gen.gen(&ty);
pred.insert_before_ctrl(ExtRc::new(Inst::Ptr {
base: RefCell::new(base_val),
off: off_val,
ind: idx_val,
dst: RefCell::new(dst_sym.clone()),
}));
// Add to value table and leader sets
let expr_num = self.table.find_or_add(Expr::Ptr(
PtrExpr { ty, base, off, idx }
));
self.table.add_num(expr_num, Expr::Temp(dst_sym.clone()));
sets.get_mut(pred).unwrap().avail_out
.insert(expr_num, Expr::Temp(dst_sym.clone()));
avail.insert(pred.clone(), Expr::Temp(dst_sym));
true
}
// Other instructions will not be inserted
_ => true
}
}
fn phi_trans_one(&mut self, num: usize, expr: Expr, pred: BlockRef, succ: BlockRef)
-> (usize, Expr)
{
let set = HashMap::from_iter(vec![(num, expr)]);
let res: Vec<(usize, Expr)> = self.phi_trans(set, pred, succ).into_iter().collect();
res[0].clone()
}
fn phi_trans(&mut self, set: HashMap<usize, Expr>, pred: BlockRef, succ: BlockRef)
-> HashMap<usize, Expr>
{
// Build number map for all phi destinations in successor block
let mut num_map: HashMap<usize, (usize, Expr)> = HashMap::new();
for instr in succ.inst.borrow().iter() {
match instr.deref() {
Inst::Phi { src, dst } => {
let dst_num = self.table.find(&Expr::Temp(dst.borrow().clone())).unwrap();
if num_map.contains_key(&dst_num) { continue; }
let src_opd = &src.iter().find(|(block, _)| *block.borrow() == pred)
.unwrap().1;
num_map.insert(dst_num, self.find_value(src_opd));
}
_ => break
}
}
// Replace expressions in the given set
set.into_iter().map(move |(num, expr)| {
num_map.get(&num).cloned().unwrap_or_else(|| {
match expr {
// Replace operand values in binary expressions
Expr::Bin(BinExpr { op, ty, fst, snd }) => {
let fst = num_map.get(&fst).map(|(num, _)| *num).unwrap_or(fst);
let snd = num_map.get(&snd).map(|(num, _)| *num).unwrap_or(snd);
let new_expr = Expr::Bin(BinExpr { op, ty, fst, snd });
(self.table.find_or_add(new_expr.clone()), new_expr)
}
Expr::Ptr(PtrExpr { ty, base, off, idx }) => {
let base = num_map.get(&base).map(|(num, _)| *num).unwrap_or(base);
let off = num_map.get(&off).map(|(num, _)| *num).unwrap_or(off);
let idx = num_map.get(&idx).map(|(num, _)| *num).unwrap_or(idx);
let new_expr = Expr::Ptr(PtrExpr { ty, base, off, idx });
(self.table.find_or_add(new_expr.clone()), new_expr)
}
// For other expressions that cannot be translated, just return them
_ => (num, expr)
}
})
}).collect()
}
/// Find leader temporary of `num` in `set` first. If a symbol is found, a local variable is
/// created. Otherwise, a constant is returned. In this optimization, no global variable is
/// considered, so this method is complete.
fn create_opd(&self, set: &HashMap<usize, Expr>, num: usize) -> Option<Value> {
match Self::find_leader(set, num) {
Some(leader) => Some(Value::Var(leader)),
None => self.table.find_const(num).and_then(|c| Some(Value::Const(c)))
}
}
fn find_value(&mut self, val: &RefCell<Value>) -> (usize, Expr) {
match val.borrow().deref() {
Value::Var(sym) => {
let expr = Expr::Temp(sym.clone());
(self.table.find(&expr).unwrap(), expr)
}
Value::Const(c) => {
let expr = Expr::Const(*c);
(self.table.find_or_add(expr.clone()), expr)
}
}
}
fn find_leader(set: &HashMap<usize, Expr>, num: usize) -> Option<SymbolRef> {
set.get(&num).and_then(|expr| match expr {
Expr::Temp(sym) => Some(sym.clone()),
_ => None
})
}
fn remove_tmp(set: &HashMap<usize, Expr>, tmp: &HashMap<usize, SymbolRef>)
-> HashMap<usize, Expr>
{
let mut set = set.clone();
set.retain(|num, expr| {
match tmp.get(num) {
Some(sym) => expr != &Expr::Temp(sym.clone()),
None => true
}
});
set
}
fn clean(set: &mut HashMap<usize, Expr>) {
// Build dependency graph
let mut dep: HashMap<usize, Vec<usize>> = HashMap::new();
set.iter().for_each(|(num, expr)| {
expr.opd().into_iter().for_each(|o| {
match dep.get_mut(&o) {
Some(list) => list.push(*num),
None => { dep.insert(o, vec![*num]); }
}
});
});
// Eliminate killed values using work list algorithm
let mut work: WorkList<usize> = WorkList::from_iter(set.keys().cloned());
while !work.is_empty() {
let ref num = work.pick().unwrap();
let ref expr = set[num].clone();
if !expr.opd().iter().all(|o| set.contains_key(o)) {
set.remove(num);
dep.get(num).map(|list| list.iter().for_each(|val| work.insert(*val)));
}
}
}
}
/// Keep record of leader sets used in PRE for each basic block
#[derive(Debug)]
struct LeaderSet {
/// Expressions generated by this block
expr: HashMap<usize, Expr>,
/// Phi destinations of this block
phi: HashMap<usize, SymbolRef>,
/// Temporaries created in this block
tmp: HashMap<usize, SymbolRef>,
/// Available expressions at exit of this block
avail_out: HashMap<usize, Expr>,
/// Anticipated expressions at entrance and exit of this block
antic_in: HashMap<usize, Expr>,
}
impl LeaderSet {
fn new() -> LeaderSet {
LeaderSet {
expr: Default::default(),
phi: Default::default(),
tmp: Default::default(),
avail_out: Default::default(),
antic_in: Default::default(),
}
}
}
struct SetBuilder<'a> {
sym_num: HashMap<SymbolRef, usize>,
table: &'a mut ValueTable,
sets: HashMap<BlockRef, LeaderSet>,
}
impl DomTreeListener for SetBuilder<'_> {
fn on_begin(&mut self, func: &Fn) {
// Add parameters to value table and available set of entrance
let ent = func.ent.borrow().clone();
let avail_in: HashMap<usize, Expr> = func.param.iter().map(|p| {
let sym = p.borrow().clone();
let num = self.sym_num[&sym];
self.table.add_num(num, Expr::Temp(sym.clone()));
(num, Expr::Temp(sym.clone()))
}).collect();
let mut leader = LeaderSet::new();
leader.avail_out = avail_in;
self.sets.insert(ent, leader);
}
fn on_end(&mut self, _func: &Fn) {}
fn on_enter(&mut self, block: BlockRef) {
// Register this block
if !self.sets.contains_key(&block) { // not entrance block
let mut leader = LeaderSet::new();
leader.avail_out = self.sets[&block.parent().unwrap()].avail_out.clone();
self.sets.insert(block.clone(), leader);
}
// Visit instructions
block.inst.borrow().iter().for_each(|instr| {
// Skip those whose results are not stored in local variables
match instr.dst() {
None => return, // this instruction does not produce a value
Some(sym) if sym.borrow().is_global_var() => return, // result stored to global
_ => {}
}
// Process destination symbol
macro_rules! set {
($name:ident) => {self.sets.get_mut(&block).unwrap().$name};
}
let dst = instr.dst().unwrap().borrow().clone();
let mut dst_num = self.sym_num[&dst]; // may changed later due to re-association
let dst_expr = Expr::Temp(dst.clone());
// Visit interested instruction
match instr.deref() {
Inst::Phi { src: _, dst: _ } => {
self.table.add_num(dst_num, dst_expr.clone());
Self::try_insert(&mut set!(phi), dst_num, dst);
Self::try_insert(&mut set!(avail_out), dst_num, dst_expr);
}
Inst::Mov { src, dst: _ } => {
if !src.borrow().is_global_var() {
let (src_num, src_expr) = self.find_src(src);
Self::try_insert(&mut set!(expr), src_num, src_expr);
}
self.table.add_num(dst_num, dst_expr.clone());
Self::try_insert(&mut set!(tmp), dst_num, dst);
Self::try_insert(&mut set!(avail_out), dst_num, dst_expr);
}
Inst::Bin { op, fst, snd, dst: _ } => {
// Once global variable appears in either operand, this expression will not be
// considered.
if !fst.borrow().is_global_var() && !snd.borrow().is_global_var() {
// First operand
let (fst_num, fst_expr) = self.find_src(fst);
Self::try_insert(&mut set!(expr), fst_num, fst_expr);
// Second operand
let (snd_num, snd_expr) = self.find_src(snd);
Self::try_insert(&mut set!(expr), snd_num, snd_expr);
// Create expression
let bin_expr = Expr::Bin(BinExpr {
op: *op,
ty: fst.borrow().get_type(),
fst: fst_num,
snd: snd_num,
});
dst_num = self.table.find(&bin_expr).unwrap_or(dst_num);
self.table.add_num(dst_num, bin_expr.clone());
Self::try_insert(&mut set!(expr), dst_num, bin_expr);
}
self.table.add_num(dst_num, dst_expr.clone());
Self::try_insert(&mut set!(tmp), dst_num, dst);
Self::try_insert(&mut set!(avail_out), dst_num, dst_expr);
}
// Only pointer operation with offset and without indices are considered
Inst::Ptr { base, off, ind, dst: _ } if ind.len() <= 1 => {
if base.borrow().is_local_var()
&& (off.is_none() || !off.as_ref().unwrap().borrow().is_global_var())
&& (ind.is_empty() || !ind[0].borrow().is_global_var()) {
// Base pointer
let (base_num, base_expr) = self.find_src(base);
Self::try_insert(&mut set!(expr), base_num, base_expr);
// Pointer offset
let (off_num, off_expr) = match off {
Some(off) => self.find_src(off),
None => {
let zero = Expr::Const(Const::I64(0));
(self.table.find_or_add(zero.clone()), zero)
}
};
Self::try_insert(&mut set!(expr), off_num, off_expr);
// Single index
let idx_num = match ind.len() {
0 => NONE,
1 => {
let (idx_num, idx_expr) = self.find_src(&ind[0]);
Self::try_insert(&mut set!(expr), idx_num, idx_expr);
idx_num
}
_ => unreachable!()
};
// Create expression
let ptr_expr = Expr::Ptr(PtrExpr {
ty: base.borrow().get_type(),
base: base_num,
off: off_num,
idx: idx_num,
});
dst_num = self.table.find(&ptr_expr).unwrap_or(dst_num);
self.table.add_num(dst_num, ptr_expr.clone());
Self::try_insert(&mut set!(expr), dst_num, ptr_expr);
}
self.table.add_num(dst_num, dst_expr.clone());
Self::try_insert(&mut set!(tmp), dst_num, dst);
Self::try_insert(&mut set!(avail_out), dst_num, dst_expr);
}
_ => {
self.table.add_num(dst_num, dst_expr.clone());
Self::try_insert(&mut set!(tmp), dst_num, dst);
Self::try_insert(&mut set!(avail_out), dst_num, dst_expr);
}
}
})
}
fn on_exit(&mut self, _block: BlockRef) {}
fn on_enter_child(&mut self, _this: BlockRef, _child: BlockRef) {}
fn on_exit_child(&mut self, _this: BlockRef, _child: BlockRef) {}
}
impl SetBuilder<'_> {
fn find_src(&mut self, opd: &RefCell<Value>) -> (usize, Expr) {
match opd.borrow().deref() {
// Local variable must have been numbered before.
// Through algebraic simplification, the symbol may have have different number.
Value::Var(sym) if sym.is_local_var() => {
let sym_expr = Expr::Temp(sym.clone());
self.table.find(&sym_expr).map(|num| (num, sym_expr.clone()))
.unwrap_or((self.sym_num[sym], sym_expr))
}
// Must allocate new number for each use of global variable
Value::Var(sym) => {
let expr = Expr::Temp(sym.clone());
(self.table.add(expr.clone()), expr)
}
// Find number of existing constant or allocate new number for new constant
Value::Const(c) => {
let expr = Expr::Const(c.clone());
(self.table.find_or_add(expr.clone()), expr)
}
}
}
fn try_insert<T>(set: &mut HashMap<usize, T>, num: usize, elem: T) {
if !set.contains_key(&num) { set.insert(num, elem); }
}
}
#[test]
fn test_pre() {
use crate::irc::lex::Lexer;
use crate::irc::parse::Parser;
use crate::irc::build::Builder;
use crate::lang::print::Printer;
use crate::vm::exec::Machine;
use std::io::stdout;
use std::fs::File;
use std::convert::TryFrom;
use std::io::Read;
use std::borrow::BorrowMut;
let mut file = File::open("test/pre.ir").unwrap();
let lexer = Lexer::try_from(&mut file as &mut dyn Read).unwrap();
let parser = Parser::new(lexer);
let tree = parser.parse().unwrap();
let builder = Builder::new(tree);
let mut pro = builder.build().unwrap();
let mut opt = PreOpt::new();
Pass::run(&mut opt, &mut pro);
let mut out = stdout();
let mut printer = Printer::new(out.borrow_mut());
printer.print(&pro).unwrap();
let mut mach = Machine::new();
mach.run(&mut pro).unwrap();
}