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Group by stack slot earlier

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This commit is contained in:
bjorn3 2019-12-27 16:27:05 +01:00
parent 9d77cb95e1
commit a8daa7115e
1 changed files with 42 additions and 107 deletions
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149
src/optimize/stack2reg.rs
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@ -1,4 +1,5 @@
use std::collections::{BTreeMap, BTreeSet, HashSet};
use std::ops::Not;
use cranelift_codegen::cursor::{Cursor, FuncCursor};
use cranelift_codegen::ir::{Opcode, InstructionData, ValueDef};
@ -22,6 +23,13 @@ fn cmp(&self, rhs: &Self) -> std::cmp::Ordering {
}
}
#[derive(Debug, Default)]
struct StackSlotUsage {
stack_addr: HashSet<Inst>,
stack_load: HashSet<Inst>,
stack_store: HashSet<Inst>,
}
pub(super) fn optimize_function(
func: &mut Function,
clif_comments: &mut crate::pretty_clif::CommentWriter,
@ -31,10 +39,8 @@ pub(super) fn optimize_function(
// Record all stack_addr, stack_load and stack_store instructions. Also record all stack_addr
// and stack_load insts whose result is used.
let mut stack_addr_load_insts_users = BTreeMap::<Inst, HashSet<Inst>>::new();
let mut stack_addr_insts = BTreeSet::new();
let mut stack_load_insts = BTreeSet::new();
let mut stack_store_insts = BTreeSet::new();
let mut stack_addr_load_insts_users = HashMap::<Inst, HashSet<Inst>>::new();
let mut stack_slot_usage_map = BTreeMap::<OrdStackSlot, StackSlotUsage>::new();
let mut cursor = FuncCursor::new(func);
while let Some(_ebb) = cursor.next_ebb() {
@ -42,25 +48,25 @@ pub(super) fn optimize_function(
match cursor.func.dfg[inst] {
InstructionData::StackLoad {
opcode: Opcode::StackAddr,
stack_slot: _,
stack_slot,
offset: _,
} => {
stack_addr_insts.insert(inst);
stack_slot_usage_map.entry(OrdStackSlot(stack_slot)).or_insert_with(StackSlotUsage::default).stack_addr.insert(inst);
}
InstructionData::StackLoad {
opcode: Opcode::StackLoad,
stack_slot: _,
stack_slot,
offset: _,
} => {
stack_load_insts.insert(inst);
stack_slot_usage_map.entry(OrdStackSlot(stack_slot)).or_insert_with(StackSlotUsage::default).stack_load.insert(inst);
}
InstructionData::StackStore {
opcode: Opcode::StackStore,
arg: _,
stack_slot: _,
stack_slot,
offset: _,
} => {
stack_store_insts.insert(inst);
stack_slot_usage_map.entry(OrdStackSlot(stack_slot)).or_insert_with(StackSlotUsage::default).stack_store.insert(inst);
}
_ => {}
}
@ -79,125 +85,54 @@ pub(super) fn optimize_function(
}
println!(
"{}:\nstack_addr/stack_load users: {:?}\nstack_addr: {:?}\nstack_load: {:?}\nstack_store: {:?}",
"{}:\nstack_addr/stack_load users: {:?}\nstack slot usage: {:?}",
name,
stack_addr_load_insts_users,
stack_addr_insts,
stack_load_insts,
stack_store_insts,
stack_slot_usage_map,
);
for inst in stack_addr_load_insts_users.keys() {
assert!(stack_addr_insts.contains(inst) || stack_load_insts.contains(inst));
}
// Replace all unused stack_addr instructions with nop.
// FIXME remove clone
for &inst in stack_addr_insts.clone().iter() {
if stack_addr_load_insts_users.get(&inst).map(|users| users.is_empty()).unwrap_or(true) {
println!("Removing unused stack_addr {}", inst);
func.dfg.detach_results(inst);
func.dfg.replace(inst).nop();
stack_addr_insts.remove(&inst);
let mut is_recorded_stack_addr_or_stack_load = false;
for stack_slot_users in stack_slot_usage_map.values() {
is_recorded_stack_addr_or_stack_load |= stack_slot_users.stack_addr.contains(inst) || stack_slot_users.stack_load.contains(inst);
}
assert!(is_recorded_stack_addr_or_stack_load);
}
// Replace all unused stack_load instructions with nop.
// FIXME remove clone
for &inst in stack_load_insts.clone().iter() {
if stack_addr_load_insts_users.get(&inst).map(|users| users.is_empty()).unwrap_or(true) {
println!("Removing unused stack_load {}", inst);
func.dfg.detach_results(inst);
func.dfg.replace(inst).nop();
stack_load_insts.remove(&inst);
}
}
//println!("stack_addr (after): [{}]", bool_secondary_map_to_string(&stack_addr_insts));
let mut stack_slot_usage_map: BTreeMap<OrdStackSlot, HashSet<Inst>> = BTreeMap::new();
for &inst in stack_load_insts.iter() {
match func.dfg[inst] {
InstructionData::StackLoad {
opcode: Opcode::StackLoad,
stack_slot,
offset: _,
} => {
stack_slot_usage_map.entry(OrdStackSlot(stack_slot)).or_insert_with(HashSet::new).insert(inst);
// Replace all unused stack_addr and stack_load instructions with nop.
for stack_slot_users in stack_slot_usage_map.values_mut() {
// FIXME remove clone
for &inst in stack_slot_users.stack_addr.clone().iter() {
if stack_addr_load_insts_users.get(&inst).map(|users| users.is_empty()).unwrap_or(true) {
println!("Removing unused stack_addr {}", inst);
func.dfg.detach_results(inst);
func.dfg.replace(inst).nop();
stack_slot_users.stack_addr.remove(&inst);
}
ref data => unreachable!("{:?}", data),
}
}
for &inst in stack_store_insts.iter() {
match func.dfg[inst] {
InstructionData::StackStore {
opcode: Opcode::StackStore,
arg: _,
stack_slot,
offset: _,
} => {
stack_slot_usage_map.entry(OrdStackSlot(stack_slot)).or_insert_with(HashSet::new).insert(inst);
for &inst in stack_slot_users.stack_load.clone().iter() {
if stack_addr_load_insts_users.get(&inst).map(|users| users.is_empty()).unwrap_or(true) {
println!("Removing unused stack_addr {}", inst);
func.dfg.detach_results(inst);
func.dfg.replace(inst).nop();
stack_slot_users.stack_load.remove(&inst);
}
ref data => unreachable!("{:?}", data),
}
}
for &inst in stack_addr_insts.iter() {
match func.dfg[inst] {
InstructionData::StackLoad {
opcode: Opcode::StackAddr,
stack_slot,
offset: _,
} => {
stack_slot_usage_map.entry(OrdStackSlot(stack_slot)).or_insert_with(HashSet::new).insert(inst);
}
ref data => unreachable!("{:?}", data),
}
}
println!("stack slot usage: {:?}", stack_slot_usage_map);
println!("stack slot usage (after): {:?}", stack_slot_usage_map);
for (stack_slot, users) in stack_slot_usage_map.iter_mut() {
let mut is_addr_leaked = false;
let mut is_loaded = false;
let mut is_stored = false;
for &user in users.iter() {
match func.dfg[user] {
InstructionData::StackLoad {
opcode: Opcode::StackAddr,
stack_slot,
offset: _,
} => {
is_addr_leaked = true;
}
InstructionData::StackLoad {
opcode: Opcode::StackLoad,
stack_slot,
offset: _,
} => {
is_loaded = true;
}
InstructionData::StackStore {
opcode: Opcode::StackStore,
arg: _,
stack_slot,
offset: _,
} => {
is_stored = true;
}
ref data => unreachable!("{:?}", data),
}
}
if is_addr_leaked || (is_loaded && is_stored) {
if users.stack_addr.is_empty().not() || (users.stack_load.is_empty().not() && users.stack_store.is_empty().not()) {
continue;
}
if is_loaded {
if users.stack_load.is_empty().not() {
println!("[{}] [BUG?] Reading uninitialized memory", name);
} else {
// Stored value never read; just remove reads.
for &user in users.iter() {
for user in users.stack_store.drain() {
println!("[{}] Remove dead stack store {} of {}", name, user, stack_slot.0);
func.dfg.replace(user).nop();
}