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Run dead stack_store removal after stack_store to stack_load forwarding

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bjorn3 2019-12-28 11:36:00 +01:00
parent 7d35db5319
commit c5f42aef1d
1 changed files with 42 additions and 45 deletions
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87
src/optimize/stack2reg.rs
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@ -84,58 +84,55 @@ pub(super) fn optimize_function(
continue;
}
let is_loaded = users.stack_load.is_empty().not();
let is_stored = users.stack_store.is_empty().not();
match (is_loaded, is_stored) {
(true, true) => {
for load in users.stack_load.clone().drain() {
let load_ebb = func.layout.inst_ebb(load).unwrap();
let loaded_value = func.dfg.inst_results(load)[0];
let loaded_type = func.dfg.value_type(loaded_value);
for load in users.stack_load.clone().drain() {
let load_ebb = func.layout.inst_ebb(load).unwrap();
let loaded_value = func.dfg.inst_results(load)[0];
let loaded_type = func.dfg.value_type(loaded_value);
let potential_stores = users.stack_store.iter().cloned().filter(|&store| {
match spatial_overlap(func, load, store) {
SpatialOverlap::No => false, // Can never be the source of the loaded value.
SpatialOverlap::Partial | SpatialOverlap::Full => true,
}
}).filter(|&store| {
if load_ebb == func.layout.inst_ebb(store).unwrap() {
func.layout.cmp(store, load) == std::cmp::Ordering::Less
} else {
true // FIXME
}
}).collect::<Vec<Inst>>();
for &store in &potential_stores {
println!("Potential store -> load forwarding {} -> {} ({:?})", func.dfg.display_inst(store, None), func.dfg.display_inst(load, None), spatial_overlap(func, load, store));
}
match *potential_stores {
[] => println!("[{}] [BUG?] Reading uninitialized memory", name),
[store] if spatial_overlap(func, load, store) == SpatialOverlap::Full => {
let store_ebb = func.layout.inst_ebb(store).unwrap();
let stored_value = func.dfg.inst_args(store)[0];
let stored_type = func.dfg.value_type(stored_value);
if stored_type == loaded_type && store_ebb == load_ebb {
println!("Store to load forward {} -> {}", store, load);
func.dfg.detach_results(load);
func.dfg.replace(load).nop();
func.dfg.change_to_alias(loaded_value, stored_value);
}
}
_ => {} // FIXME implement this
let potential_stores = users.stack_store.iter().cloned().filter(|&store| {
match spatial_overlap(func, load, store) {
SpatialOverlap::No => false, // Can never be the source of the loaded value.
SpatialOverlap::Partial | SpatialOverlap::Full => true,
}
}).filter(|&store| {
if load_ebb == func.layout.inst_ebb(store).unwrap() {
func.layout.cmp(store, load) == std::cmp::Ordering::Less
} else {
true // FIXME
}
}).collect::<Vec<Inst>>();
for &store in &potential_stores {
println!("Potential store -> load forwarding {} -> {} ({:?})", func.dfg.display_inst(store, None), func.dfg.display_inst(load, None), spatial_overlap(func, load, store));
}
match *potential_stores {
[] => println!("[{}] [BUG?] Reading uninitialized memory", name),
[store] if spatial_overlap(func, load, store) == SpatialOverlap::Full => {
let store_ebb = func.layout.inst_ebb(store).unwrap();
let stored_value = func.dfg.inst_args(store)[0];
let stored_type = func.dfg.value_type(stored_value);
if stored_type == loaded_type && store_ebb == load_ebb {
println!("Store to load forward {} -> {}", store, load);
func.dfg.detach_results(load);
func.dfg.replace(load).nop();
func.dfg.change_to_alias(loaded_value, stored_value);
users.stack_load.remove(&load);
}
}
_ => {} // FIXME implement this
}
(true, false) => println!("[{}] [BUG?] Reading uninitialized memory", name),
(false, _) => {
// Never loaded; can safely remove all stores and the stack slot.
for user in users.stack_store.drain() {
println!("[{}] Remove dead stack store {} of {}", name, user, stack_slot.0);
func.dfg.replace(user).nop();
}
}
// FIXME make stack_slot zero sized.
if users.stack_load.is_empty() {
// Never loaded; can safely remove all stores and the stack slot.
for user in users.stack_store.drain() {
println!("[{}] Remove dead stack store {} of {}", name, user, stack_slot.0);
func.dfg.replace(user).nop();
}
}
if users.stack_store.is_empty() && users.stack_load.is_empty() {
// FIXME make stack_slot zero sized.
}
}
println!();