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Add functions to remove loads stores etc

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This commit is contained in:
bjorn3 2019-12-30 20:25:34 +01:00
parent 79148a3c1e
commit 7c4debdb7c
1 changed files with 29 additions and 12 deletions
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41
src/optimize/stack2reg.rs
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@ -59,6 +59,31 @@ impl StackSlotUsage {
}
}).collect::<Vec<Inst>>()
}
fn remove_unused_stack_addr(&mut self, func: &mut Function, inst: Inst) {
func.dfg.detach_results(inst);
func.dfg.replace(inst).nop();
self.stack_addr.remove(&inst);
}
fn remove_unused_load(&mut self, func: &mut Function, load: Inst) {
func.dfg.detach_results(load);
func.dfg.replace(load).nop();
self.stack_load.remove(&load);
}
fn remove_dead_store(&mut self, func: &mut Function, store: Inst) {
func.dfg.replace(store).nop();
self.stack_store.remove(&store);
}
fn change_load_to_alias(&mut self, func: &mut Function, load: Inst, value: Value) {
let loaded_value = func.dfg.inst_results(load)[0];
func.dfg.detach_results(load);
func.dfg.replace(load).nop();
func.dfg.change_to_alias(loaded_value, value);
self.stack_load.remove(&load);
}
}
struct OptimizeContext<'a> {
@ -159,10 +184,7 @@ pub(super) fn optimize_function(
let stored_type = opt_ctx.ctx.func.dfg.value_type(stored_value);
if stored_type == loaded_type && store_ebb == load_ebb {
println!("Store to load forward {} -> {}", store, load);
opt_ctx.ctx.func.dfg.detach_results(load);
opt_ctx.ctx.func.dfg.replace(load).nop();
opt_ctx.ctx.func.dfg.change_to_alias(loaded_value, stored_value);
users.stack_load.remove(&load);
users.change_load_to_alias(&mut opt_ctx.ctx.func, load, stored_value);
}
}
_ => {} // FIXME implement this
@ -186,8 +208,7 @@ pub(super) fn optimize_function(
// Never loaded; can safely remove all stores and the stack slot.
// FIXME also remove stores when there is always a next store before a load.
println!("[{}] Remove dead stack store {} of {}", name, opt_ctx.ctx.func.dfg.display_inst(store, None), stack_slot.0);
opt_ctx.ctx.func.dfg.replace(store).nop();
users.stack_store.remove(&store);
users.remove_dead_store(&mut opt_ctx.ctx.func, store);
}
}
@ -265,17 +286,13 @@ fn remove_unused_stack_addr_and_stack_load(opt_ctx: &mut OptimizeContext) {
// 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) {
opt_ctx.ctx.func.dfg.detach_results(inst);
opt_ctx.ctx.func.dfg.replace(inst).nop();
stack_slot_users.stack_addr.remove(&inst);
stack_slot_users.remove_unused_stack_addr(&mut opt_ctx.ctx.func, 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) {
opt_ctx.ctx.func.dfg.detach_results(inst);
opt_ctx.ctx.func.dfg.replace(inst).nop();
stack_slot_users.stack_load.remove(&inst);
stack_slot_users.remove_unused_load(&mut opt_ctx.ctx.func, inst);
}
}
}