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reflect: improve inout link algorithm

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chyyran 2024-08-19 01:31:26 -04:00 committed by Ronny Chan
parent cd14bca23a
commit 9b40c10466
2 changed files with 96 additions and 25 deletions
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5
librashader-reflect/src/front/glslang.rs
View file

@ -41,11 +41,12 @@ pub(crate) fn compile_spirv(source: &ShaderSource) -> Result<SpirvCompilation, S
let vertex = load_module(&vertex);
let fragment = load_module(&fragment);
let mut fragment = Builder::new_from_module(fragment);
let mut vertex = Builder::new_from_module(vertex);
let mut pass = link_input_outputs::LinkInputs::new(&vertex, &mut fragment);
let mut pass = link_input_outputs::LinkInputs::new(&mut vertex, &mut fragment, false);
pass.do_pass();
let vertex = vertex.assemble();
let vertex = vertex.module().assemble();
let fragment = fragment.module().assemble();
Ok(SpirvCompilation { vertex, fragment })

114
librashader-reflect/src/front/spirv_passes/link_input_outputs.rs
View file

@ -2,12 +2,21 @@ use rspirv::dr::{Builder, Module, Operand};
use rustc_hash::{FxHashMap, FxHashSet};
use spirv::{Decoration, Op, StorageClass};
/// Do DCE on inputs of the fragment shader, then
/// link by downgrading outputs of unused fragment inputs
/// to global variables on the vertex shader.
pub struct LinkInputs<'a> {
pub frag_builder: &'a mut Builder,
pub inputs: FxHashSet<spirv::Word>,
pub vert_builder: &'a mut Builder,
// binding -> ID
pub outputs: FxHashMap<u32, spirv::Word>,
// id -> binding
pub inputs_to_remove: FxHashMap<spirv::Word, u32>,
}
impl<'a> LinkInputs<'a> {
/// Get the value of the location of the inout in the module
fn find_location(module: &Module, id: spirv::Word) -> Option<u32> {
module.annotations.iter().find_map(|op| {
if op.class.opcode != Op::Decorate {
@ -33,9 +42,11 @@ impl<'a> LinkInputs<'a> {
})
}
pub fn new(vert: &'a Module, frag: &'a mut Builder) -> Self {
let mut inputs = FxHashSet::default();
let mut bindings = FxHashMap::default();
pub fn new(vert: &'a mut Builder, frag: &'a mut Builder, keep_if_bound: bool) -> Self {
let mut outputs = FxHashMap::default();
let mut inputs_to_remove = FxHashMap::default();
let mut inputs = FxHashMap::default();
for global in frag.module_ref().types_global_values.iter() {
if global.class.opcode == spirv::Op::Variable
&& global.operands[0] == Operand::StorageClass(StorageClass::Input)
@ -45,24 +56,32 @@ impl<'a> LinkInputs<'a> {
continue;
};
inputs.insert(id);
bindings.insert(location, id);
inputs_to_remove.insert(id, location);
inputs.insert(location, id);
}
}
}
for global in vert.types_global_values.iter() {
for global in vert.module_ref().types_global_values.iter() {
if global.class.opcode == spirv::Op::Variable
&& global.operands[0] == Operand::StorageClass(StorageClass::Output)
{
if let Some(id) = global.result_id {
let Some(location) = Self::find_location(vert, id) else {
let Some(location) = Self::find_location(vert.module_ref(), id) else {
continue;
};
if let Some(frag_ref) = bindings.get(&location) {
// if something is bound to the same location in the vertex shader,
// we're good.
inputs.remove(&frag_ref);
// Add to list of outputs
outputs.insert(location, id);
// Keep the input, if it is bound to both stages.Otherwise, do DCE analysis on
// the input, and remove it regardless if bound, if unused by the fragment stage.
if keep_if_bound {
if let Some(frag_ref) = inputs.get(&location) {
// if something is bound to the same location in the vertex shader,
// we're good.
inputs_to_remove.remove(&frag_ref);
}
}
}
}
@ -70,11 +89,63 @@ impl<'a> LinkInputs<'a> {
Self {
frag_builder: frag,
inputs,
vert_builder: vert,
outputs,
inputs_to_remove,
}
}
pub fn do_pass(&mut self) {
self.trim_inputs();
self.downgrade_outputs();
}
/// Downgrade dead inputs corresponding to outputs to global variables, keeping existing mappings.
fn downgrade_outputs(&mut self) {
let dead_outputs = self
.inputs_to_remove
.values()
.filter_map(|i| self.outputs.get(i).cloned())
.collect::<FxHashSet<spirv::Word>>();
let module = self.vert_builder.module_mut();
for global in module.types_global_values.iter_mut() {
if global.class.opcode != spirv::Op::Variable
|| global.operands[0] != Operand::StorageClass(StorageClass::Output)
{
continue;
}
if let Some(id) = global.result_id {
if !dead_outputs.contains(&id) {
continue;
}
// downgrade the OpVariable if it's in dead_outputs
global.operands[0] = Operand::StorageClass(StorageClass::Private);
}
}
module.annotations.retain_mut(|op| {
if op.class.opcode != Op::Decorate {
return true;
}
let Some(Operand::Decoration(Decoration::Location)) = op.operands.get(1) else {
return true;
};
let Some(&Operand::IdRef(target)) = op.operands.get(0) else {
return true;
};
// If target is in dead outputs, then don't keep it.
!dead_outputs.contains(&target)
});
}
// Trim unused fragment shader inputs
fn trim_inputs(&mut self) {
let functions = &self.frag_builder.module_ref().functions;
// literally if it has any reference at all we can keep it
@ -82,8 +153,8 @@ impl<'a> LinkInputs<'a> {
for param in &function.parameters {
for op in &param.operands {
if let Some(word) = op.id_ref_any() {
if self.inputs.contains(&word) {
self.inputs.remove(&word);
if self.inputs_to_remove.contains_key(&word) {
self.inputs_to_remove.remove(&word);
}
}
}
@ -93,8 +164,8 @@ impl<'a> LinkInputs<'a> {
for inst in &block.instructions {
for op in &inst.operands {
if let Some(word) = op.id_ref_any() {
if self.inputs.contains(&word) {
self.inputs.remove(&word);
if self.inputs_to_remove.contains_key(&word) {
self.inputs_to_remove.remove(&word);
}
}
}
@ -103,11 +174,10 @@ impl<'a> LinkInputs<'a> {
}
// ok well guess we dont
self.frag_builder.module_mut().debug_names.retain(|instr| {
for op in &instr.operands {
if let Some(word) = op.id_ref_any() {
if self.inputs.contains(&word) {
if self.inputs_to_remove.contains_key(&word) {
return false;
}
}
@ -118,7 +188,7 @@ impl<'a> LinkInputs<'a> {
self.frag_builder.module_mut().annotations.retain(|instr| {
for op in &instr.operands {
if let Some(word) = op.id_ref_any() {
if self.inputs.contains(&word) {
if self.inputs_to_remove.contains_key(&word) {
return false;
}
}
@ -129,7 +199,7 @@ impl<'a> LinkInputs<'a> {
for entry_point in self.frag_builder.module_mut().entry_points.iter_mut() {
entry_point.operands.retain(|op| {
if let Some(word) = op.id_ref_any() {
if self.inputs.contains(&word) {
if self.inputs_to_remove.contains_key(&word) {
return false;
}
}
@ -145,7 +215,7 @@ impl<'a> LinkInputs<'a> {
return true;
};
!self.inputs.contains(&id)
!self.inputs_to_remove.contains_key(&id)
});
}
}