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/*!
Backend functions that export shader [`Module`](super::Module)s into binary and text formats.
*/
#![allow(dead_code)] // can be dead if none of the enabled backends need it
use crate::proc::ExpressionKindTracker;
#[cfg(dot_out)]
pub mod dot;
#[cfg(glsl_out)]
pub mod glsl;
#[cfg(hlsl_out)]
pub mod hlsl;
#[cfg(msl_out)]
pub mod msl;
#[cfg(spv_out)]
pub mod spv;
#[cfg(wgsl_out)]
pub mod wgsl;
#[cfg(any(hlsl_out, msl_out, spv_out, glsl_out))]
pub mod pipeline_constants;
#[cfg(any(hlsl_out, glsl_out))]
mod continue_forward;
/// Names of vector components.
pub const COMPONENTS: &[char] = &['x', 'y', 'z', 'w'];
/// Indent for backends.
pub const INDENT: &str = " ";
/// Expressions that need baking.
pub type NeedBakeExpressions = crate::FastHashSet<crate::Handle<crate::Expression>>;
/// A type for displaying expression handles as baking identifiers.
///
/// Given an [`Expression`] [`Handle`] `h`, `Baked(h)` implements
/// [`std::fmt::Display`], showing the handle's index prefixed by
/// `_e`.
///
/// [`Expression`]: crate::Expression
/// [`Handle`]: crate::Handle
struct Baked(crate::Handle<crate::Expression>);
impl std::fmt::Display for Baked {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
self.0.write_prefixed(f, "_e")
}
}
/// Specifies the values of pipeline-overridable constants in the shader module.
///
/// If an `@id` attribute was specified on the declaration,
/// the key must be the pipeline constant ID as a decimal ASCII number; if not,
/// the key must be the constant's identifier name.
///
/// The value may represent any of WGSL's concrete scalar types.
pub type PipelineConstants = std::collections::HashMap<String, f64>;
/// Indentation level.
#[derive(Clone, Copy)]
pub struct Level(pub usize);
impl Level {
const fn next(&self) -> Self {
Level(self.0 + 1)
}
}
impl std::fmt::Display for Level {
fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> {
(0..self.0).try_for_each(|_| formatter.write_str(INDENT))
}
}
/// Whether we're generating an entry point or a regular function.
///
/// Backend languages often require different code for a [`Function`]
/// depending on whether it represents an [`EntryPoint`] or not.
/// Backends can pass common code one of these values to select the
/// right behavior.
///
/// These values also carry enough information to find the `Function`
/// in the [`Module`]: the `Handle` for a regular function, or the
/// index into [`Module::entry_points`] for an entry point.
///
/// [`Function`]: crate::Function
/// [`EntryPoint`]: crate::EntryPoint
/// [`Module`]: crate::Module
/// [`Module::entry_points`]: crate::Module::entry_points
pub enum FunctionType {
/// A regular function.
Function(crate::Handle<crate::Function>),
/// An [`EntryPoint`], and its index in [`Module::entry_points`].
///
/// [`EntryPoint`]: crate::EntryPoint
/// [`Module::entry_points`]: crate::Module::entry_points
EntryPoint(crate::proc::EntryPointIndex),
}
impl FunctionType {
/// Returns true if the function is an entry point for a compute shader.
pub fn is_compute_entry_point(&self, module: &crate::Module) -> bool {
match *self {
FunctionType::EntryPoint(index) => {
module.entry_points[index as usize].stage == crate::ShaderStage::Compute
}
FunctionType::Function(_) => false,
}
}
}
/// Helper structure that stores data needed when writing the function
pub struct FunctionCtx<'a> {
/// The current function being written
pub ty: FunctionType,
/// Analysis about the function
pub info: &'a crate::valid::FunctionInfo,
/// The expression arena of the current function being written
pub expressions: &'a crate::Arena<crate::Expression>,
/// Map of expressions that have associated variable names
pub named_expressions: &'a crate::NamedExpressions,
/// For constness checks
pub expr_kind_tracker: ExpressionKindTracker,
}
impl FunctionCtx<'_> {
/// Helper method that resolves a type of a given expression.
pub fn resolve_type<'a>(
&'a self,
handle: crate::Handle<crate::Expression>,
types: &'a crate::UniqueArena<crate::Type>,
) -> &'a crate::TypeInner {
self.info[handle].ty.inner_with(types)
}
/// Helper method that generates a [`NameKey`](crate::proc::NameKey) for a local in the current function
pub const fn name_key(
&self,
local: crate::Handle<crate::LocalVariable>,
) -> crate::proc::NameKey {
match self.ty {
FunctionType::Function(handle) => crate::proc::NameKey::FunctionLocal(handle, local),
FunctionType::EntryPoint(idx) => crate::proc::NameKey::EntryPointLocal(idx, local),
}
}
/// Helper method that generates a [`NameKey`](crate::proc::NameKey) for a function argument.
///
/// # Panics
/// - If the function arguments are less or equal to `arg`
pub const fn argument_key(&self, arg: u32) -> crate::proc::NameKey {
match self.ty {
FunctionType::Function(handle) => crate::proc::NameKey::FunctionArgument(handle, arg),
FunctionType::EntryPoint(ep_index) => {
crate::proc::NameKey::EntryPointArgument(ep_index, arg)
}
}
}
/// Returns true if the given expression points to a fixed-function pipeline input.
pub fn is_fixed_function_input(
&self,
mut expression: crate::Handle<crate::Expression>,
module: &crate::Module,
) -> Option<crate::BuiltIn> {
let ep_function = match self.ty {
FunctionType::Function(_) => return None,
FunctionType::EntryPoint(ep_index) => &module.entry_points[ep_index as usize].function,
};
let mut built_in = None;
loop {
match self.expressions[expression] {
crate::Expression::FunctionArgument(arg_index) => {
return match ep_function.arguments[arg_index as usize].binding {
Some(crate::Binding::BuiltIn(bi)) => Some(bi),
_ => built_in,
};
}
crate::Expression::AccessIndex { base, index } => {
match *self.resolve_type(base, &module.types) {
crate::TypeInner::Struct { ref members, .. } => {
if let Some(crate::Binding::BuiltIn(bi)) =
members[index as usize].binding
{
built_in = Some(bi);
}
}
_ => return None,
}
expression = base;
}
_ => return None,
}
}
}
}
impl crate::Expression {
/// Returns the ref count, upon reaching which this expression
/// should be considered for baking.
///
/// Note: we have to cache any expressions that depend on the control flow,
/// or otherwise they may be moved into a non-uniform control flow, accidentally.
/// See the [module-level documentation][emit] for details.
///
/// [emit]: index.html#expression-evaluation-time
pub const fn bake_ref_count(&self) -> usize {
match *self {
// accesses are never cached, only loads are
crate::Expression::Access { .. } | crate::Expression::AccessIndex { .. } => usize::MAX,
// sampling may use the control flow, and image ops look better by themselves
crate::Expression::ImageSample { .. } | crate::Expression::ImageLoad { .. } => 1,
// derivatives use the control flow
crate::Expression::Derivative { .. } => 1,
// TODO: We need a better fix for named `Load` expressions
crate::Expression::Load { .. } => 1,
// cache expressions that are referenced multiple times
_ => 2,
}
}
}
/// Helper function that returns the string corresponding to the [`BinaryOperator`](crate::BinaryOperator)
pub const fn binary_operation_str(op: crate::BinaryOperator) -> &'static str {
use crate::BinaryOperator as Bo;
match op {
Bo::Add => "+",
Bo::Subtract => "-",
Bo::Multiply => "*",
Bo::Divide => "/",
Bo::Modulo => "%",
Bo::Equal => "==",
Bo::NotEqual => "!=",
Bo::Less => "<",
Bo::LessEqual => "<=",
Bo::Greater => ">",
Bo::GreaterEqual => ">=",
Bo::And => "&",
Bo::ExclusiveOr => "^",
Bo::InclusiveOr => "|",
Bo::LogicalAnd => "&&",
Bo::LogicalOr => "||",
Bo::ShiftLeft => "<<",
Bo::ShiftRight => ">>",
}
}
/// Helper function that returns the string corresponding to the [`VectorSize`](crate::VectorSize)
const fn vector_size_str(size: crate::VectorSize) -> &'static str {
match size {
crate::VectorSize::Bi => "2",
crate::VectorSize::Tri => "3",
crate::VectorSize::Quad => "4",
}
}
impl crate::TypeInner {
/// Returns true if this is a handle to a type rather than the type directly.
pub const fn is_handle(&self) -> bool {
match *self {
crate::TypeInner::Image { .. }
| crate::TypeInner::Sampler { .. }
| crate::TypeInner::AccelerationStructure { .. } => true,
_ => false,
}
}
}
impl crate::Statement {
/// Returns true if the statement directly terminates the current block.
///
/// Used to decide whether case blocks require a explicit `break`.
pub const fn is_terminator(&self) -> bool {
match *self {
crate::Statement::Break
| crate::Statement::Continue
| crate::Statement::Return { .. }
| crate::Statement::Kill => true,
_ => false,
}
}
}
bitflags::bitflags! {
/// Ray flags, for a [`RayDesc`]'s `flags` field.
///
/// Note that these exactly correspond to the SPIR-V "Ray Flags" mask, and
/// the SPIR-V backend passes them directly through to the
/// [`OpRayQueryInitializeKHR`][op] instruction. (We have to choose something, so
/// we might as well make one back end's life easier.)
///
/// [`RayDesc`]: crate::Module::generate_ray_desc_type
#[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
pub struct RayFlag: u32 {
const OPAQUE = 0x01;
const NO_OPAQUE = 0x02;
const TERMINATE_ON_FIRST_HIT = 0x04;
const SKIP_CLOSEST_HIT_SHADER = 0x08;
const CULL_BACK_FACING = 0x10;
const CULL_FRONT_FACING = 0x20;
const CULL_OPAQUE = 0x40;
const CULL_NO_OPAQUE = 0x80;
const SKIP_TRIANGLES = 0x100;
const SKIP_AABBS = 0x200;
}
}
/// The intersection test to use for ray queries.
#[repr(u32)]
pub enum RayIntersectionType {
Triangle = 1,
BoundingBox = 4,
}