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Initial GLSL constant evaluation implementation #94

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merged 1 commit into from
Jul 10, 2020
Merged

Initial GLSL constant evaluation implementation #94

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255 changes: 186 additions & 69 deletions src/front/glsl/mod.rs
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -63,6 +63,8 @@ pub enum ErrorKind {
EOL,
#[error("End of file")]
EOF,
#[error("Non constant expression encountered where a constant expression was expected")]
NonConstantExpr,
}

#[derive(Debug, thiserror::Error)]
Expand All @@ -83,6 +85,7 @@ struct Parser<'a> {
types: Arena<Type>,
globals: Arena<GlobalVariable>,
globals_lookup: FastHashMap<String, Global>,
globals_constants: FastHashMap<String, Handle<Constant>>,
constants: Arena<Constant>,
functions: Arena<Function>,
shader_stage: ShaderStage,
Expand All @@ -95,6 +98,7 @@ impl<'a> Parser<'a> {
types: Arena::new(),
globals: Arena::new(),
globals_lookup: FastHashMap::default(),
globals_constants: FastHashMap::default(),
constants: Arena::new(),
functions: Arena::new(),
shader_stage,
Expand All @@ -107,6 +111,10 @@ impl<'a> Parser<'a> {
//println!("{:#?}", ast);

let mut entry_point = None;
let parameter_lookup = FastHashMap::default();
let mut locals = Arena::<LocalVariable>::new();
let mut locals_map = FastHashMap::default();
let mut expressions = Arena::<Expression>::new();

for declaration in ast {
match declaration {
Expand All @@ -125,9 +133,32 @@ impl<'a> Parser<'a> {
}
}
ExternalDeclaration::Declaration(decl) => match decl {
Declaration::InitDeclaratorList(init) => {
let handle = self.parse_global(init);
Declaration::InitDeclaratorList(mut init) => {
// Get initializer out for lifetime reasons. Maybe self.parse_global needs
// to take a reference and clone what it needs?
let mut initializer = None;
std::mem::swap(&mut initializer, &mut init.head.initializer);

let handle = self.parse_global(init.head)?;
let name = self.globals[handle].name.clone().unwrap();
if let Some(initializer) = initializer {
match initializer {
Initializer::Simple(expr) => {
let expr = self.parse_expression(
*expr,
&mut expressions,
&mut locals,
&mut locals_map,
&parameter_lookup,
)?;
let handle = expressions.append(expr);
let val = self.eval_const_expr(handle, &expressions)?;
self.globals_constants.insert(name.clone(), val);
}
_ => todo!(),
}
}

self.globals_lookup.insert(name, Global::Variable(handle));
}
Declaration::Block(block) => {
Expand All @@ -151,16 +182,12 @@ impl<'a> Parser<'a> {
name: Some(field_name.clone()),
origin,
ty: if let Some(array_spec) = ident.array_spec {
let size = self.parse_array_size(array_spec)?;
self.types.fetch_or_append(Type {
name: None,
inner: TypeInner::Array {
base: ty,
size: match array_spec {
ArraySpecifier::Unsized => ArraySize::Dynamic,
ArraySpecifier::ExplicitlySized(_expr) => {
unimplemented!()
}
},
size,
stride: None,
},
})
Expand All @@ -184,14 +211,12 @@ impl<'a> Parser<'a> {
inner: TypeInner::Struct { members: fields },
});

let size = self.parse_array_size(array_spec)?;
self.types.fetch_or_append(Type {
name: None,
inner: TypeInner::Array {
base,
size: match array_spec {
ArraySpecifier::Unsized => ArraySize::Dynamic,
ArraySpecifier::ExplicitlySized(_expr) => unimplemented!(),
},
size,
stride: None,
},
})
Expand Down Expand Up @@ -259,18 +284,16 @@ impl<'a> Parser<'a> {
FunctionParameterDeclaration::Named(_ /* TODO */, decl) => {
let ty = self.parse_type(decl.ty).unwrap();

let ty = if let Some(specifier) = decl.ident.array_spec {
match specifier {
ArraySpecifier::Unsized => self.types.fetch_or_append(Type {
name: None,
inner: TypeInner::Array {
base: ty,
size: ArraySize::Dynamic,
stride: None,
},
}),
ArraySpecifier::ExplicitlySized(_) => unimplemented!(),
}
let ty = if let Some(array_spec) = decl.ident.array_spec {
let size = self.parse_array_size(array_spec)?;
self.types.fetch_or_append(Type {
name: None,
inner: TypeInner::Array {
base: ty,
size,
stride: None,
},
})
} else {
ty
};
Expand Down Expand Up @@ -303,12 +326,7 @@ impl<'a> Parser<'a> {
}
_ => unimplemented!(),
},
SimpleStatement::Expression(expr) => {
let expr = match expr {
Some(expr) => expr,
None => continue,
};

SimpleStatement::Expression(Some(expr)) => {
body.push(self.parse_statement(
expr,
&mut expressions,
Expand All @@ -317,6 +335,7 @@ impl<'a> Parser<'a> {
&parameter_lookup,
)?);
}
SimpleStatement::Expression(None) => (),
SimpleStatement::Selection(_) => unimplemented!(),
SimpleStatement::Switch(_) => unimplemented!(),
SimpleStatement::CaseLabel(_) => unimplemented!(),
Expand Down Expand Up @@ -368,18 +387,16 @@ impl<'a> Parser<'a> {
let ty = {
let ty = self.parse_type(init.head.ty.ty).unwrap();

if let Some(specifier) = init.head.array_specifier {
match specifier {
ArraySpecifier::Unsized => self.types.fetch_or_append(Type {
name: None,
inner: TypeInner::Array {
base: ty,
size: ArraySize::Dynamic,
stride: None,
},
}),
ArraySpecifier::ExplicitlySized(_) => unimplemented!(),
}
if let Some(array_spec) = init.head.array_specifier {
let size = self.parse_array_size(array_spec)?;
self.types.fetch_or_append(Type {
name: None,
inner: TypeInner::Array {
base: ty,
size,
stride: None,
},
})
} else {
ty
}
Expand Down Expand Up @@ -980,19 +997,17 @@ impl<'a> Parser<'a> {
fn parse_type(&mut self, ty: TypeSpecifier) -> Option<Handle<Type>> {
let base_ty = helpers::glsl_to_spirv_type(ty.ty, &mut self.types)?;

let ty = if let Some(specifier) = ty.array_specifier {
let ty = if let Some(array_spec) = ty.array_specifier {
let handle = self.types.fetch_or_append(Type {
name: None,
inner: base_ty,
});
let size = self.parse_array_size(array_spec).unwrap();

match specifier {
ArraySpecifier::Unsized => TypeInner::Array {
base: handle,
size: ArraySize::Dynamic,
stride: None,
},
ArraySpecifier::ExplicitlySized(_) => unimplemented!(),
TypeInner::Array {
base: handle,
size,
stride: None,
}
} else {
base_ty
Expand All @@ -1004,41 +1019,143 @@ impl<'a> Parser<'a> {
}))
}

fn parse_global(&mut self, init: InitDeclaratorList) -> Handle<GlobalVariable> {
let name = init.head.name.map(|d| d.0);
fn parse_global(&mut self, head: SingleDeclaration) -> Result<Handle<GlobalVariable>, Error> {
let name = head.name.map(|d| d.0);
let ty = {
let ty = self.parse_type(init.head.ty.ty).unwrap();
let ty = self.parse_type(head.ty.ty).unwrap();

if let Some(specifier) = init.head.array_specifier {
match specifier {
ArraySpecifier::Unsized => self.types.fetch_or_append(Type {
name: None,
inner: TypeInner::Array {
base: ty,
size: ArraySize::Dynamic,
stride: None,
},
}),
ArraySpecifier::ExplicitlySized(_) => unimplemented!(),
}
if let Some(array_spec) = head.array_specifier {
let size = self.parse_array_size(array_spec)?;
self.types.fetch_or_append(Type {
name: None,
inner: TypeInner::Array {
base: ty,
size,
stride: None,
},
})
} else {
ty
}
};

let (class, binding) = init
.head
let (class, binding) = head
.ty
.qualifier
.map(Self::parse_type_qualifier)
.unwrap_or((StorageClass::Private, None));

self.globals.append(GlobalVariable {
Ok(self.globals.append(GlobalVariable {
name,
class,
binding,
ty,
})
}))
}

/// https://www.khronos.org/opengl/wiki/Core_Language_(GLSL)#Constant_expression
pub fn eval_const_expr(
&mut self,
expr: Handle<Expression>,
expressions: &Arena<Expression>,
) -> Result<Handle<Constant>, Error> {
match &expressions[expr] {
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note: we strongly prefer to match on values everywhere, not references

Expression::Constant(handle) => Ok(*handle),
Expression::Call { .. } => todo!(),
Expression::GlobalVariable(handle) => {
let name = self.globals[*handle].name.as_ref().unwrap();
if let Some(handle) = self.globals_constants.get(name) {
Ok(*handle)
} else {
todo!("Global const error")
}
}
Expression::Binary { left, right, op } => {
let left = self.eval_const_expr(*left, expressions)?;
let right = self.eval_const_expr(*right, expressions)?;
let inner: ConstantInner;
let ty;
match op {
BinaryOperator::Add => {
match (&self.constants[left].inner, &self.constants[right].inner) {
(ConstantInner::Sint(left), ConstantInner::Sint(right)) => {
inner = ConstantInner::Sint(left + right);
ty = self.types.fetch_or_append(Type {
name: None,
inner: TypeInner::Scalar {
kind: ScalarKind::Sint,
width: 4,
},
})
}
(ConstantInner::Uint(left), ConstantInner::Uint(right)) => {
inner = ConstantInner::Uint(left + right);
ty = self.types.fetch_or_append(Type {
name: None,
inner: TypeInner::Scalar {
kind: ScalarKind::Uint,
width: 4,
},
})
}
(ConstantInner::Float(left), ConstantInner::Float(right)) => {
inner = ConstantInner::Float(left + right);
ty = self.types.fetch_or_append(Type {
name: None,
inner: TypeInner::Scalar {
kind: ScalarKind::Float,
width: 4,
},
})
}
_ => todo!(),
}
}

_ => todo!(),
}
Ok(self.constants.fetch_or_append(Constant {
name: None,
specialization: None,
inner,
ty,
}))
}
expr => todo!("Const eval for {:?}", expr),
}
}

pub fn parse_array_size(&mut self, array_spec: ArraySpecifier) -> Result<ArraySize, Error> {
let parameter_lookup = FastHashMap::default();
let mut locals = Arena::<LocalVariable>::new();
let mut locals_map = FastHashMap::default();
let mut expressions = Arena::<Expression>::new();
let size = match array_spec {
ArraySpecifier::Unsized => ArraySize::Dynamic,
ArraySpecifier::ExplicitlySized(expr) => {
let expr = self.parse_expression(
*expr,
&mut expressions,
&mut locals,
&mut locals_map,
&parameter_lookup,
)?;
let handle = expressions.append(expr);

let const_handle = self.eval_const_expr(handle, &expressions)?;

match &self.constants[const_handle].inner {
ConstantInner::Sint(val) => ArraySize::Static(*val as u32),
ConstantInner::Uint(val) => ArraySize::Static(*val as u32),
val => panic!(
"Array size must be an integral constant expression, got: {:?}",
val
),
}
}
};

Ok(size)
}

fn parse_type_qualifier(qualifier: TypeQualifier) -> (StorageClass, Option<Binding>) {
Expand Down
9 changes: 9 additions & 0 deletions test-data/glsl_constant_expression.vert
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Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
#version 450 core

const int N = 5;

float foo[2+N];

void main() {
gl_Position = vec4(1);
}
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