naga/front/glsl/parser/functions.rs
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use alloc::{vec, vec::Vec};
use crate::front::glsl::context::ExprPos;
use crate::front::glsl::Span;
use crate::Literal;
use crate::{
front::glsl::{
ast::ParameterQualifier,
context::Context,
parser::ParsingContext,
token::{Token, TokenValue},
variables::VarDeclaration,
Error, ErrorKind, Frontend, Result,
},
Block, Expression, Statement, SwitchCase, UnaryOperator,
};
impl ParsingContext<'_> {
pub fn peek_parameter_qualifier(&mut self, frontend: &mut Frontend) -> bool {
self.peek(frontend).is_some_and(|t| match t.value {
TokenValue::In | TokenValue::Out | TokenValue::InOut | TokenValue::Const => true,
_ => false,
})
}
/// Returns the parsed `ParameterQualifier` or `ParameterQualifier::In`
pub fn parse_parameter_qualifier(&mut self, frontend: &mut Frontend) -> ParameterQualifier {
if self.peek_parameter_qualifier(frontend) {
match self.bump(frontend).unwrap().value {
TokenValue::In => ParameterQualifier::In,
TokenValue::Out => ParameterQualifier::Out,
TokenValue::InOut => ParameterQualifier::InOut,
TokenValue::Const => ParameterQualifier::Const,
_ => unreachable!(),
}
} else {
ParameterQualifier::In
}
}
pub fn parse_statement(
&mut self,
frontend: &mut Frontend,
ctx: &mut Context,
terminator: &mut Option<usize>,
is_inside_loop: bool,
) -> Result<Option<Span>> {
// Type qualifiers always identify a declaration statement
if self.peek_type_qualifier(frontend) {
return self.parse_declaration(frontend, ctx, false, is_inside_loop);
}
// Type names can identify either declaration statements or type constructors
// depending on whether the token following the type name is a `(` (LeftParen)
if self.peek_type_name(frontend) {
// Start by consuming the type name so that we can peek the token after it
let token = self.bump(frontend)?;
// Peek the next token and check if it's a `(` (LeftParen) if so the statement
// is a constructor, otherwise it's a declaration. We need to do the check
// beforehand and not in the if since we will backtrack before the if
let declaration = TokenValue::LeftParen != self.expect_peek(frontend)?.value;
self.backtrack(token)?;
if declaration {
return self.parse_declaration(frontend, ctx, false, is_inside_loop);
}
}
let new_break = || {
let mut block = Block::new();
block.push(Statement::Break, Span::default());
block
};
let &Token {
ref value,
mut meta,
} = self.expect_peek(frontend)?;
let meta_rest = match *value {
TokenValue::Continue => {
let meta = self.bump(frontend)?.meta;
ctx.body.push(Statement::Continue, meta);
terminator.get_or_insert(ctx.body.len());
self.expect(frontend, TokenValue::Semicolon)?.meta
}
TokenValue::Break => {
let meta = self.bump(frontend)?.meta;
ctx.body.push(Statement::Break, meta);
terminator.get_or_insert(ctx.body.len());
self.expect(frontend, TokenValue::Semicolon)?.meta
}
TokenValue::Return => {
self.bump(frontend)?;
let (value, meta) = match self.expect_peek(frontend)?.value {
TokenValue::Semicolon => (None, self.bump(frontend)?.meta),
_ => {
// TODO: Implicit conversions
let mut stmt = ctx.stmt_ctx();
let expr = self.parse_expression(frontend, ctx, &mut stmt)?;
self.expect(frontend, TokenValue::Semicolon)?;
let (handle, meta) =
ctx.lower_expect(stmt, frontend, expr, ExprPos::Rhs)?;
(Some(handle), meta)
}
};
ctx.emit_restart();
ctx.body.push(Statement::Return { value }, meta);
terminator.get_or_insert(ctx.body.len());
meta
}
TokenValue::Discard => {
let meta = self.bump(frontend)?.meta;
ctx.body.push(Statement::Kill, meta);
terminator.get_or_insert(ctx.body.len());
self.expect(frontend, TokenValue::Semicolon)?.meta
}
TokenValue::If => {
let mut meta = self.bump(frontend)?.meta;
self.expect(frontend, TokenValue::LeftParen)?;
let condition = {
let mut stmt = ctx.stmt_ctx();
let expr = self.parse_expression(frontend, ctx, &mut stmt)?;
let (handle, more_meta) =
ctx.lower_expect(stmt, frontend, expr, ExprPos::Rhs)?;
meta.subsume(more_meta);
handle
};
self.expect(frontend, TokenValue::RightParen)?;
let accept = ctx.new_body(|ctx| {
if let Some(more_meta) =
self.parse_statement(frontend, ctx, &mut None, is_inside_loop)?
{
meta.subsume(more_meta);
}
Ok(())
})?;
let reject = ctx.new_body(|ctx| {
if self.bump_if(frontend, TokenValue::Else).is_some() {
if let Some(more_meta) =
self.parse_statement(frontend, ctx, &mut None, is_inside_loop)?
{
meta.subsume(more_meta);
}
}
Ok(())
})?;
ctx.body.push(
Statement::If {
condition,
accept,
reject,
},
meta,
);
meta
}
TokenValue::Switch => {
let mut meta = self.bump(frontend)?.meta;
let end_meta;
self.expect(frontend, TokenValue::LeftParen)?;
let (selector, uint) = {
let mut stmt = ctx.stmt_ctx();
let expr = self.parse_expression(frontend, ctx, &mut stmt)?;
let (root, meta) = ctx.lower_expect(stmt, frontend, expr, ExprPos::Rhs)?;
let uint = ctx.resolve_type(root, meta)?.scalar_kind()
== Some(crate::ScalarKind::Uint);
(root, uint)
};
self.expect(frontend, TokenValue::RightParen)?;
ctx.emit_restart();
let mut cases = Vec::new();
// Track if any default case is present in the switch statement.
let mut default_present = false;
self.expect(frontend, TokenValue::LeftBrace)?;
loop {
let value = match self.expect_peek(frontend)?.value {
TokenValue::Case => {
self.bump(frontend)?;
let (const_expr, meta) = self.parse_constant_expression(
frontend,
ctx.module,
ctx.global_expression_kind_tracker,
)?;
match ctx.module.global_expressions[const_expr] {
Expression::Literal(Literal::I32(value)) => match uint {
// This unchecked cast isn't good, but since
// we only reach this code when the selector
// is unsigned but the case label is signed,
// verification will reject the module
// anyway (which also matches GLSL's rules).
true => crate::SwitchValue::U32(value as u32),
false => crate::SwitchValue::I32(value),
},
Expression::Literal(Literal::U32(value)) => {
crate::SwitchValue::U32(value)
}
_ => {
frontend.errors.push(Error {
kind: ErrorKind::SemanticError(
"Case values can only be integers".into(),
),
meta,
});
crate::SwitchValue::I32(0)
}
}
}
TokenValue::Default => {
self.bump(frontend)?;
default_present = true;
crate::SwitchValue::Default
}
TokenValue::RightBrace => {
end_meta = self.bump(frontend)?.meta;
break;
}
_ => {
let Token { value, meta } = self.bump(frontend)?;
return Err(Error {
kind: ErrorKind::InvalidToken(
value,
vec![
TokenValue::Case.into(),
TokenValue::Default.into(),
TokenValue::RightBrace.into(),
],
),
meta,
});
}
};
self.expect(frontend, TokenValue::Colon)?;
let mut fall_through = true;
let body = ctx.new_body(|ctx| {
let mut case_terminator = None;
loop {
match self.expect_peek(frontend)?.value {
TokenValue::Case | TokenValue::Default | TokenValue::RightBrace => {
break
}
_ => {
self.parse_statement(
frontend,
ctx,
&mut case_terminator,
is_inside_loop,
)?;
}
}
}
if let Some(mut idx) = case_terminator {
if let Statement::Break = ctx.body[idx - 1] {
fall_through = false;
idx -= 1;
}
ctx.body.cull(idx..)
}
Ok(())
})?;
cases.push(SwitchCase {
value,
body,
fall_through,
})
}
meta.subsume(end_meta);
// NOTE: do not unwrap here since a switch statement isn't required
// to have any cases.
if let Some(case) = cases.last_mut() {
// GLSL requires that the last case not be empty, so we check
// that here and produce an error otherwise (fall_through must
// also be checked because `break`s count as statements but
// they aren't added to the body)
if case.body.is_empty() && case.fall_through {
frontend.errors.push(Error {
kind: ErrorKind::SemanticError(
"last case/default label must be followed by statements".into(),
),
meta,
})
}
// GLSL allows the last case to not have any `break` statement,
// this would mark it as fall through but naga's IR requires that
// the last case must not be fall through, so we mark need to mark
// the last case as not fall through always.
case.fall_through = false;
}
// Add an empty default case in case non was present, this is needed because
// naga's IR requires that all switch statements must have a default case but
// GLSL doesn't require that, so we might need to add an empty default case.
if !default_present {
cases.push(SwitchCase {
value: crate::SwitchValue::Default,
body: Block::new(),
fall_through: false,
})
}
ctx.body.push(Statement::Switch { selector, cases }, meta);
meta
}
TokenValue::While => {
let mut meta = self.bump(frontend)?.meta;
let loop_body = ctx.new_body(|ctx| {
let mut stmt = ctx.stmt_ctx();
self.expect(frontend, TokenValue::LeftParen)?;
let root = self.parse_expression(frontend, ctx, &mut stmt)?;
meta.subsume(self.expect(frontend, TokenValue::RightParen)?.meta);
let (expr, expr_meta) = ctx.lower_expect(stmt, frontend, root, ExprPos::Rhs)?;
let condition = ctx.add_expression(
Expression::Unary {
op: UnaryOperator::LogicalNot,
expr,
},
expr_meta,
)?;
ctx.emit_restart();
ctx.body.push(
Statement::If {
condition,
accept: new_break(),
reject: Block::new(),
},
Span::default(),
);
meta.subsume(expr_meta);
if let Some(body_meta) = self.parse_statement(frontend, ctx, &mut None, true)? {
meta.subsume(body_meta);
}
Ok(())
})?;
ctx.body.push(
Statement::Loop {
body: loop_body,
continuing: Block::new(),
break_if: None,
},
meta,
);
meta
}
TokenValue::Do => {
let mut meta = self.bump(frontend)?.meta;
let loop_body = ctx.new_body(|ctx| {
let mut terminator = None;
self.parse_statement(frontend, ctx, &mut terminator, true)?;
let mut stmt = ctx.stmt_ctx();
self.expect(frontend, TokenValue::While)?;
self.expect(frontend, TokenValue::LeftParen)?;
let root = self.parse_expression(frontend, ctx, &mut stmt)?;
let end_meta = self.expect(frontend, TokenValue::RightParen)?.meta;
meta.subsume(end_meta);
let (expr, expr_meta) = ctx.lower_expect(stmt, frontend, root, ExprPos::Rhs)?;
let condition = ctx.add_expression(
Expression::Unary {
op: UnaryOperator::LogicalNot,
expr,
},
expr_meta,
)?;
ctx.emit_restart();
ctx.body.push(
Statement::If {
condition,
accept: new_break(),
reject: Block::new(),
},
Span::default(),
);
if let Some(idx) = terminator {
ctx.body.cull(idx..)
}
Ok(())
})?;
ctx.body.push(
Statement::Loop {
body: loop_body,
continuing: Block::new(),
break_if: None,
},
meta,
);
meta
}
TokenValue::For => {
let mut meta = self.bump(frontend)?.meta;
ctx.symbol_table.push_scope();
self.expect(frontend, TokenValue::LeftParen)?;
if self.bump_if(frontend, TokenValue::Semicolon).is_none() {
if self.peek_type_name(frontend) || self.peek_type_qualifier(frontend) {
self.parse_declaration(frontend, ctx, false, is_inside_loop)?;
} else {
let mut stmt = ctx.stmt_ctx();
let expr = self.parse_expression(frontend, ctx, &mut stmt)?;
ctx.lower(stmt, frontend, expr, ExprPos::Rhs)?;
self.expect(frontend, TokenValue::Semicolon)?;
}
}
let loop_body = ctx.new_body(|ctx| {
if self.bump_if(frontend, TokenValue::Semicolon).is_none() {
let (expr, expr_meta) = if self.peek_type_name(frontend)
|| self.peek_type_qualifier(frontend)
{
let mut qualifiers = self.parse_type_qualifiers(frontend, ctx)?;
let (ty, mut meta) = self.parse_type_non_void(frontend, ctx)?;
let name = self.expect_ident(frontend)?.0;
self.expect(frontend, TokenValue::Assign)?;
let (value, end_meta) = self.parse_initializer(frontend, ty, ctx)?;
meta.subsume(end_meta);
let decl = VarDeclaration {
qualifiers: &mut qualifiers,
ty,
name: Some(name),
init: None,
meta,
};
let pointer = frontend.add_local_var(ctx, decl)?;
ctx.emit_restart();
ctx.body.push(Statement::Store { pointer, value }, meta);
(value, end_meta)
} else {
let mut stmt = ctx.stmt_ctx();
let root = self.parse_expression(frontend, ctx, &mut stmt)?;
ctx.lower_expect(stmt, frontend, root, ExprPos::Rhs)?
};
let condition = ctx.add_expression(
Expression::Unary {
op: UnaryOperator::LogicalNot,
expr,
},
expr_meta,
)?;
ctx.emit_restart();
ctx.body.push(
Statement::If {
condition,
accept: new_break(),
reject: Block::new(),
},
Span::default(),
);
self.expect(frontend, TokenValue::Semicolon)?;
}
Ok(())
})?;
let continuing = ctx.new_body(|ctx| {
match self.expect_peek(frontend)?.value {
TokenValue::RightParen => {}
_ => {
let mut stmt = ctx.stmt_ctx();
let rest = self.parse_expression(frontend, ctx, &mut stmt)?;
ctx.lower(stmt, frontend, rest, ExprPos::Rhs)?;
}
}
Ok(())
})?;
meta.subsume(self.expect(frontend, TokenValue::RightParen)?.meta);
let loop_body = ctx.with_body(loop_body, |ctx| {
if let Some(stmt_meta) = self.parse_statement(frontend, ctx, &mut None, true)? {
meta.subsume(stmt_meta);
}
Ok(())
})?;
ctx.body.push(
Statement::Loop {
body: loop_body,
continuing,
break_if: None,
},
meta,
);
ctx.symbol_table.pop_scope();
meta
}
TokenValue::LeftBrace => {
let mut meta = self.bump(frontend)?.meta;
let mut block_terminator = None;
let block = ctx.new_body(|ctx| {
let block_meta = self.parse_compound_statement(
meta,
frontend,
ctx,
&mut block_terminator,
is_inside_loop,
)?;
meta.subsume(block_meta);
Ok(())
})?;
ctx.body.push(Statement::Block(block), meta);
if block_terminator.is_some() {
terminator.get_or_insert(ctx.body.len());
}
meta
}
TokenValue::Semicolon => self.bump(frontend)?.meta,
_ => {
// Attempt to force expression parsing for remainder of the
// tokens. Unknown or invalid tokens will be caught there and
// turned into an error.
let mut stmt = ctx.stmt_ctx();
let expr = self.parse_expression(frontend, ctx, &mut stmt)?;
ctx.lower(stmt, frontend, expr, ExprPos::Rhs)?;
self.expect(frontend, TokenValue::Semicolon)?.meta
}
};
meta.subsume(meta_rest);
Ok(Some(meta))
}
pub fn parse_compound_statement(
&mut self,
mut meta: Span,
frontend: &mut Frontend,
ctx: &mut Context,
terminator: &mut Option<usize>,
is_inside_loop: bool,
) -> Result<Span> {
ctx.symbol_table.push_scope();
loop {
if let Some(Token {
meta: brace_meta, ..
}) = self.bump_if(frontend, TokenValue::RightBrace)
{
meta.subsume(brace_meta);
break;
}
let stmt = self.parse_statement(frontend, ctx, terminator, is_inside_loop)?;
if let Some(stmt_meta) = stmt {
meta.subsume(stmt_meta);
}
}
if let Some(idx) = *terminator {
ctx.body.cull(idx..)
}
ctx.symbol_table.pop_scope();
Ok(meta)
}
pub fn parse_function_args(
&mut self,
frontend: &mut Frontend,
ctx: &mut Context,
) -> Result<()> {
if self.bump_if(frontend, TokenValue::Void).is_some() {
return Ok(());
}
loop {
if self.peek_type_name(frontend) || self.peek_parameter_qualifier(frontend) {
let qualifier = self.parse_parameter_qualifier(frontend);
let mut ty = self.parse_type_non_void(frontend, ctx)?.0;
match self.expect_peek(frontend)?.value {
TokenValue::Comma => {
self.bump(frontend)?;
ctx.add_function_arg(None, ty, qualifier)?;
continue;
}
TokenValue::Identifier(_) => {
let mut name = self.expect_ident(frontend)?;
self.parse_array_specifier(frontend, ctx, &mut name.1, &mut ty)?;
ctx.add_function_arg(Some(name), ty, qualifier)?;
if self.bump_if(frontend, TokenValue::Comma).is_some() {
continue;
}
break;
}
_ => break,
}
}
break;
}
Ok(())
}
}