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goodby static mut, welcome back to UnsafeCell

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This commit is contained in:
Per Lindgren 2021-03-10 15:37:11 +01:00
parent 3c86d713a6
commit db1574bf6b
5 changed files with 108 additions and 12 deletions
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10
macros/src/codegen/post_init.rs
View file

@ -17,10 +17,14 @@ pub fn codegen(app: &App, analysis: &Analysis) -> Vec<TokenStream2> {
// If it's live
let cfgs = app.late_resources[name].cfgs.clone();
if analysis.locations.get(name).is_some() {
// Need to also include the cfgs
stmts.push(quote!(
#(#cfgs)*
#mangled_name.as_mut_ptr().write(late.#name);
// We include the cfgs
#(#cfgs)*
// Late resource is a RacyCell<MaybeUninit<T>>
// - `get_mut_unchecked` to obtain `MaybeUninit<T>`
// - `as_mut_ptr` to obtain a raw pointer to `MaybeUninit<T>`
// - `write` the defined value for the late resource T
#mangled_name.get_mut_unchecked().as_mut_ptr().write(late.#name);
));
}
}

35
macros/src/codegen/resources.rs
View file

@ -4,13 +4,20 @@ use rtic_syntax::{analyze::Ownership, ast::App};
use crate::{analyze::Analysis, check::Extra, codegen::util};
/// Generates `static [mut]` variables and resource proxies
/// Generates `static` variables and resource proxies
/// Early resources are stored in `RacyCell<T>`
/// Late resource are stored in `RacyCell<MaybeUninit<T>>`
///
/// Safety:
/// - RacyCell<T> access is `unsafe`.
/// - RacyCell<MaybeUninit> is always written to before user access, thus
// the generated code for user access can safely `assume_init`.
pub fn codegen(
app: &App,
analysis: &Analysis,
extra: &Extra,
) -> (
// mod_app -- the `static [mut]` variables behind the proxies
// mod_app -- the `static` variables behind the proxies
Vec<TokenStream2>,
// mod_resources -- the `resources` module
TokenStream2,
@ -24,18 +31,26 @@ pub fn codegen(
let mangled_name = util::mark_internal_ident(&name);
{
// TODO: do we really need this in the single core case
// late resources in `util::link_section_uninit`
let section = if expr.is_none() {
util::link_section_uninit(true)
} else {
None
};
// resource type and assigned value
let (ty, expr) = if let Some(expr) = expr {
(quote!(#ty), quote!(#expr))
} else {
// early resource
(
quote!(core::mem::MaybeUninit<#ty>),
quote!(core::mem::MaybeUninit::uninit()),
quote!(rtic::RacyCell<#ty>),
quote!(rtic::RacyCell::new(#expr)),
)
} else {
// late resource
(
quote!(rtic::RacyCell<core::mem::MaybeUninit<#ty>>),
quote!(rtic::RacyCell::new(core::mem::MaybeUninit::uninit())),
)
};
@ -46,7 +61,7 @@ pub fn codegen(
#(#attrs)*
#(#cfgs)*
#section
static mut #mangled_name: #ty = #expr;
static #mangled_name: #ty = #expr;
));
}
@ -74,14 +89,16 @@ pub fn codegen(
));
let ptr = if expr.is_none() {
// late resource
quote!(
#(#cfgs)*
#mangled_name.as_mut_ptr()
&mut #mangled_name.get_mut_unchecked().assume_init()
)
} else {
// early resource
quote!(
#(#cfgs)*
&mut #mangled_name
unsafe { #mangled_name.get_mut_unchecked() }
)
};