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CoAlloc: Limited working around rust-lang/rust issue rust-lang#106473.
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@peter-lyons-kehl
peter-lyons-kehl committed Feb 20, 2023
1 parent f8fea89 commit 579ca14
Showing 1 changed file with 59 additions and 18 deletions.
77 changes: 59 additions & 18 deletions library/alloc/src/macros.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -125,14 +125,32 @@ macro_rules! __rust_force_expr {
};
}

// ----- CoAlloc constant-like macros:
// ----- CoAlloc ICE workaround macro:
/// This "validates" type of a given `const` expression, and it casts it. That helps to prevent mix ups with macros/integer constant values.
#[doc(hidden)]
#[macro_export]
#[unstable(feature = "global_co_alloc_meta", issue = "none")]macro_rules! check_type_and_cast {
// Use the following for compile-time/build check only. And use it
// with a hard-coded `0` version of `meta_num_slots` - otherwise you get an ICE.
//
/*($e:expr, $t_check:ty, $t_cast:ty) => {
($e + 0 as $t_check) as $t_cast
}*/
// Use the following to build for testing/using, while rustc causes an ICE with the above and
// with a full version of `meta_num_slots`.
($e:expr, $t_check:ty, $t_cast:ty) => {
$e
}
}

// ----- CoAlloc constant-like macros:
/// Coallocation option/parameter about using metadata that does prefer to use meta data. This is of type [::alloc::co_alloc::CoAllocMetaNumSlotsPref] (but not a whole []::alloc::co_alloc::CoAllocPref]).
#[doc(hidden)]
#[unstable(feature = "global_co_alloc_meta", issue = "none")]
#[macro_export]
macro_rules! CO_ALLOC_PREF_NUM_META_SLOTS_ONE {
() => {
(1 as $crate::co_alloc::CoAllocMetaNumSlotsPref)
$crate::check_type_and_cast!(1, i32, $crate::co_alloc::CoAllocMetaNumSlotsPref)
};
}

Expand All @@ -141,7 +159,7 @@ macro_rules! CO_ALLOC_PREF_NUM_META_SLOTS_ONE {
#[macro_export]
macro_rules! CO_ALLOC_PREF_NUM_META_SLOTS_ZERO {
() => {
(0 as $crate::co_alloc::CoAllocMetaNumSlotsPref)
$crate::check_type_and_cast!(0, i32, $crate::co_alloc::CoAllocMetaNumSlotsPref)
};
}

Expand All @@ -150,7 +168,7 @@ macro_rules! CO_ALLOC_PREF_NUM_META_SLOTS_ZERO {
#[macro_export]
macro_rules! CO_ALLOC_PREF_NUM_META_SLOTS_DEFAULT {
() => {
(0 as $crate::co_alloc::CoAllocMetaNumSlotsPref)
$crate::check_type_and_cast!(0, i32, $crate::co_alloc::CoAllocMetaNumSlotsPref)
};
}

Expand All @@ -167,6 +185,7 @@ macro_rules! CO_ALLOC_PREF_NUM_META_SLOTS_DEFAULT {
#[macro_export]
macro_rules! CO_ALLOC_PREF_META_YES {
() => {
//1usize
$crate::co_alloc_pref!($crate::CO_ALLOC_PREF_NUM_META_SLOTS_ONE!())
};
}
Expand All @@ -184,6 +203,7 @@ macro_rules! CO_ALLOC_PREF_META_YES {
#[macro_export]
macro_rules! CO_ALLOC_PREF_META_NO {
() => {
//0usize
$crate::co_alloc_pref!($crate::CO_ALLOC_PREF_NUM_META_SLOTS_ZERO!())
};
}
Expand All @@ -202,6 +222,7 @@ macro_rules! CO_ALLOC_PREF_META_NO {
#[macro_export]
macro_rules! CO_ALLOC_PREF_META_DEFAULT {
() => {
//0usize
$crate::co_alloc_pref!($crate::CO_ALLOC_PREF_NUM_META_SLOTS_DEFAULT!())
};
}
Expand All @@ -211,6 +232,7 @@ macro_rules! CO_ALLOC_PREF_META_DEFAULT {
#[macro_export]
macro_rules! CO_ALLOC_PREF_DEFAULT {
() => {
//0usize
$crate::CO_ALLOC_PREF_META_DEFAULT!()
};
}
Expand All @@ -221,6 +243,7 @@ macro_rules! CO_ALLOC_PREF_DEFAULT {
#[macro_export]
macro_rules! SHORT_TERM_VEC_CO_ALLOC_PREF {
() => {
//0usize
$crate::CO_ALLOC_PREF_META_NO!()
};
}
Expand All @@ -242,8 +265,8 @@ macro_rules! co_alloc_pref {
// report the incorrect type of $meta_pref (if $meta_pref were some other integer, casting would
// compile, and we would not be notified).
($meta_pref:expr) => {
(($meta_pref + (0 as $crate::co_alloc::CoAllocMetaNumSlotsPref))
as $crate::co_alloc::CoAllocPref)
$crate::check_type_and_cast!($meta_pref,$crate::co_alloc::CoAllocMetaNumSlotsPref,
$crate::co_alloc::CoAllocPref)
};
}

Expand All @@ -267,18 +290,29 @@ macro_rules! co_alloc_pref {
#[unstable(feature = "global_co_alloc", issue = "none")]
#[macro_export]
macro_rules! meta_num_slots {
// Generating, for example, (0 as usize), here, triggers an ICE.

// This "validates" types of both params - to prevent mix ups.
// @FIXME remove this comment line: Removing/commenting out the part: <$alloc as ::core::alloc::Allocator>::CO_ALLOC_META_NUM_SLOTS +
// does NOT fix the ICE (unless there are multiple ICE's).
// @FIXME Use this only
// - once the ICE gets fixed, or
// - (until the ICE is fixed) with a related change in `check_type_and_cast` that makes it pass
// the given expression (parameter) unchecked & uncast.
/*($alloc:ty, $co_alloc_pref:expr) => {
$crate::check_type_and_cast!(<$alloc as ::core::alloc::Allocator>::CO_ALLOC_META_NUM_SLOTS,::core::alloc::CoAllocatorMetaNumSlots,
usize) *
$crate::check_type_and_cast!($co_alloc_pref, $crate::co_alloc::CoAllocPref, usize)
};*/
// Use for testing & production, until ICE gets fixed. (Regardless of $co_alloc_pref.)
//
// Why still ICE?!
($alloc:ty, $co_alloc_pref:expr) => {
/*(
((<$alloc as ::core::alloc::Allocator>::CO_ALLOC_META_NUM_SLOTS + (0 as ::core::alloc::CoAllocatorMetaNumSlots))0
as usize)
* ($co_alloc_pref + (0 as $crate::co_alloc::CoAllocPref))
as usize)*/0usize
};
// The following fails here - even if not used from meta_num_slots_default nor from meta_num_slots_global!
//<$alloc as ::core::alloc::Allocator>::CO_ALLOC_META_NUM_SLOTS
//<$crate::alloc::Global as ::core::alloc::Allocator>::CO_ALLOC_META_NUM_SLOTS
//1usize
$co_alloc_pref
}
// Use for testing & production as enforcing no meta.
/*($alloc:ty, $co_alloc_pref:expr) => {
0usize // compiles
}*/
}
// -\---> replace with something like:
/*
Expand All @@ -304,7 +338,10 @@ macro_rules! meta_num_slots_default {
// Can't generate if ... {1} else {0}
// because it's "overly complex generic constant".
($alloc:ty) => {
// EITHER of the following are OK here
$crate::meta_num_slots!($alloc, $crate::CO_ALLOC_PREF_DEFAULT!())
//<$alloc as ::core::alloc::Allocator>::CO_ALLOC_META_NUM_SLOTS
//<$crate::alloc::Global as ::core::alloc::Allocator>::CO_ALLOC_META_NUM_SLOTS
};
}

Expand All @@ -320,10 +357,13 @@ macro_rules! meta_num_slots_default {
#[macro_export]
macro_rules! meta_num_slots_global {
($co_alloc_pref:expr) => {
// EITHER of the following are OK here
$crate::meta_num_slots!($crate::alloc::Global, $co_alloc_pref)
// The following is OK here:
//<$crate::alloc::Global as ::core::alloc::Allocator>::CO_ALLOC_META_NUM_SLOTS
};
}

/*
/// Like `meta_num_slots`, but for `Global allocator and default coallocation preference
/// (`CO_ALLOC_PREF_DEFAULT`).
///
Expand All @@ -336,3 +376,4 @@ macro_rules! meta_num_slots_default_global {
$crate::meta_num_slots!($crate::alloc::Global, $crate::CO_ALLOC_PREF_DEFAULT!())
};
}
*/

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