LLVM doesn't handle i1 value in allocas/memory very well and skips a number of optimizations if it hits it. So we have to do the same thing that Clang does, using i1 for SSA values, but storing i8 in memory.
Fixes#15203.
LLVM doesn't really like types with a bit-width that isn't a multiple of
8 and disable various optimizations if it encounters such types used
with loads/stores. OTOH, booleans must be represented as i1 when used as
SSA values. To get the best results, we must use i1 for SSA values, and
i8 when storing the value to memory.
By using range asserts on loads, LLVM can eliminate the required
zero-extend and truncate operations.
Fixes#15203
The f128 type has very little support in the compiler and the feature is
basically unusable today. Supporting half-baked features in the compiler can be
detrimental to the long-term development of the compiler, and hence this feature
is being removed.
We currently compiled bools to i8 values, because there was a bug in
LLVM that sometimes caused miscompilations when using i1 in, for
example, structs.
Using i8 means a lot of unnecessary zero-extend and truncate operations
though, since we have to convert the value from and to i1 when using for
example icmp or br instructions. Besides the unnecessary overhead caused
by this, it also sometimes made LLVM miss some optimizations.
Fixes#8106.
Use ty_rptr/ty_uniq(ty_trait) rather than TraitStore to represent trait types.
Also addresses (but doesn't close) #12470.
Part of the work towards DST (#12938).
[breaking-change] lifetime parameters in `&mut trait` are now invariant. They used to be contravariant.
parameters
This involves numerous substeps:
1. Treat Self same as any other parameter.
2. No longer compute offsets for method parameters.
3. Store all generic types (both trait/impl and method) with a method,
eliminating odd discrepancies.
4. Stop doing unspeakable things to static methods and instead just use
the natural types, now that we can easily add the type parameters from
trait into the method's polytype.
5. No doubt some more. It was hard to separate these into distinct commits.
Fixes#13564
This commit removes the <M: Any + Send> type parameter from Option::expect in
favor of just taking a hard-coded `&str` argument. This allows this function to
move into libcore.
Previous code using strings with `expect` will continue to work, but code using
this implicitly to transmit task failure will need to unwrap manually with a
`match` statement.
[breaking-change]
Closes#14008
Previously, the parser would not allow you to simultaneously implement a
function with a different abi as well as being unsafe at the same time. This
extends the parser to allow functions of the form:
unsafe extern fn foo() {
// ...
}
The closure type grammar was also changed to reflect this reversal, types
previously written as "extern unsafe fn()" must now be written as
"unsafe extern fn()". The parser currently has a hack which allows the old
style, but this will go away once a snapshot has landed.
Closes#10025
[breaking-change]
Similar to my recent changes to ~[T]/&[T], these changes remove the vstore abstraction and represent str types as ~(str) and &(str). The Option<uint> in ty_str is the length of the string, None if the string is dynamically sized.
This currently requires linking against a library like libquadmath (or
libgcc), because compiler-rt barely has any support for this and most
hardware does not yet have 128-bit precision floating point. For this
reason, it's currently hidden behind a feature gate.
When compiler-rt is updated to trunk, some tests can be added for
constant evaluation since there will be support for the comparison
operators.
Closes#13381
Refactores all uses of ty_vec and associated things to remove the vstore abstraction (still used for strings, for now). Pointers to vectors are stored as ty_rptr or ty_uniq wrapped around a ty_vec. There are no user-facing changes. Existing behaviour is preserved by special-casing many instances of pointers containing vectors. Hopefully with DST most of these hacks will go away. For now it is useful to leave them hanging around rather than abstracting them into a method or something.
Closes#13554.
Cleans up some remnants of the old mutability system and only allows vector/trait mutability in `VstoreSlice` (`&mut [T]`) and `RegionTraitStore` (`&mut Trait`).
`RefCell::get` can be a bit surprising, because it actually clones the wrapped value. This removes `RefCell::get` and replaces all the users with `RefCell::borrow()` when it can, and `RefCell::borrow().clone()` when it can't. It removes `RefCell::set` for consistency. This closes#13182.
It also fixes an infinite loop in a test when debugging is on.
This was missed when dropping the null-termination from our string
types. An explicit null byte can still be placed anywhere in a string if
desired, but there's no reason to stick one at the end of every string
constant.
It's surprising that `RefCell::get()` is implicitly doing a clone
on a value. This patch removes it and replaces all users with
either `.borrow()` when we can autoderef, or `.borrow().clone()`
when we cannot.
This was missed when dropping the null-termination from our string
types. An explicit null byte can still be placed anywhere in a string if
desired, but there's no reason to stick one at the end of every string
constant.
This reduces ty::sty from 160 bytes to just 112, and some measurements
eddyb made suggest that the ty_trait variant occurs very
rarely (e.g. ~1% of all sty instances) hence this will result in a large
memory saving, and the cost of the indirection is unlikely to be an
issue.
