Remove fewer Storage calls in CopyProp and GVN
Modify the CopyProp and GVN MIR optimization passes to remove fewer `Storage{Live,Dead}` calls, allowing for better optimizations by LLVM - see rust-lang/rust#141649.
### Details
The idea is to use a new `MaybeUninitializedLocals` analysis and remove only the storage calls of locals that are maybe-uninit when accessed in a new location.
Updated slice tests to pass for big endian hosts for `multiple-option-or-permutations.rs`
It was discovered that the FileCheck tests when performing an `Option::or` operation on a slice was failing when tested on a big endian host.
The compiler explorer link is here outlining the codegen output differences - https://rust.godbolt.org/z/qdE7d3G4f
This MR relaxes the constraints for the `*slice_u8` variants of the test (by changing `CHECK-NEXT` to `CHECK-DAG`), whilst still maintaining the check for the necessary `or` logic.
Huge thanks to @Gelbpunkt for identifying this issue! It has been confirmed that this fix passes on a big endian target now as well.
Closesrust-lang/rust#151718
Simplify internals of `{Rc,Arc}::default`
This commit simplifies the internal implementation of `Default` for these two pointer types to have the same performance characteristics as before (a side effect of changes in rust-lang/rust#131460) while avoid use of internal private APIs of Rc/Arc. To preserve the same codegen as before some non-generic functions needed to be tagged as `#[inline]` as well, but otherwise the same IR is produced before/after this change.
The motivation of this commit is I was studying up on the state of initialization of `Arc` and `Rc` and figured it'd be nicer to reduce the use of internal APIs and instead use public stable APIs where possible, even in the implementation itself.
This commit simplifies the internal implementation of `Default` for
these two pointer types to have the same performance characteristics as
before (a side effect of changes in 131460) while avoid use of internal
private APIs of Rc/Arc. To preserve the same codegen as before some
non-generic functions needed to be tagged as `#[inline]` as well, but
otherwise the same IR is produced before/after this change.
The motivation of this commit is I was studying up on the state of
initialization of `Arc` and `Rc` and figured it'd be nicer to reduce the
use of internal APIs and instead use public stable APIs where possible,
even in the implementation itself.
Rust's current mangling scheme depends on compiler internals; loses
information about generic parameters (and other things) which makes for
a worse experience when using external tools that need to interact with
Rust symbol names; is inconsistent; and can contain `.` characters
which aren't universally supported. Therefore, Rust has defined its own
symbol mangling scheme which is defined in terms of the Rust language,
not the compiler implementation; encodes information about generic
parameters in a reversible way; has a consistent definition; and
generates symbols that only use the characters `A-Z`, `a-z`, `0-9`, and
`_`.
Support for the new Rust symbol mangling scheme has been added to
upstream tools that will need to interact with Rust symbols (e.g.
debuggers).
This commit changes the default symbol mangling scheme from the legacy
scheme to the new Rust mangling scheme.
Signed-off-by: David Wood <david.wood@huawei.com>
tests: relax expectations after llvm change 902ddda120a5
LLVM 22 is able to drop assumes that seem to not help further optimizations, which actually seems to dramatically _help_ further optimizations in some of our small test cases.
I'm a little unclear how to fix the last failure, in `tests/codegen-llvm/issues/issue-122600-ptr-discriminant-update.rs`:
```
-; Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(argmem: readwrite, inaccessiblemem: write) uwtable
+; Function Attrs: mustprogress nofree norecurse nosync nounwind nonlazybind willreturn memory(argmem: readwrite, inaccessiblemem: write) uwtable
define void ``@update(ptr`` noundef captures(none) %s) unnamed_addr #0 {
start:
- %_3.sroa.0.0.copyload = load i8, ptr %s, align 1
- %0 = trunc nuw i8 %_3.sroa.0.0.copyload to i1
- %1 = xor i1 %0, true
- tail call void ``@llvm.assume(i1`` %1)
store i8 1, ptr %s, align 1
ret void
}
```
I'm just not conversant enough in LLVM IR to follow the changes here.
``@rustbot`` label llvm-main
r? nikic
LLVM 22 is able to drop assumes that seem to not help further
optimizations, which actually seems to dramatically _help_ further
optimizations in some of our small test cases.
llvm: Accept new LLVM lifetime format
In llvm/llvm-project#150248 LLVM removed the size parameter from the lifetime format. Tolerate not having that size parameter.
bors