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.
