LLVM does not expect to ever see multiple dbg_declares for the same variable at the same
location with different values. proc-macros make it possible for arbitrary code,
including multiple calls that get inlined, to happen at any given location in the source
code. Add discriminators when that happens so these locations are different to LLVM.
This may interfere with the AddDiscriminators pass in LLVM, which is added by the
unstable flag -Zdebug-info-for-profiling.
Fixes#131944
Trim and tidy includes in `rustc_llvm`
These includes tend to accumulate over time, and are usually only removed when something breaks in a new LLVM version, so it's nice to clean them up manually once in a while.
General strategy used for this PR:
- Remove all includes from `LLVMWrapper.h` that aren't needed by the header itself, transplanting them to individual source files as necessary.
- For each source file, temporarily remove each include if doing so doesn't cause a compile error.
- If a “required” include looks like it shouldn't be needed, try replacing it with its sub-includes, then trim that list.
- After doing all of the above, go back and re-add any removed include if the file does actually use things defined in that header, even if the header happens to also be included by something else.
cg_llvm: Clean up FFI calls for setting module flags
This is a combination of several inter-related changes to how module flags are set:
- Remove some unnecessary code for setting an `"LTOPostLink"` flag, which has been obsolete since LLVM 17.
- Define our own enum instead of relying on enum values defined by LLVM's unstable C++ API.
- Use safe wrapper functions to set module flags, instead of direct `unsafe` calls.
- Consistently pass pointer/length strings instead of C strings.
- Remove or shrink some `unsafe` blocks.
- Don't rely on enum values defined by LLVM's C++ API
- Use safe wrapper functions instead of direct `unsafe` calls
- Consistently pass pointer/length strings instead of C strings
Disable the tests and generate an error if MC/DC is used on LLVM 19.
The support will be ported separately, as it is substantially
different on LLVM 19, and there are no plans to support both
versions.
The return value changed from an Instruction to a DbgRecord in
LLVM 19. As we don't actually use the result, drop the return
value entirely to support both.
Set writable and dead_on_unwind attributes for sret arguments
Set the `writable` and `dead_on_unwind` attributes for `sret` arguments. This allows call slot optimization to remove more memcpy's.
See https://llvm.org/docs/LangRef.html#parameter-attributes for the specification of these attributes. In short, the statement we're making here is that:
* The return slot is writable.
* The return slot will not be read if the function unwinds.
Fixes https://github.com/rust-lang/rust/issues/90595.
Rust passes a *const &OperandBundleDef to these APIs, usually from a
Vec<&OperandBundleDef> or so. Previously we were dereferencing that
pointer and passing it to the ArrayRef constructor with some length (N).
This meant that if the length was 0, we were dereferencing a pointer to
nowhere, and if the length was >1 then loading the *second* element
somewhere in LLVM would've been reading past the end.
Since Rust can't hold OperandBundleDef by-value we're forced to indirect
through a vector that copies out the OperandBundleDefs from the
by-reference list on the Rust side in order to match the LLVM expected
API.
This particular cast appears to have been copied over from clang, but there are
plenty of other call sites in clang that don't bother with a cast here, and it
works fine without one.
For context, `llvm::Intrinsic::ID` is a typedef for `unsigned`, and
`llvm::Intrinsic::instrprof_increment` is a member of
`enum IndependentIntrinsics : unsigned`.
The bad-alloc installer was incorrectly asserting that the other handler
isn't set yet, instead of checking its own, but we can avoid that by
changing the order we install them.
Ref: https://github.com/llvm/llvm-project/issues/83040
LLVM's default bad-alloc handler may throw if exceptions are enabled,
and `operator new` isn't hooked at all by default. Now we register our
own handler that prints a message similar to fatal errors, then aborts.
We also call the function that registers the C++ `std::new_handler`.
Add asm goto support to `asm!`
Tracking issue: #119364
This PR implements asm-goto support, using the syntax described in "future possibilities" section of [RFC2873](https://rust-lang.github.io/rfcs/2873-inline-asm.html#asm-goto).
Currently I have only implemented the `label` part, not the `fallthrough` part (i.e. fallthrough is implicit). This doesn't reduce the expressive though, since you can use label-break to get arbitrary control flow or simply set a value and rely on jump threading optimisation to get the desired control flow. I can add that later if deemed necessary.
r? ``@Amanieu``
cc ``@ojeda``
Explicitly assign constructed C++ classes
C++ style guides I am aware of recommend specifically preferring = syntax for any classes with fairly obvious constructors[^0] that do not perform any complicated logic in their constructor. I contend that all constructors that the `rustc_llvm` code uses qualify. This has only become more common since C++ 17 guaranteed many cases of copy initialization elision.
The other detail is that I tried to ask another contributor with infinitely more C++ experience than me (i.e. any) what this constructor syntax was, and they thought it was a macro. I know of no other language that has adopted this same syntax. As the rustc codebase features many contributors experienced in many other languages, using a less... unique... style has many other benefits in making this code more lucid and maintainable, which is something it direly needs.
[^0]: e.g. https://abseil.io/tips/88
C++ style guides I am aware of recommend specifically preferring = syntax
for any classes with fairly obvious constructors[^0] that do not perform
any complicated logic in their constructor. I contend that all constructors
that the `rustc_llvm` code uses qualify. This has only become more common
since C++ 17 guaranteed many cases of copy initialization elision.
The other detail is that I tried to ask another contributor with
infinitely more C++ experience than me (i.e. any) what this constructor
syntax was, and they thought it was a macro. I know of no other language
that has adopted this same syntax. As the rustc codebase features many
contributors experienced in many other languages, using a less...
unique... style has many other benefits in making this code more
lucid and maintainable, which is something it direly needs.
[^0]: e.g. https://abseil.io/tips/88
