Allow building std with cranelift
- Don't pass llvm-specific args when using cranelift
- Don't use `asm` in compiler_builtins when using cranelift
r? `@bjorn3` cc `@Mark-Simulacrum`
Correct branch-protection ModFlagBehavior for Aarch64 on LLVM-15
When building with Fat LTO and BTI enabled on aarch64, the BTI is set to `Module::Min` for alloc shim but is set to `Module::Error` for the crate. This was fine when we were using LLVM-14 but LLVM-15 changes it's behaviour to support for compiling with different `mbranch-protection` flags.
Refer:
b0343a38a5
fixes https://github.com/rust-lang/rust/issues/102162
When building with Fat LTO and BTI enabled on aarch64, the BTI is set to
`Module::Min` for alloc shim but is set to `Module::Error` for the
crate. This was fine when we were using LLVM-14 but LLVM-15 changes it's
behaviour to support for compiling with different `mbranch-protection`
flags.
Refer:
b0343a38a5
Following the s390x ELF ABI and based on the clang implementation,
provide appropriate definitions of va_list in library/core/src/ffi/mod.rs
and va_arg handling in compiler/rustc_codegen_llvm/src/va_arg.rs.
Fixes the following test cases on s390x:
src/test/run-make-fulldeps/c-link-to-rust-va-list-fn
src/test/ui/abi/variadic-ffi.rs
Fixes https://github.com/rust-lang/rust/issues/84628.
Use struct types during codegen in less places
This makes it easier to use cg_ssa from a backend like Cranelift that doesn't have any struct types at all. After this PR struct types are still used for function arguments and return values. Removing those usages is harder but should still be doable.
Don't internalize __llvm_profile_counter_bias
Currently, LLVM profiling runtime counter relocation cannot be used by rust during LTO because symbols are being internalized before all symbol information is known.
This mode makes LLVM emit a __llvm_profile_counter_bias symbol which is referenced by the profiling initialization, which itself is pulled in by the rust driver here [1].
It is enabled with -Cllvm-args=-runtime-counter-relocation for platforms which are opt-in to this mode like Linux. On these platforms there will be no link error, rather just surprising behavior for a user which request runtime counter relocation. The profiling runtime will not see that symbol go on as if it were never there. On Fuchsia, the profiling runtime must have this symbol which will cause a hard link error.
As an aside, I don't have enough context as to why rust's LTO model is how it is. AFAICT, the internalize pass is only safe to run at link time when all symbol information is actually known, this being an example as to why. I think special casing this symbol as a known one that LLVM can emit which should not have it's visbility de-escalated should be fine given how seldom this pattern of defining an undefined symbol to get initilization code pulled in is. From a quick grep, __llvm_profile_runtime is the only symbol that rustc does this for.
[1] 0265a3e93b/compiler/rustc_codegen_ssa/src/back/linker.rs (L598)
Add LLVM KCFI support to the Rust compiler
This PR adds LLVM Kernel Control Flow Integrity (KCFI) support to the Rust compiler. It initially provides forward-edge control flow protection for operating systems kernels for Rust-compiled code only by aggregating function pointers in groups identified by their return and parameter types. (See llvm/llvm-project@cff5bef.)
Forward-edge control flow protection for C or C++ and Rust -compiled code "mixed binaries" (i.e., for when C or C++ and Rust -compiled code share the same virtual address space) will be provided in later work as part of this project by identifying C char and integer type uses at the time types are encoded (see Type metadata in the design document in the tracking issue #89653).
LLVM KCFI can be enabled with -Zsanitizer=kcfi.
Thank you again, `@bjorn3,` `@eddyb,` `@nagisa,` and `@ojeda,` for all the help!
This commit adds LLVM Kernel Control Flow Integrity (KCFI) support to
the Rust compiler. It initially provides forward-edge control flow
protection for operating systems kernels for Rust-compiled code only by
aggregating function pointers in groups identified by their return and
parameter types. (See llvm/llvm-project@cff5bef.)
Forward-edge control flow protection for C or C++ and Rust -compiled
code "mixed binaries" (i.e., for when C or C++ and Rust -compiled code
share the same virtual address space) will be provided in later work as
part of this project by identifying C char and integer type uses at the
time types are encoded (see Type metadata in the design document in the
tracking issue #89653).
LLVM KCFI can be enabled with -Zsanitizer=kcfi.
Co-authored-by: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Currently, LLVM profiling runtime counter relocation cannot be
used by rust during LTO because symbols are being internalized
before all symbol information is known.
This mode makes LLVM emit a __llvm_profile_counter_bias symbol
which is referenced by the profiling initialization, which itself
is pulled in by the rust driver here [1].
It is enabled with -Cllvm-args=-runtime-counter-relocation for
platforms which are opt-in to this mode like Linux. On these
platforms there will be no link error, rather just surprising
behavior for a user which request runtime counter relocation.
The profiling runtime will not see that symbol go on as if it
were never there. On Fuchsia, the profiling runtime must have
this symbol which will cause a hard link error.
As an aside, I don't have enough context as to why rust's LTO
model is how it is. AFAICT, the internalize pass is only safe
to run at link time when all symbol information is actually
known, this being an example as to why. I think special casing
this symbol as a known one that LLVM can emit which should not
have it's visbility de-escalated should be fine given how
seldom this pattern of defining an undefined symbol to get
initilization code pulled in is. From a quick grep,
__llvm_profile_runtime is the only symbol that rustc does this
for.
[1] 0265a3e93b/compiler/rustc_codegen_ssa/src/back/linker.rs (L598)
This ensures that the error is printed even for unused variables,
as well as unifying the handling between the LLVM and GCC backends.
This also fixes unusual behavior around exported Rust-defined variables
with linkage attributes. With the previous behavior, it appears to be
impossible to define such a variable such that it can actually be imported
and used by another crate. This is because on the importing side, the
variable is required to be a pointer, but on the exporting side, the
type checker rejects static variables of pointer type because they do
not implement `Sync`. Even if it were possible to import such a type, it
appears that code generation on the importing side would add an unexpected
additional level of pointer indirection, which would break type safety.
This highlighted that the semantics of linkage on Rust-defined variables
is different to linkage on foreign items. As such, we now model the
difference with two different codegen attributes: linkage for Rust-defined
variables, and import_linkage for foreign items.
This change gives semantics to the test
src/test/ui/linkage-attr/auxiliary/def_illtyped_external.rs which was
previously expected to fail to compile. Therefore, convert it into a
test that is expected to successfully compile.
The update to the GCC backend is speculative and untested.
Rollup of 9 pull requests
Successful merges:
- #104199 (Keep track of the start of the argument block of a closure)
- #105050 (Remove useless borrows and derefs)
- #105153 (Create a hacky fail-fast mode that stops tests at the first failure)
- #105164 (Restore `use` suggestion for `dyn` method call requiring `Sized`)
- #105193 (Disable coverage instrumentation for naked functions)
- #105200 (Remove useless filter in unused extern crate check.)
- #105201 (Do not call fn_sig on non-functions.)
- #105208 (Add AmbiguityError for inconsistent resolution for an import)
- #105214 (update Miri)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
codegen-llvm: never combine DSOLocal and DllImport
Prevent DllImport from being attached to DSOLocal definitions in the LLVM IR. The combination makes no sense, since definitions local to the compilation unit will never be imported from external objects.
Additionally, LLVM will refuse the IR if it encounters the combination (introduced in [1]):
```
if (GV.hasDLLImportStorageClass())
Assert(!GV.isDSOLocal(),
"GlobalValue with DLLImport Storage is dso_local!", &GV);
```
Right now, codegen-llvm will only apply DllImport to constants and rely on call-stubs for functions. Hence, we simply extend the codegen of constants to skip DllImport for any local definitions.
This was discovered when switching the EFI targets to the static relocation model [2]. With this fixed, we can start another attempt at this.
[1] 509132b368
[2] https://github.com/rust-lang/rust/issues/101656
Print all features with --print target-features
This fixes `rustc --print target-features` with respect to aliases and tied features.
Before this change, the print command assumed that each LLVM feature corresponds exactly to one rustc feature. In the case of aliases and tied features, this assumption failed and some features (such as aarch64's "pacg") were missing. With this change, every target feature is listed.
Prevent DllImport from being attached to DSOLocal definitions in the
LLVM IR. The combination makes no sense, since definitions local to the
compilation unit will never be imported from external objects.
Additionally, LLVM will refuse the IR if it encounters the
combination (introduced in [1]):
if (GV.hasDLLImportStorageClass())
Assert(!GV.isDSOLocal(),
"GlobalValue with DLLImport Storage is dso_local!", &GV);
Right now, codegen-llvm will only apply DllImport to constants and rely
on call-stubs for functions. Hence, we simply extend the codegen of
constants to skip DllImport for any local definitions.
This was discovered when switching the EFI targets to the static
relocation model [2]. With this fixed, we can start another attempt at
this.
[1] 509132b368
[2] https://github.com/rust-lang/rust/issues/101656
After https://github.com/llvm/llvm-project/commit/8689f5e landed, LLVM takes the intersection of v8a and v8r as default.
This commit brings back v8a support by explicitly specifying v8a in the feature list.
This should solve #97724.
Use `as_deref` in compiler (but only where it makes sense)
This simplifies some code :3
(there are some changes that are not exacly `as_deref`, but more like "clever `Option`/`Result` method use")
Mark functions created for `raw-dylib` on x86 with DllImport storage class
Fix for #104453
## Issue Details
On x86 Windows, LLVM uses 'L' as the prefix for any private global symbols (`PrivateGlobalPrefix`), so when the `raw-dylib` feature creates an undecorated function symbol that begins with an 'L' LLVM misinterprets that as a private global symbol that it created and so fails the compilation at a later stage since such a symbol must have a definition.
## Fix Details
Mark the function we are creating for `raw-dylib` with `DllImport` storage class (this was already being done for MSVC at a later point for `callee::get_fn` but not for GNU (due to "backwards compatibility")): this will cause LLVM to prefix the name with `__imp_` and so it won't mistake it for a private global symbol.
Pass 128-bit C-style enum enumerator values to LLVM
Pass the full 128 bits of C-style enum enumerators through to LLVM. This means that debuginfo for C-style repr128 enums is now emitted correctly for DWARF platforms (as compared to not being correctly emitted on any platform).
Tracking issue: #56071
