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Sync from rust 2023-06-03 #280

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antoyo
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@antoyo antoyo commented Jun 3, 2023

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cuviper and others added 30 commits August 16, 2022 15:46
Now that we require at least LLVM 13, that codegen backend is always
using its intrinsic `fptosi.sat` and `fptoui.sat` conversions, so it
doesn't need the manual implementation. However, the GCC backend still
needs it, so we can move all of that code down there.
Because `PassMode::Cast` is by far the largest variant, but is
relatively rare.

This requires making `PassMode` not impl `Copy`, and `Clone` is no
longer necessary. This causes lots of sigil adjusting, but nothing very
notable.
Currently they try to be very precise. But they are wrong, i.e. they
don't match what's happening in the loop below. This code isn't hot
enough for it to matter that much.
Because it's only ever set to `None` or `Some(Reg::i32())`.
Because it's only needed for that variant. This shrinks the types and
clarifies the logic.
Shrink `FnAbi`

Because they can take up a lot of memory in debug and release builds.

r? `@bjorn3`
Add pointer masking convenience functions

This PR adds the following public API:
```rust
impl<T: ?Sized> *const T {
    fn mask(self, mask: usize) -> *const T;
}

impl<T: ?Sized> *mut T {
    fn mask(self, mask: usize) -> *const T;
}

// mod intrinsics
fn mask<T>(ptr: *const T, mask: usize) -> *const T
```
This is equivalent to `ptr.map_addr(|a| a & mask)` but also uses a cool llvm intrinsic.

Proposed in rust-lang/rust#95643 (comment)

cc `@Gankra` `@scottmcm` `@RalfJung`

r? rust-lang/libs-api
interpret: make read-pointer-as-bytes a CTFE-only error with extra information

Next step in the reaction to rust-lang/rust#99923. Also teaches Miri to implicitly strip provenance in more situations when transmuting pointers to integers, which fixes rust-lang/miri#2456.

Pointer-to-int transmutation during CTFE now produces a message like this:
```
   = help: this code performed an operation that depends on the underlying bytes representing a pointer
   = help: the absolute address of a pointer is not known at compile-time, so such operations are not supported
```

r? ``@oli-obk``
Move the cast_float_to_int fallback code to GCC

Now that we require at least LLVM 13, that codegen backend is always
using its intrinsic `fptosi.sat` and `fptoui.sat` conversions, so it
doesn't need the manual implementation. However, the GCC backend still
needs it, so we can move all of that code down there.
zhaixiaojuan and others added 28 commits April 25, 2023 14:15
This commit adds cross-language LLVM Control Flow Integrity (CFI)
support to the Rust compiler by adding the
`-Zsanitizer-cfi-normalize-integers` option to be used with Clang
`-fsanitize-cfi-icall-normalize-integers` for normalizing integer types
(see https://reviews.llvm.org/D139395).

It provides 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). For more
information about LLVM CFI and cross-language LLVM CFI support for the
Rust compiler, see design document in the tracking issue #89653.

Cross-language LLVM CFI can be enabled with -Zsanitizer=cfi and
-Zsanitizer-cfi-normalize-integers, and requires proper (i.e.,
non-rustc) LTO (i.e., -Clinker-plugin-lto).
Add cross-language LLVM CFI support to the Rust compiler

This PR adds cross-language LLVM Control Flow Integrity (CFI) support to the Rust compiler by adding the `-Zsanitizer-cfi-normalize-integers` option to be used with Clang `-fsanitize-cfi-icall-normalize-integers` for normalizing integer types (see https://reviews.llvm.org/D139395).

It provides 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). For more information about LLVM CFI and cross-language LLVM CFI support for the Rust compiler, see design document in the tracking issue #89653.

Cross-language LLVM CFI can be enabled with -Zsanitizer=cfi and -Zsanitizer-cfi-normalize-integers, and requires proper (i.e., non-rustc) LTO (i.e., -Clinker-plugin-lto).

Thank you again, ``@bjorn3,`` ``@nikic,`` ``@samitolvanen,`` and the Rust community for all the help!
This makes it possible to use liballoc/libstd in combination with
`--emit obj` if you use `#[global_allocator]`. Making it work for the
default libstd allocator would require weak functions, which are not
well supported on all systems.
You will need to add the following as replacement for the old __rust_*
definitions when not using the alloc shim.

    #[no_mangle]
    static __rust_no_alloc_shim_is_unstable: u8 = 0;
Support #[global_allocator] without the allocator shim

This makes it possible to use liballoc/libstd in combination with `--emit obj` if you use `#[global_allocator]`. This is what rust-for-linux uses right now and systemd may use in the future. Currently they have to depend on the exact implementation of the allocator shim to create one themself as `--emit obj` doesn't create an allocator shim.

Note that currently the allocator shim also defines the oom error handler, which is normally required too. Once `#![feature(default_alloc_error_handler)]` becomes the only option, this can be avoided. In addition when using only fallible allocator methods and either `--cfg no_global_oom_handling` for liballoc (like rust-for-linux) or `--gc-sections` no references to the oom error handler will exist.

To avoid this feature being insta-stable, you will have to define `__rust_no_alloc_shim_is_unstable` to avoid linker errors.

(Labeling this with both T-compiler and T-lang as it originally involved both an implementation detail and had an insta-stable user facing change. As noted above, the `__rust_no_alloc_shim_is_unstable` symbol requirement should prevent unintended dependence on this unstable feature.)
Optimize scalar and scalar pair representations loaded from ByRef in llvm

in rust-lang/rust#105653 I noticed that we were generating suboptimal LLVM IR if we had a `ConstValue::ByRef` that could be represented by a `ScalarPair`. Before rust-lang/rust#105653 this is probably rare, but after it, every slice will go down this suboptimal code path that requires LLVM to untangle a bunch of indirections and translate static allocations that are only used once to read a scalar pair from.
These tend to have special handling in a bunch of places anyway, so the variant helps remember that.  And I think it's easier to grok than non-Scalar Aggregates sometimes being `Immediates` (like I got wrong and caused 109992).  As a minor bonus, it means we don't need to generate poison LLVM values for them to pass around in `OperandValue::Immediate`s.
Comment on lines +357 to +361
# TODO(antoyo): find a faster way to do this.
# FIXME: this makes the stderr different since it changes the line numbers.
for file in $(find tests/ui -type f -name '*.rs'); do
sed -ie "1i // compile-flags: --sysroot "$(pwd)"/../build_sysroot/sysroot\n" $file
done
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Don't forget to remove.

sed -ie "1i // compile-flags: --sysroot "$(pwd)"/../build_sysroot/sysroot\n" $file
done

RUSTC_ARGS="$TEST_FLAGS -Csymbol-mangling-version=v0 -Zcodegen-backend="$(pwd)"/../target/"$CHANNEL"/librustc_codegen_gcc."$dylib_ext""
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Add back the --sysroot option when rust-lang/rust#112435 is merged.

@antoyo antoyo closed this Jun 19, 2023
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