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Add aarch64_be-unknown-none-softfloat target
Signed-off-by: Jens Reidel <[email protected]>
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‎compiler/rustc_target/src/spec/mod.rs

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("aarch64-unknown-none", aarch64_unknown_none),
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("aarch64-unknown-none-softfloat", aarch64_unknown_none_softfloat),
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("aarch64_be-unknown-none-softfloat", aarch64_be_unknown_none_softfloat),
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("aarch64-unknown-nuttx", aarch64_unknown_nuttx),
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("x86_64-fortanix-unknown-sgx", x86_64_fortanix_unknown_sgx),

‎compiler/rustc_target/src/spec/targets/aarch64_be_unknown_none_softfloat.rs

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// Generic big-endian AArch64 target for bare-metal code - Floating point disabled
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//
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// Can be used in conjunction with the `target-feature` and
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// `target-cpu` compiler flags to opt-in more hardware-specific
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// features.
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//
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// For example, `-C target-cpu=cortex-a53`.
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use rustc_abi::Endian;
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use crate::spec::{
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Cc, LinkerFlavor, Lld, PanicStrategy, RelocModel, SanitizerSet, StackProbeType, Target,
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TargetMetadata, TargetOptions,
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};
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pub(crate) fn target() -> Target {
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let opts = TargetOptions {
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abi: "softfloat".into(),
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linker_flavor: LinkerFlavor::Gnu(Cc::No, Lld::Yes),
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linker: Some("rust-lld".into()),
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features: "+v8a,+strict-align,-neon,-fp-armv8".into(),
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relocation_model: RelocModel::Static,
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disable_redzone: true,
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max_atomic_width: Some(128),
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supported_sanitizers: SanitizerSet::KCFI | SanitizerSet::KERNELADDRESS,
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stack_probes: StackProbeType::Inline,
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panic_strategy: PanicStrategy::Abort,
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endian: Endian::Big,
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..Default::default()
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};
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Target {
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llvm_target: "aarch64_be-unknown-none".into(),
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metadata: TargetMetadata {
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description: Some("Bare ARM64 (big-endian), softfloat".into()),
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tier: Some(3),
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host_tools: Some(false),
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std: Some(false),
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},
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pointer_width: 64,
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data_layout: "E-m:e-p270:32:32-p271:32:32-p272:64:64-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128-Fn32".into(),
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arch: "aarch64".into(),
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options: opts,
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}
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}

‎src/doc/rustc/src/platform-support.md

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`aarch64_be-unknown-linux-gnu` | ✓ | ✓ | ARM64 Linux (big-endian)
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`aarch64_be-unknown-linux-gnu_ilp32` | ✓ | ✓ | ARM64 Linux (big-endian, ILP32 ABI)
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[`aarch64_be-unknown-netbsd`](platform-support/netbsd.md) | ✓ | ✓ | ARM64 NetBSD (big-endian)
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[`aarch64_be-unknown-none-softfloat`](platform-support/aarch64_be-unknown-none-softfloat.md) | * | | Bare big-endian ARM64, softfloat
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[`amdgcn-amd-amdhsa`](platform-support/amdgcn-amd-amdhsa.md) | * | | `-Ctarget-cpu=gfx...` to specify [the AMD GPU] to compile for
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[`arm64_32-apple-watchos`](platform-support/apple-watchos.md) | ✓ | | Arm Apple WatchOS 64-bit with 32-bit pointers
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[`arm64e-apple-darwin`](platform-support/arm64e-apple-darwin.md) | ✓ | ✓ | ARM64e Apple Darwin

‎src/doc/rustc/src/platform-support/aarch64_be-unknown-none-softfloat.md

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# aarch64_be-unknown-none-softfloat
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**Tier: 3**
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Target for freestanding/bare-metal big-endian ARM64 binaries in ELF format:
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firmware, kernels, etc.
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## Target maintainers
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[@Gelbpunkt](https://github.com/Gelbpunkt)
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## Requirements
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This target is cross-compiled. There is no support for `std`. There is no
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default allocator, but it's possible to use `alloc` by supplying an allocator.
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The target does not assume existence of a FPU and does not make use of any
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non-GPR register. This allows the generated code to run in environments, such
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as kernels, which may need to avoid the use of such registers or which may have
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special considerations about the use of such registers (e.g. saving and
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restoring them to avoid breaking userspace code using the same registers). You
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can change code generation to use additional CPU features via the
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`-C target-feature=` codegen options to rustc, or via the `#[target_feature]`
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mechanism within Rust code.
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By default, code generated with the soft-float target should run on any
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big-endian ARM64 hardware, enabling additional target features may raise this
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baseline.
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`extern "C"` uses the [architecture's standard calling convention][aapcs64].
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[aapcs64]: https://github.com/ARM-software/abi-aa/blob/main/aapcs64/aapcs64.rst
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The targets generate binaries in the ELF format. Any alternate formats or
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special considerations for binary layout will require linker options or linker
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scripts.
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## Building the target
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You can build Rust with support for the target by adding it to the `target`
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list in `bootstrap.toml`:
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```toml
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[build]
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target = ["aarch64_be-unknown-none-softfloat"]
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```
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## Building Rust programs
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Rust does not yet ship pre-compiled artifacts for this target. To compile for
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this target, you will first need to build Rust with the target enabled (see
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"Building the target" above).
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## Cross-compilation
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For cross builds, you will need an appropriate ARM64 C/C++ toolchain for
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linking, or if you want to compile C code along with Rust (such as for Rust
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crates with C dependencies).
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Rust *may* be able to use an `aarch64_be-unknown-linux-{gnu,musl}-` toolchain
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with appropriate standalone flags to build for this target (depending on the
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assumptions of that toolchain, see below), or you may wish to use a separate
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`aarch64_be-unknown-none-softfloat` toolchain.
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On some ARM64 hosts that use ELF binaries, you *may* be able to use the host C
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toolchain, if it does not introduce assumptions about the host environment that
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don't match the expectations of a standalone environment. Otherwise, you may
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need a separate toolchain for standalone/freestanding development, just as when
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cross-compiling from a non-ARM64 platform.
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## Testing
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As the target supports a variety of different environments and does not support
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`std`, it does not support running the Rust test suite.

‎tests/assembly-llvm/targets/targets-elf.rs

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//@ revisions: aarch64_be_unknown_netbsd
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//@ [aarch64_be_unknown_netbsd] compile-flags: --target aarch64_be-unknown-netbsd
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//@ [aarch64_be_unknown_netbsd] needs-llvm-components: aarch64
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//@ revisions: aarch64_be_unknown_none_softfloat
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//@ [aarch64_be_unknown_none_softfloat] compile-flags: --target aarch64_be-unknown-none-softfloat
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//@ [aarch64_be_unknown_none_softfloat] needs-llvm-components: aarch64
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//@ revisions: aarch64_kmc_solid_asp3
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//@ [aarch64_kmc_solid_asp3] compile-flags: --target aarch64-kmc-solid_asp3
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//@ [aarch64_kmc_solid_asp3] needs-llvm-components: aarch64

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