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custom VaList layout for Hexagon #149967

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Merged
bors merged 1 commit into from
Dec 17, 2025
+20 −0
Merged

custom VaList layout for Hexagon #149967

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20 changes: 20 additions & 0 deletions library/core/src/ffi/va_list.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,9 @@ use crate::marker::PhantomCovariantLifetime;
// the pointer decay behavior in Rust, while otherwise matching Rust semantics.
// This attribute ensures that the compiler uses the correct ABI for functions
// like `extern "C" fn takes_va_list(va: VaList<'_>)` by passing `va` indirectly.
//
// The Clang `BuiltinVaListKind` enumerates the `va_list` variations that Clang supports,
// and we mirror these here.
crate::cfg_select! {
all(
target_arch = "aarch64",
Expand Down Expand Up @@ -124,6 +127,23 @@ crate::cfg_select! {
}
}

all(target_arch = "hexagon", target_env = "musl") => {
/// Hexagon Musl implementation of a `va_list`.
///
/// See the [LLVM source] for more details. On bare metal Hexagon uses an opaque pointer.
///
/// [LLVM source]:
/// https://github.com/llvm/llvm-project/blob/0cdc1b6dd4a870fc41d4b15ad97e0001882aba58/clang/lib/CodeGen/Targets/Hexagon.cpp#L407-L417
#[repr(C)]
#[derive(Debug)]
#[rustc_pass_indirectly_in_non_rustic_abis]
struct VaListInner {
__current_saved_reg_area_pointer: *const c_void,
__saved_reg_area_end_pointer: *const c_void,
__overflow_area_pointer: *const c_void,
}
}

// The fallback implementation, used for:
//
// - apple aarch64 (see https://github.com/rust-lang/rust/pull/56599)
Expand Down
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