Implement va_arg for Hexagon targets #150008
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cc @folkertdev Tested with #150009 #150010, and this |
Implements proper variadic argument handling for hexagon-unknown-linux-musl targets using a 3-pointer VaList structure compatible with LLVM's HexagonBuiltinVaList implementation. * Handles register save area vs overflow area transition * Provides proper 4-byte and 8-byte alignment for arguments * Only activates for hexagon+musl targets via Arch::Hexagon & Env::Musl
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This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed. Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers. |
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@rustbot reroll |
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r? folkertdev |
folkertdev
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Dec 15, 2025
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On its own this will miscompile, so maybe you can copy the changes from #149967 and just add them to this commit.
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folkertdev
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Dec 16, 2025
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| // Calculate offset: round up type size to 4-byte boundary (minimum stack slot size) | ||
| let type_size = layout.size.bytes(); | ||
| let offset = ((type_size + 3) / 4) * 4; // align to 4 bytes |
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I believe that is
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| let offset = ((type_size + 3) / 4) * 4; // align to 4 bytes | |
| let offset = type_size.next_multiple_of(4); // align to 4 bytes |
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| fn emit_hexagon_va_arg_bare_metal<'ll, 'tcx>( | ||
| bx: &mut Builder<'_, 'll, 'tcx>, | ||
| list: OperandRef<'tcx, &'ll Value>, | ||
| target_ty: Ty<'tcx>, | ||
| ) -> &'ll Value { |
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is this different from emit_ptr_va_arg?
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Like, I know that this is what LLVM does, but unless I'm missing something LLVM implementation could also use emitVoidPtrVAArg
| // This includes `target.is_like_darwin`, which on x86_64 targets is like sysv64. | ||
| Arch::X86_64 => emit_x86_64_sysv64_va_arg(bx, addr, target_ty), | ||
| Arch::Xtensa => emit_xtensa_va_arg(bx, addr, target_ty), | ||
| Arch::Hexagon => emit_hexagon_va_arg(bx, addr, target_ty, target.env == Env::Musl), |
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I'd just inline emit_hexagon_va_arg here
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Implements proper variadic argument handling for hexagon-unknown-linux-musl targets using a 3-pointer VaList structure compatible with LLVM's HexagonBuiltinVaList implementation.