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use custom types to clarify arguments to emit_ptr_va_arg #141623

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merged 1 commit into from
May 27, 2025
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use custom types to clarify arguments to emit_ptr_va_arg #141623

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83 changes: 61 additions & 22 deletions compiler/rustc_codegen_llvm/src/va_arg.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -63,14 +63,33 @@ fn emit_direct_ptr_va_arg<'ll, 'tcx>(
}
}

enum PassMode {
Direct,
Indirect,
}

enum SlotSize {
Bytes8 = 8,
Bytes4 = 4,
}

enum AllowHigherAlign {
No,
Yes,
}

fn emit_ptr_va_arg<'ll, 'tcx>(
bx: &mut Builder<'_, 'll, 'tcx>,
list: OperandRef<'tcx, &'ll Value>,
target_ty: Ty<'tcx>,
indirect: bool,
slot_size: Align,
allow_higher_align: bool,
pass_mode: PassMode,
slot_size: SlotSize,
allow_higher_align: AllowHigherAlign,
) -> &'ll Value {
let indirect = matches!(pass_mode, PassMode::Indirect);
let allow_higher_align = matches!(allow_higher_align, AllowHigherAlign::Yes);
let slot_size = Align::from_bytes(slot_size as u64).unwrap();

let layout = bx.cx.layout_of(target_ty);
let (llty, size, align) = if indirect {
(
Expand Down Expand Up @@ -179,8 +198,14 @@ fn emit_aapcs_va_arg<'ll, 'tcx>(

// On Stack block
bx.switch_to_block(on_stack);
let stack_value =
emit_ptr_va_arg(bx, list, target_ty, false, Align::from_bytes(8).unwrap(), true);
let stack_value = emit_ptr_va_arg(
bx,
list,
target_ty,
PassMode::Direct,
SlotSize::Bytes8,
AllowHigherAlign::Yes,
);
bx.br(end);

bx.switch_to_block(end);
Expand Down Expand Up @@ -386,29 +411,43 @@ pub(super) fn emit_va_arg<'ll, 'tcx>(
// Determine the va_arg implementation to use. The LLVM va_arg instruction
// is lacking in some instances, so we should only use it as a fallback.
let target = &bx.cx.tcx.sess.target;
let arch = &bx.cx.tcx.sess.target.arch;
match &**arch {
// Windows x86
"x86" if target.is_like_windows => {
emit_ptr_va_arg(bx, addr, target_ty, false, Align::from_bytes(4).unwrap(), false)
}
// Generic x86
"x86" => emit_ptr_va_arg(bx, addr, target_ty, false, Align::from_bytes(4).unwrap(), true),
// Windows AArch64
"aarch64" | "arm64ec" if target.is_like_windows => {
emit_ptr_va_arg(bx, addr, target_ty, false, Align::from_bytes(8).unwrap(), false)
}
// macOS / iOS AArch64
"aarch64" if target.is_like_darwin => {
emit_ptr_va_arg(bx, addr, target_ty, false, Align::from_bytes(8).unwrap(), true)

match &*target.arch {
"x86" => emit_ptr_va_arg(
bx,
addr,
target_ty,
PassMode::Direct,
SlotSize::Bytes4,
if target.is_like_windows { AllowHigherAlign::No } else { AllowHigherAlign::Yes },
),
"aarch64" | "arm64ec" if target.is_like_windows || target.is_like_darwin => {
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there is currently only

> rustc --print target-list | grep "arm64ec"
arm64ec-pc-windows-msvc

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There will never be a non-Windows "arm64ec" target.

emit_ptr_va_arg(
bx,
addr,
target_ty,
PassMode::Direct,
SlotSize::Bytes8,
if target.is_like_windows { AllowHigherAlign::No } else { AllowHigherAlign::Yes },
)
}
"aarch64" => emit_aapcs_va_arg(bx, addr, target_ty),
"s390x" => emit_s390x_va_arg(bx, addr, target_ty),
// Windows x86_64
"x86_64" if target.is_like_windows => {
let target_ty_size = bx.cx.size_of(target_ty).bytes();
let indirect: bool = target_ty_size > 8 || !target_ty_size.is_power_of_two();
emit_ptr_va_arg(bx, addr, target_ty, indirect, Align::from_bytes(8).unwrap(), false)
emit_ptr_va_arg(
bx,
addr,
target_ty,
if target_ty_size > 8 || !target_ty_size.is_power_of_two() {
PassMode::Indirect
} else {
PassMode::Direct
},
SlotSize::Bytes8,
AllowHigherAlign::No,
)
}
"xtensa" => emit_xtensa_va_arg(bx, addr, target_ty),
// For all other architecture/OS combinations fall back to using
Expand Down
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