diff --git a/compiler/rustc_target/src/callconv/mod.rs b/compiler/rustc_target/src/callconv/mod.rs index 1c044fe98b3ef..8fe19358954e0 100644 --- a/compiler/rustc_target/src/callconv/mod.rs +++ b/compiler/rustc_target/src/callconv/mod.rs @@ -31,6 +31,7 @@ mod sparc64; mod wasm; mod x86; mod x86_64; +mod x86_win32; mod x86_win64; mod xtensa; @@ -649,7 +650,11 @@ impl<'a, Ty> FnAbi<'a, Ty> { }; let reg_struct_return = cx.x86_abi_opt().reg_struct_return; let opts = x86::X86Options { flavor, regparm, reg_struct_return }; - x86::compute_abi_info(cx, self, opts); + if spec.is_like_msvc { + x86_win32::compute_abi_info(cx, self, opts); + } else { + x86::compute_abi_info(cx, self, opts); + } } "x86_64" => match abi { ExternAbi::SysV64 { .. } => x86_64::compute_abi_info(cx, self), diff --git a/compiler/rustc_target/src/callconv/x86.rs b/compiler/rustc_target/src/callconv/x86.rs index 7e5aab0201b6d..828725e946923 100644 --- a/compiler/rustc_target/src/callconv/x86.rs +++ b/compiler/rustc_target/src/callconv/x86.rs @@ -36,7 +36,7 @@ where if t.abi_return_struct_as_int || opts.reg_struct_return { // According to Clang, everyone but MSVC returns single-element // float aggregates directly in a floating-point register. - if !t.is_like_msvc && fn_abi.ret.layout.is_single_fp_element(cx) { + if fn_abi.ret.layout.is_single_fp_element(cx) { match fn_abi.ret.layout.size.bytes() { 4 => fn_abi.ret.cast_to(Reg::f32()), 8 => fn_abi.ret.cast_to(Reg::f64()), @@ -64,31 +64,11 @@ where continue; } - // FIXME: MSVC 2015+ will pass the first 3 vector arguments in [XYZ]MM0-2 - // See https://reviews.llvm.org/D72114 for Clang behavior - let t = cx.target_spec(); let align_4 = Align::from_bytes(4).unwrap(); let align_16 = Align::from_bytes(16).unwrap(); - if t.is_like_msvc - && arg.layout.is_adt() - && let Some(max_repr_align) = arg.layout.max_repr_align - && max_repr_align > align_4 - { - // MSVC has special rules for overaligned arguments: https://reviews.llvm.org/D72114. - // Summarized here: - // - Arguments with _requested_ alignment > 4 are passed indirectly. - // - For backwards compatibility, arguments with natural alignment > 4 are still passed - // on stack (via `byval`). For example, this includes `double`, `int64_t`, - // and structs containing them, provided they lack an explicit alignment attribute. - assert!( - arg.layout.align.abi >= max_repr_align, - "abi alignment {:?} less than requested alignment {max_repr_align:?}", - arg.layout.align.abi, - ); - arg.make_indirect(); - } else if arg.layout.is_aggregate() { + if arg.layout.is_aggregate() { // We need to compute the alignment of the `byval` argument. The rules can be found in // `X86_32ABIInfo::getTypeStackAlignInBytes` in Clang's `TargetInfo.cpp`. Summarized // here, they are: diff --git a/compiler/rustc_target/src/callconv/x86_win32.rs b/compiler/rustc_target/src/callconv/x86_win32.rs new file mode 100644 index 0000000000000..554a7368848b5 --- /dev/null +++ b/compiler/rustc_target/src/callconv/x86_win32.rs @@ -0,0 +1,81 @@ +use rustc_abi::{Align, HasDataLayout, Reg, TyAbiInterface}; + +use crate::callconv::FnAbi; +use crate::spec::HasTargetSpec; + +pub(crate) fn compute_abi_info<'a, Ty, C>( + cx: &C, + fn_abi: &mut FnAbi<'a, Ty>, + opts: super::x86::X86Options, +) where + Ty: TyAbiInterface<'a, C> + Copy, + C: HasDataLayout + HasTargetSpec, +{ + if !fn_abi.ret.is_ignore() { + if fn_abi.ret.layout.is_aggregate() && fn_abi.ret.layout.is_sized() { + // Returning a structure. Most often, this will use + // a hidden first argument. On some platforms, though, + // small structs are returned as integers. + // + // Some links: + // https://www.angelcode.com/dev/callconv/callconv.html + // Clang's ABI handling is in lib/CodeGen/TargetInfo.cpp + let t = cx.target_spec(); + // MSVC does not special-case 1-element float aggregates, unlike others. + // GCC used to apply the SysV rule here, breaking windows-gnu's ABI, but was fixed: + // - reported in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82028 + // - fixed in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85667 + if t.abi_return_struct_as_int || opts.reg_struct_return { + match fn_abi.ret.layout.size.bytes() { + 1 => fn_abi.ret.cast_to(Reg::i8()), + 2 => fn_abi.ret.cast_to(Reg::i16()), + 4 => fn_abi.ret.cast_to(Reg::i32()), + 8 => fn_abi.ret.cast_to(Reg::i64()), + _ => fn_abi.ret.make_indirect(), + } + } else { + fn_abi.ret.make_indirect(); + } + } else { + fn_abi.ret.extend_integer_width_to(32); + } + } + + for arg in fn_abi.args.iter_mut() { + if arg.is_ignore() || !arg.layout.is_sized() { + continue; + } + + // FIXME: MSVC 2015+ will pass the first 3 vector arguments in [XYZ]MM0-2 + // See https://reviews.llvm.org/D72114 for Clang behavior + + let align_4 = Align::from_bytes(4).unwrap(); + + if arg.layout.is_adt() + && let Some(max_repr_align) = arg.layout.max_repr_align + && max_repr_align > align_4 + { + // MSVC has special rules for overaligned arguments: https://reviews.llvm.org/D72114. + // Summarized here: + // - Arguments with _requested_ alignment > 4 are passed indirectly. + // - For backwards compatibility, arguments with natural alignment > 4 are still passed + // on stack (via `byval`). For example, this includes `double`, `int64_t`, + // and structs containing them, provided they lack an explicit alignment attribute. + assert!( + arg.layout.align.abi >= max_repr_align, + "abi alignment {:?} less than requested alignment {max_repr_align:?}", + arg.layout.align.abi, + ); + arg.make_indirect(); + } else if arg.layout.is_aggregate() { + // Alignment of the `byval` argument. + // The rules can be found in `X86_32ABIInfo::getTypeStackAlignInBytes` in Clang's `TargetInfo.cpp`. + let byval_align = align_4; + arg.pass_by_stack_offset(Some(byval_align)); + } else { + arg.extend_integer_width_to(32); + } + } + + super::x86::fill_inregs(cx, fn_abi, opts, false); +}