From eb22d70aed39614dd9318e3fa1bf91846d74b8aa Mon Sep 17 00:00:00 2001 From: Ulrich Weigand Date: Tue, 6 Dec 2022 17:36:09 +0100 Subject: [PATCH] Implement va_list and va_arg for s390x FFI Following the s390x ELF ABI and based on the clang implementation, provide appropriate definitions of va_list in library/core/src/ffi/mod.rs and va_arg handling in compiler/rustc_codegen_llvm/src/va_arg.rs. Fixes the following test cases on s390x: src/test/run-make-fulldeps/c-link-to-rust-va-list-fn src/test/ui/abi/variadic-ffi.rs Fixes https://github.com/rust-lang/rust/issues/84628. --- compiler/rustc_codegen_llvm/src/va_arg.rs | 84 +++++++++++++++++++++++ library/core/src/ffi/mod.rs | 55 +++++++++++++-- 2 files changed, 134 insertions(+), 5 deletions(-) diff --git a/compiler/rustc_codegen_llvm/src/va_arg.rs b/compiler/rustc_codegen_llvm/src/va_arg.rs index ceb3d5a84ab..b19398e68c2 100644 --- a/compiler/rustc_codegen_llvm/src/va_arg.rs +++ b/compiler/rustc_codegen_llvm/src/va_arg.rs @@ -175,6 +175,89 @@ fn emit_aapcs_va_arg<'ll, 'tcx>( val } +fn emit_s390x_va_arg<'ll, 'tcx>( + bx: &mut Builder<'_, 'll, 'tcx>, + list: OperandRef<'tcx, &'ll Value>, + target_ty: Ty<'tcx>, +) -> &'ll Value { + // Implementation of the s390x ELF ABI calling convention for va_args see + // https://github.com/IBM/s390x-abi (chapter 1.2.4) + let va_list_addr = list.immediate(); + let va_list_layout = list.deref(bx.cx).layout; + let va_list_ty = va_list_layout.llvm_type(bx); + let layout = bx.cx.layout_of(target_ty); + + let in_reg = bx.append_sibling_block("va_arg.in_reg"); + let in_mem = bx.append_sibling_block("va_arg.in_mem"); + let end = bx.append_sibling_block("va_arg.end"); + + // FIXME: vector ABI not yet supported. + 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(); + let unpadded_size = if indirect { 8 } else { target_ty_size }; + let padded_size = 8; + let padding = padded_size - unpadded_size; + + let gpr_type = indirect || !layout.is_single_fp_element(bx.cx); + let (max_regs, reg_count_field, reg_save_index, reg_padding) = + if gpr_type { (5, 0, 2, padding) } else { (4, 1, 16, 0) }; + + // Check whether the value was passed in a register or in memory. + let reg_count = bx.struct_gep( + va_list_ty, + va_list_addr, + va_list_layout.llvm_field_index(bx.cx, reg_count_field), + ); + let reg_count_v = bx.load(bx.type_i64(), reg_count, Align::from_bytes(8).unwrap()); + let use_regs = bx.icmp(IntPredicate::IntULT, reg_count_v, bx.const_u64(max_regs)); + bx.cond_br(use_regs, in_reg, in_mem); + + // Emit code to load the value if it was passed in a register. + bx.switch_to_block(in_reg); + + // Work out the address of the value in the register save area. + let reg_ptr = + bx.struct_gep(va_list_ty, va_list_addr, va_list_layout.llvm_field_index(bx.cx, 3)); + let reg_ptr_v = bx.load(bx.type_i8p(), reg_ptr, bx.tcx().data_layout.pointer_align.abi); + let scaled_reg_count = bx.mul(reg_count_v, bx.const_u64(8)); + let reg_off = bx.add(scaled_reg_count, bx.const_u64(reg_save_index * 8 + reg_padding)); + let reg_addr = bx.gep(bx.type_i8(), reg_ptr_v, &[reg_off]); + + // Update the register count. + let new_reg_count_v = bx.add(reg_count_v, bx.const_u64(1)); + bx.store(new_reg_count_v, reg_count, Align::from_bytes(8).unwrap()); + bx.br(end); + + // Emit code to load the value if it was passed in memory. + bx.switch_to_block(in_mem); + + // Work out the address of the value in the argument overflow area. + let arg_ptr = + bx.struct_gep(va_list_ty, va_list_addr, va_list_layout.llvm_field_index(bx.cx, 2)); + let arg_ptr_v = bx.load(bx.type_i8p(), arg_ptr, bx.tcx().data_layout.pointer_align.abi); + let arg_off = bx.const_u64(padding); + let mem_addr = bx.gep(bx.type_i8(), arg_ptr_v, &[arg_off]); + + // Update the argument overflow area pointer. + let arg_size = bx.cx().const_u64(padded_size); + let new_arg_ptr_v = bx.inbounds_gep(bx.type_i8(), arg_ptr_v, &[arg_size]); + bx.store(new_arg_ptr_v, arg_ptr, bx.tcx().data_layout.pointer_align.abi); + bx.br(end); + + // Return the appropriate result. + bx.switch_to_block(end); + let val_addr = bx.phi(bx.type_i8p(), &[reg_addr, mem_addr], &[in_reg, in_mem]); + let val_type = layout.llvm_type(bx); + let val_addr = if indirect { + let ptr_type = bx.cx.type_ptr_to(val_type); + let ptr_addr = bx.bitcast(val_addr, bx.cx.type_ptr_to(ptr_type)); + bx.load(ptr_type, ptr_addr, bx.tcx().data_layout.pointer_align.abi) + } else { + bx.bitcast(val_addr, bx.cx.type_ptr_to(val_type)) + }; + bx.load(val_type, val_addr, layout.align.abi) +} + pub(super) fn emit_va_arg<'ll, 'tcx>( bx: &mut Builder<'_, 'll, 'tcx>, addr: OperandRef<'tcx, &'ll Value>, @@ -200,6 +283,7 @@ pub(super) fn emit_va_arg<'ll, 'tcx>( emit_ptr_va_arg(bx, addr, target_ty, false, Align::from_bytes(8).unwrap(), true) } "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(); diff --git a/library/core/src/ffi/mod.rs b/library/core/src/ffi/mod.rs index ec1eaa99f0b..76daceecd7b 100644 --- a/library/core/src/ffi/mod.rs +++ b/library/core/src/ffi/mod.rs @@ -227,7 +227,12 @@ impl fmt::Debug for c_void { /// Basic implementation of a `va_list`. // The name is WIP, using `VaListImpl` for now. #[cfg(any( - all(not(target_arch = "aarch64"), not(target_arch = "powerpc"), not(target_arch = "x86_64")), + all( + not(target_arch = "aarch64"), + not(target_arch = "powerpc"), + not(target_arch = "s390x"), + not(target_arch = "x86_64") + ), all(target_arch = "aarch64", any(target_os = "macos", target_os = "ios")), target_family = "wasm", target_arch = "asmjs", @@ -251,7 +256,12 @@ pub struct VaListImpl<'f> { } #[cfg(any( - all(not(target_arch = "aarch64"), not(target_arch = "powerpc"), not(target_arch = "x86_64")), + all( + not(target_arch = "aarch64"), + not(target_arch = "powerpc"), + not(target_arch = "s390x"), + not(target_arch = "x86_64") + ), all(target_arch = "aarch64", any(target_os = "macos", target_os = "ios")), target_family = "wasm", target_arch = "asmjs", @@ -319,6 +329,25 @@ pub struct VaListImpl<'f> { _marker: PhantomData<&'f mut &'f c_void>, } +/// s390x ABI implementation of a `va_list`. +#[cfg(target_arch = "s390x")] +#[repr(C)] +#[derive(Debug)] +#[unstable( + feature = "c_variadic", + reason = "the `c_variadic` feature has not been properly tested on \ + all supported platforms", + issue = "44930" +)] +#[lang = "va_list"] +pub struct VaListImpl<'f> { + gpr: i64, + fpr: i64, + overflow_arg_area: *mut c_void, + reg_save_area: *mut c_void, + _marker: PhantomData<&'f mut &'f c_void>, +} + /// x86_64 ABI implementation of a `va_list`. #[cfg(all(target_arch = "x86_64", not(target_os = "uefi"), not(windows)))] #[repr(C)] @@ -352,6 +381,7 @@ pub struct VaList<'a, 'f: 'a> { all( not(target_arch = "aarch64"), not(target_arch = "powerpc"), + not(target_arch = "s390x"), not(target_arch = "x86_64") ), all(target_arch = "aarch64", any(target_os = "macos", target_os = "ios")), @@ -363,7 +393,12 @@ pub struct VaList<'a, 'f: 'a> { inner: VaListImpl<'f>, #[cfg(all( - any(target_arch = "aarch64", target_arch = "powerpc", target_arch = "x86_64"), + any( + target_arch = "aarch64", + target_arch = "powerpc", + target_arch = "s390x", + target_arch = "x86_64" + ), any(not(target_arch = "aarch64"), not(any(target_os = "macos", target_os = "ios"))), not(target_family = "wasm"), not(target_arch = "asmjs"), @@ -376,7 +411,12 @@ pub struct VaList<'a, 'f: 'a> { } #[cfg(any( - all(not(target_arch = "aarch64"), not(target_arch = "powerpc"), not(target_arch = "x86_64")), + all( + not(target_arch = "aarch64"), + not(target_arch = "powerpc"), + not(target_arch = "s390x"), + not(target_arch = "x86_64") + ), all(target_arch = "aarch64", any(target_os = "macos", target_os = "ios")), target_family = "wasm", target_arch = "asmjs", @@ -398,7 +438,12 @@ impl<'f> VaListImpl<'f> { } #[cfg(all( - any(target_arch = "aarch64", target_arch = "powerpc", target_arch = "x86_64"), + any( + target_arch = "aarch64", + target_arch = "powerpc", + target_arch = "s390x", + target_arch = "x86_64" + ), any(not(target_arch = "aarch64"), not(any(target_os = "macos", target_os = "ios"))), not(target_family = "wasm"), not(target_arch = "asmjs"),