| use rustc_abi::{Align, Endian, HasDataLayout, Size}; |
| use rustc_codegen_ssa::common::IntPredicate; |
| use rustc_codegen_ssa::mir::operand::OperandRef; |
| use rustc_codegen_ssa::traits::{BaseTypeCodegenMethods, BuilderMethods, ConstCodegenMethods}; |
| use rustc_middle::ty::Ty; |
| use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf}; |
| |
| use crate::builder::Builder; |
| use crate::type_::Type; |
| use crate::type_of::LayoutLlvmExt; |
| use crate::value::Value; |
| |
| fn round_up_to_alignment<'ll>( |
| bx: &mut Builder<'_, 'll, '_>, |
| mut value: &'ll Value, |
| align: Align, |
| ) -> &'ll Value { |
| value = bx.add(value, bx.cx().const_i32(align.bytes() as i32 - 1)); |
| return bx.and(value, bx.cx().const_i32(-(align.bytes() as i32))); |
| } |
| |
| fn round_pointer_up_to_alignment<'ll>( |
| bx: &mut Builder<'_, 'll, '_>, |
| addr: &'ll Value, |
| align: Align, |
| ptr_ty: &'ll Type, |
| ) -> &'ll Value { |
| let mut ptr_as_int = bx.ptrtoint(addr, bx.cx().type_isize()); |
| ptr_as_int = round_up_to_alignment(bx, ptr_as_int, align); |
| bx.inttoptr(ptr_as_int, ptr_ty) |
| } |
| |
| fn emit_direct_ptr_va_arg<'ll, 'tcx>( |
| bx: &mut Builder<'_, 'll, 'tcx>, |
| list: OperandRef<'tcx, &'ll Value>, |
| size: Size, |
| align: Align, |
| slot_size: Align, |
| allow_higher_align: bool, |
| ) -> (&'ll Value, Align) { |
| let va_list_ty = bx.type_ptr(); |
| let va_list_addr = list.immediate(); |
| |
| let ptr = bx.load(va_list_ty, va_list_addr, bx.tcx().data_layout.pointer_align.abi); |
| |
| let (addr, addr_align) = if allow_higher_align && align > slot_size { |
| (round_pointer_up_to_alignment(bx, ptr, align, bx.type_ptr()), align) |
| } else { |
| (ptr, slot_size) |
| }; |
| |
| let aligned_size = size.align_to(slot_size).bytes() as i32; |
| let full_direct_size = bx.cx().const_i32(aligned_size); |
| let next = bx.inbounds_ptradd(addr, full_direct_size); |
| bx.store(next, va_list_addr, bx.tcx().data_layout.pointer_align.abi); |
| |
| if size.bytes() < slot_size.bytes() && bx.tcx().sess.target.endian == Endian::Big { |
| let adjusted_size = bx.cx().const_i32((slot_size.bytes() - size.bytes()) as i32); |
| let adjusted = bx.inbounds_ptradd(addr, adjusted_size); |
| (adjusted, addr_align) |
| } else { |
| (addr, addr_align) |
| } |
| } |
| |
| 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>, |
| 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 { |
| ( |
| bx.cx.layout_of(Ty::new_imm_ptr(bx.cx.tcx, target_ty)).llvm_type(bx.cx), |
| bx.cx.data_layout().pointer_size, |
| bx.cx.data_layout().pointer_align, |
| ) |
| } else { |
| (layout.llvm_type(bx.cx), layout.size, layout.align) |
| }; |
| let (addr, addr_align) = |
| emit_direct_ptr_va_arg(bx, list, size, align.abi, slot_size, allow_higher_align); |
| if indirect { |
| let tmp_ret = bx.load(llty, addr, addr_align); |
| bx.load(bx.cx.layout_of(target_ty).llvm_type(bx.cx), tmp_ret, align.abi) |
| } else { |
| bx.load(llty, addr, addr_align) |
| } |
| } |
| |
| fn emit_aapcs_va_arg<'ll, 'tcx>( |
| bx: &mut Builder<'_, 'll, 'tcx>, |
| list: OperandRef<'tcx, &'ll Value>, |
| target_ty: Ty<'tcx>, |
| ) -> &'ll Value { |
| let dl = bx.cx.data_layout(); |
| |
| // Implementation of the AAPCS64 calling convention for va_args see |
| // https://github.com/ARM-software/abi-aa/blob/master/aapcs64/aapcs64.rst |
| // |
| // typedef struct va_list { |
| // void * stack; // next stack param |
| // void * gr_top; // end of GP arg reg save area |
| // void * vr_top; // end of FP/SIMD arg reg save area |
| // int gr_offs; // offset from gr_top to next GP register arg |
| // int vr_offs; // offset from vr_top to next FP/SIMD register arg |
| // } va_list; |
| let va_list_addr = list.immediate(); |
| |
| // There is no padding between fields since `void*` is size=8 align=8, `int` is size=4 align=4. |
| // See https://github.com/ARM-software/abi-aa/blob/master/aapcs64/aapcs64.rst |
| // Table 1, Byte size and byte alignment of fundamental data types |
| // Table 3, Mapping of C & C++ built-in data types |
| let ptr_offset = 8; |
| let i32_offset = 4; |
| let gr_top = bx.inbounds_ptradd(va_list_addr, bx.cx.const_usize(ptr_offset)); |
| let vr_top = bx.inbounds_ptradd(va_list_addr, bx.cx.const_usize(2 * ptr_offset)); |
| let gr_offs = bx.inbounds_ptradd(va_list_addr, bx.cx.const_usize(3 * ptr_offset)); |
| let vr_offs = bx.inbounds_ptradd(va_list_addr, bx.cx.const_usize(3 * ptr_offset + i32_offset)); |
| |
| let layout = bx.cx.layout_of(target_ty); |
| |
| let maybe_reg = bx.append_sibling_block("va_arg.maybe_reg"); |
| let in_reg = bx.append_sibling_block("va_arg.in_reg"); |
| let on_stack = bx.append_sibling_block("va_arg.on_stack"); |
| let end = bx.append_sibling_block("va_arg.end"); |
| let zero = bx.const_i32(0); |
| let offset_align = Align::from_bytes(4).unwrap(); |
| |
| let gr_type = target_ty.is_any_ptr() || target_ty.is_integral(); |
| let (reg_off, reg_top, slot_size) = if gr_type { |
| let nreg = (layout.size.bytes() + 7) / 8; |
| (gr_offs, gr_top, nreg * 8) |
| } else { |
| let nreg = (layout.size.bytes() + 15) / 16; |
| (vr_offs, vr_top, nreg * 16) |
| }; |
| |
| // if the offset >= 0 then the value will be on the stack |
| let mut reg_off_v = bx.load(bx.type_i32(), reg_off, offset_align); |
| let use_stack = bx.icmp(IntPredicate::IntSGE, reg_off_v, zero); |
| bx.cond_br(use_stack, on_stack, maybe_reg); |
| |
| // The value at this point might be in a register, but there is a chance that |
| // it could be on the stack so we have to update the offset and then check |
| // the offset again. |
| |
| bx.switch_to_block(maybe_reg); |
| if gr_type && layout.align.abi.bytes() > 8 { |
| reg_off_v = bx.add(reg_off_v, bx.const_i32(15)); |
| reg_off_v = bx.and(reg_off_v, bx.const_i32(-16)); |
| } |
| let new_reg_off_v = bx.add(reg_off_v, bx.const_i32(slot_size as i32)); |
| |
| bx.store(new_reg_off_v, reg_off, offset_align); |
| |
| // Check to see if we have overflowed the registers as a result of this. |
| // If we have then we need to use the stack for this value |
| let use_stack = bx.icmp(IntPredicate::IntSGT, new_reg_off_v, zero); |
| bx.cond_br(use_stack, on_stack, in_reg); |
| |
| bx.switch_to_block(in_reg); |
| let top_type = bx.type_ptr(); |
| let top = bx.load(top_type, reg_top, dl.pointer_align.abi); |
| |
| // reg_value = *(@top + reg_off_v); |
| let mut reg_addr = bx.ptradd(top, reg_off_v); |
| if bx.tcx().sess.target.endian == Endian::Big && layout.size.bytes() != slot_size { |
| // On big-endian systems the value is right-aligned in its slot. |
| let offset = bx.const_i32((slot_size - layout.size.bytes()) as i32); |
| reg_addr = bx.ptradd(reg_addr, offset); |
| } |
| let reg_type = layout.llvm_type(bx); |
| let reg_value = bx.load(reg_type, reg_addr, layout.align.abi); |
| bx.br(end); |
| |
| // On Stack block |
| bx.switch_to_block(on_stack); |
| 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); |
| let val = |
| bx.phi(layout.immediate_llvm_type(bx), &[reg_value, stack_value], &[in_reg, on_stack]); |
| |
| val |
| } |
| |
| fn emit_s390x_va_arg<'ll, 'tcx>( |
| bx: &mut Builder<'_, 'll, 'tcx>, |
| list: OperandRef<'tcx, &'ll Value>, |
| target_ty: Ty<'tcx>, |
| ) -> &'ll Value { |
| let dl = bx.cx.data_layout(); |
| |
| // Implementation of the s390x ELF ABI calling convention for va_args see |
| // https://github.com/IBM/s390x-abi (chapter 1.2.4) |
| // |
| // typedef struct __va_list_tag { |
| // long __gpr; |
| // long __fpr; |
| // void *__overflow_arg_area; |
| // void *__reg_save_area; |
| // } va_list[1]; |
| let va_list_addr = list.immediate(); |
| |
| // There is no padding between fields since `long` and `void*` both have size=8 align=8. |
| // https://github.com/IBM/s390x-abi (Table 1.1.: Scalar types) |
| let i64_offset = 8; |
| let ptr_offset = 8; |
| let gpr = va_list_addr; |
| let fpr = bx.inbounds_ptradd(va_list_addr, bx.cx.const_usize(i64_offset)); |
| let overflow_arg_area = bx.inbounds_ptradd(va_list_addr, bx.cx.const_usize(2 * i64_offset)); |
| let reg_save_area = |
| bx.inbounds_ptradd(va_list_addr, bx.cx.const_usize(2 * i64_offset + ptr_offset)); |
| |
| 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, reg_save_index, reg_padding) = |
| if gpr_type { (5, gpr, 2, padding) } else { (4, fpr, 16, 0) }; |
| |
| // Check whether the value was passed in a register or in memory. |
| 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_v = bx.load(bx.type_ptr(), reg_save_area, dl.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.ptradd(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_v = |
| bx.load(bx.type_ptr(), overflow_arg_area, bx.tcx().data_layout.pointer_align.abi); |
| let arg_off = bx.const_u64(padding); |
| let mem_addr = bx.ptradd(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_ptradd(arg_ptr_v, arg_size); |
| bx.store(new_arg_ptr_v, overflow_arg_area, dl.pointer_align.abi); |
| bx.br(end); |
| |
| // Return the appropriate result. |
| bx.switch_to_block(end); |
| let val_addr = bx.phi(bx.type_ptr(), &[reg_addr, mem_addr], &[in_reg, in_mem]); |
| let val_type = layout.llvm_type(bx); |
| let val_addr = |
| if indirect { bx.load(bx.cx.type_ptr(), val_addr, dl.pointer_align.abi) } else { val_addr }; |
| bx.load(val_type, val_addr, layout.align.abi) |
| } |
| |
| fn emit_xtensa_va_arg<'ll, 'tcx>( |
| bx: &mut Builder<'_, 'll, 'tcx>, |
| list: OperandRef<'tcx, &'ll Value>, |
| target_ty: Ty<'tcx>, |
| ) -> &'ll Value { |
| // Implementation of va_arg for Xtensa. There doesn't seem to be an authoritative source for |
| // this, other than "what GCC does". |
| // |
| // The va_list type has three fields: |
| // struct __va_list_tag { |
| // int32_t *va_stk; // Arguments passed on the stack |
| // int32_t *va_reg; // Arguments passed in registers, saved to memory by the prologue. |
| // int32_t va_ndx; // Offset into the arguments, in bytes |
| // }; |
| // |
| // The first 24 bytes (equivalent to 6 registers) come from va_reg, the rest from va_stk. |
| // Thus if va_ndx is less than 24, the next va_arg *may* read from va_reg, |
| // otherwise it must come from va_stk. |
| // |
| // Primitive arguments are never split between registers and the stack. For example, if loading an 8 byte |
| // primitive value and va_ndx = 20, we instead bump the offset and read everything from va_stk. |
| let va_list_addr = list.immediate(); |
| // FIXME: handle multi-field structs that split across regsave/stack? |
| let layout = bx.cx.layout_of(target_ty); |
| let from_stack = bx.append_sibling_block("va_arg.from_stack"); |
| let from_regsave = bx.append_sibling_block("va_arg.from_regsave"); |
| let end = bx.append_sibling_block("va_arg.end"); |
| |
| // (*va).va_ndx |
| let va_reg_offset = 4; |
| let va_ndx_offset = va_reg_offset + 4; |
| let offset_ptr = |
| bx.inbounds_gep(bx.type_i8(), va_list_addr, &[bx.cx.const_usize(va_ndx_offset)]); |
| |
| let offset = bx.load(bx.type_i32(), offset_ptr, bx.tcx().data_layout.i32_align.abi); |
| let offset = round_up_to_alignment(bx, offset, layout.align.abi); |
| |
| let slot_size = layout.size.align_to(Align::from_bytes(4).unwrap()).bytes() as i32; |
| |
| // Update the offset in va_list, by adding the slot's size. |
| let offset_next = bx.add(offset, bx.const_i32(slot_size)); |
| |
| // Figure out where to look for our value. We do that by checking the end of our slot (offset_next). |
| // If that is within the regsave area, then load from there. Otherwise load from the stack area. |
| let regsave_size = bx.const_i32(24); |
| let use_regsave = bx.icmp(IntPredicate::IntULE, offset_next, regsave_size); |
| bx.cond_br(use_regsave, from_regsave, from_stack); |
| |
| bx.switch_to_block(from_regsave); |
| // update va_ndx |
| bx.store(offset_next, offset_ptr, bx.tcx().data_layout.pointer_align.abi); |
| |
| // (*va).va_reg |
| let regsave_area_ptr = |
| bx.inbounds_gep(bx.type_i8(), va_list_addr, &[bx.cx.const_usize(va_reg_offset)]); |
| let regsave_area = |
| bx.load(bx.type_ptr(), regsave_area_ptr, bx.tcx().data_layout.pointer_align.abi); |
| let regsave_value_ptr = bx.inbounds_gep(bx.type_i8(), regsave_area, &[offset]); |
| bx.br(end); |
| |
| bx.switch_to_block(from_stack); |
| |
| // The first time we switch from regsave to stack we needs to adjust our offsets a bit. |
| // va_stk is set up such that the first stack argument is always at va_stk + 32. |
| // The corrected offset is written back into the va_list struct. |
| |
| // let offset_corrected = cmp::max(offset, 32); |
| let stack_offset_start = bx.const_i32(32); |
| let needs_correction = bx.icmp(IntPredicate::IntULE, offset, stack_offset_start); |
| let offset_corrected = bx.select(needs_correction, stack_offset_start, offset); |
| |
| // let offset_next_corrected = offset_corrected + slot_size; |
| // va_ndx = offset_next_corrected; |
| let offset_next_corrected = bx.add(offset_next, bx.const_i32(slot_size)); |
| // update va_ndx |
| bx.store(offset_next_corrected, offset_ptr, bx.tcx().data_layout.pointer_align.abi); |
| |
| // let stack_value_ptr = unsafe { (*va).va_stk.byte_add(offset_corrected) }; |
| let stack_area_ptr = bx.inbounds_gep(bx.type_i8(), va_list_addr, &[bx.cx.const_usize(0)]); |
| let stack_area = bx.load(bx.type_ptr(), stack_area_ptr, bx.tcx().data_layout.pointer_align.abi); |
| let stack_value_ptr = bx.inbounds_gep(bx.type_i8(), stack_area, &[offset_corrected]); |
| bx.br(end); |
| |
| bx.switch_to_block(end); |
| |
| // On big-endian, for values smaller than the slot size we'd have to align the read to the end |
| // of the slot rather than the start. While the ISA and GCC support big-endian, all the Xtensa |
| // targets supported by rustc are litte-endian so don't worry about it. |
| |
| // if from_regsave { |
| // unsafe { *regsave_value_ptr } |
| // } else { |
| // unsafe { *stack_value_ptr } |
| // } |
| assert!(bx.tcx().sess.target.endian == Endian::Little); |
| let value_ptr = |
| bx.phi(bx.type_ptr(), &[regsave_value_ptr, stack_value_ptr], &[from_regsave, from_stack]); |
| return bx.load(layout.llvm_type(bx), value_ptr, layout.align.abi); |
| } |
| |
| pub(super) fn emit_va_arg<'ll, 'tcx>( |
| bx: &mut Builder<'_, 'll, 'tcx>, |
| addr: OperandRef<'tcx, &'ll Value>, |
| target_ty: Ty<'tcx>, |
| ) -> &'ll Value { |
| // 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; |
| |
| 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 => { |
| 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(); |
| 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 |
| // the LLVM va_arg instruction. |
| // https://llvm.org/docs/LangRef.html#va-arg-instruction |
| _ => bx.va_arg(addr.immediate(), bx.cx.layout_of(target_ty).llvm_type(bx.cx)), |
| } |
| } |
