1 use crate::builder::Builder;
2 use crate::type_::Type;
3 use crate::type_of::LayoutLlvmExt;
4 use crate::value::Value;
5 use rustc_codegen_ssa::mir::operand::OperandRef;
6 use rustc_codegen_ssa::{
8 traits::{BaseTypeMethods, BuilderMethods, ConstMethods, DerivedTypeMethods},
10 use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf};
11 use rustc_middle::ty::Ty;
12 use rustc_target::abi::{Align, Endian, HasDataLayout, Size};
14 fn round_pointer_up_to_alignment<'ll>(
15 bx: &mut Builder<'_, 'll, '_>,
20 let mut ptr_as_int = bx.ptrtoint(addr, bx.cx().type_isize());
21 ptr_as_int = bx.add(ptr_as_int, bx.cx().const_i32(align.bytes() as i32 - 1));
22 ptr_as_int = bx.and(ptr_as_int, bx.cx().const_i32(-(align.bytes() as i32)));
23 bx.inttoptr(ptr_as_int, ptr_ty)
26 fn emit_direct_ptr_va_arg<'ll, 'tcx>(
27 bx: &mut Builder<'_, 'll, 'tcx>,
28 list: OperandRef<'tcx, &'ll Value>,
33 allow_higher_align: bool,
34 ) -> (&'ll Value, Align) {
35 let va_list_ty = bx.type_i8p();
36 let va_list_ptr_ty = bx.type_ptr_to(va_list_ty);
37 let va_list_addr = if list.layout.llvm_type(bx.cx) != va_list_ptr_ty {
38 bx.bitcast(list.immediate(), va_list_ptr_ty)
43 let ptr = bx.load(va_list_ty, va_list_addr, bx.tcx().data_layout.pointer_align.abi);
45 let (addr, addr_align) = if allow_higher_align && align > slot_size {
46 (round_pointer_up_to_alignment(bx, ptr, align, bx.cx().type_i8p()), align)
51 let aligned_size = size.align_to(slot_size).bytes() as i32;
52 let full_direct_size = bx.cx().const_i32(aligned_size);
53 let next = bx.inbounds_gep(bx.type_i8(), addr, &[full_direct_size]);
54 bx.store(next, va_list_addr, bx.tcx().data_layout.pointer_align.abi);
56 if size.bytes() < slot_size.bytes() && bx.tcx().sess.target.endian == Endian::Big {
57 let adjusted_size = bx.cx().const_i32((slot_size.bytes() - size.bytes()) as i32);
58 let adjusted = bx.inbounds_gep(bx.type_i8(), addr, &[adjusted_size]);
59 (bx.bitcast(adjusted, bx.cx().type_ptr_to(llty)), addr_align)
61 (bx.bitcast(addr, bx.cx().type_ptr_to(llty)), addr_align)
65 fn emit_ptr_va_arg<'ll, 'tcx>(
66 bx: &mut Builder<'_, 'll, 'tcx>,
67 list: OperandRef<'tcx, &'ll Value>,
71 allow_higher_align: bool,
73 let layout = bx.cx.layout_of(target_ty);
74 let (llty, size, align) = if indirect {
76 bx.cx.layout_of(bx.cx.tcx.mk_imm_ptr(target_ty)).llvm_type(bx.cx),
77 bx.cx.data_layout().pointer_size,
78 bx.cx.data_layout().pointer_align,
81 (layout.llvm_type(bx.cx), layout.size, layout.align)
83 let (addr, addr_align) =
84 emit_direct_ptr_va_arg(bx, list, llty, size, align.abi, slot_size, allow_higher_align);
86 let tmp_ret = bx.load(llty, addr, addr_align);
87 bx.load(bx.cx.layout_of(target_ty).llvm_type(bx.cx), tmp_ret, align.abi)
89 bx.load(llty, addr, addr_align)
93 fn emit_aapcs_va_arg<'ll, 'tcx>(
94 bx: &mut Builder<'_, 'll, 'tcx>,
95 list: OperandRef<'tcx, &'ll Value>,
98 // Implementation of the AAPCS64 calling convention for va_args see
99 // https://github.com/ARM-software/abi-aa/blob/master/aapcs64/aapcs64.rst
100 let va_list_addr = list.immediate();
101 let va_list_layout = list.deref(bx.cx).layout;
102 let va_list_ty = va_list_layout.llvm_type(bx);
103 let layout = bx.cx.layout_of(target_ty);
105 let mut maybe_reg = bx.build_sibling_block("va_arg.maybe_reg");
106 let mut in_reg = bx.build_sibling_block("va_arg.in_reg");
107 let mut on_stack = bx.build_sibling_block("va_arg.on_stack");
108 let mut end = bx.build_sibling_block("va_arg.end");
109 let zero = bx.const_i32(0);
110 let offset_align = Align::from_bytes(4).unwrap();
112 let gr_type = target_ty.is_any_ptr() || target_ty.is_integral();
113 let (reg_off, reg_top_index, slot_size) = if gr_type {
115 bx.struct_gep(va_list_ty, va_list_addr, va_list_layout.llvm_field_index(bx.cx, 3));
116 let nreg = (layout.size.bytes() + 7) / 8;
117 (gr_offs, va_list_layout.llvm_field_index(bx.cx, 1), nreg * 8)
120 bx.struct_gep(va_list_ty, va_list_addr, va_list_layout.llvm_field_index(bx.cx, 4));
121 let nreg = (layout.size.bytes() + 15) / 16;
122 (vr_off, va_list_layout.llvm_field_index(bx.cx, 2), nreg * 16)
125 // if the offset >= 0 then the value will be on the stack
126 let mut reg_off_v = bx.load(bx.type_i32(), reg_off, offset_align);
127 let use_stack = bx.icmp(IntPredicate::IntSGE, reg_off_v, zero);
128 bx.cond_br(use_stack, on_stack.llbb(), maybe_reg.llbb());
130 // The value at this point might be in a register, but there is a chance that
131 // it could be on the stack so we have to update the offset and then check
134 if gr_type && layout.align.abi.bytes() > 8 {
135 reg_off_v = maybe_reg.add(reg_off_v, bx.const_i32(15));
136 reg_off_v = maybe_reg.and(reg_off_v, bx.const_i32(-16));
138 let new_reg_off_v = maybe_reg.add(reg_off_v, bx.const_i32(slot_size as i32));
140 maybe_reg.store(new_reg_off_v, reg_off, offset_align);
142 // Check to see if we have overflowed the registers as a result of this.
143 // If we have then we need to use the stack for this value
144 let use_stack = maybe_reg.icmp(IntPredicate::IntSGT, new_reg_off_v, zero);
145 maybe_reg.cond_br(use_stack, on_stack.llbb(), in_reg.llbb());
147 let top_type = bx.type_i8p();
148 let top = in_reg.struct_gep(va_list_ty, va_list_addr, reg_top_index);
149 let top = in_reg.load(top_type, top, bx.tcx().data_layout.pointer_align.abi);
151 // reg_value = *(@top + reg_off_v);
152 let mut reg_addr = in_reg.gep(bx.type_i8(), top, &[reg_off_v]);
153 if bx.tcx().sess.target.endian == Endian::Big && layout.size.bytes() != slot_size {
154 // On big-endian systems the value is right-aligned in its slot.
155 let offset = bx.const_i32((slot_size - layout.size.bytes()) as i32);
156 reg_addr = in_reg.gep(bx.type_i8(), reg_addr, &[offset]);
158 let reg_type = layout.llvm_type(bx);
159 let reg_addr = in_reg.bitcast(reg_addr, bx.cx.type_ptr_to(reg_type));
160 let reg_value = in_reg.load(reg_type, reg_addr, layout.align.abi);
161 in_reg.br(end.llbb());
165 emit_ptr_va_arg(&mut on_stack, list, target_ty, false, Align::from_bytes(8).unwrap(), true);
166 on_stack.br(end.llbb());
169 layout.immediate_llvm_type(bx),
170 &[reg_value, stack_value],
171 &[in_reg.llbb(), on_stack.llbb()],
178 pub(super) fn emit_va_arg<'ll, 'tcx>(
179 bx: &mut Builder<'_, 'll, 'tcx>,
180 addr: OperandRef<'tcx, &'ll Value>,
183 // Determine the va_arg implementation to use. The LLVM va_arg instruction
184 // is lacking in some instances, so we should only use it as a fallback.
185 let target = &bx.cx.tcx.sess.target;
186 let arch = &bx.cx.tcx.sess.target.arch;
189 "x86" if target.is_like_windows => {
190 emit_ptr_va_arg(bx, addr, target_ty, false, Align::from_bytes(4).unwrap(), false)
193 "x86" => emit_ptr_va_arg(bx, addr, target_ty, false, Align::from_bytes(4).unwrap(), true),
195 "aarch64" if target.is_like_windows => {
196 emit_ptr_va_arg(bx, addr, target_ty, false, Align::from_bytes(8).unwrap(), false)
198 // macOS / iOS AArch64
199 "aarch64" if target.is_like_osx => {
200 emit_ptr_va_arg(bx, addr, target_ty, false, Align::from_bytes(8).unwrap(), true)
202 "aarch64" => emit_aapcs_va_arg(bx, addr, target_ty),
204 "x86_64" if target.is_like_windows => {
205 let target_ty_size = bx.cx.size_of(target_ty).bytes();
206 let indirect: bool = target_ty_size > 8 || !target_ty_size.is_power_of_two();
207 emit_ptr_va_arg(bx, addr, target_ty, indirect, Align::from_bytes(8).unwrap(), false)
209 // For all other architecture/OS combinations fall back to using
210 // the LLVM va_arg instruction.
211 // https://llvm.org/docs/LangRef.html#va-arg-instruction
212 _ => bx.va_arg(addr.immediate(), bx.cx.layout_of(target_ty).llvm_type(bx.cx)),