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;
11 use rustc_middle::ty::Ty;
12 use rustc_target::abi::{Align, HasDataLayout, LayoutOf, Size};
14 fn round_pointer_up_to_alignment(
15 bx: &mut Builder<'a, 'll, 'tcx>,
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(
27 bx: &mut Builder<'a, 'll, 'tcx>,
28 list: OperandRef<'tcx, &'ll Value>,
33 allow_higher_align: bool,
34 ) -> (&'ll Value, Align) {
35 let va_list_ptr_ty = bx.cx().type_ptr_to(bx.cx.type_i8p());
36 let va_list_addr = if list.layout.llvm_type(bx.cx) != va_list_ptr_ty {
37 bx.bitcast(list.immediate(), va_list_ptr_ty)
42 let ptr = bx.load(va_list_addr, bx.tcx().data_layout.pointer_align.abi);
44 let (addr, addr_align) = if allow_higher_align && align > slot_size {
45 (round_pointer_up_to_alignment(bx, ptr, align, bx.cx().type_i8p()), align)
50 let aligned_size = size.align_to(slot_size).bytes() as i32;
51 let full_direct_size = bx.cx().const_i32(aligned_size);
52 let next = bx.inbounds_gep(addr, &[full_direct_size]);
53 bx.store(next, va_list_addr, bx.tcx().data_layout.pointer_align.abi);
55 if size.bytes() < slot_size.bytes() && &*bx.tcx().sess.target.endian == "big" {
56 let adjusted_size = bx.cx().const_i32((slot_size.bytes() - size.bytes()) as i32);
57 let adjusted = bx.inbounds_gep(addr, &[adjusted_size]);
58 (bx.bitcast(adjusted, bx.cx().type_ptr_to(llty)), addr_align)
60 (bx.bitcast(addr, bx.cx().type_ptr_to(llty)), addr_align)
65 bx: &mut Builder<'a, 'll, 'tcx>,
66 list: OperandRef<'tcx, &'ll Value>,
70 allow_higher_align: bool,
72 let layout = bx.cx.layout_of(target_ty);
73 let (llty, size, align) = if indirect {
75 bx.cx.layout_of(bx.cx.tcx.mk_imm_ptr(target_ty)).llvm_type(bx.cx),
76 bx.cx.data_layout().pointer_size,
77 bx.cx.data_layout().pointer_align,
80 (layout.llvm_type(bx.cx), layout.size, layout.align)
82 let (addr, addr_align) =
83 emit_direct_ptr_va_arg(bx, list, llty, size, align.abi, slot_size, allow_higher_align);
85 let tmp_ret = bx.load(addr, addr_align);
86 bx.load(tmp_ret, align.abi)
88 bx.load(addr, addr_align)
93 bx: &mut Builder<'a, 'll, 'tcx>,
94 list: OperandRef<'tcx, &'ll Value>,
97 // Implementation of the AAPCS64 calling convention for va_args see
98 // https://github.com/ARM-software/abi-aa/blob/master/aapcs64/aapcs64.rst
99 let va_list_addr = list.immediate();
100 let layout = bx.cx.layout_of(target_ty);
102 let mut maybe_reg = bx.build_sibling_block("va_arg.maybe_reg");
103 let mut in_reg = bx.build_sibling_block("va_arg.in_reg");
104 let mut on_stack = bx.build_sibling_block("va_arg.on_stack");
105 let mut end = bx.build_sibling_block("va_arg.end");
106 let zero = bx.const_i32(0);
107 let offset_align = Align::from_bytes(4).unwrap();
108 assert!(&*bx.tcx().sess.target.endian == "little");
110 let gr_type = target_ty.is_any_ptr() || target_ty.is_integral();
111 let (reg_off, reg_top_index, slot_size) = if gr_type {
112 let gr_offs = bx.struct_gep(va_list_addr, 7);
113 let nreg = (layout.size.bytes() + 7) / 8;
114 (gr_offs, 3, nreg * 8)
116 let vr_off = bx.struct_gep(va_list_addr, 9);
117 let nreg = (layout.size.bytes() + 15) / 16;
118 (vr_off, 5, nreg * 16)
121 // if the offset >= 0 then the value will be on the stack
122 let mut reg_off_v = bx.load(reg_off, offset_align);
123 let use_stack = bx.icmp(IntPredicate::IntSGE, reg_off_v, zero);
124 bx.cond_br(use_stack, &on_stack.llbb(), &maybe_reg.llbb());
126 // The value at this point might be in a register, but there is a chance that
127 // it could be on the stack so we have to update the offset and then check
130 if gr_type && layout.align.abi.bytes() > 8 {
131 reg_off_v = maybe_reg.add(reg_off_v, bx.const_i32(15));
132 reg_off_v = maybe_reg.and(reg_off_v, bx.const_i32(-16));
134 let new_reg_off_v = maybe_reg.add(reg_off_v, bx.const_i32(slot_size as i32));
136 maybe_reg.store(new_reg_off_v, reg_off, offset_align);
138 // Check to see if we have overflowed the registers as a result of this.
139 // If we have then we need to use the stack for this value
140 let use_stack = maybe_reg.icmp(IntPredicate::IntSGT, new_reg_off_v, zero);
141 maybe_reg.cond_br(use_stack, &on_stack.llbb(), &in_reg.llbb());
143 let top = in_reg.struct_gep(va_list_addr, reg_top_index);
144 let top = in_reg.load(top, bx.tcx().data_layout.pointer_align.abi);
146 // reg_value = *(@top + reg_off_v);
147 let top = in_reg.gep(top, &[reg_off_v]);
148 let top = in_reg.bitcast(top, bx.cx.type_ptr_to(layout.llvm_type(bx)));
149 let reg_value = in_reg.load(top, layout.align.abi);
150 in_reg.br(&end.llbb());
154 emit_ptr_va_arg(&mut on_stack, list, target_ty, false, Align::from_bytes(8).unwrap(), true);
155 on_stack.br(&end.llbb());
158 layout.immediate_llvm_type(bx),
159 &[reg_value, stack_value],
160 &[&in_reg.llbb(), &on_stack.llbb()],
167 pub(super) fn emit_va_arg(
168 bx: &mut Builder<'a, 'll, 'tcx>,
169 addr: OperandRef<'tcx, &'ll Value>,
172 // Determine the va_arg implementation to use. The LLVM va_arg instruction
173 // is lacking in some instances, so we should only use it as a fallback.
174 let target = &bx.cx.tcx.sess.target;
175 let arch = &bx.cx.tcx.sess.target.arch;
178 "x86" if target.is_like_windows => {
179 emit_ptr_va_arg(bx, addr, target_ty, false, Align::from_bytes(4).unwrap(), false)
182 "x86" => emit_ptr_va_arg(bx, addr, target_ty, false, Align::from_bytes(4).unwrap(), true),
184 "aarch64" if target.is_like_windows => {
185 emit_ptr_va_arg(bx, addr, target_ty, false, Align::from_bytes(8).unwrap(), false)
187 // macOS / iOS AArch64
188 "aarch64" if target.is_like_osx => {
189 emit_ptr_va_arg(bx, addr, target_ty, false, Align::from_bytes(8).unwrap(), true)
191 "aarch64" => emit_aapcs_va_arg(bx, addr, target_ty),
193 "x86_64" if target.is_like_windows => {
194 let target_ty_size = bx.cx.size_of(target_ty).bytes();
195 let indirect: bool = target_ty_size > 8 || !target_ty_size.is_power_of_two();
196 emit_ptr_va_arg(bx, addr, target_ty, indirect, Align::from_bytes(8).unwrap(), false)
198 // For all other architecture/OS combinations fall back to using
199 // the LLVM va_arg instruction.
200 // https://llvm.org/docs/LangRef.html#va-arg-instruction
201 _ => bx.va_arg(addr.immediate(), bx.cx.layout_of(target_ty).llvm_type(bx.cx)),