1 //! Codegen of [`asm!`] invocations.
7 use rustc_ast::ast::{InlineAsmOptions, InlineAsmTemplatePiece};
8 use rustc_middle::mir::InlineAsmOperand;
9 use rustc_target::asm::*;
11 pub(crate) fn codegen_inline_asm<'tcx>(
12 fx: &mut FunctionCx<'_, '_, 'tcx>,
14 template: &[InlineAsmTemplatePiece],
15 operands: &[InlineAsmOperand<'tcx>],
16 options: InlineAsmOptions,
18 // FIXME add .eh_frame unwind info directives
20 if template.is_empty() {
25 let mut slot_size = Size::from_bytes(0);
26 let mut clobbered_regs = Vec::new();
27 let mut inputs = Vec::new();
28 let mut outputs = Vec::new();
30 let mut new_slot = |reg_class: InlineAsmRegClass| {
31 let reg_size = reg_class
32 .supported_types(InlineAsmArch::X86_64)
34 .map(|(ty, _)| ty.size())
37 let align = rustc_target::abi::Align::from_bytes(reg_size.bytes()).unwrap();
38 slot_size = slot_size.align_to(align);
39 let offset = slot_size;
40 slot_size += reg_size;
44 // FIXME overlap input and output slots to save stack space
45 for operand in operands {
47 InlineAsmOperand::In { reg, ref value } => {
48 let reg = expect_reg(reg);
49 clobbered_regs.push((reg, new_slot(reg.reg_class())));
52 new_slot(reg.reg_class()),
53 crate::base::codegen_operand(fx, value).load_scalar(fx),
56 InlineAsmOperand::Out {
61 let reg = expect_reg(reg);
62 clobbered_regs.push((reg, new_slot(reg.reg_class())));
63 if let Some(place) = place {
66 new_slot(reg.reg_class()),
67 crate::base::codegen_place(fx, place),
71 InlineAsmOperand::InOut {
77 let reg = expect_reg(reg);
78 clobbered_regs.push((reg, new_slot(reg.reg_class())));
81 new_slot(reg.reg_class()),
82 crate::base::codegen_operand(fx, in_value).load_scalar(fx),
84 if let Some(out_place) = out_place {
87 new_slot(reg.reg_class()),
88 crate::base::codegen_place(fx, out_place),
92 InlineAsmOperand::Const { value: _ } => todo!(),
93 InlineAsmOperand::SymFn { value: _ } => todo!(),
94 InlineAsmOperand::SymStatic { def_id: _ } => todo!(),
98 let inline_asm_index = fx.inline_asm_index;
99 fx.inline_asm_index += 1;
100 let asm_name = format!(
102 fx.tcx.symbol_name(fx.instance).name,
106 let generated_asm = generate_asm_wrapper(
108 InlineAsmArch::X86_64,
115 fx.cx.global_asm.push_str(&generated_asm);
117 call_inline_asm(fx, &asm_name, slot_size, inputs, outputs);
120 fn generate_asm_wrapper(
123 options: InlineAsmOptions,
124 template: &[InlineAsmTemplatePiece],
125 clobbered_regs: Vec<(InlineAsmReg, Size)>,
126 inputs: &[(InlineAsmReg, Size, Value)],
127 outputs: &[(InlineAsmReg, Size, CPlace<'_>)],
129 let mut generated_asm = String::new();
130 writeln!(generated_asm, ".globl {}", asm_name).unwrap();
131 writeln!(generated_asm, ".type {},@function", asm_name).unwrap();
134 ".section .text.{},\"ax\",@progbits",
138 writeln!(generated_asm, "{}:", asm_name).unwrap();
140 generated_asm.push_str(".intel_syntax noprefix\n");
141 generated_asm.push_str(" push rbp\n");
142 generated_asm.push_str(" mov rbp,rdi\n");
144 // Save clobbered registers
145 if !options.contains(InlineAsmOptions::NORETURN) {
146 // FIXME skip registers saved by the calling convention
147 for &(reg, offset) in &clobbered_regs {
148 save_register(&mut generated_asm, arch, reg, offset);
152 // Write input registers
153 for &(reg, offset, _value) in inputs {
154 restore_register(&mut generated_asm, arch, reg, offset);
157 if options.contains(InlineAsmOptions::ATT_SYNTAX) {
158 generated_asm.push_str(".att_syntax\n");
161 // The actual inline asm
162 for piece in template {
164 InlineAsmTemplatePiece::String(s) => {
165 generated_asm.push_str(s);
167 InlineAsmTemplatePiece::Placeholder {
174 generated_asm.push('\n');
176 if options.contains(InlineAsmOptions::ATT_SYNTAX) {
177 generated_asm.push_str(".intel_syntax noprefix\n");
180 if !options.contains(InlineAsmOptions::NORETURN) {
181 // Read output registers
182 for &(reg, offset, _place) in outputs {
183 save_register(&mut generated_asm, arch, reg, offset);
186 // Restore clobbered registers
187 for &(reg, offset) in clobbered_regs.iter().rev() {
188 restore_register(&mut generated_asm, arch, reg, offset);
191 generated_asm.push_str(" pop rbp\n");
192 generated_asm.push_str(" ret\n");
194 generated_asm.push_str(" ud2\n");
197 generated_asm.push_str(".att_syntax\n");
198 writeln!(generated_asm, ".size {name}, .-{name}", name = asm_name).unwrap();
199 generated_asm.push_str(".text\n");
200 generated_asm.push_str("\n\n");
205 fn call_inline_asm<'tcx>(
206 fx: &mut FunctionCx<'_, '_, 'tcx>,
209 inputs: Vec<(InlineAsmReg, Size, Value)>,
210 outputs: Vec<(InlineAsmReg, Size, CPlace<'tcx>)>,
212 let stack_slot = fx.bcx.func.create_stack_slot(StackSlotData {
213 kind: StackSlotKind::ExplicitSlot,
215 size: u32::try_from(slot_size.bytes()).unwrap(),
217 #[cfg(debug_assertions)]
218 fx.add_comment(stack_slot, "inline asm scratch slot");
220 let inline_asm_func = fx
227 call_conv: CallConv::SystemV,
228 params: vec![AbiParam::new(fx.pointer_type)],
233 let inline_asm_func = fx
236 .declare_func_in_func(inline_asm_func, &mut fx.bcx.func);
237 #[cfg(debug_assertions)]
238 fx.add_comment(inline_asm_func, asm_name);
240 for (_reg, offset, value) in inputs {
243 .stack_store(value, stack_slot, i32::try_from(offset.bytes()).unwrap());
246 let stack_slot_addr = fx.bcx.ins().stack_addr(fx.pointer_type, stack_slot, 0);
247 fx.bcx.ins().call(inline_asm_func, &[stack_slot_addr]);
249 for (_reg, offset, place) in outputs {
250 let ty = fx.clif_type(place.layout().ty).unwrap();
254 .stack_load(ty, stack_slot, i32::try_from(offset.bytes()).unwrap());
255 place.write_cvalue(fx, CValue::by_val(value, place.layout()));
259 fn expect_reg(reg_or_class: InlineAsmRegOrRegClass) -> InlineAsmReg {
261 InlineAsmRegOrRegClass::Reg(reg) => reg,
262 InlineAsmRegOrRegClass::RegClass(class) => unimplemented!("{:?}", class),
266 fn save_register(generated_asm: &mut String, arch: InlineAsmArch, reg: InlineAsmReg, offset: Size) {
268 InlineAsmArch::X86_64 => {
269 write!(generated_asm, " mov [rbp+0x{:x}], ", offset.bytes()).unwrap();
270 reg.emit(generated_asm, InlineAsmArch::X86_64, None)
272 generated_asm.push('\n');
274 _ => unimplemented!("save_register for {:?}", arch),
279 generated_asm: &mut String,
285 InlineAsmArch::X86_64 => {
286 generated_asm.push_str(" mov ");
287 reg.emit(generated_asm, InlineAsmArch::X86_64, None)
289 writeln!(generated_asm, ", [rbp+0x{:x}]", offset.bytes()).unwrap();
291 _ => unimplemented!("restore_register for {:?}", arch),