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() {
23 } else if template[0] == InlineAsmTemplatePiece::String("int $$0x29".to_string()) {
24 let true_ = fx.bcx.ins().iconst(types::I32, 1);
25 fx.bcx.ins().trapnz(true_, TrapCode::User(1));
29 let mut slot_size = Size::from_bytes(0);
30 let mut clobbered_regs = Vec::new();
31 let mut inputs = Vec::new();
32 let mut outputs = Vec::new();
34 let mut new_slot = |reg_class: InlineAsmRegClass| {
35 let reg_size = reg_class
36 .supported_types(InlineAsmArch::X86_64)
38 .map(|(ty, _)| ty.size())
41 let align = rustc_target::abi::Align::from_bytes(reg_size.bytes()).unwrap();
42 slot_size = slot_size.align_to(align);
43 let offset = slot_size;
44 slot_size += reg_size;
48 // FIXME overlap input and output slots to save stack space
49 for operand in operands {
51 InlineAsmOperand::In { reg, ref value } => {
52 let reg = expect_reg(reg);
53 clobbered_regs.push((reg, new_slot(reg.reg_class())));
56 new_slot(reg.reg_class()),
57 crate::base::codegen_operand(fx, value).load_scalar(fx),
60 InlineAsmOperand::Out { reg, late: _, place } => {
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 { reg, late: _, ref in_value, out_place } => {
72 let reg = expect_reg(reg);
73 clobbered_regs.push((reg, new_slot(reg.reg_class())));
76 new_slot(reg.reg_class()),
77 crate::base::codegen_operand(fx, in_value).load_scalar(fx),
79 if let Some(out_place) = out_place {
82 new_slot(reg.reg_class()),
83 crate::base::codegen_place(fx, out_place),
87 InlineAsmOperand::Const { value: _ } => todo!(),
88 InlineAsmOperand::SymFn { value: _ } => todo!(),
89 InlineAsmOperand::SymStatic { def_id: _ } => todo!(),
93 let inline_asm_index = fx.inline_asm_index;
94 fx.inline_asm_index += 1;
95 let asm_name = format!("{}__inline_asm_{}", fx.symbol_name, inline_asm_index);
97 let generated_asm = generate_asm_wrapper(
99 InlineAsmArch::X86_64,
106 fx.cx.global_asm.push_str(&generated_asm);
108 call_inline_asm(fx, &asm_name, slot_size, inputs, outputs);
111 fn generate_asm_wrapper(
114 options: InlineAsmOptions,
115 template: &[InlineAsmTemplatePiece],
116 clobbered_regs: Vec<(InlineAsmReg, Size)>,
117 inputs: &[(InlineAsmReg, Size, Value)],
118 outputs: &[(InlineAsmReg, Size, CPlace<'_>)],
120 let mut generated_asm = String::new();
121 writeln!(generated_asm, ".globl {}", asm_name).unwrap();
122 writeln!(generated_asm, ".type {},@function", asm_name).unwrap();
123 writeln!(generated_asm, ".section .text.{},\"ax\",@progbits", asm_name).unwrap();
124 writeln!(generated_asm, "{}:", asm_name).unwrap();
126 generated_asm.push_str(".intel_syntax noprefix\n");
127 generated_asm.push_str(" push rbp\n");
128 generated_asm.push_str(" mov rbp,rdi\n");
130 // Save clobbered registers
131 if !options.contains(InlineAsmOptions::NORETURN) {
132 // FIXME skip registers saved by the calling convention
133 for &(reg, offset) in &clobbered_regs {
134 save_register(&mut generated_asm, arch, reg, offset);
138 // Write input registers
139 for &(reg, offset, _value) in inputs {
140 restore_register(&mut generated_asm, arch, reg, offset);
143 if options.contains(InlineAsmOptions::ATT_SYNTAX) {
144 generated_asm.push_str(".att_syntax\n");
147 // The actual inline asm
148 for piece in template {
150 InlineAsmTemplatePiece::String(s) => {
151 generated_asm.push_str(s);
153 InlineAsmTemplatePiece::Placeholder { operand_idx: _, modifier: _, span: _ } => todo!(),
156 generated_asm.push('\n');
158 if options.contains(InlineAsmOptions::ATT_SYNTAX) {
159 generated_asm.push_str(".intel_syntax noprefix\n");
162 if !options.contains(InlineAsmOptions::NORETURN) {
163 // Read output registers
164 for &(reg, offset, _place) in outputs {
165 save_register(&mut generated_asm, arch, reg, offset);
168 // Restore clobbered registers
169 for &(reg, offset) in clobbered_regs.iter().rev() {
170 restore_register(&mut generated_asm, arch, reg, offset);
173 generated_asm.push_str(" pop rbp\n");
174 generated_asm.push_str(" ret\n");
176 generated_asm.push_str(" ud2\n");
179 generated_asm.push_str(".att_syntax\n");
180 writeln!(generated_asm, ".size {name}, .-{name}", name = asm_name).unwrap();
181 generated_asm.push_str(".text\n");
182 generated_asm.push_str("\n\n");
187 fn call_inline_asm<'tcx>(
188 fx: &mut FunctionCx<'_, '_, 'tcx>,
191 inputs: Vec<(InlineAsmReg, Size, Value)>,
192 outputs: Vec<(InlineAsmReg, Size, CPlace<'tcx>)>,
194 let stack_slot = fx.bcx.func.create_stack_slot(StackSlotData {
195 kind: StackSlotKind::ExplicitSlot,
197 size: u32::try_from(slot_size.bytes()).unwrap(),
199 if fx.clif_comments.enabled() {
200 fx.add_comment(stack_slot, "inline asm scratch slot");
203 let inline_asm_func = fx
209 call_conv: CallConv::SystemV,
210 params: vec![AbiParam::new(fx.pointer_type)],
215 let inline_asm_func = fx.module.declare_func_in_func(inline_asm_func, &mut fx.bcx.func);
216 if fx.clif_comments.enabled() {
217 fx.add_comment(inline_asm_func, asm_name);
220 for (_reg, offset, value) in inputs {
221 fx.bcx.ins().stack_store(value, stack_slot, i32::try_from(offset.bytes()).unwrap());
224 let stack_slot_addr = fx.bcx.ins().stack_addr(fx.pointer_type, stack_slot, 0);
225 fx.bcx.ins().call(inline_asm_func, &[stack_slot_addr]);
227 for (_reg, offset, place) in outputs {
228 let ty = fx.clif_type(place.layout().ty).unwrap();
229 let value = fx.bcx.ins().stack_load(ty, stack_slot, i32::try_from(offset.bytes()).unwrap());
230 place.write_cvalue(fx, CValue::by_val(value, place.layout()));
234 fn expect_reg(reg_or_class: InlineAsmRegOrRegClass) -> InlineAsmReg {
236 InlineAsmRegOrRegClass::Reg(reg) => reg,
237 InlineAsmRegOrRegClass::RegClass(class) => unimplemented!("{:?}", class),
241 fn save_register(generated_asm: &mut String, arch: InlineAsmArch, reg: InlineAsmReg, offset: Size) {
243 InlineAsmArch::X86_64 => {
244 write!(generated_asm, " mov [rbp+0x{:x}], ", offset.bytes()).unwrap();
245 reg.emit(generated_asm, InlineAsmArch::X86_64, None).unwrap();
246 generated_asm.push('\n');
248 _ => unimplemented!("save_register for {:?}", arch),
253 generated_asm: &mut String,
259 InlineAsmArch::X86_64 => {
260 generated_asm.push_str(" mov ");
261 reg.emit(generated_asm, InlineAsmArch::X86_64, None).unwrap();
262 writeln!(generated_asm, ", [rbp+0x{:x}]", offset.bytes()).unwrap();
264 _ => unimplemented!("restore_register for {:?}", arch),