1 //! ARM 64-bit Instruction Set Architecture.
2 
3 use crate::dominator_tree::DominatorTree;
4 use crate::ir::{self, Function, Type};
5 use crate::isa::aarch64::settings as aarch64_settings;
6 #[cfg(feature = "unwind")]
7 use crate::isa::unwind::systemv;
8 use crate::isa::{Builder as IsaBuilder, FunctionAlignment, IsaFlagsHashKey, TargetIsa};
9 #[cfg(feature = "unwind")]
10 use crate::machinst::CompiledCode;
11 use crate::machinst::{
12     CompiledCodeStencil, MachInst, MachTextSectionBuilder, Reg, SigSet, TextSectionBuilder, VCode,
13     compile,
14 };
15 use crate::result::CodegenResult;
16 use crate::settings as shared_settings;
17 use alloc::string::String;
18 use alloc::{boxed::Box, vec::Vec};
19 use core::fmt;
20 use cranelift_control::ControlPlane;
21 #[cfg(feature = "unwind")]
22 use target_lexicon::OperatingSystem;
23 use target_lexicon::{Aarch64Architecture, Architecture, Triple};
24 
25 // New backend:
26 mod abi;
27 pub mod inst;
28 mod lower;
29 mod pcc;
30 pub mod settings;
31 
32 use self::inst::EmitInfo;
33 
34 /// An AArch64 backend.
35 pub struct AArch64Backend {
36     triple: Triple,
37     flags: shared_settings::Flags,
38     isa_flags: aarch64_settings::Flags,
39 }
40 
41 impl AArch64Backend {
42     /// Create a new AArch64 backend with the given (shared) flags.
43     pub fn new_with_flags(
44         triple: Triple,
45         flags: shared_settings::Flags,
46         isa_flags: aarch64_settings::Flags,
47     ) -> AArch64Backend {
48         AArch64Backend {
49             triple,
50             flags,
51             isa_flags,
52         }
53     }
54 
55     /// This performs lowering to VCode, register-allocates the code, computes block layout and
56     /// finalizes branches. The result is ready for binary emission.
57     fn compile_vcode(
58         &self,
59         func: &Function,
60         domtree: &DominatorTree,
61         ctrl_plane: &mut ControlPlane,
62     ) -> CodegenResult<(VCode<inst::Inst>, regalloc2::Output)> {
63         let emit_info = EmitInfo::new(self.flags.clone());
64         let sigs = SigSet::new::<abi::AArch64MachineDeps>(func, &self.flags)?;
65         let abi = abi::AArch64Callee::new(func, self, &self.isa_flags, &sigs)?;
66         compile::compile::<AArch64Backend>(func, domtree, self, abi, emit_info, sigs, ctrl_plane)
67     }
68 }
69 
70 impl TargetIsa for AArch64Backend {
71     fn compile_function(
72         &self,
73         func: &Function,
74         domtree: &DominatorTree,
75         want_disasm: bool,
76         ctrl_plane: &mut ControlPlane,
77     ) -> CodegenResult<CompiledCodeStencil> {
78         let (vcode, regalloc_result) = self.compile_vcode(func, domtree, ctrl_plane)?;
79 
80         let emit_result = vcode.emit(&regalloc_result, want_disasm, &self.flags, ctrl_plane);
81         let value_labels_ranges = emit_result.value_labels_ranges;
82         let buffer = emit_result.buffer;
83 
84         if let Some(disasm) = emit_result.disasm.as_ref() {
85             log::debug!("disassembly:\n{disasm}");
86         }
87 
88         Ok(CompiledCodeStencil {
89             buffer,
90             vcode: emit_result.disasm,
91             value_labels_ranges,
92             bb_starts: emit_result.bb_offsets,
93             bb_edges: emit_result.bb_edges,
94         })
95     }
96 
97     fn name(&self) -> &'static str {
98         "aarch64"
99     }
100 
101     fn triple(&self) -> &Triple {
102         &self.triple
103     }
104 
105     fn flags(&self) -> &shared_settings::Flags {
106         &self.flags
107     }
108 
109     fn isa_flags(&self) -> Vec<shared_settings::Value> {
110         self.isa_flags.iter().collect()
111     }
112 
113     fn isa_flags_hash_key(&self) -> IsaFlagsHashKey<'_> {
114         IsaFlagsHashKey(self.isa_flags.hash_key())
115     }
116 
117     fn is_branch_protection_enabled(&self) -> bool {
118         self.isa_flags.use_bti()
119     }
120 
121     fn dynamic_vector_bytes(&self, _dyn_ty: Type) -> u32 {
122         16
123     }
124 
125     #[cfg(feature = "unwind")]
126     fn emit_unwind_info(
127         &self,
128         result: &CompiledCode,
129         kind: crate::isa::unwind::UnwindInfoKind,
130     ) -> CodegenResult<Option<crate::isa::unwind::UnwindInfo>> {
131         use crate::isa::unwind::UnwindInfo;
132         use crate::isa::unwind::UnwindInfoKind;
133         Ok(match kind {
134             UnwindInfoKind::SystemV => {
135                 let mapper = self::inst::unwind::systemv::RegisterMapper;
136                 Some(UnwindInfo::SystemV(
137                     crate::isa::unwind::systemv::create_unwind_info_from_insts(
138                         &result.buffer.unwind_info[..],
139                         result.buffer.data().len(),
140                         &mapper,
141                     )?,
142                 ))
143             }
144             UnwindInfoKind::Windows => Some(UnwindInfo::WindowsArm64(
145                 crate::isa::unwind::winarm64::create_unwind_info_from_insts(
146                     &result.buffer.unwind_info[..],
147                 )?,
148             )),
149             _ => None,
150         })
151     }
152 
153     #[cfg(feature = "unwind")]
154     fn create_systemv_cie(&self) -> Option<gimli::write::CommonInformationEntry> {
155         let is_apple_os = match self.triple.operating_system {
156             OperatingSystem::Darwin(_)
157             | OperatingSystem::IOS(_)
158             | OperatingSystem::MacOSX { .. }
159             | OperatingSystem::TvOS(_) => true,
160             _ => false,
161         };
162 
163         if self.isa_flags.sign_return_address()
164             && self.isa_flags.sign_return_address_with_bkey()
165             && !is_apple_os
166         {
167             unimplemented!(
168                 "Specifying that the B key is used with pointer authentication instructions in the CIE is not implemented."
169             );
170         }
171 
172         Some(inst::unwind::systemv::create_cie())
173     }
174 
175     fn text_section_builder(&self, num_funcs: usize) -> Box<dyn TextSectionBuilder> {
176         Box::new(MachTextSectionBuilder::<inst::Inst>::new(num_funcs))
177     }
178 
179     #[cfg(feature = "unwind")]
180     fn map_regalloc_reg_to_dwarf(&self, reg: Reg) -> Result<u16, systemv::RegisterMappingError> {
181         inst::unwind::systemv::map_reg(reg).map(|reg| reg.0)
182     }
183 
184     fn function_alignment(&self) -> FunctionAlignment {
185         inst::Inst::function_alignment()
186     }
187 
188     fn page_size_align_log2(&self) -> u8 {
189         use target_lexicon::*;
190         match self.triple().operating_system {
191             OperatingSystem::MacOSX { .. }
192             | OperatingSystem::Darwin(_)
193             | OperatingSystem::IOS(_)
194             | OperatingSystem::TvOS(_) => {
195                 debug_assert_eq!(1 << 14, 0x4000);
196                 14
197             }
198             _ => {
199                 debug_assert_eq!(1 << 16, 0x10000);
200                 16
201             }
202         }
203     }
204 
205     #[cfg(feature = "disas")]
206     fn to_capstone(&self) -> Result<capstone::Capstone, capstone::Error> {
207         use capstone::prelude::*;
208         let mut cs = Capstone::new()
209             .arm64()
210             .mode(arch::arm64::ArchMode::Arm)
211             .detail(true)
212             .build()?;
213         // AArch64 uses inline constants rather than a separate constant pool right now.
214         // Without this option, Capstone will stop disassembling as soon as it sees
215         // an inline constant that is not also a valid instruction. With this option,
216         // Capstone will print a `.byte` directive with the bytes of the inline constant
217         // and continue to the next instruction.
218         cs.set_skipdata(true)?;
219         Ok(cs)
220     }
221 
222     fn pretty_print_reg(&self, reg: Reg, _size: u8) -> String {
223         inst::regs::pretty_print_reg(reg)
224     }
225 
226     fn has_native_fma(&self) -> bool {
227         true
228     }
229 
230     fn has_round(&self) -> bool {
231         true
232     }
233 
234     fn has_blendv_lowering(&self, _: Type) -> bool {
235         false
236     }
237 
238     fn has_x86_pshufb_lowering(&self) -> bool {
239         false
240     }
241 
242     fn has_x86_pmulhrsw_lowering(&self) -> bool {
243         false
244     }
245 
246     fn has_x86_pmaddubsw_lowering(&self) -> bool {
247         false
248     }
249 
250     fn default_argument_extension(&self) -> ir::ArgumentExtension {
251         // This is copied/carried over from a historical piece of code in
252         // Wasmtime:
253         //
254         // https://github.com/bytecodealliance/wasmtime/blob/a018a5a9addb77d5998021a0150192aa955c71bf/crates/cranelift/src/lib.rs#L366-L374
255         //
256         // Whether or not it is still applicable here is unsure, but it's left
257         // the same as-is for now to reduce the likelihood of problems arising.
258         ir::ArgumentExtension::Uext
259     }
260 }
261 
262 impl fmt::Display for AArch64Backend {
263     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
264         f.debug_struct("MachBackend")
265             .field("name", &self.name())
266             .field("triple", &self.triple())
267             .field("flags", &format!("{}", self.flags()))
268             .finish()
269     }
270 }
271 
272 /// Create a new `isa::Builder`.
273 pub fn isa_builder(triple: Triple) -> IsaBuilder {
274     assert!(triple.architecture == Architecture::Aarch64(Aarch64Architecture::Aarch64));
275     IsaBuilder {
276         triple,
277         setup: aarch64_settings::builder(),
278         constructor: |triple, shared_flags, builder| {
279             let isa_flags = aarch64_settings::Flags::new(&shared_flags, builder);
280             let backend = AArch64Backend::new_with_flags(triple, shared_flags, isa_flags);
281             Ok(backend.wrapped())
282         },
283     }
284 }
285