rustc_target/spec/
abi_map.rs

1use rustc_abi::{ArmCall, CanonAbi, ExternAbi, InterruptKind, X86Call};
2
3use crate::spec::Target;
4
5/// Mapping for ExternAbi to CanonAbi according to a Target
6///
7/// A maybe-transitional structure circa 2025 for hosting future experiments in
8/// encapsulating arch-specific ABI lowering details to make them more testable.
9#[derive(Clone, Debug)]
10pub struct AbiMap {
11    arch: Arch,
12    os: OsKind,
13}
14
15/// result from trying to map an ABI
16#[derive(Copy, Clone, Debug)]
17pub enum AbiMapping {
18    /// this ABI is exactly mapped for this platform
19    Direct(CanonAbi),
20    /// we don't yet warn on this, but we will
21    Deprecated(CanonAbi),
22    /// ABI we do not map for this platform: it must not reach codegen
23    Invalid,
24}
25
26impl AbiMapping {
27    /// optionally get a [CanonAbi], even if Deprecated
28    pub fn into_option(self) -> Option<CanonAbi> {
29        match self {
30            Self::Direct(abi) | Self::Deprecated(abi) => Some(abi),
31            Self::Invalid => None,
32        }
33    }
34
35    /// get a [CanonAbi] even if Deprecated, panicking if Invalid
36    #[track_caller]
37    pub fn unwrap(self) -> CanonAbi {
38        self.into_option().unwrap()
39    }
40
41    pub fn is_mapped(self) -> bool {
42        self.into_option().is_some()
43    }
44}
45
46impl AbiMap {
47    /// create an AbiMap according to arbitrary fields on the [Target]
48    pub fn from_target(target: &Target) -> Self {
49        // the purpose of this little exercise is to force listing what affects these mappings
50        let arch = match &*target.arch {
51            "aarch64" => Arch::Aarch64,
52            "amdgpu" => Arch::Amdgpu,
53            "arm" if target.llvm_target.starts_with("thumbv8m") => Arch::Arm(ArmVer::ThumbV8M),
54            "arm" => Arch::Arm(ArmVer::Other),
55            "avr" => Arch::Avr,
56            "msp430" => Arch::Msp430,
57            "nvptx64" => Arch::Nvptx,
58            "riscv32" | "riscv64" => Arch::Riscv,
59            "x86" => Arch::X86,
60            "x86_64" => Arch::X86_64,
61            _ => Arch::Other,
62        };
63        let os = if target.is_like_windows { OsKind::Windows } else { OsKind::Other };
64        AbiMap { arch, os }
65    }
66
67    /// lower an [ExternAbi] to a [CanonAbi] if this AbiMap allows
68    pub fn canonize_abi(&self, extern_abi: ExternAbi, has_c_varargs: bool) -> AbiMapping {
69        let AbiMap { os, arch } = *self;
70
71        let canon_abi = match (extern_abi, arch) {
72            // infallible lowerings
73            (ExternAbi::C { .. }, _) => CanonAbi::C,
74            (ExternAbi::Rust | ExternAbi::RustCall, _) => CanonAbi::Rust,
75            (ExternAbi::Unadjusted, _) => CanonAbi::C,
76
77            (ExternAbi::RustCold, _) if self.os == OsKind::Windows => CanonAbi::Rust,
78            (ExternAbi::RustCold, _) => CanonAbi::RustCold,
79
80            (ExternAbi::Custom, _) => CanonAbi::Custom,
81
82            (ExternAbi::System { .. }, Arch::X86) if os == OsKind::Windows && !has_c_varargs => {
83                CanonAbi::X86(X86Call::Stdcall)
84            }
85            (ExternAbi::System { .. }, _) => CanonAbi::C,
86
87            // fallible lowerings
88            (ExternAbi::EfiApi, Arch::Arm(..)) => CanonAbi::Arm(ArmCall::Aapcs),
89            (ExternAbi::EfiApi, Arch::X86_64) => CanonAbi::X86(X86Call::Win64),
90            (ExternAbi::EfiApi, Arch::Aarch64 | Arch::Riscv | Arch::X86) => CanonAbi::C,
91            (ExternAbi::EfiApi, _) => return AbiMapping::Invalid,
92
93            (ExternAbi::Aapcs { .. }, Arch::Arm(..)) => CanonAbi::Arm(ArmCall::Aapcs),
94            (ExternAbi::Aapcs { .. }, _) => return AbiMapping::Invalid,
95
96            (ExternAbi::CCmseNonSecureCall, Arch::Arm(ArmVer::ThumbV8M)) => {
97                CanonAbi::Arm(ArmCall::CCmseNonSecureCall)
98            }
99            (ExternAbi::CCmseNonSecureEntry, Arch::Arm(ArmVer::ThumbV8M)) => {
100                CanonAbi::Arm(ArmCall::CCmseNonSecureEntry)
101            }
102            (ExternAbi::CCmseNonSecureCall | ExternAbi::CCmseNonSecureEntry, ..) => {
103                return AbiMapping::Invalid;
104            }
105
106            (ExternAbi::Cdecl { .. }, Arch::X86) => CanonAbi::C,
107            (ExternAbi::Cdecl { .. }, _) => return AbiMapping::Deprecated(CanonAbi::C),
108
109            (ExternAbi::Fastcall { .. }, Arch::X86) => CanonAbi::X86(X86Call::Fastcall),
110            (ExternAbi::Fastcall { .. }, _) if os == OsKind::Windows => {
111                return AbiMapping::Deprecated(CanonAbi::C);
112            }
113            (ExternAbi::Fastcall { .. }, _) => return AbiMapping::Invalid,
114
115            (ExternAbi::Stdcall { .. }, Arch::X86) => CanonAbi::X86(X86Call::Stdcall),
116            (ExternAbi::Stdcall { .. }, _) if os == OsKind::Windows => {
117                return AbiMapping::Deprecated(CanonAbi::C);
118            }
119            (ExternAbi::Stdcall { .. }, _) => return AbiMapping::Invalid,
120
121            (ExternAbi::Thiscall { .. }, Arch::X86) => CanonAbi::X86(X86Call::Thiscall),
122            (ExternAbi::Thiscall { .. }, _) => return AbiMapping::Invalid,
123
124            (ExternAbi::Vectorcall { .. }, Arch::X86 | Arch::X86_64) => {
125                CanonAbi::X86(X86Call::Vectorcall)
126            }
127            (ExternAbi::Vectorcall { .. }, _) => return AbiMapping::Invalid,
128
129            (ExternAbi::SysV64 { .. }, Arch::X86_64) => CanonAbi::X86(X86Call::SysV64),
130            (ExternAbi::Win64 { .. }, Arch::X86_64) => CanonAbi::X86(X86Call::Win64),
131            (ExternAbi::SysV64 { .. } | ExternAbi::Win64 { .. }, _) => return AbiMapping::Invalid,
132
133            (ExternAbi::PtxKernel, Arch::Nvptx) => CanonAbi::GpuKernel,
134            (ExternAbi::GpuKernel, Arch::Amdgpu | Arch::Nvptx) => CanonAbi::GpuKernel,
135            (ExternAbi::PtxKernel | ExternAbi::GpuKernel, _) => return AbiMapping::Invalid,
136
137            (ExternAbi::AvrInterrupt, Arch::Avr) => CanonAbi::Interrupt(InterruptKind::Avr),
138            (ExternAbi::AvrNonBlockingInterrupt, Arch::Avr) => {
139                CanonAbi::Interrupt(InterruptKind::AvrNonBlocking)
140            }
141            (ExternAbi::Msp430Interrupt, Arch::Msp430) => {
142                CanonAbi::Interrupt(InterruptKind::Msp430)
143            }
144            (ExternAbi::RiscvInterruptM, Arch::Riscv) => {
145                CanonAbi::Interrupt(InterruptKind::RiscvMachine)
146            }
147            (ExternAbi::RiscvInterruptS, Arch::Riscv) => {
148                CanonAbi::Interrupt(InterruptKind::RiscvSupervisor)
149            }
150            (ExternAbi::X86Interrupt, Arch::X86 | Arch::X86_64) => {
151                CanonAbi::Interrupt(InterruptKind::X86)
152            }
153            (
154                ExternAbi::AvrInterrupt
155                | ExternAbi::AvrNonBlockingInterrupt
156                | ExternAbi::Msp430Interrupt
157                | ExternAbi::RiscvInterruptM
158                | ExternAbi::RiscvInterruptS
159                | ExternAbi::X86Interrupt
160                | ExternAbi::RustInvalid,
161                _,
162            ) => return AbiMapping::Invalid,
163        };
164
165        AbiMapping::Direct(canon_abi)
166    }
167}
168
169#[derive(Debug, PartialEq, Copy, Clone)]
170enum Arch {
171    Aarch64,
172    Amdgpu,
173    Arm(ArmVer),
174    Avr,
175    Msp430,
176    Nvptx,
177    Riscv,
178    X86,
179    X86_64,
180    /// Architectures which don't need other considerations for ABI lowering
181    Other,
182}
183
184#[derive(Debug, PartialEq, Copy, Clone)]
185enum OsKind {
186    Windows,
187    Other,
188}
189
190#[derive(Debug, PartialEq, Copy, Clone)]
191enum ArmVer {
192    ThumbV8M,
193    Other,
194}
rustc_target/spec/abi_map.rs

rustc_target/spec/
abi_map.rs
