cranelift_codegen/isa/
call_conv.rs

1use crate::settings::{self, LibcallCallConv};
2use core::fmt;
3use core::str;
4use target_lexicon::{CallingConvention, Triple};
5
6#[cfg(feature = "enable-serde")]
7use serde_derive::{Deserialize, Serialize};
8
9/// Calling convention identifiers.
10#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
11#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
12pub enum CallConv {
13    /// Best performance, not ABI-stable.
14    Fast,
15    /// Smallest caller code size, not ABI-stable.
16    Cold,
17    /// Supports tail calls, not ABI-stable.
18    //
19    // Currently, this is basically sys-v except that callees pop stack
20    // arguments, rather than callers. Expected to change even more in the
21    // future, however!
22    Tail,
23    /// System V-style convention used on many platforms.
24    SystemV,
25    /// Windows "fastcall" convention, also used for x64 and ARM.
26    WindowsFastcall,
27    /// Mac aarch64 calling convention, which is a tweaked aarch64 ABI.
28    AppleAarch64,
29    /// Specialized convention for the probestack function.
30    Probestack,
31    /// Wasmtime equivalent of SystemV, not ABI-stable.
32    ///
33    /// FIXME: remove this when Wasmtime uses the "tail" calling convention for
34    /// all wasm functions.
35    WasmtimeSystemV,
36    /// The winch calling convention, not ABI-stable.
37    ///
38    /// The main difference to WasmtimeSystemV is that the winch calling
39    /// convention defines no callee-save registers, and restricts the number
40    /// of return registers to one integer, and one floating point.
41    Winch,
42}
43
44impl CallConv {
45    /// Return the default calling convention for the given target triple.
46    pub fn triple_default(triple: &Triple) -> Self {
47        match triple.default_calling_convention() {
48            // Default to System V for unknown targets because most everything
49            // uses System V.
50            Ok(CallingConvention::SystemV) | Err(()) => Self::SystemV,
51            Ok(CallingConvention::AppleAarch64) => Self::AppleAarch64,
52            Ok(CallingConvention::WindowsFastcall) => Self::WindowsFastcall,
53            Ok(unimp) => unimplemented!("calling convention: {:?}", unimp),
54        }
55    }
56
57    /// Returns the calling convention used for libcalls according to the current flags.
58    pub fn for_libcall(flags: &settings::Flags, default_call_conv: CallConv) -> Self {
59        match flags.libcall_call_conv() {
60            LibcallCallConv::IsaDefault => default_call_conv,
61            LibcallCallConv::Fast => Self::Fast,
62            LibcallCallConv::Cold => Self::Cold,
63            LibcallCallConv::SystemV => Self::SystemV,
64            LibcallCallConv::WindowsFastcall => Self::WindowsFastcall,
65            LibcallCallConv::AppleAarch64 => Self::AppleAarch64,
66            LibcallCallConv::Probestack => Self::Probestack,
67        }
68    }
69
70    /// Does this calling convention support tail calls?
71    pub fn supports_tail_calls(&self) -> bool {
72        match self {
73            CallConv::Tail => true,
74            _ => false,
75        }
76    }
77
78    /// Is the calling convention extending the Windows Fastcall ABI?
79    pub fn extends_windows_fastcall(self) -> bool {
80        match self {
81            Self::WindowsFastcall => true,
82            _ => false,
83        }
84    }
85
86    /// Is the calling convention extending the Apple aarch64 ABI?
87    pub fn extends_apple_aarch64(self) -> bool {
88        match self {
89            Self::AppleAarch64 => true,
90            _ => false,
91        }
92    }
93}
94
95impl fmt::Display for CallConv {
96    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
97        f.write_str(match *self {
98            Self::Fast => "fast",
99            Self::Cold => "cold",
100            Self::Tail => "tail",
101            Self::SystemV => "system_v",
102            Self::WindowsFastcall => "windows_fastcall",
103            Self::AppleAarch64 => "apple_aarch64",
104            Self::Probestack => "probestack",
105            Self::WasmtimeSystemV => "wasmtime_system_v",
106            Self::Winch => "winch",
107        })
108    }
109}
110
111impl str::FromStr for CallConv {
112    type Err = ();
113    fn from_str(s: &str) -> Result<Self, Self::Err> {
114        match s {
115            "fast" => Ok(Self::Fast),
116            "cold" => Ok(Self::Cold),
117            "tail" => Ok(Self::Tail),
118            "system_v" => Ok(Self::SystemV),
119            "windows_fastcall" => Ok(Self::WindowsFastcall),
120            "apple_aarch64" => Ok(Self::AppleAarch64),
121            "probestack" => Ok(Self::Probestack),
122            "wasmtime_system_v" => Ok(Self::WasmtimeSystemV),
123            "winch" => Ok(Self::Winch),
124            _ => Err(()),
125        }
126    }
127}
cranelift_codegen/isa/call_conv.rs

cranelift_codegen/isa/
call_conv.rs
