1 use crate::settings::{self, LibcallCallConv};
2 use core::fmt;
3 use core::str;
4 use target_lexicon::{CallingConvention, Triple};
5 
6 #[cfg(feature = "enable-serde")]
7 use serde::{Deserialize, Serialize};
8 
9 /// Calling convention identifiers.
10 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
11 #[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
12 pub enum CallConv {
13     /// Best performance, not ABI-stable.
14     Fast,
15     /// Smallest caller code size, not ABI-stable.
16     Cold,
17     /// System V-style convention used on many platforms.
18     SystemV,
19     /// Windows "fastcall" convention, also used for x64 and ARM.
20     WindowsFastcall,
21     /// Mac aarch64 calling convention, which is a tweaked aarch64 ABI.
22     AppleAarch64,
23     /// Specialized convention for the probestack function.
24     Probestack,
25     /// Wasmtime equivalent of SystemV, not ABI-stable.
26     ///
27     /// Currently only differs in how multiple return values are handled,
28     /// returning the first return value in a register and everything else
29     /// through a return-pointer.
30     WasmtimeSystemV,
31     /// Wasmtime equivalent of WindowsFastcall, not ABI-stable.
32     ///
33     /// Differs from fastcall in the same way as `WasmtimeSystemV`.
34     WasmtimeFastcall,
35     /// Wasmtime equivalent of AppleAarch64, not ABI-stable.
36     ///
37     /// Differs from apple-aarch64 in the same way as `WasmtimeSystemV`.
38     WasmtimeAppleAarch64,
39 }
40 
41 impl CallConv {
42     /// Return the default calling convention for the given target triple.
43     pub fn triple_default(triple: &Triple) -> Self {
44         match triple.default_calling_convention() {
45             // Default to System V for unknown targets because most everything
46             // uses System V.
47             Ok(CallingConvention::SystemV) | Err(()) => Self::SystemV,
48             Ok(CallingConvention::AppleAarch64) => Self::AppleAarch64,
49             Ok(CallingConvention::WindowsFastcall) => Self::WindowsFastcall,
50             Ok(unimp) => unimplemented!("calling convention: {:?}", unimp),
51         }
52     }
53 
54     /// Returns the calling convention used for libcalls according to the current flags.
55     pub fn for_libcall(flags: &settings::Flags, default_call_conv: CallConv) -> Self {
56         match flags.libcall_call_conv() {
57             LibcallCallConv::IsaDefault => default_call_conv,
58             LibcallCallConv::Fast => Self::Fast,
59             LibcallCallConv::Cold => Self::Cold,
60             LibcallCallConv::SystemV => Self::SystemV,
61             LibcallCallConv::WindowsFastcall => Self::WindowsFastcall,
62             LibcallCallConv::AppleAarch64 => Self::AppleAarch64,
63             LibcallCallConv::Probestack => Self::Probestack,
64         }
65     }
66 
67     /// Is the calling convention extending the Windows Fastcall ABI?
68     pub fn extends_windows_fastcall(self) -> bool {
69         match self {
70             Self::WindowsFastcall | Self::WasmtimeFastcall => true,
71             _ => false,
72         }
73     }
74 
75     /// Is the calling convention extending the Apple aarch64 ABI?
76     pub fn extends_apple_aarch64(self) -> bool {
77         match self {
78             Self::AppleAarch64 | Self::WasmtimeAppleAarch64 => true,
79             _ => false,
80         }
81     }
82 
83     /// Is the calling convention extending the Wasmtime ABI?
84     pub fn extends_wasmtime(self) -> bool {
85         match self {
86             Self::WasmtimeSystemV | Self::WasmtimeFastcall | Self::WasmtimeAppleAarch64 => true,
87             _ => false,
88         }
89     }
90 }
91 
92 impl fmt::Display for CallConv {
93     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
94         f.write_str(match *self {
95             Self::Fast => "fast",
96             Self::Cold => "cold",
97             Self::SystemV => "system_v",
98             Self::WindowsFastcall => "windows_fastcall",
99             Self::AppleAarch64 => "apple_aarch64",
100             Self::Probestack => "probestack",
101             Self::WasmtimeSystemV => "wasmtime_system_v",
102             Self::WasmtimeFastcall => "wasmtime_fastcall",
103             Self::WasmtimeAppleAarch64 => "wasmtime_apple_aarch64",
104         })
105     }
106 }
107 
108 impl str::FromStr for CallConv {
109     type Err = ();
110     fn from_str(s: &str) -> Result<Self, Self::Err> {
111         match s {
112             "fast" => Ok(Self::Fast),
113             "cold" => Ok(Self::Cold),
114             "system_v" => Ok(Self::SystemV),
115             "windows_fastcall" => Ok(Self::WindowsFastcall),
116             "apple_aarch64" => Ok(Self::AppleAarch64),
117             "probestack" => Ok(Self::Probestack),
118             "wasmtime_system_v" => Ok(Self::WasmtimeSystemV),
119             "wasmtime_fastcall" => Ok(Self::WasmtimeFastcall),
120             "wasmtime_apple_aarch64" => Ok(Self::WasmtimeAppleAarch64),
121             _ => Err(()),
122         }
123     }
124 }
125