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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
use crate::NativeType;
use crate::{tcc::Compiler, Symbol};
use std::ffi::c_void;
use std::ffi::CString;
use std::fmt::Write as _;
pub(crate) struct Allocation {
pub addr: *mut c_void,
_ctx: Compiler,
_sym: Box<Symbol>,
}
macro_rules! cstr {
($st:expr) => {
&CString::new($st).unwrap()
};
}
fn native_arg_to_c(ty: &NativeType) -> &'static str {
match ty {
NativeType::U8 | NativeType::U16 | NativeType::U32 => "uint32_t",
NativeType::I8 | NativeType::I16 | NativeType::I32 => "int32_t",
NativeType::Void => "void",
NativeType::F32 => "float",
NativeType::F64 => "double",
_ => unimplemented!(),
}
}
fn native_to_c(ty: &NativeType) -> &'static str {
match ty {
NativeType::U8 => "uint8_t",
NativeType::U16 => "uint16_t",
NativeType::U32 => "uint32_t",
NativeType::I8 => "int8_t",
NativeType::I16 => "uint16_t",
NativeType::I32 => "int32_t",
NativeType::Void => "void",
NativeType::F32 => "float",
NativeType::F64 => "double",
_ => unimplemented!(),
}
}
pub(crate) fn codegen(sym: &crate::Symbol) -> String {
let mut c = String::from("#include <stdint.h>\n");
let ret = native_to_c(&sym.result_type);
// extern <return_type> func(
c += "\nextern ";
c += ret;
c += " func(";
// <param_type> p0, <param_type> p1, ...);
for (i, ty) in sym.parameter_types.iter().enumerate() {
if i > 0 {
c += ", ";
}
c += native_to_c(ty);
let _ = write!(c, " p{i}");
}
c += ");\n\n";
// void* recv, <param_type> p0, <param_type> p1, ...);
c += ret;
c += " func_trampoline(";
c += "void* recv";
for (i, ty) in sym.parameter_types.iter().enumerate() {
c += ", ";
c += native_arg_to_c(ty);
let _ = write!(c, " p{i}");
}
c += ") {\n";
// return func(p0, p1, ...);
c += " return func(";
for (i, _) in sym.parameter_types.iter().enumerate() {
if i > 0 {
c += ", ";
}
let _ = write!(c, "p{i}");
}
c += ");\n}\n\n";
c
}
pub(crate) fn gen_trampoline(
sym: Box<crate::Symbol>,
) -> Result<Box<Allocation>, ()> {
let mut ctx = Compiler::new()?;
ctx.set_options(cstr!("-nostdlib"));
// SAFETY: symbol satisfies ABI requirement.
unsafe { ctx.add_symbol(cstr!("func"), sym.ptr.0 as *const c_void) };
let c = codegen(&sym);
ctx.compile_string(cstr!(c))?;
let alloc = Allocation {
addr: ctx.relocate_and_get_symbol(cstr!("func_trampoline"))?,
_ctx: ctx,
_sym: sym,
};
Ok(Box::new(alloc))
}
#[cfg(test)]
mod tests {
use super::*;
use libffi::middle::Type;
use std::ptr::null_mut;
fn codegen(parameters: Vec<NativeType>, ret: NativeType) -> String {
let sym = Box::new(crate::Symbol {
cif: libffi::middle::Cif::new(vec![], Type::void()),
ptr: libffi::middle::CodePtr(null_mut()),
parameter_types: parameters,
result_type: ret,
can_callback: false,
});
super::codegen(&sym)
}
#[test]
fn test_gen_trampoline() {
assert_eq!(
codegen(vec![], NativeType::Void),
"#include <stdint.h>\n\nextern void func();\n\nvoid func_trampoline(void* recv) {\n return func();\n}\n\n"
);
assert_eq!(
codegen(vec![NativeType::U32, NativeType::U32], NativeType::U32),
"#include <stdint.h>\n\nextern uint32_t func(uint32_t p0, uint32_t p1);\n\nuint32_t func_trampoline(void* recv, uint32_t p0, uint32_t p1) {\n return func(p0, p1);\n}\n\n"
);
assert_eq!(
codegen(vec![NativeType::I32, NativeType::I32], NativeType::I32),
"#include <stdint.h>\n\nextern int32_t func(int32_t p0, int32_t p1);\n\nint32_t func_trampoline(void* recv, int32_t p0, int32_t p1) {\n return func(p0, p1);\n}\n\n"
);
assert_eq!(
codegen(vec![NativeType::F32, NativeType::F32], NativeType::F32),
"#include <stdint.h>\n\nextern float func(float p0, float p1);\n\nfloat func_trampoline(void* recv, float p0, float p1) {\n return func(p0, p1);\n}\n\n"
);
assert_eq!(
codegen(vec![NativeType::F64, NativeType::F64], NativeType::F64),
"#include <stdint.h>\n\nextern double func(double p0, double p1);\n\ndouble func_trampoline(void* recv, double p0, double p1) {\n return func(p0, p1);\n}\n\n"
);
}
#[test]
fn test_gen_trampoline_implicit_cast() {
assert_eq!(
codegen(vec![NativeType::I8, NativeType::U8], NativeType::I8),
"#include <stdint.h>\n\nextern int8_t func(int8_t p0, uint8_t p1);\n\nint8_t func_trampoline(void* recv, int32_t p0, uint32_t p1) {\n return func(p0, p1);\n}\n\n"
)
}
}
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