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refactor handling of diverging intrinsics/foreign functions

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This commit is contained in:
Ralf Jung 2020-03-12 21:20:16 +01:00
parent 5531a79f4c
commit 13ae3147f0
2 changed files with 40 additions and 40 deletions
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55
src/shims/foreign_items.rs
View File

@ -127,9 +127,31 @@ fn emulate_foreign_item(
let tcx = &{ this.tcx.tcx };
// First: functions that diverge.
let (dest, ret) = match link_name {
// Note that this matches calls to the *foreign* item `__rust_start_panic* -
// that is, calls to `extern "Rust" { fn __rust_start_panic(...) }`.
let (dest, ret) = match ret {
None => match link_name {
// This matches calls to the foreign item `panic_impl`.
// The implementation is provided by the function with the `#[panic_handler]` attribute.
"panic_impl" => {
let panic_impl_id = this.tcx.lang_items().panic_impl().unwrap();
let panic_impl_instance = ty::Instance::mono(*this.tcx, panic_impl_id);
return Ok(Some(&*this.load_mir(panic_impl_instance.def, None)?));
}
| "exit"
| "ExitProcess"
=> {
// it's really u32 for ExitProcess, but we have to put it into the `Exit` variant anyway
let code = this.read_scalar(args[0])?.to_i32()?;
throw_machine_stop!(TerminationInfo::Exit(code.into()));
}
_ => throw_unsup_format!("can't call (diverging) foreign function: {}", link_name),
},
Some(p) => p,
};
// Second: some functions that we forward to MIR implementations.
match link_name {
// This matches calls to the *foreign* item `__rust_start_panic*, that is,
// calls to `extern "Rust" { fn __rust_start_panic(...) }`.
// We forward this to the underlying *implementation* in the panic runtime crate.
// Normally, this will be either `libpanic_unwind` or `libpanic_abort`, but it could
// also be a custom user-provided implementation via `#![feature(panic_runtime)]`
@ -145,31 +167,10 @@ fn emulate_foreign_item(
this.resolve_path(&[&*panic_runtime.as_str(), "__rust_start_panic"])?;
return Ok(Some(&*this.load_mir(start_panic_instance.def, None)?));
}
// Similarly, we forward calls to the `panic_impl` foreign item to its implementation.
// The implementation is provided by the function with the `#[panic_handler]` attribute.
"panic_impl" => {
let panic_impl_id = this.tcx.lang_items().panic_impl().unwrap();
let panic_impl_instance = ty::Instance::mono(*this.tcx, panic_impl_id);
return Ok(Some(&*this.load_mir(panic_impl_instance.def, None)?));
}
_ => {}
}
| "exit"
| "ExitProcess"
=> {
// it's really u32 for ExitProcess, but we have to put it into the `Exit` variant anyway
let code = this.read_scalar(args[0])?.to_i32()?;
throw_machine_stop!(TerminationInfo::Exit(code.into()));
}
_ => {
if let Some(p) = ret {
p
} else {
throw_unsup_format!("can't call (diverging) foreign function: {}", link_name);
}
}
};
// Next: functions that return.
// Third: functions that return.
if this.emulate_foreign_item_by_name(link_name, args, dest, ret)? {
this.dump_place(*dest);
this.go_to_block(ret);

25
src/shims/intrinsics.rs
View File

@ -31,22 +31,21 @@ fn call_intrinsic(
// that might still hang around!
let intrinsic_name = &*tcx.item_name(instance.def_id()).as_str();
// Handle diverging intrinsics.
let (dest, ret) = match intrinsic_name {
"abort" => {
// FIXME: remove, once the intrinsic on the rustc side is fixed.
throw_machine_stop!(TerminationInfo::Abort);
}
"miri_start_panic" => return this.handle_miri_start_panic(args, unwind),
_ =>
if let Some(p) = ret {
p
} else {
throw_unsup_format!("unimplemented (diverging) intrinsic: {}", intrinsic_name);
},
// First handle intrinsics without return place.
let (dest, ret) = match ret {
None => match intrinsic_name {
"abort" => {
// FIXME: remove, once the intrinsic on the rustc side is fixed.
throw_machine_stop!(TerminationInfo::Abort);
}
_ => throw_unsup_format!("unimplemented (diverging) intrinsic: {}", intrinsic_name),
},
Some(p) => p,
};
match intrinsic_name {
"miri_start_panic" => return this.handle_miri_start_panic(args, unwind),
"arith_offset" => {
let offset = this.read_scalar(args[1])?.to_machine_isize(this)?;
let ptr = this.read_scalar(args[0])?.not_undef()?;