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Rollup merge of #100887 - eholk:codegen_call_terminator-cleanup, r=fee1-dead

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Refactor part of codegen_call_terminator

I was reading through this code and found the chain of `if let` and a nested match on the same value that was matched in the `if let` to be kind of hard to follow. This PR cleans it up by flattening the `if let` chain and nested match into a single `match` expression.
This commit is contained in:
Matthias Krüger 2022-08-23 06:55:30 +02:00 committed by GitHub
commit 234e0f27c2
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1 changed files with 44 additions and 47 deletions
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91
compiler/rustc_codegen_ssa/src/mir/block.rs
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@ -798,58 +798,55 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
let mut op = self.codegen_operand(&mut bx, arg);
if let (0, Some(ty::InstanceDef::Virtual(_, idx))) = (i, def) {
if let Pair(..) = op.val {
// In the case of Rc<Self>, we need to explicitly pass a
// *mut RcBox<Self> with a Scalar (not ScalarPair) ABI. This is a hack
// that is understood elsewhere in the compiler as a method on
// `dyn Trait`.
// To get a `*mut RcBox<Self>`, we just keep unwrapping newtypes until
// we get a value of a built-in pointer type
'descend_newtypes: while !op.layout.ty.is_unsafe_ptr()
&& !op.layout.ty.is_region_ptr()
{
for i in 0..op.layout.fields.count() {
let field = op.extract_field(&mut bx, i);
if !field.layout.is_zst() {
// we found the one non-zero-sized field that is allowed
// now find *its* non-zero-sized field, or stop if it's a
// pointer
op = field;
continue 'descend_newtypes;
match op.val {
Pair(data_ptr, meta) => {
// In the case of Rc<Self>, we need to explicitly pass a
// *mut RcBox<Self> with a Scalar (not ScalarPair) ABI. This is a hack
// that is understood elsewhere in the compiler as a method on
// `dyn Trait`.
// To get a `*mut RcBox<Self>`, we just keep unwrapping newtypes until
// we get a value of a built-in pointer type
'descend_newtypes: while !op.layout.ty.is_unsafe_ptr()
&& !op.layout.ty.is_region_ptr()
{
for i in 0..op.layout.fields.count() {
let field = op.extract_field(&mut bx, i);
if !field.layout.is_zst() {
// we found the one non-zero-sized field that is allowed
// now find *its* non-zero-sized field, or stop if it's a
// pointer
op = field;
continue 'descend_newtypes;
}
}
span_bug!(span, "receiver has no non-zero-sized fields {:?}", op);
}
span_bug!(span, "receiver has no non-zero-sized fields {:?}", op);
// now that we have `*dyn Trait` or `&dyn Trait`, split it up into its
// data pointer and vtable. Look up the method in the vtable, and pass
// the data pointer as the first argument
llfn = Some(meth::VirtualIndex::from_index(idx).get_fn(
&mut bx,
meta,
op.layout.ty,
&fn_abi,
));
llargs.push(data_ptr);
continue 'make_args;
}
// now that we have `*dyn Trait` or `&dyn Trait`, split it up into its
// data pointer and vtable. Look up the method in the vtable, and pass
// the data pointer as the first argument
match op.val {
Pair(data_ptr, meta) => {
llfn = Some(meth::VirtualIndex::from_index(idx).get_fn(
&mut bx,
meta,
op.layout.ty,
&fn_abi,
));
llargs.push(data_ptr);
continue 'make_args;
}
other => bug!("expected a Pair, got {:?}", other),
Ref(data_ptr, Some(meta), _) => {
// by-value dynamic dispatch
llfn = Some(meth::VirtualIndex::from_index(idx).get_fn(
&mut bx,
meta,
op.layout.ty,
&fn_abi,
));
llargs.push(data_ptr);
continue;
}
} else if let Ref(data_ptr, Some(meta), _) = op.val {
// by-value dynamic dispatch
llfn = Some(meth::VirtualIndex::from_index(idx).get_fn(
&mut bx,
meta,
op.layout.ty,
&fn_abi,
));
llargs.push(data_ptr);
continue;
} else {
span_bug!(span, "can't codegen a virtual call on {:?}", op);
_ => span_bug!(span, "can't codegen a virtual call on {:?}", op),
}
}