bjoernager/rust
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Clarify Layout interning.

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`Layout` is another type that is sometimes interned, sometimes not, and
we always use references to refer to it so we can't take any advantage
of the uniqueness properties for hashing or equality checks.

This commit renames `Layout` as `LayoutS`, and then introduces a new
`Layout` that is a newtype around an `Interned<LayoutS>`. It also
interns more layouts than before. Previously layouts within layouts
(via the `variants` field) were never interned, but now they are. Hence
the lifetime on the new `Layout` type.

Unlike other interned types, these ones are in `rustc_target` instead of
`rustc_middle`. This reflects the existing structure of the code, which
does layout-specific stuff in `rustc_target` while `TyAndLayout` is
generic over the `Ty`, allowing the type-specific stuff to occur in
`rustc_middle`.

The commit also adds a `HashStable` impl for `Interned`, which was
needed. It hashes the contents, unlike the `Hash` impl which hashes the
pointer.
This commit is contained in:
Nicholas Nethercote 2022-03-04 13:46:56 +11:00
parent 8876ca3dd4
commit 4f008e06c3
17 changed files with 177 additions and 87 deletions
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14
compiler/rustc_codegen_llvm/src/intrinsic.rs
View file

@ -300,34 +300,34 @@ impl<'ll, 'tcx> IntrinsicCallMethods<'tcx> for Builder<'_, 'll, 'tcx> {
use abi::Abi::*;
let tp_ty = substs.type_at(0);
let layout = self.layout_of(tp_ty).layout;
let use_integer_compare = match layout.abi {
let use_integer_compare = match layout.abi() {
Scalar(_) | ScalarPair(_, _) => true,
Uninhabited | Vector { .. } => false,
Aggregate { .. } => {
// For rusty ABIs, small aggregates are actually passed
// as `RegKind::Integer` (see `FnAbi::adjust_for_abi`),
// so we re-use that same threshold here.
layout.size <= self.data_layout().pointer_size * 2
layout.size() <= self.data_layout().pointer_size * 2
}
};
let a = args[0].immediate();
let b = args[1].immediate();
if layout.size.bytes() == 0 {
if layout.size().bytes() == 0 {
self.const_bool(true)
} else if use_integer_compare {
let integer_ty = self.type_ix(layout.size.bits());
let integer_ty = self.type_ix(layout.size().bits());
let ptr_ty = self.type_ptr_to(integer_ty);
let a_ptr = self.bitcast(a, ptr_ty);
let a_val = self.load(integer_ty, a_ptr, layout.align.abi);
let a_val = self.load(integer_ty, a_ptr, layout.align().abi);
let b_ptr = self.bitcast(b, ptr_ty);
let b_val = self.load(integer_ty, b_ptr, layout.align.abi);
let b_val = self.load(integer_ty, b_ptr, layout.align().abi);
self.icmp(IntPredicate::IntEQ, a_val, b_val)
} else {
let i8p_ty = self.type_i8p();
let a_ptr = self.bitcast(a, i8p_ty);
let b_ptr = self.bitcast(b, i8p_ty);
let n = self.const_usize(layout.size.bytes());
let n = self.const_usize(layout.size().bytes());
let cmp = self.call_intrinsic("memcmp", &[a_ptr, b_ptr, n]);
self.icmp(IntPredicate::IntEQ, cmp, self.const_i32(0))
}