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Rollup merge of #124251 - scottmcm:unop-ptr-metadata, r=oli-obk

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Add an intrinsic for `ptr::metadata`

The follow-up to #123840, so we can remove `PtrComponents` and `PtrRepr` from libcore entirely (well, after a bootstrap update).

As discussed in <https://rust-lang.zulipchat.com/#narrow/stream/189540-t-compiler.2Fwg-mir-opt/topic/.60ptr_metadata.60.20in.20MIR/near/435637808>, this introduces `UnOp::PtrMetadata` taking a raw pointer and returning the associated metadata value.

By no longer going through a `union`, this should also help future PRs better optimize pointer operations.

r? ``@oli-obk``
This commit is contained in:
许杰友 Jieyou Xu (Joe) 2024-05-29 03:25:07 +01:00 committed by GitHub
commit db4dbc84a5
3 changed files with 34 additions and 14 deletions
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38
src/base.rs
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@ -616,22 +616,34 @@ fn codegen_stmt<'tcx>(
Rvalue::UnaryOp(un_op, ref operand) => {
let operand = codegen_operand(fx, operand);
let layout = operand.layout();
let val = operand.load_scalar(fx);
let res = match un_op {
UnOp::Not => match layout.ty.kind() {
ty::Bool => {
let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
CValue::by_val(res, layout)
UnOp::Not => {
let val = operand.load_scalar(fx);
match layout.ty.kind() {
ty::Bool => {
let res = fx.bcx.ins().icmp_imm(IntCC::Equal, val, 0);
CValue::by_val(res, layout)
}
ty::Uint(_) | ty::Int(_) => {
CValue::by_val(fx.bcx.ins().bnot(val), layout)
}
_ => unreachable!("un op Not for {:?}", layout.ty),
}
ty::Uint(_) | ty::Int(_) => {
CValue::by_val(fx.bcx.ins().bnot(val), layout)
}
UnOp::Neg => {
let val = operand.load_scalar(fx);
match layout.ty.kind() {
ty::Int(_) => CValue::by_val(fx.bcx.ins().ineg(val), layout),
ty::Float(_) => CValue::by_val(fx.bcx.ins().fneg(val), layout),
_ => unreachable!("un op Neg for {:?}", layout.ty),
}
_ => unreachable!("un op Not for {:?}", layout.ty),
},
UnOp::Neg => match layout.ty.kind() {
ty::Int(_) => CValue::by_val(fx.bcx.ins().ineg(val), layout),
ty::Float(_) => CValue::by_val(fx.bcx.ins().fneg(val), layout),
_ => unreachable!("un op Neg for {:?}", layout.ty),
}
UnOp::PtrMetadata => match layout.abi {
Abi::Scalar(_) => CValue::zst(dest_layout),
Abi::ScalarPair(_, _) => {
CValue::by_val(operand.load_scalar_pair(fx).1, dest_layout)
}
_ => bug!("Unexpected `PtrToMetadata` operand: {operand:?}"),
},
};
lval.write_cvalue(fx, res);

2
src/constant.rs
View File

@ -100,7 +100,7 @@ pub(crate) fn codegen_const_value<'tcx>(
assert!(layout.is_sized(), "unsized const value");
if layout.is_zst() {
return CValue::by_ref(crate::Pointer::dangling(layout.align.pref), layout);
return CValue::zst(layout);
}
match const_val {

8
src/value_and_place.rs
View File

@ -95,6 +95,14 @@ impl<'tcx> CValue<'tcx> {
CValue(CValueInner::ByValPair(value, extra), layout)
}
/// Create an instance of a ZST
///
/// The is represented by a dangling pointer of suitable alignment.
pub(crate) fn zst(layout: TyAndLayout<'tcx>) -> CValue<'tcx> {
assert!(layout.is_zst());
CValue::by_ref(crate::Pointer::dangling(layout.align.pref), layout)
}
pub(crate) fn layout(&self) -> TyAndLayout<'tcx> {
self.1
}