also do not add noalias on not-Unpin Box
This commit is contained in:
Ralf Jung
parent
ea541bc2ee
commit
1ef16874b5
6 changed files with 183 additions and 119 deletions
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@ -818,110 +818,114 @@ where
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let tcx = cx.tcx();
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let param_env = cx.param_env();
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let pointee_info =
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match *this.ty.kind() {
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ty::RawPtr(mt) if offset.bytes() == 0 => {
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tcx.layout_of(param_env.and(mt.ty)).ok().map(|layout| PointeeInfo {
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size: layout.size,
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align: layout.align.abi,
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safe: None,
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})
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}
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ty::FnPtr(fn_sig) if offset.bytes() == 0 => {
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tcx.layout_of(param_env.and(tcx.mk_fn_ptr(fn_sig))).ok().map(|layout| {
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PointeeInfo { size: layout.size, align: layout.align.abi, safe: None }
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})
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}
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ty::Ref(_, ty, mt) if offset.bytes() == 0 => {
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// Use conservative pointer kind if not optimizing. This saves us the
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// Freeze/Unpin queries, and can save time in the codegen backend (noalias
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// attributes in LLVM have compile-time cost even in unoptimized builds).
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let optimize = tcx.sess.opts.optimize != OptLevel::No;
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let kind = match mt {
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hir::Mutability::Not => PointerKind::SharedRef {
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frozen: optimize && ty.is_freeze(tcx, cx.param_env()),
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},
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hir::Mutability::Mut => PointerKind::MutableRef {
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unpin: optimize && ty.is_unpin(tcx, cx.param_env()),
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},
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};
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let pointee_info = match *this.ty.kind() {
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ty::RawPtr(mt) if offset.bytes() == 0 => {
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tcx.layout_of(param_env.and(mt.ty)).ok().map(|layout| PointeeInfo {
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size: layout.size,
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align: layout.align.abi,
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safe: None,
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})
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}
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ty::FnPtr(fn_sig) if offset.bytes() == 0 => {
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tcx.layout_of(param_env.and(tcx.mk_fn_ptr(fn_sig))).ok().map(|layout| PointeeInfo {
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size: layout.size,
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align: layout.align.abi,
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safe: None,
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})
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}
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ty::Ref(_, ty, mt) if offset.bytes() == 0 => {
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// Use conservative pointer kind if not optimizing. This saves us the
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// Freeze/Unpin queries, and can save time in the codegen backend (noalias
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// attributes in LLVM have compile-time cost even in unoptimized builds).
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let optimize = tcx.sess.opts.optimize != OptLevel::No;
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let kind = match mt {
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hir::Mutability::Not => PointerKind::SharedRef {
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frozen: optimize && ty.is_freeze(tcx, cx.param_env()),
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},
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hir::Mutability::Mut => PointerKind::MutableRef {
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unpin: optimize && ty.is_unpin(tcx, cx.param_env()),
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},
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};
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tcx.layout_of(param_env.and(ty)).ok().map(|layout| PointeeInfo {
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size: layout.size,
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align: layout.align.abi,
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safe: Some(kind),
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})
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}
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tcx.layout_of(param_env.and(ty)).ok().map(|layout| PointeeInfo {
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size: layout.size,
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align: layout.align.abi,
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safe: Some(kind),
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})
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}
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_ => {
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let mut data_variant = match this.variants {
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// Within the discriminant field, only the niche itself is
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// always initialized, so we only check for a pointer at its
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// offset.
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//
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// If the niche is a pointer, it's either valid (according
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// to its type), or null (which the niche field's scalar
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// validity range encodes). This allows using
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// `dereferenceable_or_null` for e.g., `Option<&T>`, and
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// this will continue to work as long as we don't start
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// using more niches than just null (e.g., the first page of
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// the address space, or unaligned pointers).
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Variants::Multiple {
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tag_encoding: TagEncoding::Niche { untagged_variant, .. },
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tag_field,
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..
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} if this.fields.offset(tag_field) == offset => {
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Some(this.for_variant(cx, untagged_variant))
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}
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_ => Some(this),
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};
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if let Some(variant) = data_variant {
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// We're not interested in any unions.
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if let FieldsShape::Union(_) = variant.fields {
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data_variant = None;
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}
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_ => {
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let mut data_variant = match this.variants {
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// Within the discriminant field, only the niche itself is
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// always initialized, so we only check for a pointer at its
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// offset.
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//
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// If the niche is a pointer, it's either valid (according
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// to its type), or null (which the niche field's scalar
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// validity range encodes). This allows using
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// `dereferenceable_or_null` for e.g., `Option<&T>`, and
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// this will continue to work as long as we don't start
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// using more niches than just null (e.g., the first page of
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// the address space, or unaligned pointers).
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Variants::Multiple {
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tag_encoding: TagEncoding::Niche { untagged_variant, .. },
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tag_field,
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..
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} if this.fields.offset(tag_field) == offset => {
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Some(this.for_variant(cx, untagged_variant))
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}
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_ => Some(this),
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};
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let mut result = None;
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if let Some(variant) = data_variant {
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// We're not interested in any unions.
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if let FieldsShape::Union(_) = variant.fields {
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data_variant = None;
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}
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}
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if let Some(variant) = data_variant {
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// FIXME(erikdesjardins): handle non-default addrspace ptr sizes
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// (requires passing in the expected address space from the caller)
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let ptr_end = offset + Pointer(AddressSpace::DATA).size(cx);
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for i in 0..variant.fields.count() {
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let field_start = variant.fields.offset(i);
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if field_start <= offset {
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let field = variant.field(cx, i);
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result = field.to_result().ok().and_then(|field| {
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if ptr_end <= field_start + field.size {
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// We found the right field, look inside it.
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let field_info =
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field.pointee_info_at(cx, offset - field_start);
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field_info
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} else {
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None
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}
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});
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if result.is_some() {
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break;
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let mut result = None;
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if let Some(variant) = data_variant {
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// FIXME(erikdesjardins): handle non-default addrspace ptr sizes
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// (requires passing in the expected address space from the caller)
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let ptr_end = offset + Pointer(AddressSpace::DATA).size(cx);
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for i in 0..variant.fields.count() {
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let field_start = variant.fields.offset(i);
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if field_start <= offset {
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let field = variant.field(cx, i);
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result = field.to_result().ok().and_then(|field| {
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if ptr_end <= field_start + field.size {
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// We found the right field, look inside it.
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let field_info =
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field.pointee_info_at(cx, offset - field_start);
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field_info
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} else {
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None
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}
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});
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if result.is_some() {
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break;
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}
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}
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}
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// FIXME(eddyb) This should be for `ptr::Unique<T>`, not `Box<T>`.
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if let Some(ref mut pointee) = result {
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if let ty::Adt(def, _) = this.ty.kind() {
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if def.is_box() && offset.bytes() == 0 {
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pointee.safe = Some(PointerKind::Box);
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}
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}
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}
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result
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}
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};
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// FIXME(eddyb) This should be for `ptr::Unique<T>`, not `Box<T>`.
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if let Some(ref mut pointee) = result {
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if let ty::Adt(def, _) = this.ty.kind() {
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if def.is_box() && offset.bytes() == 0 {
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let optimize = tcx.sess.opts.optimize != OptLevel::No;
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pointee.safe = Some(PointerKind::Box {
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unpin: optimize && this.ty.boxed_ty().is_unpin(tcx, cx.param_env()),
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});
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}
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}
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}
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result
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}
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};
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debug!(
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"pointee_info_at (offset={:?}, type kind: {:?}) => {:?}",
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