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Panic for size_of_val and align_of_val of extern type
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cc rust-lang/rust#118534
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@bjorn3
bjorn3 committed Dec 18, 2023
1 parent b1c925b commit fdcf56c
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Showing 4 changed files with 85 additions and 58 deletions.
16 changes: 8 additions & 8 deletions src/base.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -353,7 +353,7 @@ fn codegen_fn_body(fx: &mut FunctionCx<'_, '_, '_>, start_block: Block) {
fx,
rustc_hir::LangItem::PanicBoundsCheck,
&[index, len, location],
source_info.span,
Some(source_info.span),
);
}
AssertKind::MisalignedPointerDereference { ref required, ref found } => {
Expand All @@ -365,7 +365,7 @@ fn codegen_fn_body(fx: &mut FunctionCx<'_, '_, '_>, start_block: Block) {
fx,
rustc_hir::LangItem::PanicMisalignedPointerDereference,
&[required, found, location],
source_info.span,
Some(source_info.span),
);
}
_ => {
Expand Down Expand Up @@ -945,19 +945,19 @@ pub(crate) fn codegen_panic<'tcx>(
let msg_len = fx.bcx.ins().iconst(fx.pointer_type, i64::try_from(msg_str.len()).unwrap());
let args = [msg_ptr, msg_len, location];

codegen_panic_inner(fx, rustc_hir::LangItem::Panic, &args, source_info.span);
codegen_panic_inner(fx, rustc_hir::LangItem::Panic, &args, Some(source_info.span));
}

pub(crate) fn codegen_panic_nounwind<'tcx>(
fx: &mut FunctionCx<'_, '_, 'tcx>,
msg_str: &str,
source_info: mir::SourceInfo,
span: Option<Span>,
) {
let msg_ptr = fx.anonymous_str(msg_str);
let msg_len = fx.bcx.ins().iconst(fx.pointer_type, i64::try_from(msg_str.len()).unwrap());
let args = [msg_ptr, msg_len];

codegen_panic_inner(fx, rustc_hir::LangItem::PanicNounwind, &args, source_info.span);
codegen_panic_inner(fx, rustc_hir::LangItem::PanicNounwind, &args, span);
}

pub(crate) fn codegen_unwind_terminate<'tcx>(
Expand All @@ -967,16 +967,16 @@ pub(crate) fn codegen_unwind_terminate<'tcx>(
) {
let args = [];

codegen_panic_inner(fx, reason.lang_item(), &args, source_info.span);
codegen_panic_inner(fx, reason.lang_item(), &args, Some(source_info.span));
}

fn codegen_panic_inner<'tcx>(
fx: &mut FunctionCx<'_, '_, 'tcx>,
lang_item: rustc_hir::LangItem,
args: &[Value],
span: Span,
span: Option<Span>,
) {
let def_id = fx.tcx.require_lang_item(lang_item, Some(span));
let def_id = fx.tcx.require_lang_item(lang_item, span);

let instance = Instance::mono(fx.tcx, def_id).polymorphize(fx.tcx);
let symbol_name = fx.tcx.symbol_name(instance).name;
Expand Down
20 changes: 9 additions & 11 deletions src/intrinsics/mod.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -487,13 +487,12 @@ fn codegen_regular_intrinsic_call<'tcx>(
let layout = fx.layout_of(generic_args.type_at(0));
// Note: Can't use is_unsized here as truly unsized types need to take the fixed size
// branch
let size = if let Abi::ScalarPair(_, _) = ptr.layout().abi {
let (_ptr, info) = ptr.load_scalar_pair(fx);
let (size, _align) = crate::unsize::size_and_align_of_dst(fx, layout, info);
size
let meta = if let Abi::ScalarPair(_, _) = ptr.layout().abi {
Some(ptr.load_scalar_pair(fx).1)
} else {
fx.bcx.ins().iconst(fx.pointer_type, layout.size.bytes() as i64)
None
};
let (size, _align) = crate::unsize::size_and_align_of(fx, layout, meta);
ret.write_cvalue(fx, CValue::by_val(size, usize_layout));
}
sym::min_align_of_val => {
Expand All @@ -502,13 +501,12 @@ fn codegen_regular_intrinsic_call<'tcx>(
let layout = fx.layout_of(generic_args.type_at(0));
// Note: Can't use is_unsized here as truly unsized types need to take the fixed size
// branch
let align = if let Abi::ScalarPair(_, _) = ptr.layout().abi {
let (_ptr, info) = ptr.load_scalar_pair(fx);
let (_size, align) = crate::unsize::size_and_align_of_dst(fx, layout, info);
align
let meta = if let Abi::ScalarPair(_, _) = ptr.layout().abi {
Some(ptr.load_scalar_pair(fx).1)
} else {
fx.bcx.ins().iconst(fx.pointer_type, layout.align.abi.bytes() as i64)
None
};
let (_size, align) = crate::unsize::size_and_align_of(fx, layout, meta);
ret.write_cvalue(fx, CValue::by_val(align, usize_layout));
}

Expand Down Expand Up @@ -688,7 +686,7 @@ fn codegen_regular_intrinsic_call<'tcx>(
}
})
});
crate::base::codegen_panic_nounwind(fx, &msg_str, source_info);
crate::base::codegen_panic_nounwind(fx, &msg_str, Some(source_info.span));
return;
}
}
Expand Down
55 changes: 47 additions & 8 deletions src/unsize.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,9 @@
//!
//! [`PointerCoercion::Unsize`]: `rustc_middle::ty::adjustment::PointerCoercion::Unsize`
use rustc_middle::ty::print::{with_no_trimmed_paths, with_no_visible_paths};

use crate::base::codegen_panic_nounwind;
use crate::prelude::*;

// Adapted from https://github.com/rust-lang/rust/blob/2a663555ddf36f6b041445894a8c175cd1bc718c/src/librustc_codegen_ssa/base.rs#L159-L307
Expand Down Expand Up @@ -187,27 +190,62 @@ pub(crate) fn coerce_dyn_star<'tcx>(

// Adapted from https://github.com/rust-lang/rust/blob/2a663555ddf36f6b041445894a8c175cd1bc718c/src/librustc_codegen_ssa/glue.rs

pub(crate) fn size_and_align_of_dst<'tcx>(
pub(crate) fn size_and_align_of<'tcx>(
fx: &mut FunctionCx<'_, '_, 'tcx>,
layout: TyAndLayout<'tcx>,
info: Value,
info: Option<Value>,
) -> (Value, Value) {
assert!(layout.is_unsized() || layout.abi == Abi::Uninhabited);
match layout.ty.kind() {
if layout.is_sized() {
return (
fx.bcx.ins().iconst(fx.pointer_type, layout.size.bytes() as i64),
fx.bcx.ins().iconst(fx.pointer_type, layout.align.abi.bytes() as i64),
);
}

let ty = layout.ty;
match ty.kind() {
ty::Dynamic(..) => {
// load size/align from vtable
(crate::vtable::size_of_obj(fx, info), crate::vtable::min_align_of_obj(fx, info))
(
crate::vtable::size_of_obj(fx, info.unwrap()),
crate::vtable::min_align_of_obj(fx, info.unwrap()),
)
}
ty::Slice(_) | ty::Str => {
let unit = layout.field(fx, 0);
// The info in this case is the length of the str, so the size is that
// times the unit size.
(
fx.bcx.ins().imul_imm(info, unit.size.bytes() as i64),
fx.bcx.ins().imul_imm(info.unwrap(), unit.size.bytes() as i64),
fx.bcx.ins().iconst(fx.pointer_type, unit.align.abi.bytes() as i64),
)
}
_ => {
ty::Foreign(_) => {
let trap_block = fx.bcx.create_block();
let true_ = fx.bcx.ins().iconst(types::I8, 1);
let next_block = fx.bcx.create_block();
fx.bcx.ins().brif(true_, trap_block, &[], next_block, &[]);
fx.bcx.seal_block(trap_block);
fx.bcx.seal_block(next_block);
fx.bcx.switch_to_block(trap_block);

// `extern` type. We cannot compute the size, so panic.
let msg_str = with_no_visible_paths!({
with_no_trimmed_paths!({
format!("attempted to compute the size or alignment of extern type `{ty}`")
})
});

codegen_panic_nounwind(fx, &msg_str, None);

fx.bcx.switch_to_block(next_block);

// This function does not return so we can now return whatever we want.
let size = fx.bcx.ins().iconst(fx.pointer_type, 42);
let align = fx.bcx.ins().iconst(fx.pointer_type, 42);
(size, align)
}
ty::Adt(..) | ty::Tuple(..) => {
// First get the size of all statically known fields.
// Don't use size_of because it also rounds up to alignment, which we
// want to avoid, as the unsized field's alignment could be smaller.
Expand All @@ -221,7 +259,7 @@ pub(crate) fn size_and_align_of_dst<'tcx>(
// Recurse to get the size of the dynamically sized field (must be
// the last field).
let field_layout = layout.field(fx, i);
let (unsized_size, mut unsized_align) = size_and_align_of_dst(fx, field_layout, info);
let (unsized_size, mut unsized_align) = size_and_align_of(fx, field_layout, info);

// FIXME (#26403, #27023): We should be adding padding
// to `sized_size` (to accommodate the `unsized_align`
Expand Down Expand Up @@ -262,5 +300,6 @@ pub(crate) fn size_and_align_of_dst<'tcx>(

(size, align)
}
_ => bug!("size_and_align_of_dst: {ty} not supported"),
}
}
52 changes: 21 additions & 31 deletions src/value_and_place.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -20,34 +20,29 @@ fn codegen_field<'tcx>(
(base.offset_i64(fx, i64::try_from(field_offset.bytes()).unwrap()), field_layout)
};

if let Some(extra) = extra {
if field_layout.is_sized() {
return simple(fx);
if field_layout.is_sized() {
return simple(fx);
}
match field_layout.ty.kind() {
ty::Slice(..) | ty::Str => simple(fx),
ty::Adt(def, _) if def.repr().packed() => {
assert_eq!(layout.align.abi.bytes(), 1);
simple(fx)
}
match field_layout.ty.kind() {
ty::Slice(..) | ty::Str | ty::Foreign(..) => simple(fx),
ty::Adt(def, _) if def.repr().packed() => {
assert_eq!(layout.align.abi.bytes(), 1);
simple(fx)
}
_ => {
// We have to align the offset for DST's
let unaligned_offset = field_offset.bytes();
let (_, unsized_align) =
crate::unsize::size_and_align_of_dst(fx, field_layout, extra);
_ => {
// We have to align the offset for DST's
let unaligned_offset = field_offset.bytes();
let (_, unsized_align) = crate::unsize::size_and_align_of(fx, field_layout, extra);

let one = fx.bcx.ins().iconst(fx.pointer_type, 1);
let align_sub_1 = fx.bcx.ins().isub(unsized_align, one);
let and_lhs = fx.bcx.ins().iadd_imm(align_sub_1, unaligned_offset as i64);
let zero = fx.bcx.ins().iconst(fx.pointer_type, 0);
let and_rhs = fx.bcx.ins().isub(zero, unsized_align);
let offset = fx.bcx.ins().band(and_lhs, and_rhs);
let one = fx.bcx.ins().iconst(fx.pointer_type, 1);
let align_sub_1 = fx.bcx.ins().isub(unsized_align, one);
let and_lhs = fx.bcx.ins().iadd_imm(align_sub_1, unaligned_offset as i64);
let zero = fx.bcx.ins().iconst(fx.pointer_type, 0);
let and_rhs = fx.bcx.ins().isub(zero, unsized_align);
let offset = fx.bcx.ins().band(and_lhs, and_rhs);

(base.offset_value(fx, offset), field_layout)
}
(base.offset_value(fx, offset), field_layout)
}
} else {
simple(fx)
}
}

Expand Down Expand Up @@ -731,13 +726,8 @@ impl<'tcx> CPlace<'tcx> {
};

let (field_ptr, field_layout) = codegen_field(fx, base, extra, layout, field);
if field_layout.is_unsized() {
if let ty::Foreign(_) = field_layout.ty.kind() {
assert!(extra.is_none());
CPlace::for_ptr(field_ptr, field_layout)
} else {
CPlace::for_ptr_with_extra(field_ptr, extra.unwrap(), field_layout)
}
if has_ptr_meta(fx.tcx, field_layout.ty) {
CPlace::for_ptr_with_extra(field_ptr, extra.unwrap(), field_layout)
} else {
CPlace::for_ptr(field_ptr, field_layout)
}
Expand Down

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