diff --git a/compiler/rustc_codegen_cranelift/build_system/tests.rs b/compiler/rustc_codegen_cranelift/build_system/tests.rs index 3309a0a6abd..1a38d5967f4 100644 --- a/compiler/rustc_codegen_cranelift/build_system/tests.rs +++ b/compiler/rustc_codegen_cranelift/build_system/tests.rs @@ -75,11 +75,6 @@ const fn jit_bin(config: &'static str, source: &'static str, args: &'static str) "example/arbitrary_self_types_pointers_and_wrappers.rs", &[], ), - TestCase::build_bin_and_run( - "aot.issue_91827_extern_types", - "example/issue-91827-extern-types.rs", - &[], - ), TestCase::build_lib("build.alloc_system", "example/alloc_system.rs", "lib"), TestCase::build_bin_and_run("aot.alloc_example", "example/alloc_example.rs", &[]), TestCase::jit_bin("jit.std_example", "example/std_example.rs", ""), diff --git a/compiler/rustc_codegen_cranelift/example/issue-91827-extern-types.rs b/compiler/rustc_codegen_cranelift/example/issue-91827-extern-types.rs deleted file mode 100644 index 6f39c5edcad..00000000000 --- a/compiler/rustc_codegen_cranelift/example/issue-91827-extern-types.rs +++ /dev/null @@ -1,55 +0,0 @@ -// Copied from rustc ui test suite - -// run-pass -// -// Test that we can handle unsized types with an extern type tail part. -// Regression test for issue #91827. - -#![feature(extern_types)] - -use std::ptr::addr_of; - -extern "C" { - type Opaque; -} - -unsafe impl Sync for Opaque {} - -#[repr(C)] -pub struct List { - len: usize, - data: [T; 0], - tail: Opaque, -} - -#[repr(C)] -pub struct ListImpl { - len: usize, - data: [T; N], -} - -impl List { - const fn as_slice(&self) -> &[T] { - unsafe { std::slice::from_raw_parts(self.data.as_ptr(), self.len) } - } -} - -impl ListImpl { - const fn as_list(&self) -> &List { - unsafe { std::mem::transmute(self) } - } -} - -pub static A: ListImpl = ListImpl { len: 3, data: [5, 6, 7] }; -pub static A_REF: &'static List = A.as_list(); -pub static A_TAIL_OFFSET: isize = tail_offset(A.as_list()); - -const fn tail_offset(list: &List) -> isize { - unsafe { (addr_of!(list.tail) as *const u8).offset_from(list as *const List as *const u8) } -} - -fn main() { - assert_eq!(A_REF.as_slice(), &[5, 6, 7]); - // Check that interpreter and code generation agree about the position of the tail field. - assert_eq!(A_TAIL_OFFSET, tail_offset(A_REF)); -} diff --git a/compiler/rustc_codegen_ssa/src/lib.rs b/compiler/rustc_codegen_ssa/src/lib.rs index cd5eb77e06e..9b60f0844a0 100644 --- a/compiler/rustc_codegen_ssa/src/lib.rs +++ b/compiler/rustc_codegen_ssa/src/lib.rs @@ -51,10 +51,10 @@ pub mod common; pub mod debuginfo; pub mod errors; -pub mod glue; pub mod meth; pub mod mir; pub mod mono_item; +pub mod size_of_val; pub mod target_features; pub mod traits; diff --git a/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs b/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs index 136d06d561a..a5bffc33d39 100644 --- a/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs +++ b/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs @@ -4,8 +4,8 @@ use crate::common::IntPredicate; use crate::errors; use crate::errors::InvalidMonomorphization; -use crate::glue; use crate::meth; +use crate::size_of_val; use crate::traits::*; use crate::MemFlags; @@ -88,21 +88,17 @@ pub fn codegen_intrinsic_call( sym::va_end => bx.va_end(args[0].immediate()), sym::size_of_val => { let tp_ty = fn_args.type_at(0); - if let OperandValue::Pair(_, meta) = args[0].val { - let (llsize, _) = glue::size_and_align_of_dst(bx, tp_ty, Some(meta)); - llsize - } else { - bx.const_usize(bx.layout_of(tp_ty).size.bytes()) - } + let meta = + if let OperandValue::Pair(_, meta) = args[0].val { Some(meta) } else { None }; + let (llsize, _) = size_of_val::size_and_align_of_dst(bx, tp_ty, meta); + llsize } sym::min_align_of_val => { let tp_ty = fn_args.type_at(0); - if let OperandValue::Pair(_, meta) = args[0].val { - let (_, llalign) = glue::size_and_align_of_dst(bx, tp_ty, Some(meta)); - llalign - } else { - bx.const_usize(bx.layout_of(tp_ty).align.abi.bytes()) - } + let meta = + if let OperandValue::Pair(_, meta) = args[0].val { Some(meta) } else { None }; + let (_, llalign) = size_of_val::size_and_align_of_dst(bx, tp_ty, meta); + llalign } sym::vtable_size | sym::vtable_align => { let vtable = args[0].immediate(); diff --git a/compiler/rustc_codegen_ssa/src/mir/operand.rs b/compiler/rustc_codegen_ssa/src/mir/operand.rs index feee3ac03d0..e8c58f6b6f8 100644 --- a/compiler/rustc_codegen_ssa/src/mir/operand.rs +++ b/compiler/rustc_codegen_ssa/src/mir/operand.rs @@ -2,7 +2,7 @@ use super::{FunctionCx, LocalRef}; use crate::base; -use crate::glue; +use crate::size_of_val; use crate::traits::*; use crate::MemFlags; @@ -466,13 +466,13 @@ pub fn store_unsized>( .ty; let OperandValue::Ref(llptr, Some(llextra), _) = self else { - bug!("store_unsized called with a sized value") + bug!("store_unsized called with a sized value (or with an extern type)") }; // Allocate an appropriate region on the stack, and copy the value into it. Since alloca // doesn't support dynamic alignment, we allocate an extra align - 1 bytes, and align the // pointer manually. - let (size, align) = glue::size_and_align_of_dst(bx, unsized_ty, Some(llextra)); + let (size, align) = size_of_val::size_and_align_of_dst(bx, unsized_ty, Some(llextra)); let one = bx.const_usize(1); let align_minus_1 = bx.sub(align, one); let size_extra = bx.add(size, align_minus_1); diff --git a/compiler/rustc_codegen_ssa/src/mir/place.rs b/compiler/rustc_codegen_ssa/src/mir/place.rs index 83425dee1a8..c0bb3ac5661 100644 --- a/compiler/rustc_codegen_ssa/src/mir/place.rs +++ b/compiler/rustc_codegen_ssa/src/mir/place.rs @@ -2,7 +2,7 @@ use super::{FunctionCx, LocalRef}; use crate::common::IntPredicate; -use crate::glue; +use crate::size_of_val; use crate::traits::*; use rustc_middle::mir; @@ -99,6 +99,8 @@ pub fn project_field>( let offset = self.layout.fields.offset(ix); let effective_field_align = self.align.restrict_for_offset(offset); + // `simple` is called when we don't need to adjust the offset to + // the dynamic alignment of the field. let mut simple = || { let llval = match self.layout.abi { _ if offset.bytes() == 0 => { @@ -141,28 +143,21 @@ pub fn project_field>( }; // Simple cases, which don't need DST adjustment: - // * no metadata available - just log the case - // * known alignment - sized types, `[T]`, `str` or a foreign type + // * known alignment - sized types, `[T]`, `str` + // * offset 0 -- rounding up to alignment cannot change the offset // Note that looking at `field.align` is incorrect since that is not necessarily equal // to the dynamic alignment of the type. match field.ty.kind() { - _ if self.llextra.is_none() => { - debug!( - "unsized field `{}`, of `{:?}` has no metadata for adjustment", - ix, self.llval - ); - return simple(); - } _ if field.is_sized() => return simple(), - ty::Slice(..) | ty::Str | ty::Foreign(..) => return simple(), + ty::Slice(..) | ty::Str => return simple(), + _ if offset.bytes() == 0 => return simple(), _ => {} } // We need to get the pointer manually now. // We do this by casting to a `*i8`, then offsetting it by the appropriate amount. // We do this instead of, say, simply adjusting the pointer from the result of a GEP - // because the field may have an arbitrary alignment in the LLVM representation - // anyway. + // because the field may have an arbitrary alignment in the LLVM representation. // // To demonstrate: // @@ -179,7 +174,7 @@ pub fn project_field>( let unaligned_offset = bx.cx().const_usize(offset.bytes()); // Get the alignment of the field - let (_, mut unsized_align) = glue::size_and_align_of_dst(bx, field.ty, meta); + let (_, mut unsized_align) = size_of_val::size_and_align_of_dst(bx, field.ty, meta); // For packed types, we need to cap alignment. if let ty::Adt(def, _) = self.layout.ty.kind() diff --git a/compiler/rustc_codegen_ssa/src/glue.rs b/compiler/rustc_codegen_ssa/src/size_of_val.rs similarity index 78% rename from compiler/rustc_codegen_ssa/src/glue.rs rename to compiler/rustc_codegen_ssa/src/size_of_val.rs index c34f1dbf856..b8a4949d59f 100644 --- a/compiler/rustc_codegen_ssa/src/glue.rs +++ b/compiler/rustc_codegen_ssa/src/size_of_val.rs @@ -1,10 +1,11 @@ -//! -// -// Code relating to drop glue. +//! Computing the size and alignment of a value. +use crate::common; use crate::common::IntPredicate; use crate::meth; use crate::traits::*; +use rustc_hir::LangItem; +use rustc_middle::ty::print::{with_no_trimmed_paths, with_no_visible_paths}; use rustc_middle::ty::{self, Ty}; use rustc_target::abi::WrappingRange; @@ -14,7 +15,7 @@ pub fn size_and_align_of_dst<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( info: Option, ) -> (Bx::Value, Bx::Value) { let layout = bx.layout_of(t); - debug!("size_and_align_of_dst(ty={}, info={:?}): layout: {:?}", t, info, layout); + trace!("size_and_align_of_dst(ty={}, info={:?}): layout: {:?}", t, info, layout); if layout.is_sized() { let size = bx.const_usize(layout.size.bytes()); let align = bx.const_usize(layout.align.abi.bytes()); @@ -51,7 +52,31 @@ pub fn size_and_align_of_dst<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( bx.const_usize(unit.align.abi.bytes()), ) } - _ => { + ty::Foreign(_) => { + // `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 `{t}`") + }) + }); + let msg = bx.const_str(&msg_str); + + // Obtain the panic entry point. + let (fn_abi, llfn) = common::build_langcall(bx, None, LangItem::PanicNounwind); + + // Generate the call. + // Cannot use `do_call` since we don't have a MIR terminator so we can't create a `TerminationCodegenHelper`. + // (But we are in good company, this code is duplicated plenty of times.) + let fn_ty = bx.fn_decl_backend_type(fn_abi); + + bx.call(fn_ty, /* fn_attrs */ None, Some(fn_abi), llfn, &[msg.0, msg.1], None); + + // This function does not return so we can now return whatever we want. + let size = bx.const_usize(layout.size.bytes()); + let align = bx.const_usize(layout.align.abi.bytes()); + (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. @@ -122,5 +147,6 @@ pub fn size_and_align_of_dst<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( (size, align) } + _ => bug!("size_and_align_of_dst: {t} not supported"), } } diff --git a/compiler/rustc_const_eval/src/interpret/projection.rs b/compiler/rustc_const_eval/src/interpret/projection.rs index 4d9e296d544..0f3b6b25c61 100644 --- a/compiler/rustc_const_eval/src/interpret/projection.rs +++ b/compiler/rustc_const_eval/src/interpret/projection.rs @@ -174,12 +174,15 @@ pub fn project_field>( }; (base_meta, offset.align_to(align)) } - None => { - // For unsized types with an extern type tail we perform no adjustments. - // NOTE: keep this in sync with `PlaceRef::project_field` in the codegen backend. - assert!(matches!(base_meta, MemPlaceMeta::None)); + None if offset == Size::ZERO => { + // If the offset is 0, then rounding it up to alignment wouldn't change anything, + // so we can do this even for types where we cannot determine the alignment. (base_meta, offset) } + None => { + // We don't know the alignment of this field, so we cannot adjust. + throw_unsup_format!("`extern type` does not have a known offset") + } } } else { // base_meta could be present; we might be accessing a sized field of an unsized diff --git a/src/tools/miri/tests/fail/extern-type-field-offset.rs b/src/tools/miri/tests/fail/extern-type-field-offset.rs new file mode 100644 index 00000000000..139405fc374 --- /dev/null +++ b/src/tools/miri/tests/fail/extern-type-field-offset.rs @@ -0,0 +1,29 @@ +#![feature(extern_types)] + +extern "C" { + type Opaque; +} + +struct Newtype(Opaque); + +struct S { + i: i32, + j: i32, + a: Newtype, +} + +fn main() { + let buf = [0i32; 4]; + + let x: &Newtype = unsafe { &*(&buf as *const _ as *const Newtype) }; + // Projecting to the newtype works, because it is always at offset 0. + let _field = &x.0; + + let x: &S = unsafe { &*(&buf as *const _ as *const S) }; + // Accessing sized fields is perfectly fine, even at non-zero offsets. + let _field = &x.i; + let _field = &x.j; + // This needs to compute the field offset, but we don't know the type's alignment, + // so this panics. + let _field = &x.a; //~ERROR: does not have a known offset +} diff --git a/src/tools/miri/tests/fail/extern-type-field-offset.stderr b/src/tools/miri/tests/fail/extern-type-field-offset.stderr new file mode 100644 index 00000000000..cbbf1b38361 --- /dev/null +++ b/src/tools/miri/tests/fail/extern-type-field-offset.stderr @@ -0,0 +1,14 @@ +error: unsupported operation: `extern type` does not have a known offset + --> $DIR/extern-type-field-offset.rs:LL:CC + | +LL | let _field = &x.a; + | ^^^^ `extern type` does not have a known offset + | + = help: this is likely not a bug in the program; it indicates that the program performed an operation that the interpreter does not support + = note: BACKTRACE: + = note: inside `main` at $DIR/extern-type-field-offset.rs:LL:CC + +note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace + +error: aborting due to 1 previous error + diff --git a/tests/ui/consts/const-eval/issue-91827-extern-types-field-offset.rs b/tests/ui/consts/const-eval/issue-91827-extern-types-field-offset.rs new file mode 100644 index 00000000000..c6960fa7259 --- /dev/null +++ b/tests/ui/consts/const-eval/issue-91827-extern-types-field-offset.rs @@ -0,0 +1,43 @@ +// Test that we can handle unsized types with an extern type tail part. +// Regression test for issue #91827. + +#![feature(extern_types)] + +use std::ptr::addr_of; + +extern "C" { + type Opaque; +} + +struct Newtype(Opaque); + +struct S { + i: i32, + j: i32, + a: Newtype, +} + +const NEWTYPE: () = unsafe { + let buf = [0i32; 4]; + let x: &Newtype = &*(&buf as *const _ as *const Newtype); + + // Projecting to the newtype works, because it is always at offset 0. + let field = &x.0; +}; + +const OFFSET: () = unsafe { + let buf = [0i32; 4]; + let x: &S = &*(&buf as *const _ as *const S); + + // Accessing sized fields is perfectly fine, even at non-zero offsets. + let field = &x.i; + let field = &x.j; + + // This needs to compute the field offset, but we don't know the type's alignment, so this + // fails. + let field = &x.a; + //~^ ERROR: evaluation of constant value failed + //~| does not have a known offset +}; + +fn main() {} diff --git a/tests/ui/consts/const-eval/issue-91827-extern-types-field-offset.stderr b/tests/ui/consts/const-eval/issue-91827-extern-types-field-offset.stderr new file mode 100644 index 00000000000..99f37fedd3d --- /dev/null +++ b/tests/ui/consts/const-eval/issue-91827-extern-types-field-offset.stderr @@ -0,0 +1,9 @@ +error[E0080]: evaluation of constant value failed + --> $DIR/issue-91827-extern-types-field-offset.rs:38:17 + | +LL | let field = &x.a; + | ^^^^ `extern type` does not have a known offset + +error: aborting due to 1 previous error + +For more information about this error, try `rustc --explain E0080`. diff --git a/tests/ui/consts/const-eval/issue-91827-extern-types.rs b/tests/ui/consts/const-eval/issue-91827-extern-types.rs deleted file mode 100644 index c9aaa6e5587..00000000000 --- a/tests/ui/consts/const-eval/issue-91827-extern-types.rs +++ /dev/null @@ -1,59 +0,0 @@ -// run-pass -// -// Test that we can handle unsized types with an extern type tail part. -// Regression test for issue #91827. - -#![feature(extern_types)] - -use std::ptr::addr_of; - -extern "C" { - type Opaque; -} - -unsafe impl Sync for Opaque {} - -#[repr(C)] -pub struct List { - len: usize, - data: [T; 0], - tail: Opaque, -} - -#[repr(C)] -pub struct ListImpl { - len: usize, - data: [T; N], -} - -impl List { - const fn as_slice(&self) -> &[T] { - unsafe { - let ptr = addr_of!(self.tail) as *const T; - std::slice::from_raw_parts(ptr, self.len) - } - } -} - -impl ListImpl { - const fn as_list(&self) -> &List { - unsafe { std::mem::transmute(self) } - } -} - -pub static A: ListImpl = ListImpl { - len: 3, - data: [5, 6, 7], -}; -pub static A_REF: &'static List = A.as_list(); -pub static A_TAIL_OFFSET: isize = tail_offset(A.as_list()); - -const fn tail_offset(list: &List) -> isize { - unsafe { (addr_of!(list.tail) as *const u8).offset_from(list as *const List as *const u8) } -} - -fn main() { - assert_eq!(A_REF.as_slice(), &[5, 6, 7]); - // Check that interpreter and code generation agree about the position of the tail field. - assert_eq!(A_TAIL_OFFSET, tail_offset(A_REF)); -} diff --git a/tests/ui/extern/extern-types-field-offset.rs b/tests/ui/extern/extern-types-field-offset.rs new file mode 100644 index 00000000000..bfbc1e9bffa --- /dev/null +++ b/tests/ui/extern/extern-types-field-offset.rs @@ -0,0 +1,33 @@ +// run-fail +// check-run-results +// exec-env:RUST_BACKTRACE=0 +// normalize-stderr-test: "(core/src/panicking\.rs):[0-9]+:[0-9]+" -> "$1:$$LINE:$$COL" +#![feature(extern_types)] + +extern "C" { + type Opaque; +} + +struct Newtype(Opaque); + +struct S { + i: i32, + j: i32, + a: Newtype, +} + +fn main() { + let buf = [0i32; 4]; + + let x: &Newtype = unsafe { &*(&buf as *const _ as *const Newtype) }; + // Projecting to the newtype works, because it is always at offset 0. + let field = &x.0; + + let x: &S = unsafe { &*(&buf as *const _ as *const S) }; + // Accessing sized fields is perfectly fine, even at non-zero offsets. + let field = &x.i; + let field = &x.j; + // This needs to compute the field offset, but we don't know the type's alignment, + // so this panics. + let field = &x.a; +} diff --git a/tests/ui/extern/extern-types-field-offset.run.stderr b/tests/ui/extern/extern-types-field-offset.run.stderr new file mode 100644 index 00000000000..1b04b860db5 --- /dev/null +++ b/tests/ui/extern/extern-types-field-offset.run.stderr @@ -0,0 +1,4 @@ +thread 'main' panicked at library/core/src/panicking.rs:$LINE:$COL: +attempted to compute the size or alignment of extern type `Opaque` +note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace +thread caused non-unwinding panic. aborting. diff --git a/tests/ui/extern/extern-types-size_of_val.align.run.stderr b/tests/ui/extern/extern-types-size_of_val.align.run.stderr new file mode 100644 index 00000000000..20c4d8785e8 --- /dev/null +++ b/tests/ui/extern/extern-types-size_of_val.align.run.stderr @@ -0,0 +1,4 @@ +thread 'main' panicked at library/core/src/panicking.rs:$LINE:$COL: +attempted to compute the size or alignment of extern type `A` +note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace +thread caused non-unwinding panic. aborting. diff --git a/tests/ui/extern/extern-types-size_of_val.rs b/tests/ui/extern/extern-types-size_of_val.rs index 3b02ea28eaa..4c4de873b7f 100644 --- a/tests/ui/extern/extern-types-size_of_val.rs +++ b/tests/ui/extern/extern-types-size_of_val.rs @@ -1,4 +1,8 @@ -// run-pass +// run-fail +// check-run-results +// exec-env:RUST_BACKTRACE=0 +// normalize-stderr-test: "(core/src/panicking\.rs):[0-9]+:[0-9]+" -> "$1:$$LINE:$$COL" +// revisions: size align #![feature(extern_types)] use std::mem::{align_of_val, size_of_val}; @@ -10,6 +14,10 @@ fn main() { let x: &A = unsafe { &*(1usize as *const A) }; - assert_eq!(size_of_val(x), 0); - assert_eq!(align_of_val(x), 1); + // These don't have a dynamic size, so this should panic. + if cfg!(size) { + assert_eq!(size_of_val(x), 0); + } else { + assert_eq!(align_of_val(x), 1); + } } diff --git a/tests/ui/extern/extern-types-size_of_val.size.run.stderr b/tests/ui/extern/extern-types-size_of_val.size.run.stderr new file mode 100644 index 00000000000..20c4d8785e8 --- /dev/null +++ b/tests/ui/extern/extern-types-size_of_val.size.run.stderr @@ -0,0 +1,4 @@ +thread 'main' panicked at library/core/src/panicking.rs:$LINE:$COL: +attempted to compute the size or alignment of extern type `A` +note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace +thread caused non-unwinding panic. aborting.