From b1613ebc432ae495ecfcfa822548390c250849a8 Mon Sep 17 00:00:00 2001 From: Ralf Jung Date: Sat, 2 Dec 2023 12:25:01 +0100 Subject: [PATCH] codegen: panic when trying to compute size/align of extern type --- compiler/rustc_codegen_ssa/src/lib.rs | 2 +- .../rustc_codegen_ssa/src/mir/intrinsic.rs | 22 +++++------- compiler/rustc_codegen_ssa/src/mir/operand.rs | 6 ++-- compiler/rustc_codegen_ssa/src/mir/place.rs | 4 +-- .../src/{glue.rs => size_of_val.rs} | 36 ++++++++++++++++--- tests/ui/extern/extern-types-size_of_val.rs | 5 ++- .../extern-types-size_of_val.run.stderr | 4 +++ 7 files changed, 54 insertions(+), 25 deletions(-) rename compiler/rustc_codegen_ssa/src/{glue.rs => size_of_val.rs} (78%) create mode 100644 tests/ui/extern/extern-types-size_of_val.run.stderr diff --git a/compiler/rustc_codegen_ssa/src/lib.rs b/compiler/rustc_codegen_ssa/src/lib.rs index cd5eb77e06e8c..9b60f0844a067 100644 --- a/compiler/rustc_codegen_ssa/src/lib.rs +++ b/compiler/rustc_codegen_ssa/src/lib.rs @@ -51,10 +51,10 @@ pub mod codegen_attrs; 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 136d06d561a5a..a5bffc33d393c 100644 --- a/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs +++ b/compiler/rustc_codegen_ssa/src/mir/intrinsic.rs @@ -4,8 +4,8 @@ use super::FunctionCx; 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 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { 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 feee3ac03d0a7..e8c58f6b6f805 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::place::PlaceRef; 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 @@ impl<'a, 'tcx, V: CodegenObject> OperandValue { .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 83425dee1a8db..a3fb3b9d783ef 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::operand::OperandValue; use super::{FunctionCx, LocalRef}; use crate::common::IntPredicate; -use crate::glue; +use crate::size_of_val; use crate::traits::*; use rustc_middle::mir; @@ -179,7 +179,7 @@ impl<'a, 'tcx, V: CodegenObject> PlaceRef<'tcx, V> { 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 c34f1dbf8569d..b8a4949d59ff9 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/tests/ui/extern/extern-types-size_of_val.rs b/tests/ui/extern/extern-types-size_of_val.rs index 3b02ea28eaa28..c48db60d40adf 100644 --- a/tests/ui/extern/extern-types-size_of_val.rs +++ b/tests/ui/extern/extern-types-size_of_val.rs @@ -1,4 +1,6 @@ -// run-pass +// run-fail +// check-run-results +// normalize-stderr-test "panicking\.rs:\d+:\d+:" -> "panicking.rs:" #![feature(extern_types)] use std::mem::{align_of_val, size_of_val}; @@ -10,6 +12,7 @@ extern "C" { fn main() { let x: &A = unsafe { &*(1usize as *const A) }; + // These don't have a dynamic size, so this should panic. assert_eq!(size_of_val(x), 0); assert_eq!(align_of_val(x), 1); } diff --git a/tests/ui/extern/extern-types-size_of_val.run.stderr b/tests/ui/extern/extern-types-size_of_val.run.stderr new file mode 100644 index 0000000000000..cf39c71a04b19 --- /dev/null +++ b/tests/ui/extern/extern-types-size_of_val.run.stderr @@ -0,0 +1,4 @@ +thread 'main' panicked at library/core/src/panicking.rs: +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.