diff options
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/rustc_codegen_llvm/src/builder.rs | 2 | ||||
| -rw-r--r-- | compiler/rustc_mir_transform/src/check_alignment.rs | 4 | ||||
| -rw-r--r-- | compiler/rustc_target/src/callconv/mod.rs | 1 | ||||
| -rw-r--r-- | compiler/rustc_target/src/spec/mod.rs | 23 | ||||
| -rw-r--r-- | compiler/rustc_ty_utils/src/abi.rs | 3 |
5 files changed, 29 insertions, 4 deletions
diff --git a/compiler/rustc_codegen_llvm/src/builder.rs b/compiler/rustc_codegen_llvm/src/builder.rs index 35134e9f5a0..cf98cee0c15 100644 --- a/compiler/rustc_codegen_llvm/src/builder.rs +++ b/compiler/rustc_codegen_llvm/src/builder.rs @@ -594,6 +594,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> { fn load(&mut self, ty: &'ll Type, ptr: &'ll Value, align: Align) -> &'ll Value { unsafe { let load = llvm::LLVMBuildLoad2(self.llbuilder, ty, ptr, UNNAMED); + let align = align.min(self.cx().tcx.sess.target.max_reliable_alignment()); llvm::LLVMSetAlignment(load, align.bytes() as c_uint); load } @@ -807,6 +808,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> { assert_eq!(self.cx.type_kind(self.cx.val_ty(ptr)), TypeKind::Pointer); unsafe { let store = llvm::LLVMBuildStore(self.llbuilder, val, ptr); + let align = align.min(self.cx().tcx.sess.target.max_reliable_alignment()); let align = if flags.contains(MemFlags::UNALIGNED) { 1 } else { align.bytes() as c_uint }; llvm::LLVMSetAlignment(store, align); diff --git a/compiler/rustc_mir_transform/src/check_alignment.rs b/compiler/rustc_mir_transform/src/check_alignment.rs index b70cca14840..3991f1b98cd 100644 --- a/compiler/rustc_mir_transform/src/check_alignment.rs +++ b/compiler/rustc_mir_transform/src/check_alignment.rs @@ -1,3 +1,4 @@ +use rustc_abi::Align; use rustc_index::IndexVec; use rustc_middle::mir::interpret::Scalar; use rustc_middle::mir::visit::PlaceContext; @@ -11,8 +12,7 @@ pub(super) struct CheckAlignment; impl<'tcx> crate::MirPass<'tcx> for CheckAlignment { fn is_enabled(&self, sess: &Session) -> bool { - // FIXME(#112480) MSVC and rustc disagree on minimum stack alignment on x86 Windows - if sess.target.llvm_target == "i686-pc-windows-msvc" { + if sess.target.max_reliable_alignment() < Align::MAX { return false; } sess.ub_checks() diff --git a/compiler/rustc_target/src/callconv/mod.rs b/compiler/rustc_target/src/callconv/mod.rs index 7ecc46cc69d..ae366e29e32 100644 --- a/compiler/rustc_target/src/callconv/mod.rs +++ b/compiler/rustc_target/src/callconv/mod.rs @@ -144,6 +144,7 @@ pub struct ArgAttributes { /// (corresponding to LLVM's dereferenceable_or_null attributes, i.e., it is okay for this to be /// set on a null pointer, but all non-null pointers must be dereferenceable). pub pointee_size: Size, + /// The minimum alignment of the pointee, if any. pub pointee_align: Option<Align>, } diff --git a/compiler/rustc_target/src/spec/mod.rs b/compiler/rustc_target/src/spec/mod.rs index 64171fcc7ab..300e1ec372a 100644 --- a/compiler/rustc_target/src/spec/mod.rs +++ b/compiler/rustc_target/src/spec/mod.rs @@ -42,7 +42,9 @@ use std::path::{Path, PathBuf}; use std::str::FromStr; use std::{fmt, io}; -use rustc_abi::{Endian, ExternAbi, Integer, Size, TargetDataLayout, TargetDataLayoutErrors}; +use rustc_abi::{ + Align, Endian, ExternAbi, Integer, Size, TargetDataLayout, TargetDataLayoutErrors, +}; use rustc_data_structures::fx::{FxHashSet, FxIndexSet}; use rustc_fs_util::try_canonicalize; use rustc_macros::{Decodable, Encodable, HashStable_Generic}; @@ -3598,6 +3600,25 @@ impl Target { _ => return None, }) } + + /// Returns whether this target is known to have unreliable alignment: + /// native C code for the target fails to align some data to the degree + /// required by the C standard. We can't *really* do anything about that + /// since unsafe Rust code may assume alignment any time, but we can at least + /// inhibit some optimizations, and we suppress the alignment checks that + /// would detect this unsoundness. + /// + /// Every target that returns less than `Align::MAX` here is still has a soundness bug. + pub fn max_reliable_alignment(&self) -> Align { + // FIXME(#112480) MSVC on x86-32 is unsound and fails to properly align many types with + // more-than-4-byte-alignment on the stack. This makes alignments larger than 4 generally + // unreliable on 32bit Windows. + if self.is_like_windows && self.arch == "x86" { + Align::from_bytes(4).unwrap() + } else { + Align::MAX + } + } } /// Either a target tuple string or a path to a JSON file. diff --git a/compiler/rustc_ty_utils/src/abi.rs b/compiler/rustc_ty_utils/src/abi.rs index 3d4ab33240a..63ea035bd0e 100644 --- a/compiler/rustc_ty_utils/src/abi.rs +++ b/compiler/rustc_ty_utils/src/abi.rs @@ -347,7 +347,8 @@ fn adjust_for_rust_scalar<'tcx>( None }; if let Some(kind) = kind { - attrs.pointee_align = Some(pointee.align); + attrs.pointee_align = + Some(pointee.align.min(cx.tcx().sess.target.max_reliable_alignment())); // `Box` are not necessarily dereferenceable for the entire duration of the function as // they can be deallocated at any time. Same for non-frozen shared references (see |