From 2678d04dd97444cf444c31be92bfd281f9986a47 Mon Sep 17 00:00:00 2001 From: Ralf Jung Date: Wed, 2 Apr 2025 08:31:42 +0200 Subject: mitigate MSVC unsoundness by not emitting alignment attributes on win32-msvc targets also mention the MSVC alignment issue in platform-support.md --- compiler/rustc_codegen_llvm/src/builder.rs | 2 ++ 1 file changed, 2 insertions(+) (limited to 'compiler/rustc_codegen_llvm/src/builder.rs') 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); -- cgit 1.4.1-3-g733a5