diff options
Diffstat (limited to 'src/librustc_codegen_llvm')
| -rw-r--r-- | src/librustc_codegen_llvm/type_of.rs | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/src/librustc_codegen_llvm/type_of.rs b/src/librustc_codegen_llvm/type_of.rs index 4728d7717a1..751c4ea5ce6 100644 --- a/src/librustc_codegen_llvm/type_of.rs +++ b/src/librustc_codegen_llvm/type_of.rs @@ -10,11 +10,9 @@ use abi::{FnType, FnTypeExt}; use common::*; -use llvm; use rustc::hir; use rustc::ty::{self, Ty, TypeFoldable}; use rustc::ty::layout::{self, Align, LayoutOf, Size, TyLayout}; -use rustc_target::spec::PanicStrategy; use rustc_target::abi::FloatTy; use rustc_mir::monomorphize::item::DefPathBasedNames; use type_::Type; @@ -429,12 +427,19 @@ impl<'tcx> LayoutLlvmExt<'tcx> for TyLayout<'tcx> { PointerKind::Shared }, hir::MutMutable => { - // Only emit noalias annotations for LLVM >= 6 or in panic=abort - // mode, as prior versions had many bugs in conjunction with - // unwinding. See also issue #31681. + // Previously we would only emit noalias annotations for LLVM >= 6 or in + // panic=abort mode. That was deemed right, as prior versions had many bugs + // in conjunction with unwinding, but later versions didn’t seem to have + // said issues. See issue #31681. + // + // Alas, later on we encountered a case where noalias would generate wrong + // code altogether even with recent versions of LLVM in *safe* code with no + // unwinding involved. See #54462. + // + // For now, do not enable mutable_noalias by default at all, while the + // issue is being figured out. let mutable_noalias = cx.tcx.sess.opts.debugging_opts.mutable_noalias - .unwrap_or(unsafe { llvm::LLVMRustVersionMajor() >= 6 } - || cx.tcx.sess.panic_strategy() == PanicStrategy::Abort); + .unwrap_or(false); if mutable_noalias { PointerKind::UniqueBorrowed } else { |