From d2e7dca5ca92c655e451d6fcb806df38d7f2d56b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Jan=20Ole=20H=C3=BCser?= Date: Thu, 5 Nov 2020 11:01:51 -0800 Subject: [CodeGen] Fix Bug 47499: __unaligned extension inconsistent behaviour with C and C++ For the language C++ the keyword __unaligned (a Microsoft extension) had no effect on pointers. The reason, why there was a difference between C and C++ for the keyword __unaligned: For C, the Method getAsCXXREcordDecl() returns nullptr. That guarantees that hasUnaligned() is called. If the language is C++, it is not guaranteed, that hasUnaligend() is called and evaluated. Here are some links: The Bug: https://bugs.llvm.org/show_bug.cgi?id=47499 Thread on the cfe-dev mailing list: http://lists.llvm.org/pipermail/cfe-dev/2020-September/066783.html Diff, that introduced the check hasUnaligned() in getNaturalTypeAlignment(): https://reviews.llvm.org/D30166 Reviewed By: rnk Differential Revision: https://reviews.llvm.org/D90630 --- clang/lib/CodeGen/CodeGenModule.cpp | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) (limited to 'clang/lib/CodeGen/CodeGenModule.cpp') diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp index 24c0675..ccf5d24 100644 --- a/clang/lib/CodeGen/CodeGenModule.cpp +++ b/clang/lib/CodeGen/CodeGenModule.cpp @@ -6197,16 +6197,17 @@ CharUnits CodeGenModule::getNaturalTypeAlignment(QualType T, *BaseInfo = LValueBaseInfo(AlignmentSource::Type); CharUnits Alignment; - // For C++ class pointees, we don't know whether we're pointing at a - // base or a complete object, so we generally need to use the - // non-virtual alignment. const CXXRecordDecl *RD; - if (forPointeeType && !AlignForArray && (RD = T->getAsCXXRecordDecl())) { + if (T.getQualifiers().hasUnaligned()) { + Alignment = CharUnits::One(); + } else if (forPointeeType && !AlignForArray && + (RD = T->getAsCXXRecordDecl())) { + // For C++ class pointees, we don't know whether we're pointing at a + // base or a complete object, so we generally need to use the + // non-virtual alignment. Alignment = getClassPointerAlignment(RD); } else { Alignment = getContext().getTypeAlignInChars(T); - if (T.getQualifiers().hasUnaligned()) - Alignment = CharUnits::One(); } // Cap to the global maximum type alignment unless the alignment -- cgit v1.1