Revert "GCC ABI Compatibility: Preserve alignment of non-pod members in packed structs"release/14.x

This reverts commit 277123376ce08c98b07c154bf83e4092a5d4d3c6.

There are still some issues with this change to be worked out, so revert
this patch to avoid having to change ABIs from LLVM 13->14 and then again from
LLVM 14->15.  See discussion in https://reviews.llvm.org/D118511

5 files changed, 1 insertions, 57 deletions

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 4eaa589b542d..5821e41fc733 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -338,12 +338,6 @@ ABI Changes in Clang
   is still in the process of being stabilized, so this type should not yet be
   used in interfaces that require ABI stability.
 
-- GCC doesn't pack non-POD members in packed structs unless the packed
-  attribute is also specified on the member. Clang historically did perform
-  such packing. Clang now matches the gcc behavior (except on Darwin and PS4).
-  You can switch back to the old ABI behavior with the flag:
-  ``-fclang-abi-compat=13.0``.
-
 OpenMP Support in Clang
 -----------------------
 
diff --git a/clang/include/clang/Basic/LangOptions.h b/clang/include/clang/Basic/LangOptions.h
index 50c7f038fc6b..09afa641acf9 100644
--- a/clang/include/clang/Basic/LangOptions.h
+++ b/clang/include/clang/Basic/LangOptions.h
@@ -181,10 +181,6 @@ public:
     /// global-scope inline variables incorrectly.
     Ver12,
 
-    /// Attempt to be ABI-compatible with code generated by Clang 13.0.x.
-    /// This causes clang to not pack non-POD members of packed structs.
-    Ver13,
-
     /// Conform to the underlying platform's C and C++ ABIs as closely
     /// as we can.
     Latest
diff --git a/clang/lib/AST/RecordLayoutBuilder.cpp b/clang/lib/AST/RecordLayoutBuilder.cpp
index 709e05716a56..61a30ead165e 100644
--- a/clang/lib/AST/RecordLayoutBuilder.cpp
+++ b/clang/lib/AST/RecordLayoutBuilder.cpp
@@ -1887,12 +1887,7 @@ void ItaniumRecordLayoutBuilder::LayoutField(const FieldDecl *D,
   UnfilledBitsInLastUnit = 0;
   LastBitfieldStorageUnitSize = 0;
 
-  llvm::Triple Target = Context.getTargetInfo().getTriple();
-  bool FieldPacked = (Packed && (!FieldClass || FieldClass->isPOD() ||
-                                 Context.getLangOpts().getClangABICompat() <=
-                                     LangOptions::ClangABI::Ver13 ||
-                                 Target.isPS4() || Target.isOSDarwin())) ||
-                     D->hasAttr<PackedAttr>();
+  bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
 
   AlignRequirementKind AlignRequirement = AlignRequirementKind::None;
   CharUnits FieldSize;
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 553a0b31c0ab..7f1ce3da7e7e 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -3560,8 +3560,6 @@ void CompilerInvocation::GenerateLangArgs(const LangOptions &Opts,
     GenerateArg(Args, OPT_fclang_abi_compat_EQ, "11.0", SA);
   else if (Opts.getClangABICompat() == LangOptions::ClangABI::Ver12)
     GenerateArg(Args, OPT_fclang_abi_compat_EQ, "12.0", SA);
-  else if (Opts.getClangABICompat() == LangOptions::ClangABI::Ver13)
-    GenerateArg(Args, OPT_fclang_abi_compat_EQ, "13.0", SA);
 
   if (Opts.getSignReturnAddressScope() ==
       LangOptions::SignReturnAddressScopeKind::All)
@@ -4064,8 +4062,6 @@ bool CompilerInvocation::ParseLangArgs(LangOptions &Opts, ArgList &Args,
         Opts.setClangABICompat(LangOptions::ClangABI::Ver11);
       else if (Major <= 12)
         Opts.setClangABICompat(LangOptions::ClangABI::Ver12);
-      else if (Major <= 13)
-        Opts.setClangABICompat(LangOptions::ClangABI::Ver13);
     } else if (Ver != "latest") {
       Diags.Report(diag::err_drv_invalid_value)
           << A->getAsString(Args) << A->getValue();
diff --git a/clang/test/SemaCXX/class-layout.cpp b/clang/test/SemaCXX/class-layout.cpp
index 79fa67707110..5403bd6e6a6f 100644
--- a/clang/test/SemaCXX/class-layout.cpp
+++ b/clang/test/SemaCXX/class-layout.cpp
@@ -1,9 +1,6 @@
 // RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++98 -Wno-inaccessible-base
 // RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base
-// RUN: %clang_cc1 -triple x86_64-apple-darwin    %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -DCLANG_ABI_COMPAT=13
-// RUN: %clang_cc1 -triple x86_64-scei-ps4        %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -DCLANG_ABI_COMPAT=6
 // RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=6 -DCLANG_ABI_COMPAT=6
-// RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=13 -DCLANG_ABI_COMPAT=13
 // expected-no-diagnostics
 
 #define SA(n, p) int a##n[(p) ? 1 : -1]
@@ -607,37 +604,3 @@ namespace PR37275 {
 #endif
 #pragma pack(pop)
 }
-
-namespace non_pod {
-struct t1 {
-protected:
-  int a;
-};
-// GCC prints warning: ignoring packed attribute because of unpacked non-POD field 't1 t2::v1'`
-struct t2 {
-  char c1;
-  short s1;
-  char c2;
-  t1 v1;
-} __attribute__((packed));
-#if defined(CLANG_ABI_COMPAT) && CLANG_ABI_COMPAT <= 13
-_Static_assert(_Alignof(t1) == 4, "");
-_Static_assert(_Alignof(t2) == 1, "");
-#else
-_Static_assert(_Alignof(t1) == 4, "");
-_Static_assert(_Alignof(t2) == 4, "");
-#endif
-_Static_assert(sizeof(t2) == 8, ""); // it's still packing the rest of the struct
-} // namespace non_pod
-
-namespace non_pod_packed {
-struct t1 {
-protected:
-  int a;
-} __attribute__((packed));
-struct t2 {
-  t1 v1;
-} __attribute__((packed));
-_Static_assert(_Alignof(t1) == 1, "");
-_Static_assert(_Alignof(t2) == 1, "");
-} // namespace non_pod_packed