Mangle __unaligned in Itanium ABI

__unaligned is not currently mangled in any way in the Itanium ABI. This causes
failures when using -fms-extensions and C++ in targets using Itanium ABI.

As suggested by @rsmith the simplest thing to do here is actually mangle the
qualifier as a vendor extension.

This patch also removes the change done in D31976 and updates its test to the
new reality.

This fixes
  https://bugs.llvm.org/show_bug.cgi?id=33080
  https://bugs.llvm.org/show_bug.cgi?id=33178

Differential Revision: https://reviews.llvm.org/D33398

llvm-svn: 304523

clang/lib/AST/ItaniumMangle.cpp

@@ -1459,8 +1459,6 @@ void CXXNameMangler::mangleNestedName(const NamedDecl *ND,
     // We do not consider restrict a distinguishing attribute for overloading
     // purposes so we must not mangle it.
     MethodQuals.removeRestrict();
-    // __unaligned is not currently mangled in any way, so remove it.
-    MethodQuals.removeUnaligned();
     mangleQualifiers(MethodQuals);
     mangleRefQualifier(Method->getRefQualifier());
   }
@@ -2140,7 +2138,8 @@ CXXNameMangler::mangleOperatorName(OverloadedOperatorKind OO, unsigned Arity) {
 }
 
 void CXXNameMangler::mangleQualifiers(Qualifiers Quals) {
-  // Vendor qualifiers come first.
+  // Vendor qualifiers come first and if they are order-insensitive they must
+  // be emitted in reversed alphabetical order, see Itanium ABI 5.1.5.
 
   // Address space qualifiers start with an ordinary letter.
   if (Quals.hasAddressSpace()) {
@@ -2176,17 +2175,28 @@ void CXXNameMangler::mangleQualifiers(Qualifiers Quals) {
   }
 
   // The ARC ownership qualifiers start with underscores.
-  switch (Quals.getObjCLifetime()) {
   // Objective-C ARC Extension:
   //
   //   <type> ::= U "__strong"
   //   <type> ::= U "__weak"
   //   <type> ::= U "__autoreleasing"
+  //
+  // Note: we emit __weak first to preserve the order as
+  // required by the Itanium ABI.
+  if (Quals.getObjCLifetime() == Qualifiers::OCL_Weak)
+    mangleVendorQualifier("__weak");
+
+  // __unaligned (from -fms-extensions)
+  if (Quals.hasUnaligned())
+    mangleVendorQualifier("__unaligned");
+
+  // Remaining ARC ownership qualifiers.
+  switch (Quals.getObjCLifetime()) {
   case Qualifiers::OCL_None:
     break;
 
   case Qualifiers::OCL_Weak:
-    mangleVendorQualifier("__weak");
+    // Do nothing as we already handled this case above.
     break;
 
   case Qualifiers::OCL_Strong:
@@ -4327,7 +4337,7 @@ bool CXXNameMangler::mangleSubstitution(const NamedDecl *ND) {
 /// substitutions.
 static bool hasMangledSubstitutionQualifiers(QualType T) {
   Qualifiers Qs = T.getQualifiers();
-  return Qs.getCVRQualifiers() || Qs.hasAddressSpace();
+  return Qs.getCVRQualifiers() || Qs.hasAddressSpace() || Qs.hasUnaligned();
 }
 
 bool CXXNameMangler::mangleSubstitution(QualType T) {

clang/test/CodeGenCXX/pr33080.cpp

@@ -0,0 +1,33 @@
+// RUN: %clang_cc1 -triple %itanium_abi_triple -fms-extensions -emit-llvm -o- %s | FileCheck %s
+
+void fa(__unaligned struct A *) {}
+// CHECK: define void @_Z2faPU11__unaligned1A(
+
+void ga(struct A *, struct A *) {}
+// CHECK: define void @_Z2gaP1AS0_(
+
+void gb(__unaligned struct A *, struct A *) {}
+// CHECK: define void @_Z2gbPU11__unaligned1APS_(
+
+void gc(struct A *, __unaligned struct A *) {}
+// CHECK: define void @_Z2gcP1APU11__unalignedS_(
+
+void gd(__unaligned struct A *, __unaligned struct A *) {}
+// CHECK: define void @_Z2gdPU11__unaligned1AS1_(
+
+void hb(__unaligned struct A *, __unaligned const struct A *) {}
+// CHECK: define void @_Z2hbPU11__unaligned1APU11__unalignedKS_(
+
+void ja(__unaligned struct A *, __unaligned struct A *__unaligned *, __unaligned struct A *__unaligned *__unaligned *) {}
+// CHECK: define void @_Z2jaPU11__unaligned1APU11__unalignedS1_PU11__unalignedS3_(
+
+void jb(__unaligned struct A *, __unaligned struct A **, __unaligned struct A *__unaligned *__unaligned *) {}
+// CHECK: @_Z2jbPU11__unaligned1APS1_PU11__unalignedPU11__unalignedS1_(
+
+template <typename T, typename Q>
+void ta(T &, Q *) {}
+
+void ia(__unaligned struct A &a) {
+  ta(a, &a);
+}
+// CHECK: @_Z2taIU11__unaligned1AS1_EvRT_PT0_(

clang/test/CodeGenCXX/unaligned-member-qualifier.cpp

@@ -0,0 +1,20 @@
+// RUN: %clang_cc1 -triple %itanium_abi_triple -fms-extensions -emit-llvm %s -o- | FileCheck %s
+
+struct A {
+  void foo() __unaligned;
+  void foo() const __unaligned;
+  void foo() volatile __unaligned;
+  void foo() const volatile __unaligned;
+};
+
+void A::foo() __unaligned {}
+// CHECK: define void @_ZNU11__unaligned1A3fooEv(
+
+void A::foo() const __unaligned {}
+// CHECK: define void @_ZNU11__unalignedK1A3fooEv(
+
+void A::foo() volatile __unaligned {}
+// CHECK: define void @_ZNU11__unalignedV1A3fooEv(
+
+void A::foo() const volatile __unaligned {}
+// CHECK: define void @_ZNU11__unalignedVK1A3fooEv(

clang/test/CodeGenObjCXX/arc-mangle.mm

@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -fobjc-arc -fobjc-runtime-has-weak -triple %itanium_abi_triple -emit-llvm -fblocks -o - %s | FileCheck %s
+// RUN: %clang_cc1 -DTEST_UNALIGNED -fms-extensions -fobjc-arc -fobjc-runtime-has-weak -triple %itanium_abi_triple -emit-llvm -fblocks -o - %s | FileCheck %s --check-prefix=UNALIGNED
 
 // CHECK-LABEL: define {{.*}}void @_Z1fPU8__strongP11objc_object(i8**)
 void f(__strong id *) {}
@@ -32,3 +33,12 @@ void f(void (^)(__attribute__((ns_consumed)) id)) {}
 // CHECK-LABEL: define weak_odr {{.*}}void @_Z1gIKvEvP10unsigned_cIXplszv1U8__bridgecvPT_v1U8__bridgecvP11objc_objectcvS3_Li0ELi1EEE
 template<typename T>void g(unsigned_c<sizeof((__bridge T*)(__bridge id)(T*)0) + 1>*) {}
 template void g<const void>(unsigned_c<sizeof(id) + 1> *);
+
+#if TEST_UNALIGNED
+// UNALIGNED-LABEL: define {{.*}}void @_Z1gPU6__weakU11__unalignedP11objc_object(i8**)
+void g(__weak __unaligned id *) {}
+// UNALIGNED-LABEL: define {{.*}}void @_Z1gPU11__unalignedU8__strongP11objc_object(i8**)
+void g(__strong __unaligned id *) {}
+// UNALIGNED-LABEL: define {{.*}}void @_Z1gPU11__unalignedU15__autoreleasingP11objc_object(i8**)
+void g(__autoreleasing __unaligned id *) {}
+#endif // TEST_UNALIGNED