mgrang updated this revision to Diff 196341.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D60349/new/

https://reviews.llvm.org/D60349

Files:
  include/clang/AST/DeclCXX.h
  include/clang/CodeGen/CGFunctionInfo.h
  lib/CodeGen/CGCall.cpp
  lib/CodeGen/MicrosoftCXXABI.cpp
  lib/Sema/SemaDeclCXX.cpp
  test/CodeGen/arm64-microsoft-arguments.cpp
  test/CodeGenCXX/microsoft-abi-sret-and-byval.cpp

Index: test/CodeGenCXX/microsoft-abi-sret-and-byval.cpp
===================================================================
--- test/CodeGenCXX/microsoft-abi-sret-and-byval.cpp
+++ test/CodeGenCXX/microsoft-abi-sret-and-byval.cpp
@@ -3,7 +3,6 @@
 // RUN: %clang_cc1 -std=c++11 -emit-llvm %s -o - -triple=thumb-pc-win32 -mconstructor-aliases -fno-rtti | FileCheck -check-prefix WOA %s
 // RUN: %clang_cc1 -std=c++11 -emit-llvm %s -o - -triple=x86_64-pc-win32 -mconstructor-aliases -fno-rtti | FileCheck -check-prefix WIN64 %s
 // RUN: %clang_cc1 -std=c++11 -emit-llvm %s -o - -triple=aarch64-windows-msvc -mconstructor-aliases -fno-rtti | FileCheck -check-prefix WOA64 %s
-
 struct Empty {};
 
 struct EmptyWithCtor {
@@ -69,6 +68,11 @@
   int bb;
 };
 
+struct SmallWithPrivate {
+private:
+ int i;
+};
+
 // WIN32: declare dso_local void @"{{.*take_bools_and_chars.*}}"
 // WIN32:       (<{ i8, [3 x i8], i8, [3 x i8], %struct.SmallWithDtor,
 // WIN32:           i8, [3 x i8], i8, [3 x i8], i32, i8, [3 x i8] }>* inalloca)
@@ -164,8 +168,8 @@
 // WIN64: define dso_local void @"?small_arg_with_dtor@@YAXUSmallWithDtor@@@Z"(i32 %s.coerce) {{.*}} {
 // WIN64:   call void @"??1SmallWithDtor@@QEAA@XZ"
 // WIN64: }
-// WOA64: define dso_local void @"?small_arg_with_dtor@@YAXUSmallWithDtor@@@Z"(i64 %s.coerce) {{.*}} {
-// WOA64:   call void @"??1SmallWithDtor@@QEAA@XZ"
+// WOA64: define dso_local void @"?small_arg_with_dtor@@YAXUSmallWithDtor@@@Z"(%struct.SmallWithDtor* %s) {{.*}} {
+// WOA64:   call void @"??1SmallWithDtor@@QEAA@XZ"(%struct.SmallWithDtor* %s)
 // WOA64: }
 
 // FIXME: MSVC incompatible!
@@ -173,6 +177,12 @@
 // WOA:   call arm_aapcs_vfpcc void @"??1SmallWithDtor@@QAA@XZ"(%struct.SmallWithDtor* %s)
 // WOA: }
 
+
+// Test that the eligible non-aggregate is passed directly, but returned
+// indirectly on ARM64 Windows.
+// WOA64: define dso_local void @"?small_arg_with_private_member@@YA?AUSmallWithPrivate@@U1@@Z"(%struct.SmallWithPrivate* inreg noalias sret %agg.result, i64 %s.coerce) {{.*}} {
+SmallWithPrivate small_arg_with_private_member(SmallWithPrivate s) { return s; }
+
 void call_small_arg_with_dtor() {
   small_arg_with_dtor(SmallWithDtor());
 }
Index: test/CodeGen/arm64-microsoft-arguments.cpp
===================================================================
--- test/CodeGen/arm64-microsoft-arguments.cpp
+++ test/CodeGen/arm64-microsoft-arguments.cpp
@@ -1,25 +1,31 @@
 // RUN: %clang_cc1 -triple aarch64-windows -ffreestanding -emit-llvm -O0 \
 // RUN: -x c++ -o - %s | FileCheck %s
 
-struct pod { int a, b, c, d, e; };
+// Return type size <= 8 bytes.
+// CHECK: define {{.*}} i64 @{{.*}}f1{{.*}}()
+struct S1 { int a, b; };
+S1 f1() { return S1{}; }
 
-struct non_pod {
-  int a;
-  non_pod() {}
-};
+// Return type size <= 16 bytes.
+// CHECK: define {{.*}} [2 x i64] @{{.*}}f2{{.*}}()
+struct S2 { int a, b, c, d; };
+S2 f2() { return S2{}; }
 
-struct pod s;
-struct non_pod t;
+// Return type size > 16 bytes.
+// CHECK: define {{.*}} void @{{.*}}f3{{.*}}(%struct.S3* noalias sret %agg.result)
+struct S3 { int a, b, c, d, e; };
+S3 f3() { return S3{}; }
 
-struct pod bar() { return s; }
-struct non_pod foo() { return t; }
-// CHECK: define {{.*}} void @{{.*}}bar{{.*}}(%struct.pod* noalias sret %agg.result)
-// CHECK: define {{.*}} void @{{.*}}foo{{.*}}(%struct.non_pod* noalias %agg.result)
+// Instance methods.
+// CHECK: define {{.*}} void @{{.*}}inst@C{{.*}}(%class.C* %this, %class.A* inreg noalias sret %agg.result)
 
+class A {};
 
-// Check instance methods.
-struct pod2 { int x; };
-struct Baz { pod2 baz(); };
+class C {
+public:
+  A inst();
+};
 
-int qux() { return Baz().baz().x; }
-// CHECK: declare {{.*}} void @{{.*}}baz@Baz{{.*}}(%struct.Baz*, %struct.pod2*)
+A C::inst() {
+  return A();
+}
Index: lib/Sema/SemaDeclCXX.cpp
===================================================================
--- lib/Sema/SemaDeclCXX.cpp
+++ lib/Sema/SemaDeclCXX.cpp
@@ -5952,7 +5952,8 @@
 
     // Note: This permits small classes with nontrivial destructors to be
     // passed in registers, which is non-conforming.
-    if (CopyCtorIsTrivial &&
+    bool isAArch64 = S.Context.getTargetInfo().getTriple().isAArch64();
+    if (!isAArch64 && CopyCtorIsTrivial &&
         S.getASTContext().getTypeSize(D->getTypeForDecl()) <= 64)
       return true;
     return false;
Index: lib/CodeGen/MicrosoftCXXABI.cpp
===================================================================
--- lib/CodeGen/MicrosoftCXXABI.cpp
+++ lib/CodeGen/MicrosoftCXXABI.cpp
@@ -52,6 +52,10 @@
 
   bool classifyReturnType(CGFunctionInfo &FI) const override;
 
+  bool passClassIndirect(const CXXRecordDecl *RD) const {
+    return !canCopyArgument(RD);
+  }
+
   RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const override;
 
   bool isSRetParameterAfterThis() const override { return true; }
@@ -1051,33 +1055,44 @@
   return isDeletingDtor(GD);
 }
 
+static bool hasMicrosoftABIRestrictions(const CXXRecordDecl *RD) {
+  // The checks below ensure that thare no user provided constructors.
+  // For AArch64, we use the C++14 definition of an aggregate, so we also
+  // check for:
+  //   No private or protected non static data members.
+  //   No base classes
+  //   No virtual functions
+  // Additionally, we need to ensure that there is a trivial copy assignment
+  // operator.
+  if (RD->hasProtectedFields() || RD->hasPrivateFields())
+    return true;
+  if (RD->getNumBases() > 0)
+    return true;
+  if (RD->isPolymorphic())
+    return true;
+  if (!RD->hasTrivialCopyAssignment())
+    return true;
+  return false;
+}
+
 bool MicrosoftCXXABI::classifyReturnType(CGFunctionInfo &FI) const {
   const CXXRecordDecl *RD = FI.getReturnType()->getAsCXXRecordDecl();
   if (!RD)
     return false;
 
-  CharUnits Align = CGM.getContext().getTypeAlignInChars(FI.getReturnType());
-  if (FI.isInstanceMethod()) {
-    // If it's an instance method, aggregates are always returned indirectly via
-    // the second parameter.
-    FI.getReturnInfo() = ABIArgInfo::getIndirect(Align, /*ByVal=*/false);
-    FI.getReturnInfo().setSRetAfterThis(FI.isInstanceMethod());
+  bool isAArch64 = CGM.getTarget().getTriple().isAArch64();
+  bool isIndirectReturn = isAArch64 ?
+    (passClassIndirect(RD) || hasMicrosoftABIRestrictions(RD)) :
+    !RD->isPOD();
+  bool isInstanceMethod = FI.isInstanceMethod();
 
-    // aarch64-windows requires that instance methods use X1 for the return
-    // address. So for aarch64-windows we do not mark the
-    // return as SRet.
-    FI.getReturnInfo().setSuppressSRet(CGM.getTarget().getTriple().getArch() ==
-                                       llvm::Triple::aarch64);
-    return true;
-  } else if (!RD->isPOD()) {
-    // If it's a free function, non-POD types are returned indirectly.
+  if (isIndirectReturn || isInstanceMethod) {
+    CharUnits Align = CGM.getContext().getTypeAlignInChars(FI.getReturnType());
     FI.getReturnInfo() = ABIArgInfo::getIndirect(Align, /*ByVal=*/false);
+    FI.getReturnInfo().setSRetAfterThis(isInstanceMethod);
+
+    FI.getReturnInfo().setInReg(isAArch64);
 
-    // aarch64-windows requires that non-POD, non-instance returns use X0 for
-    // the return address. So for aarch64-windows we do not mark the return as
-    // SRet.
-    FI.getReturnInfo().setSuppressSRet(CGM.getTarget().getTriple().getArch() ==
-                                       llvm::Triple::aarch64);
     return true;
   }
 
Index: lib/CodeGen/CGCall.cpp
===================================================================
--- lib/CodeGen/CGCall.cpp
+++ lib/CodeGen/CGCall.cpp
@@ -1999,8 +1999,7 @@
   // Attach attributes to sret.
   if (IRFunctionArgs.hasSRetArg()) {
     llvm::AttrBuilder SRETAttrs;
-    if (!RetAI.getSuppressSRet())
-      SRETAttrs.addAttribute(llvm::Attribute::StructRet);
+    SRETAttrs.addAttribute(llvm::Attribute::StructRet);
     hasUsedSRet = true;
     if (RetAI.getInReg())
       SRETAttrs.addAttribute(llvm::Attribute::InReg);
Index: include/clang/CodeGen/CGFunctionInfo.h
===================================================================
--- include/clang/CodeGen/CGFunctionInfo.h
+++ include/clang/CodeGen/CGFunctionInfo.h
@@ -95,7 +95,6 @@
   bool InReg : 1;           // isDirect() || isExtend() || isIndirect()
   bool CanBeFlattened: 1;   // isDirect()
   bool SignExt : 1;         // isExtend()
-  bool SuppressSRet : 1;    // isIndirect()
 
   bool canHavePaddingType() const {
     return isDirect() || isExtend() || isIndirect() || isExpand();
@@ -111,14 +110,13 @@
   }
 
   ABIArgInfo(Kind K)
-      : TheKind(K), PaddingInReg(false), InReg(false), SuppressSRet(false) {
+      : TheKind(K), PaddingInReg(false), InReg(false) {
   }
 
 public:
   ABIArgInfo()
       : TypeData(nullptr), PaddingType(nullptr), DirectOffset(0),
-        TheKind(Direct), PaddingInReg(false), InReg(false),
-        SuppressSRet(false) {}
+        TheKind(Direct), PaddingInReg(false), InReg(false) {}
 
   static ABIArgInfo getDirect(llvm::Type *T = nullptr, unsigned Offset = 0,
                               llvm::Type *Padding = nullptr,
@@ -407,16 +405,6 @@
     CanBeFlattened = Flatten;
   }
 
-  bool getSuppressSRet() const {
-    assert(isIndirect() && "Invalid kind!");
-    return SuppressSRet;
-  }
-
-  void setSuppressSRet(bool Suppress) {
-    assert(isIndirect() && "Invalid kind!");
-    SuppressSRet = Suppress;
-  }
-
   void dump() const;
 };
 
Index: include/clang/AST/DeclCXX.h
===================================================================
--- include/clang/AST/DeclCXX.h
+++ include/clang/AST/DeclCXX.h
@@ -1325,6 +1325,14 @@
   /// \note This does NOT include a check for union-ness.
   bool isEmpty() const { return data().Empty; }
 
+  bool hasPrivateFields() const {
+    return data().HasPrivateFields;
+  }
+
+  bool hasProtectedFields() const {
+    return data().HasProtectedFields;
+  }
+
   /// Determine whether this class has direct non-static data members.
   bool hasDirectFields() const {
     auto &D = data();
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