diff --git a/clang/lib/CodeGen/MicrosoftCXXABI.cpp b/clang/lib/CodeGen/MicrosoftCXXABI.cpp index 19b95e61e2283..5ae455dd29f75 100644 --- a/clang/lib/CodeGen/MicrosoftCXXABI.cpp +++ b/clang/lib/CodeGen/MicrosoftCXXABI.cpp @@ -13,6 +13,7 @@ // //===----------------------------------------------------------------------===// +#include "ABIInfo.h" #include "CGCXXABI.h" #include "CGCleanup.h" #include "CGVTables.h" @@ -1099,7 +1100,19 @@ bool MicrosoftCXXABI::hasMostDerivedReturn(GlobalDecl GD) const { return isDeletingDtor(GD); } -static bool isTrivialForMSVC(const CXXRecordDecl *RD) { +static bool isTrivialForMSVC(const CXXRecordDecl *RD, QualType Ty, + CodeGenModule &CGM) { + // On AArch64, HVAs that can be passed in registers can also be returned + // in registers. (Note this is using the MSVC definition of an HVA; see + // isPermittedToBeHomogeneousAggregate().) + const Type *Base = nullptr; + uint64_t NumElts = 0; + if (CGM.getTarget().getTriple().isAArch64() && + CGM.getTypes().getABIInfo().isHomogeneousAggregate(Ty, Base, NumElts) && + isa(Base)) { + return true; + } + // We use the C++14 definition of an aggregate, so we also // check for: // No private or protected non static data members. @@ -1128,7 +1141,8 @@ bool MicrosoftCXXABI::classifyReturnType(CGFunctionInfo &FI) const { if (!RD) return false; - bool isTrivialForABI = RD->canPassInRegisters() && isTrivialForMSVC(RD); + bool isTrivialForABI = RD->canPassInRegisters() && + isTrivialForMSVC(RD, FI.getReturnType(), CGM); // MSVC always returns structs indirectly from C++ instance methods. bool isIndirectReturn = !isTrivialForABI || FI.isInstanceMethod(); diff --git a/clang/test/CodeGenCXX/homogeneous-aggregates.cpp b/clang/test/CodeGenCXX/homogeneous-aggregates.cpp index 972b0031a9e38..2fcfcf4390945 100644 --- a/clang/test/CodeGenCXX/homogeneous-aggregates.cpp +++ b/clang/test/CodeGenCXX/homogeneous-aggregates.cpp @@ -285,3 +285,20 @@ struct HFA { double foo(HFA v) { return v.x + v.y; } // WOA64: define dso_local noundef double @"?foo@non_empty_field@@YANUHFA@1@@Z"([4 x double] %{{.*}}) } + +namespace pr62223 { +// HVAs don't follow the normal rules for return values. That means they can +// have base classes, user-defined ctors, and protected/private members. +// (The same restrictions that apply to HVA arguments still apply.) +typedef double V __attribute((ext_vector_type(2))); +struct base { V v; }; +struct test : base { test(double); protected: V v2;}; +test f(test *x) { return *x; } +// WOA64: define dso_local %"struct.pr62223::test" @"?f@pr62223@@YA?AUtest@1@PEAU21@@Z"(ptr noundef %{{.*}}) + +// The above rule only apples to HVAs, not HFAs. +struct base2 { double v; }; +struct test2 : base2 { test2(double); protected: double v2;}; +test2 f(test2 *x) { return *x; } +// WOA64: define dso_local void @"?f@pr62223@@YA?AUtest2@1@PEAU21@@Z"(ptr inreg noalias sret(%"struct.pr62223::test2") align 8 %{{.*}}, ptr noundef %{{.*}}) +}