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MSVC normally has a bunch of restrictions on returning values directly, which
don't apply to passing values directly. (This roughly corresponds to the
definition of a C++14 aggregate.) However, these restrictions don't apply to
HVAs; make sure we check for that.
Fixes https://github.com/llvm/llvm-project/issues/62223
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D153179
Files:
clang/lib/CodeGen/MicrosoftCXXABI.cpp
clang/test/CodeGenCXX/homogeneous-aggregates.cpp
Index: clang/test/CodeGenCXX/homogeneous-aggregates.cpp
===================================================================
--- clang/test/CodeGenCXX/homogeneous-aggregates.cpp
+++ clang/test/CodeGenCXX/homogeneous-aggregates.cpp
@@ -285,3 +285,14 @@
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 { 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 %{{.*}})
+}
Index: clang/lib/CodeGen/MicrosoftCXXABI.cpp
===================================================================
--- clang/lib/CodeGen/MicrosoftCXXABI.cpp
+++ clang/lib/CodeGen/MicrosoftCXXABI.cpp
@@ -13,6 +13,7 @@
//
//===----------------------------------------------------------------------===//
+#include "ABIInfo.h"
#include "CGCXXABI.h"
#include "CGCleanup.h"
#include "CGVTables.h"
@@ -1099,7 +1100,18 @@
return isDeletingDtor(GD);
}
-static bool isTrivialForMSVC(const CXXRecordDecl *RD) {
+static bool isTrivialForMSVC(const CXXRecordDecl *RD, QualType Ty,
+ CodeGenModule &CGM) {
+ // 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.getTypes().getABIInfo().isHomogeneousAggregate(Ty, Base, NumElts) &&
+ isa<VectorType>(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 +1140,8 @@
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();
Index: clang/test/CodeGenCXX/homogeneous-aggregates.cpp
===================================================================
--- clang/test/CodeGenCXX/homogeneous-aggregates.cpp
+++ clang/test/CodeGenCXX/homogeneous-aggregates.cpp
@@ -285,3 +285,14 @@
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 { 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 %{{.*}})
+}
Index: clang/lib/CodeGen/MicrosoftCXXABI.cpp
===================================================================
--- clang/lib/CodeGen/MicrosoftCXXABI.cpp
+++ clang/lib/CodeGen/MicrosoftCXXABI.cpp
@@ -13,6 +13,7 @@
//
//===----------------------------------------------------------------------===//
+#include "ABIInfo.h"
#include "CGCXXABI.h"
#include "CGCleanup.h"
#include "CGVTables.h"
@@ -1099,7 +1100,18 @@
return isDeletingDtor(GD);
}
-static bool isTrivialForMSVC(const CXXRecordDecl *RD) {
+static bool isTrivialForMSVC(const CXXRecordDecl *RD, QualType Ty,
+ CodeGenModule &CGM) {
+ // 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.getTypes().getABIInfo().isHomogeneousAggregate(Ty, Base, NumElts) &&
+ isa<VectorType>(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 +1140,8 @@
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();
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