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MSVC on WoA64 includes isCXX14Aggregate in its definition. This is de-facto
specification on that platform, so match msvc's behaviour.
Fixes: https://bugs.llvm.org/show_bug.cgi?id=47611
Co-authored-by: Peter Waller <peter.wal...@arm.com>
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D92751
Files:
clang/lib/CodeGen/CGCXXABI.cpp
clang/lib/CodeGen/CGCXXABI.h
clang/lib/CodeGen/MicrosoftCXXABI.cpp
clang/lib/CodeGen/TargetInfo.cpp
clang/test/CodeGenCXX/microsoft-abi-sret-and-byval.cpp
Index: clang/test/CodeGenCXX/microsoft-abi-sret-and-byval.cpp
===================================================================
--- clang/test/CodeGenCXX/microsoft-abi-sret-and-byval.cpp
+++ clang/test/CodeGenCXX/microsoft-abi-sret-and-byval.cpp
@@ -468,3 +468,31 @@
// WIN64-LABEL: define dso_local void @"?g@C@pr30293@@QEAAXXZ"(%"struct.pr30293::C"* {{[^,]*}} %this)
// WIN64: declare dso_local void @"?h@C@pr30293@@UEAAXUSmallWithDtor@@@Z"(i8*, i32)
}
+
+namespace pr47611 {
+// MSVC on Arm includes "isCXX14Aggregate" as part of its definition of
+// Homogeneous Floating-point Aggregate (HFA). Additionally, it has a different
+// handling of C++14 aggregates, which can lead to confusion.
+
+// Pod is a trivial HFA.
+struct Pod {
+ double b[2];
+};
+// Not an aggregate according to C++14 spec => not HFA according to MSVC.
+struct NotCXX14Aggregate {
+ NotCXX14Aggregate();
+ Pod p;
+};
+// NotPod is a C++14 aggregate. But not HFA, because it contains
+// NotCXX14Aggregate (which itself is not HFA because it's not a C++14
+// aggregate).
+struct NotPod {
+ NotCXX14Aggregate x;
+};
+// WOA64-LABEL: define dso_local %"struct.pr47611::Pod" @"?copy@pr47611@@YA?AUPod@1@PEAU21@@Z"(%"struct.pr47611::Pod"* %x)
+Pod copy(Pod *x) { return *x; } // MSVC: ldp d0,d1,[x0], Clang: ldp d0,d1,[x0]
+// WOA64-LABEL: define dso_local void @"?copy@pr47611@@YA?AUNotCXX14Aggregate@1@PEAU21@@Z"(%"struct.pr47611::NotCXX14Aggregate"* inreg noalias sret(%"struct.pr47611::NotCXX14Aggregate") align 8 %agg.result, %"struct.pr47611::NotCXX14Aggregate"* %x)
+NotCXX14Aggregate copy(NotCXX14Aggregate *x) { return *x; } // MSVC: stp x8,x9,[x0], Clang: str q0,[x0]
+// WOA64-LABEL: define dso_local [2 x i64] @"?copy@pr47611@@YA?AUNotPod@1@PEAU21@@Z"(%"struct.pr47611::NotPod"* %x)
+NotPod copy(NotPod *x) { return *x; }
+};
Index: clang/lib/CodeGen/TargetInfo.cpp
===================================================================
--- clang/lib/CodeGen/TargetInfo.cpp
+++ clang/lib/CodeGen/TargetInfo.cpp
@@ -5133,6 +5133,14 @@
Members += FldMembers;
}
+
+ const auto TT = CGT.getTarget().getTriple();
+ // MSVC Windows on Arm64 considers a type not HFA if it is not an
+ // aggregate according to the C++14 spec. This is not consistent with the
+ // AAPCS64, but is defacto spec on that platform.
+ if (TT.isAArch64() && TT.isWindowsMSVCEnvironment() &&
+ !CGCXXABI::isCXX14Aggregate(CXXRD))
+ return false;
}
for (const auto *FD : RD->fields()) {
Index: clang/lib/CodeGen/MicrosoftCXXABI.cpp
===================================================================
--- clang/lib/CodeGen/MicrosoftCXXABI.cpp
+++ clang/lib/CodeGen/MicrosoftCXXABI.cpp
@@ -1070,30 +1070,6 @@
return isDeletingDtor(GD);
}
-static bool isCXX14Aggregate(const CXXRecordDecl *RD) {
- // 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, a trivial destructor and no user-provided constructors.
- if (RD->hasProtectedFields() || RD->hasPrivateFields())
- return false;
- if (RD->getNumBases() > 0)
- return false;
- if (RD->isPolymorphic())
- return false;
- if (RD->hasNonTrivialCopyAssignment())
- return false;
- for (const CXXConstructorDecl *Ctor : RD->ctors())
- if (Ctor->isUserProvided())
- return false;
- if (RD->hasNonTrivialDestructor())
- return false;
- return true;
-}
-
bool MicrosoftCXXABI::classifyReturnType(CGFunctionInfo &FI) const {
const CXXRecordDecl *RD = FI.getReturnType()->getAsCXXRecordDecl();
if (!RD)
Index: clang/lib/CodeGen/CGCXXABI.h
===================================================================
--- clang/lib/CodeGen/CGCXXABI.h
+++ clang/lib/CodeGen/CGCXXABI.h
@@ -625,6 +625,8 @@
virtual std::pair<llvm::Value *, const CXXRecordDecl *>
LoadVTablePtr(CodeGenFunction &CGF, Address This,
const CXXRecordDecl *RD) = 0;
+
+ static bool isCXX14Aggregate(const CXXRecordDecl *RD);
};
// Create an instance of a C++ ABI class:
Index: clang/lib/CodeGen/CGCXXABI.cpp
===================================================================
--- clang/lib/CodeGen/CGCXXABI.cpp
+++ clang/lib/CodeGen/CGCXXABI.cpp
@@ -310,3 +310,27 @@
return AddedStructorArgCounts(AddedArgs.Prefix.size(),
AddedArgs.Suffix.size());
}
+
+bool CGCXXABI::isCXX14Aggregate(const CXXRecordDecl *RD) {
+ // 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, a trivial destructor and no user-provided constructors.
+ if (RD->hasProtectedFields() || RD->hasPrivateFields())
+ return false;
+ if (RD->getNumBases() > 0)
+ return false;
+ if (RD->isPolymorphic())
+ return false;
+ if (RD->hasNonTrivialCopyAssignment())
+ return false;
+ for (const CXXConstructorDecl *Ctor : RD->ctors())
+ if (Ctor->isUserProvided())
+ return false;
+ if (RD->hasNonTrivialDestructor())
+ return false;
+ return true;
+}
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