[MS] Pass non-trivially-copyable objects indirectly on Windows ARM

This isn't exactly what MSVC does, unfortunately. MSVC does not pass
objects with destructors but no copy constructors by address. More ARM
expertise is required to really understand what should be done here.

Fixes PR29136.

llvm-svn: 279764

2 files changed, 21 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/MicrosoftCXXABI.cpp b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
index 28312fce774..d6e86a8ecb2 100644
--- a/clang/lib/CodeGen/MicrosoftCXXABI.cpp
+++ b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
@@ -794,6 +794,12 @@ MicrosoftCXXABI::getRecordArgABI(const CXXRecordDecl *RD) const {
     // FIXME: Implement for other architectures.
     return RAA_Default;
 
+  case llvm::Triple::thumb:
+    // Use the simple Itanium rules for now.
+    // FIXME: This is incompatible with MSVC for arguments with a dtor and no
+    // copy ctor.
+    return !canCopyArgument(RD) ? RAA_Indirect : RAA_Default;
+
   case llvm::Triple::x86:
     // All record arguments are passed in memory on x86.  Decide whether to
     // construct the object directly in argument memory, or to construct the
diff --git a/clang/test/CodeGenCXX/microsoft-abi-sret-and-byval.cpp b/clang/test/CodeGenCXX/microsoft-abi-sret-and-byval.cpp
index f7dc5240674..5b5d62525e2 100644
--- a/clang/test/CodeGenCXX/microsoft-abi-sret-and-byval.cpp
+++ b/clang/test/CodeGenCXX/microsoft-abi-sret-and-byval.cpp
@@ -1,5 +1,6 @@
 // RUN: %clang_cc1 -emit-llvm %s -o - -triple=i386-pc-linux | FileCheck -check-prefix LINUX %s
 // RUN: %clang_cc1 -emit-llvm %s -o - -triple=i386-pc-win32 -mconstructor-aliases -fno-rtti | FileCheck -check-prefix WIN32 %s
+// RUN: %clang_cc1 -emit-llvm %s -o - -triple=thumb-pc-win32 -mconstructor-aliases -fno-rtti | FileCheck -check-prefix WOA %s
 // RUN: %clang_cc1 -emit-llvm %s -o - -triple=x86_64-pc-win32 -mconstructor-aliases -fno-rtti | FileCheck -check-prefix WIN64 %s
 
 struct Empty {};
@@ -92,6 +93,9 @@ SmallWithCtor small_with_ctor_return() { return SmallWithCtor(); }
 // LINUX-LABEL: define void @_Z22small_with_ctor_returnv(%struct.SmallWithCtor* noalias sret %agg.result)
 // WIN32: define void @"\01?small_with_ctor_return@@YA?AUSmallWithCtor@@XZ"(%struct.SmallWithCtor* noalias sret %agg.result)
 // WIN64: define void @"\01?small_with_ctor_return@@YA?AUSmallWithCtor@@XZ"(%struct.SmallWithCtor* noalias sret %agg.result)
+// FIXME: The 'sret' mark here doesn't seem to be enough to convince LLVM to
+// preserve the hidden sret pointer in R0 across the function.
+// WOA: define arm_aapcs_vfpcc void @"\01?small_with_ctor_return@@YA?AUSmallWithCtor@@XZ"(%struct.SmallWithCtor* noalias sret %agg.result)
 
 SmallWithVftable small_with_vftable_return() { return SmallWithVftable(); }
 // LINUX-LABEL: define void @_Z25small_with_vftable_returnv(%struct.SmallWithVftable* noalias sret %agg.result)
@@ -102,6 +106,7 @@ MediumWithCopyCtor medium_with_copy_ctor_return() { return MediumWithCopyCtor();
 // LINUX-LABEL: define void @_Z28medium_with_copy_ctor_returnv(%struct.MediumWithCopyCtor* noalias sret %agg.result)
 // WIN32: define void @"\01?medium_with_copy_ctor_return@@YA?AUMediumWithCopyCtor@@XZ"(%struct.MediumWithCopyCtor* noalias sret %agg.result)
 // WIN64: define void @"\01?medium_with_copy_ctor_return@@YA?AUMediumWithCopyCtor@@XZ"(%struct.MediumWithCopyCtor* noalias sret %agg.result)
+// WOA: define arm_aapcs_vfpcc void @"\01?medium_with_copy_ctor_return@@YA?AUMediumWithCopyCtor@@XZ"(%struct.MediumWithCopyCtor* noalias sret %agg.result)
 
 // Returning a large struct that doesn't fit into a register.
 Big big_return() { return Big(); }
@@ -114,22 +119,26 @@ void small_arg(Small s) {}
 // LINUX-LABEL: define void @_Z9small_arg5Small(i32 %s.0)
 // WIN32: define void @"\01?small_arg@@YAXUSmall@@@Z"(i32 %s.0)
 // WIN64: define void @"\01?small_arg@@YAXUSmall@@@Z"(i32 %s.coerce)
+// WOA: define arm_aapcs_vfpcc void @"\01?small_arg@@YAXUSmall@@@Z"([1 x i32] %s.coerce)
 
 void medium_arg(Medium s) {}
 // LINUX-LABEL: define void @_Z10medium_arg6Medium(i32 %s.0, i32 %s.1)
 // WIN32: define void @"\01?medium_arg@@YAXUMedium@@@Z"(i32 %s.0, i32 %s.1)
 // WIN64: define void @"\01?medium_arg@@YAXUMedium@@@Z"(i64 %s.coerce)
+// WOA: define arm_aapcs_vfpcc void @"\01?medium_arg@@YAXUMedium@@@Z"([2 x i32] %s.coerce)
 
 void small_arg_with_ctor(SmallWithCtor s) {}
 // LINUX-LABEL: define void @_Z19small_arg_with_ctor13SmallWithCtor(%struct.SmallWithCtor* byval align 4 %s)
 // WIN32: define void @"\01?small_arg_with_ctor@@YAXUSmallWithCtor@@@Z"(i32 %s.0)
 // WIN64: define void @"\01?small_arg_with_ctor@@YAXUSmallWithCtor@@@Z"(i32 %s.coerce)
+// WOA: define arm_aapcs_vfpcc void @"\01?small_arg_with_ctor@@YAXUSmallWithCtor@@@Z"([1 x i32] %s.coerce)
 
 // FIXME: We could coerce to a series of i32s here if we wanted to.
 void multibyte_arg(Multibyte s) {}
 // LINUX-LABEL: define void @_Z13multibyte_arg9Multibyte(%struct.Multibyte* byval align 4 %s)
 // WIN32: define void @"\01?multibyte_arg@@YAXUMultibyte@@@Z"(%struct.Multibyte* byval align 4 %s)
 // WIN64: define void @"\01?multibyte_arg@@YAXUMultibyte@@@Z"(i32 %s.coerce)
+// WOA: define arm_aapcs_vfpcc void @"\01?multibyte_arg@@YAXUMultibyte@@@Z"([1 x i32] %s.coerce)
 
 void packed_arg(Packed s) {}
 // LINUX-LABEL: define void @_Z10packed_arg6Packed(%struct.Packed* byval align 4 %s)
@@ -145,6 +154,11 @@ void small_arg_with_dtor(SmallWithDtor s) {}
 // WIN64:   call void @"\01??1SmallWithDtor@@QEAA@XZ"
 // WIN64: }
 
+// FIXME: MSVC incompatible!
+// WOA: define arm_aapcs_vfpcc void @"\01?small_arg_with_dtor@@YAXUSmallWithDtor@@@Z"(%struct.SmallWithDtor* %s) {{.*}} {
+// WOA:   call arm_aapcs_vfpcc void @"\01??1SmallWithDtor@@QAA@XZ"(%struct.SmallWithDtor* %s)
+// WOA: }
+
 void call_small_arg_with_dtor() {
   small_arg_with_dtor(SmallWithDtor());
 }
@@ -211,6 +225,7 @@ void medium_arg_with_copy_ctor(MediumWithCopyCtor s) {}
 // LINUX-LABEL: define void @_Z25medium_arg_with_copy_ctor18MediumWithCopyCtor(%struct.MediumWithCopyCtor* %s)
 // WIN32: define void @"\01?medium_arg_with_copy_ctor@@YAXUMediumWithCopyCtor@@@Z"(<{ %struct.MediumWithCopyCtor }>* inalloca)
 // WIN64: define void @"\01?medium_arg_with_copy_ctor@@YAXUMediumWithCopyCtor@@@Z"(%struct.MediumWithCopyCtor* %s)
+// WOA: define arm_aapcs_vfpcc void @"\01?medium_arg_with_copy_ctor@@YAXUMediumWithCopyCtor@@@Z"(%struct.MediumWithCopyCtor* %s)
 
 void big_arg(Big s) {}
 // LINUX-LABEL: define void @_Z7big_arg3Big(%struct.Big* byval align 4 %s)