Teach the swift calling convention about _Atomic types

[aschwaighofer]

Summary

rdar://67351073

[aschwaighofer]

Try to sooth clang-tidy

[rjmccall]

Please do this as a very late check rather than the first check.

You need to check for extra atomic padding. If there's any difference between the sizes of the atomic type and its element, just add it as opaque data.

[aschwaighofer]

Respect atomic padding.

[rjmccall]

Thanks, LGTM.

clang/lib/CodeGen/SwiftCallingConv.cpp

// Complex types.
     addTypedData(eltLLVMType, begin, begin + eltSize);
     addTypedData(eltLLVMType, begin + eltSize, begin + 2 * eltSize);
 
   // Member pointer types.
   } else if (type->getAs<MemberPointerType>()) {
     // Just add it all as opaque.
     addOpaqueData(begin, begin + CGM.getContext().getTypeSizeInChars(type));
 
+    // Atomic types.
+  } else if (const auto *atomicType = type->getAs<AtomicType>()) {
+    auto valueType = atomicType->getValueType();
+    auto atomicSize = CGM.getContext().getTypeSizeInChars(atomicType);
+    auto valueSize = CGM.getContext().getTypeSizeInChars(valueType);
+
+    addTypedData(atomicType->getValueType(), begin);
+
+    // Add atomic padding.
+    auto atomicPadding = atomicSize - valueSize;
+    if (atomicPadding > CharUnits::Zero())
+      addOpaqueData(begin + valueSize, begin + atomicSize);
+
     // Everything else is scalar and should not convert as an LLVM aggregate.
   } else {
     // We intentionally convert as !ForMem because we want to preserve
     // that a type was an i1.
-    auto llvmType = CGM.getTypes().ConvertType(type);
+    auto *llvmType = CGM.getTypes().ConvertType(type);
     addTypedData(llvmType, begin);
   }
 }
 
 void SwiftAggLowering::addTypedData(const RecordDecl *record, CharUnits begin) {
   addTypedData(record, begin, CGM.getContext().getASTRecordLayout(record));
 }
 

clang/test/CodeGen/64bit-swiftcall.c

 // RUN: %clang_cc1 -triple x86_64-apple-darwin10 -target-cpu core2 -emit-llvm -o - %s | FileCheck %s
 // RUN: %clang_cc1 -triple x86_64-apple-darwin10 -target-cpu core2 -emit-llvm -o - %s | FileCheck %s --check-prefix=X86-64
 // RUN: %clang_cc1 -triple arm64-apple-ios9 -target-cpu cyclone -emit-llvm -o - %s | FileCheck %s
 // RUN: %clang_cc1 -triple arm64-apple-ios9 -target-cpu cyclone -emit-llvm -o - %s | FileCheck %s --check-prefix=ARM64
 
 // REQUIRES: aarch64-registered-target,x86-registered-target
 
 #define SWIFTCALL __attribute__((swiftcall))
 #define OUT __attribute__((swift_indirect_result))
 #define ERROR __attribute__((swift_error_result))
 #define CONTEXT __attribute__((swift_context))
 
+// CHECK-DAG: %struct.atomic_padded = type { { %struct.packed, [7 x i8] } }
+// CHECK-DAG: %struct.packed = type <{ i64, i8 }>
+//
 // CHECK: [[STRUCT2_RESULT:@.*]] = private {{.*}} constant [[STRUCT2_TYPE:%.*]] { i32 0, i8 0, i8 undef, i8 0, i32 0, i32 0 }
 
 /*****************************************************************************/
 /****************************** PARAMETER ABIS *******************************/
 /*****************************************************************************/
 
 SWIFTCALL void indirect_result_1(OUT int *arg0, OUT float *arg1) {}
 // CHECK-LABEL: define {{.*}} void @indirect_result_1(i32* noalias sret align 4 dereferenceable(4){{.*}}, float* noalias align 4 dereferenceable(4){{.*}})

 // At one point, we emitted lifetime.ends without a matching lifetime.start for
 // CoerceAndExpanded args. Since we're not performing optimizations, neither
 // intrinsic should be emitted.
 // CHECK-LABEL: define void @no_lifetime_markers
 void no_lifetime_markers() {
   // CHECK-NOT: call void @llvm.lifetime.
   take_int5(return_int5());
 }
+
+typedef struct {
+  unsigned long long a;
+  unsigned long long b;
+} double_word;
+
+typedef struct {
+  _Atomic(double_word) a;
+} atomic_double_word;
+
+// CHECK-LABEL: use_atomic(i64 %0, i64 %1)
+SWIFTCALL void use_atomic(atomic_double_word a) {}
+
+typedef struct {
+  unsigned long long a;
+  unsigned char b;
+} __attribute__((packed)) packed;
+
+typedef struct {
+  _Atomic(packed) a;
+} atomic_padded;
+
+// CHECK-LABEL: use_atomic_padded(i64 %0, i64 %1)
+SWIFTCALL void use_atomic_padded(atomic_padded a) {}