x86_64: Structures with no fields but which have padding should be classified as

integer.
 - This is consistent, but may not be correct. I will revisit x86_64 ABI handling for C++ as a whole at some point.
 - PR5831.

llvm-svn: 91874

clang/lib/CodeGen/TargetABIInfo.cpp

@@ -805,6 +805,10 @@ void X86_64ABIInfo::classify(QualType Ty,
         if (Lo == Memory || Hi == Memory)
           break;
       }
+
+      // If this record has no fields but isn't empty, classify as INTEGER.
+      if (RD->field_empty() && Size)
+        Current = Integer;
     }
 
     // Classify the fields one at a time, merging the results.

clang/test/CodeGenCXX/member-functions.cpp

@@ -58,6 +58,6 @@ struct T {
 void test3() {
   T t1, t2;
   
-  // RUN: grep "call void @_ZN1TpsERKS_" %t
+  // RUN: grep "call i64 @_ZN1TpsERKS_" %t
   T result = t1 + t2;
 }

clang/test/CodeGenCXX/x86_64-arguments.cpp

@@ -21,4 +21,7 @@ struct f2_s1 : public f2_s0 { char d;};
 // CHECK: define void @_Z2f25f2_s1([[i64_i64_ty]])
 void f2(f2_s1 a0) { }
 
-
+// PR5831
+struct s3_0 {};
+struct s3_1 { struct s3_0 a; long b; };
+void f3(struct s3_1 x) {}