Cherry-pick Clang upstream r199830 - Handle va_arg on struct types for the le32 target (PNaCl and E…

test/CodeGen/le32-vaarg.c

+// RUN: %clang_cc1 -triple le32-unknown-nacl -emit-llvm -o - %s | FileCheck %s
+#include <stdarg.h>
+
+int get_int(va_list *args) {
+  return va_arg(*args, int);
+}
+// CHECK: define i32 @get_int
+// CHECK: [[RESULT:%[a-z_0-9]+]] = va_arg {{.*}}, i32{{$}}
+// CHECK: ret i32 [[RESULT]]
+
+struct Foo {
+  int x;
+};
+
+struct Foo dest;
+
+void get_struct(va_list *args) {
+  dest = va_arg(*args, struct Foo);
+}
+// CHECK: define void @get_struct
+// CHECK: [[RESULT:%[a-z_0-9]+]] = va_arg {{.*}}, %struct.Foo{{$}}
+// CHECK: store %struct.Foo [[RESULT]], %struct.Foo* @dest
+
+void skip_struct(va_list *args) {
+  va_arg(*args, struct Foo);
+}
+// CHECK: define void @skip_struct
+// CHECK: va_arg {{.*}}, %struct.Foo{{$}}