i#4318 xarch memtrace: Bump version and add message for arch tags

PR #4331 commit 5d49675 added a new marker with the architecture
early in a trace, enough to break the file_reader_t assumptions.  The
file reader was updated, but it's best to also bump the version for
old binary code.  Additionally, we provide a separate distinct message
about a version mismatch (otherwise the error message from the old
reader is the same as without the version bump).

Issue: #4318

clients/drcachesim/common/trace_entry.h

@@ -53,7 +53,7 @@
 
 typedef uintptr_t addr_t; /**< The type of a memory address. */
 
-#define TRACE_ENTRY_VERSION 1 /**< The version of the trace format. */
+#define TRACE_ENTRY_VERSION 2 /**< The version of the trace format. */
 
 /** The type of a trace entry in a #memref_t structure. */
 // The type identifier for trace entries in the raw trace_entry_t passed to

clients/drcachesim/reader/file_reader.h

@@ -163,10 +163,19 @@ template <typename T> class file_reader_t : public reader_t {
         trace_entry_t header, next, pid = {};
         for (index_ = 0; index_ < input_files_.size(); ++index_) {
             if (!read_next_thread_entry(index_, &header, &thread_eof_[index_]) ||
-                header.type != TRACE_TYPE_HEADER || header.addr != TRACE_ENTRY_VERSION) {
+                header.type != TRACE_TYPE_HEADER) {
                 ERRMSG("Invalid header for input file #%zu\n", index_);
                 return false;
             }
+            // We can handle the older version 1 as well which simply omits the
+            // early marker with the arch tag.
+            if (header.addr > TRACE_ENTRY_VERSION) {
+                ERRMSG(
+                    "Cannot handle version #%zu (expect version <= #%u) for input file "
+                    "#%zu\n",
+                    header.addr, TRACE_ENTRY_VERSION, index_);
+                return false;
+            }
             // Read the meta entries until we hit the pid.
             while (read_next_thread_entry(index_, &next, &thread_eof_[index_])) {
                 if (next.type == TRACE_TYPE_PID) {