Option to output precompiled instructions as a blob for use with mmap instead of assembly for use i…

runtime/bin/file_linux.cc

Index: runtime/bin/file_linux.cc
diff --git a/runtime/bin/file_linux.cc b/runtime/bin/file_linux.cc
index 2bf2c2edaa9847089d3deb45758c0522e41fe3a1..2e47d74978a486a0fd1a202b9f365526459ac946 100644
--- a/runtime/bin/file_linux.cc
+++ b/runtime/bin/file_linux.cc
@@ -10,6 +10,7 @@
 #include <errno.h>  // NOLINT
 #include <fcntl.h>  // NOLINT
 #include <libgen.h>  // NOLINT
+#include <sys/mman.h>  // NOLINT
 #include <sys/sendfile.h>  // NOLINT
 #include <sys/stat.h>  // NOLINT
 #include <sys/types.h>  // NOLINT
@@ -75,6 +76,21 @@ bool File::IsClosed() {
 }
 
 
+void* File::MapExecutable(intptr_t* len) {
+  ASSERT(handle_->fd() >= 0);
+  intptr_t length = Length();
+  void* addr = mmap(0, length,
+                    PROT_READ | PROT_EXEC, MAP_PRIVATE,
+                    handle_->fd(), 0);
+  if (addr == MAP_FAILED) {
+    *len = -1;
+  } else {
+    *len = length;
+  }
+  return addr;
+}
+
+
 int64_t File::Read(void* buffer, int64_t num_bytes) {
   ASSERT(handle_->fd() >= 0);
   return TEMP_FAILURE_RETRY(read(handle_->fd(), buffer, num_bytes));