With https://bugs.openjdk.java.net/browse/JDK-8149591, the assert macro in debug.hpp was changed to include another condition:

@@ -119,11 +128,13 @@
 #define vmassert(p, ...) \
 do { \
   if (!(p)) { \
+ if (is_executing_unit_tests()) { \
+ report_assert_msg(__VA_ARGS__); \
+ } \
     report_vm_error(__FILE__, __LINE__, "assert(" #p ") failed", __VA_ARGS__); \
     BREAKPOINT; \
   } \
 } while (0)

The point of this coding is to write a short one line blurb to stderr in case of an assert to help gtest death tests (tests expecting the VM to assert with a given message) to recognize the assertion. For details, please see TEST_VM_ASSERT_MSG macro in test/hotspot/gtest/unittest.hpp).

This does increase footprint of assert macros unnecessarily and should be done instead inside report_vm_error.

Doing it inside report_vm_error() reduces the assert macro size from 18 to 11 instructions (x64).

It also reduces size of the fastdebug libjvm.so by ~20Mb (394->375Mb) on linux x64.