The code introduced call to BarrierSetAssembler in sharedRuntime_x86_32.cpp, yet there is no relevant #include, like in sharedRuntime_x86_64.cpp. So, x86_32 Minimal build is failing with:

/home/buildbot/worker/jdkX-linux/build/src/hotspot/cpu/x86/sharedRuntime_x86_32.cpp: In static member function 'static AdapterHandlerEntry* SharedRuntime::generate_i2c2i_adapters(MacroAssembler*, int, int, const BasicType*, const VMRegPair*, AdapterFingerPrint*)':
/home/buildbot/worker/jdkX-linux/build/src/hotspot/cpu/x86/sharedRuntime_x86_32.cpp:979:5: error: invalid use of incomplete type 'class BarrierSetAssembler'
   bs->c2i_entry_barrier(masm);
     ^~
In file included from /home/buildbot/worker/jdkX-linux/build/src/hotspot/share/gc/shared/barrierSet.inline.hpp:27:0,
                 from /home/buildbot/worker/jdkX-linux/build/src/hotspot/share/oops/access.inline.hpp:28,
                 from /home/buildbot/worker/jdkX-linux/build/src/hotspot/share/oops/oop.inline.hpp:30,
                 from /home/buildbot/worker/jdkX-linux/build/src/hotspot/share/classfile/classLoaderData.inline.hpp:31,
                 from /home/buildbot/worker/jdkX-linux/build/src/hotspot/share/oops/klass.inline.hpp:28,
                 from /home/buildbot/worker/jdkX-linux/build/src/hotspot/cpu/x86/sharedRuntime_x86_32.cpp:37:
/home/buildbot/worker/jdkX-linux/build/src/hotspot/share/gc/shared/barrierSet.hpp:36:7: note: forward declaration of 'class BarrierSetAssembler'
 class BarrierSetAssembler;
       ^~~~~~~~~~~~~~~~~~~

Trivial fix:

diff -r 0da81bf438fe src/hotspot/cpu/x86/sharedRuntime_x86_32.cpp
--- a/src/hotspot/cpu/x86/sharedRuntime_x86_32.cpp Fri Jan 10 16:51:44 2020 +0100
+++ b/src/hotspot/cpu/x86/sharedRuntime_x86_32.cpp Fri Jan 10 16:55:06 2020 +0100
@@ -31,4 +31,6 @@
 #include "code/vtableStubs.hpp"
 #include "gc/shared/gcLocker.hpp"
+#include "gc/shared/barrierSet.hpp"
+#include "gc/shared/barrierSetAssembler.hpp"
 #include "interpreter/interpreter.hpp"
 #include "logging/log.hpp"