--- old/src/hotspot/share/opto/output.cpp	2020-06-24 18:28:38.842081000 +0200
+++ new/src/hotspot/share/opto/output.cpp	2020-06-24 18:28:38.018091000 +0200
@@ -30,6 +30,7 @@
 #include "code/debugInfoRec.hpp"
 #include "compiler/compileBroker.hpp"
 #include "compiler/compilerDirectives.hpp"
+#include "compiler/disassembler.hpp"
 #include "compiler/oopMap.hpp"
 #include "memory/allocation.inline.hpp"
 #include "opto/ad.hpp"
@@ -1399,8 +1400,17 @@
       }
 
 #ifdef ASSERT
-      if (n->size(_regalloc) < (current_offset-instr_offset)) {
+      uint n_size = n->size(C->regalloc());
+      if (n_size < (current_offset-instr_offset)) {
+        MachNode* mach = n->as_Mach();
         n->dump();
+        mach->dump_format(C->regalloc(), tty);
+        tty->print_cr(" n_size (%d), current_offset (%d), instr_offset (%d)", n_size, current_offset, instr_offset);
+        Disassembler::decode(cb->insts_begin() + instr_offset, cb->insts_begin() + current_offset + 1, tty);
+        tty->print_cr(" ------------------- ");
+        BufferBlob* blob = this->scratch_buffer_blob();
+        address blob_begin = blob->content_begin();
+        Disassembler::decode(blob_begin, blob_begin + n_size + 1, tty);
         assert(false, "wrong size of mach node");
       }
 #endif