--- old/src/hotspot/share/opto/c2compiler.cpp	2018-10-26 12:37:08.918399655 +0200
+++ new/src/hotspot/share/opto/c2compiler.cpp	2018-10-26 12:37:08.734470451 +0200
@@ -605,6 +605,8 @@
 }
 
 int C2Compiler::initial_code_buffer_size() {
-  assert(SegmentedCodeCache, "Should be only used with a segmented code cache");
-  return Compile::MAX_inst_size + Compile::MAX_locs_size + initial_const_capacity;
+  // See Compile::init_scratch_buffer_blob
+  int locs_size = sizeof(relocInfo) * Compile::MAX_locs_size;
+  int slop = 2 * CodeSection::end_slop(); // space between sections
+  return Compile::MAX_inst_size + Compile::MAX_stubs_size + initial_const_capacity + slop + locs_size;
 }