--- a/src/hotspot/share/opto/compile.hpp	Tue Oct 08 15:30:46 2019 +0200
+++ b/src/hotspot/share/opto/compile.hpp	Wed Oct 09 12:30:06 2019 +0000
@@ -55,7 +55,6 @@
 class IdealGraphPrinter;
 class InlineTree;
 class Int_Array;
-class LoadBarrierNode;
 class Matcher;
 class MachConstantNode;
 class MachConstantBaseNode;
@@ -96,7 +95,6 @@
   LoopOptsNone,
   LoopOptsShenandoahExpand,
   LoopOptsShenandoahPostExpand,
-  LoopOptsZBarrierInsertion,
   LoopOptsSkipSplitIf,
   LoopOptsVerify
 };
@@ -1186,11 +1184,7 @@
   bool           in_scratch_emit_size() const   { return _in_scratch_emit_size;     }
 
   enum ScratchBufferBlob {
-#if defined(PPC64)
     MAX_inst_size       = 2048,
-#else
-    MAX_inst_size       = 1024,
-#endif
     MAX_locs_size       = 128, // number of relocInfo elements
     MAX_const_size      = 128,
     MAX_stubs_size      = 128
@@ -1265,14 +1259,30 @@
   // Process an OopMap Element while emitting nodes
   void Process_OopMap_Node(MachNode *mach, int code_offset);
 
+  class BufferSizingData {
+  public:
+    int _stub;
+    int _code;
+    int _const;
+    int _reloc;
+
+      BufferSizingData() :
+      _stub(0),
+      _code(0),
+      _const(0),
+      _reloc(0)
+      { };
+  };
+
   // Initialize code buffer
-  CodeBuffer* init_buffer(uint* blk_starts);
+  void        estimate_buffer_size(int& const_req);
+  CodeBuffer* init_buffer(BufferSizingData& buf_sizes);
 
   // Write out basic block data to code buffer
   void fill_buffer(CodeBuffer* cb, uint* blk_starts);
 
   // Determine which variable sized branches can be shortened
-  void shorten_branches(uint* blk_starts, int& code_size, int& reloc_size, int& stub_size);
+  void shorten_branches(uint* blk_starts, BufferSizingData& buf_sizes);
 
   // Compute the size of first NumberOfLoopInstrToAlign instructions
   // at the head of a loop.