8255397: x86: coalesce reference and int entry points into vtos bytecodes

Reviewed-by: shade, coleenp

src/hotspot/cpu/x86/interp_masm_x86.cpp

@@ -605,6 +605,10 @@ void InterpreterMacroAssembler::push_i(Register r) {
   push(r);
 }
 
+void InterpreterMacroAssembler::push_i_or_ptr(Register r) {
+  push(r);
+}
+
 void InterpreterMacroAssembler::push_f(XMMRegister r) {
   subptr(rsp, wordSize);
   movflt(Address(rsp, 0), r);

src/hotspot/cpu/x86/interp_masm_x86.hpp

@@ -139,9 +139,18 @@ class InterpreterMacroAssembler: public MacroAssembler {
   // Expression stack
   void pop_ptr(Register r = rax);
   void pop_i(Register r = rax);
+
+  // On x86, pushing a ptr or an int is semantically identical, but we
+  // maintain a distinction for clarity and for making it easier to change
+  // semantics in the future
   void push_ptr(Register r = rax);
   void push_i(Register r = rax);
 
+  // push_i_or_ptr is provided for when explicitly allowing either a ptr or
+  // an int might have some advantage, while still documenting the fact that a
+  // ptr might be pushed to the stack.
+  void push_i_or_ptr(Register r = rax);
+
   void push_f(XMMRegister r);
   void pop_f(XMMRegister r);
   void pop_d(XMMRegister r);

src/hotspot/cpu/x86/templateInterpreterGenerator_x86.cpp

@@ -1761,9 +1761,6 @@ void TemplateInterpreterGenerator::set_vtos_entry_points(Template* t,
                                                          address& vep) {
   assert(t->is_valid() && t->tos_in() == vtos, "illegal template");
   Label L;
-  aep = __ pc();     // atos entry point
-      __ push_ptr();
-      __ jmp(L);
 #ifndef _LP64
   fep = __ pc();     // ftos entry point
       __ push(ftos);
@@ -1782,8 +1779,8 @@ void TemplateInterpreterGenerator::set_vtos_entry_points(Template* t,
   lep = __ pc();     // ltos entry point
       __ push_l();
       __ jmp(L);
-  bep = cep = sep = iep = __ pc();      // [bcsi]tos entry point
-      __ push_i();
+  aep = bep = cep = sep = iep = __ pc();      // [abcsi]tos entry point
+      __ push_i_or_ptr();
   vep = __ pc();    // vtos entry point
   __ bind(L);
   generate_and_dispatch(t);