8017313: PPC64 (part 6): stack handling improvements

Summary: Precompute limit for stack overflow check.
Reviewed-by: kvn, coleenp

src/share/vm/runtime/thread.cpp

@@ -312,6 +312,9 @@ void Thread::initialize_thread_local_storage() {
 void Thread::record_stack_base_and_size() {
   set_stack_base(os::current_stack_base());
   set_stack_size(os::current_stack_size());
+  if (is_Java_thread()) {
+    ((JavaThread*) this)->set_stack_overflow_limit();
+  }
   // CR 7190089: on Solaris, primordial thread's stack is adjusted
   // in initialize_thread(). Without the adjustment, stack size is
   // incorrect if stack is set to unlimited (ulimit -s unlimited).

src/share/vm/runtime/thread.hpp

@@ -893,7 +893,11 @@ class JavaThread: public Thread {
 
  private:
 
-  StackGuardState        _stack_guard_state;
+  StackGuardState  _stack_guard_state;
+
+  // Precompute the limit of the stack as used in stack overflow checks.
+  // We load it from here to simplify the stack overflow check in assembly.
+  address          _stack_overflow_limit;
 
   // Compiler exception handling (NOTE: The _exception_oop is *NOT* the same as _pending_exception. It is
   // used to temp. parsing values into and out of the runtime system during exception handling for compiled
@@ -1301,6 +1305,14 @@ class JavaThread: public Thread {
   // and reguard if possible.
   bool reguard_stack(void);
 
+  address stack_overflow_limit() { return _stack_overflow_limit; }
+  void set_stack_overflow_limit() {
+    _stack_overflow_limit = _stack_base - _stack_size +
+                            ((StackShadowPages +
+                              StackYellowPages +
+                              StackRedPages) * os::vm_page_size());
+  }
+
   // Misc. accessors/mutators
   void set_do_not_unlock(void)                   { _do_not_unlock_if_synchronized = true; }
   void clr_do_not_unlock(void)                   { _do_not_unlock_if_synchronized = false; }
@@ -1335,6 +1347,7 @@ class JavaThread: public Thread {
   static ByteSize exception_oop_offset()         { return byte_offset_of(JavaThread, _exception_oop       ); }
   static ByteSize exception_pc_offset()          { return byte_offset_of(JavaThread, _exception_pc        ); }
   static ByteSize exception_handler_pc_offset()  { return byte_offset_of(JavaThread, _exception_handler_pc); }
+  static ByteSize stack_overflow_limit_offset()  { return byte_offset_of(JavaThread, _stack_overflow_limit); }
   static ByteSize is_method_handle_return_offset() { return byte_offset_of(JavaThread, _is_method_handle_return); }
   static ByteSize stack_guard_state_offset()     { return byte_offset_of(JavaThread, _stack_guard_state   ); }
   static ByteSize suspend_flags_offset()         { return byte_offset_of(JavaThread, _suspend_flags       ); }