Add HTM fastpath and use Intel RTM for it on x86.

	* beginend.cc (htm_fastpath): New.
	(gtm_thread::begin_transaction, _ITM_commitTransaction,
	_ITM_commitTransactionEH): Add HTM fastpath handling.
	* config/linux/rwlock.h (gtm_rwlock.is_write_locked): New.
	* config/posix/rwlock.h (gtm_rwlock.is_write_locked): New.
	* config/x86/target.h (htm_available, htm_init, htm_begin_success,
	htm_begin, htm_commit, htm_abort, htm_abort_should_retry): New.
	* configure.tgt: Add -mrtm to XCFLAGS.
	* method-serial.cc (htm_mg, o_htm_mg, htm_dispatch, dispatch_htm): New.
	(gtm_thread::serialirr_mode): Add HTM fastpath handling.
	* libitm_i.h (htm_fastpath, dispatch_htm): Declare.
	* retry.cc (parse_default_method): Add HTM method parsing.
	(gtm_thread::number_of_threads_changed): Use HTM by default if
	available.

From-SVN: r193369

1 files changed, 48 insertions, 0 deletions

diff --git a/libitm/method-serial.cc b/libitm/method-serial.cc
index 09cfdd4a175..38857dcc80d 100644
--- a/libitm/method-serial.cc
+++ b/libitm/method-serial.cc
@@ -212,11 +212,46 @@ class serialirr_onwrite_dispatch : public serialirr_dispatch
   }
 };
 
+// This group is pure HTM with serial mode as a fallback.  There is no
+// difference to serial_mg except that we need to enable or disable the HTM
+// fastpath.  See gtm_thread::begin_transaction.
+struct htm_mg : public method_group
+{
+  virtual void init()
+  {
+    // Enable the HTM fastpath if the HW is available.  The fastpath is
+    // initially disabled.
+#ifdef USE_HTM_FASTPATH
+    htm_fastpath = htm_init();
+#endif
+  }
+  virtual void fini()
+  {
+    // Disable the HTM fastpath.
+    htm_fastpath = 0;
+  }
+};
+
+static htm_mg o_htm_mg;
+
+// We just need the subclass to associate it with the HTM method group that
+// sets up the HTM fast path.  This will use serial_dispatch as fallback for
+// transactions that might get canceled; it has a different method group, but
+// this is harmless for serial dispatchs because they never abort.
+class htm_dispatch : public serialirr_dispatch
+{
+ public:
+  htm_dispatch() : serialirr_dispatch(false, true, false, false,
+      gtm_thread::STATE_SERIAL | gtm_thread::STATE_IRREVOCABLE, &o_htm_mg)
+  { }
+};
+
 } // anon namespace
 
 static const serialirr_dispatch o_serialirr_dispatch;
 static const serial_dispatch o_serial_dispatch;
 static const serialirr_onwrite_dispatch o_serialirr_onwrite_dispatch;
+static const htm_dispatch o_htm_dispatch;
 
 abi_dispatch *
 GTM::dispatch_serialirr ()
@@ -237,6 +272,12 @@ GTM::dispatch_serialirr_onwrite ()
       const_cast<serialirr_onwrite_dispatch *>(&o_serialirr_onwrite_dispatch);
 }
 
+abi_dispatch *
+GTM::dispatch_htm ()
+{
+  return const_cast<htm_dispatch *>(&o_htm_dispatch);
+}
+
 // Put the transaction into serial-irrevocable mode.
 
 void
@@ -244,6 +285,13 @@ GTM::gtm_thread::serialirr_mode ()
 {
   struct abi_dispatch *disp = abi_disp ();
 
+#if defined(USE_HTM_FASTPATH)
+  // HTM fastpath.  If we are executing a HW transaction, don't go serial but
+  // continue.  See gtm_thread::begin_transaction.
+  if (likely(htm_fastpath && !gtm_thread::serial_lock.is_write_locked()))
+    return;
+#endif
+
   if (this->state & STATE_SERIAL)
     {
       if (this->state & STATE_IRREVOCABLE)