Patchwork libitm: Ask dispatch whether it requires serial mode.

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Submitter Torvald Riegel
Date Oct. 23, 2012, 3:48 p.m.
Message ID <1351007306.3374.10907.camel@triegel.csb>
Download mbox | patch
Permalink /patch/193518/
State New
Headers show

Comments

Torvald Riegel - Oct. 23, 2012, 3:48 p.m.
This patch cleans up an implicit assumption about which TM methods
actually need to be run in serial mode.  Instead, the transaction begin
code now asks a TM method's dispatch what it needs.

OK for trunk?

Torvald
commit 12170ba5013e855bf4ea784823961f63e3e2de4c
Author: Torvald Riegel <triegel@redhat.com>
Date:   Tue Oct 23 14:09:22 2012 +0200

    Ask dispatch whether it requires serial mode.
    
    	* retry.cc (gtm_thread::decide_begin_dispatch): Ask dispatch whether
    	it requires serial mode instead of assuming that for certain
    	dispatchs.
    	* dispatch.h (abi_dispatch::requires_serial): New.
    	(abi_dispatch::abi_dispatch): Adapt.
    	* method-gl.cc (gl_wt_dispatch::gl_wt_dispatch): Adapt.
    	* method-ml.cc (ml_wt_dispatch::ml_wt_dispatch): Same.
    	* method-serial.cc (serialirr_dispatch::serialirr_dispatch,
    	serial_dispatch::serial_dispatch,
    	serialirr_onwrite_dispatch::serialirr_onwrite_dispatch): Same.
Richard Henderson - Oct. 23, 2012, 9:30 p.m.
On 2012-10-24 01:48, Torvald Riegel wrote:
>     Ask dispatch whether it requires serial mode.
>     
>     	* retry.cc (gtm_thread::decide_begin_dispatch): Ask dispatch whether
>     	it requires serial mode instead of assuming that for certain
>     	dispatchs.
>     	* dispatch.h (abi_dispatch::requires_serial): New.
>     	(abi_dispatch::abi_dispatch): Adapt.
>     	* method-gl.cc (gl_wt_dispatch::gl_wt_dispatch): Adapt.
>     	* method-ml.cc (ml_wt_dispatch::ml_wt_dispatch): Same.
>     	* method-serial.cc (serialirr_dispatch::serialirr_dispatch,
>     	serial_dispatch::serial_dispatch,
>     	serialirr_onwrite_dispatch::serialirr_onwrite_dispatch): Same.

Ok.


r~

Patch

diff --git a/libitm/dispatch.h b/libitm/dispatch.h
index 6a9e62e..200138b 100644
--- a/libitm/dispatch.h
+++ b/libitm/dispatch.h
@@ -311,6 +311,9 @@  public:
   }
   // Returns true iff this TM method supports closed nesting.
   bool closed_nesting() const { return m_closed_nesting; }
+  // Returns STATE_SERIAL or STATE_SERIAL | STATE_IRREVOCABLE iff the TM
+  // method only works for serial-mode transactions.
+  uint32_t requires_serial() const { return m_requires_serial; }
   method_group* get_method_group() const { return m_method_group; }
 
   static void *operator new(size_t s) { return xmalloc (s); }
@@ -332,12 +335,14 @@  protected:
   const bool m_write_through;
   const bool m_can_run_uninstrumented_code;
   const bool m_closed_nesting;
+  const uint32_t m_requires_serial;
   method_group* const m_method_group;
   abi_dispatch(bool ro, bool wt, bool uninstrumented, bool closed_nesting,
-      method_group* mg) :
+      uint32_t requires_serial, method_group* mg) :
     m_read_only(ro), m_write_through(wt),
     m_can_run_uninstrumented_code(uninstrumented),
-    m_closed_nesting(closed_nesting), m_method_group(mg)
+    m_closed_nesting(closed_nesting), m_requires_serial(requires_serial),
+    m_method_group(mg)
   { }
 };
 
diff --git a/libitm/method-gl.cc b/libitm/method-gl.cc
index 4b6769b..be8f36c 100644
--- a/libitm/method-gl.cc
+++ b/libitm/method-gl.cc
@@ -341,7 +341,7 @@  public:
   CREATE_DISPATCH_METHODS(virtual, )
   CREATE_DISPATCH_METHODS_MEM()
 
-  gl_wt_dispatch() : abi_dispatch(false, true, false, false, &o_gl_mg)
+  gl_wt_dispatch() : abi_dispatch(false, true, false, false, 0, &o_gl_mg)
   { }
 };
 
diff --git a/libitm/method-ml.cc b/libitm/method-ml.cc
index 88455e8..80278f5 100644
--- a/libitm/method-ml.cc
+++ b/libitm/method-ml.cc
@@ -590,7 +590,7 @@  public:
   CREATE_DISPATCH_METHODS(virtual, )
   CREATE_DISPATCH_METHODS_MEM()
 
-  ml_wt_dispatch() : abi_dispatch(false, true, false, false, &o_ml_mg)
+  ml_wt_dispatch() : abi_dispatch(false, true, false, false, 0, &o_ml_mg)
   { }
 };
 
diff --git a/libitm/method-serial.cc b/libitm/method-serial.cc
index bdecd7b..09cfdd4 100644
--- a/libitm/method-serial.cc
+++ b/libitm/method-serial.cc
@@ -50,13 +50,15 @@  static serial_mg o_serial_mg;
 class serialirr_dispatch : public abi_dispatch
 {
  public:
-  serialirr_dispatch() : abi_dispatch(false, true, true, false, &o_serial_mg)
+  serialirr_dispatch() : abi_dispatch(false, true, true, false,
+      gtm_thread::STATE_SERIAL | gtm_thread::STATE_IRREVOCABLE, &o_serial_mg)
   { }
 
  protected:
   serialirr_dispatch(bool ro, bool wt, bool uninstrumented,
-      bool closed_nesting, method_group* mg) :
-    abi_dispatch(ro, wt, uninstrumented, closed_nesting, mg) { }
+      bool closed_nesting, uint32_t requires_serial, method_group* mg) :
+    abi_dispatch(ro, wt, uninstrumented, closed_nesting, requires_serial, mg)
+  { }
 
   // Transactional loads and stores simply access memory directly.
   // These methods are static to avoid indirect calls, and will be used by the
@@ -151,7 +153,9 @@  public:
   CREATE_DISPATCH_METHODS(virtual, )
   CREATE_DISPATCH_METHODS_MEM()
 
-  serial_dispatch() : abi_dispatch(false, true, false, true, &o_serial_mg) { }
+  serial_dispatch() : abi_dispatch(false, true, false, true,
+      gtm_thread::STATE_SERIAL, &o_serial_mg)
+  { }
 };
 
 
@@ -162,7 +166,7 @@  class serialirr_onwrite_dispatch : public serialirr_dispatch
 {
  public:
   serialirr_onwrite_dispatch() :
-    serialirr_dispatch(false, true, false, false, &o_serial_mg) { }
+    serialirr_dispatch(false, true, false, false, 0, &o_serial_mg) { }
 
  protected:
   static void pre_write()
diff --git a/libitm/retry.cc b/libitm/retry.cc
index 660bf52..172419b 100644
--- a/libitm/retry.cc
+++ b/libitm/retry.cc
@@ -173,7 +173,7 @@  GTM::gtm_thread::decide_begin_dispatch (uint32_t prop)
 	  && dd->closed_nesting_alternative())
 	dd = dd->closed_nesting_alternative();
 
-      if (dd != dispatch_serial() && dd != dispatch_serialirr())
+      if (!(dd->requires_serial() & STATE_SERIAL))
 	{
 	  // The current dispatch is supposedly a non-serial one.  Become an
 	  // active transaction and verify this.  Relaxed memory order is fine
@@ -193,10 +193,7 @@  GTM::gtm_thread::decide_begin_dispatch (uint32_t prop)
 
   // We are some kind of serial transaction.
   serial_lock.write_lock();
-  if (dd == dispatch_serialirr())
-    state = STATE_SERIAL | STATE_IRREVOCABLE;
-  else
-    state = STATE_SERIAL;
+  state = dd->requires_serial();
   return dd;
 }