micro-opt: replace stmGetEnclosingTRec() with a field access
[ghc-hetmet.git] / rts / Exception.cmm
index ec56738..6c887c2 100644 (file)
@@ -13,6 +13,8 @@
 #include "Cmm.h"
 #include "RaiseAsync.h"
 
+import ghczmprim_GHCziBool_True_closure;
+
 /* -----------------------------------------------------------------------------
    Exception Primitives
 
    unsafePerformIO thunk will be updated with a stack object
    containing the unblockAsyncExceptions_ret frame.  Later, when
    someone else evaluates this thunk, the blocked exception state is
-   not restored, and the result is that unblockAsyncExceptions_ret
-   will attempt to unblock exceptions in the current thread, but it'll
-   find that the CurrentTSO->blocked_exceptions is NULL.  Hence, we
-   work around this by checking for NULL in awakenBlockedQueue().
+   not restored.
 
    -------------------------------------------------------------------------- */
 
-INFO_TABLE_RET( stg_unblockAsyncExceptionszh_ret,
-               0/*framesize*/, 0/*bitmap*/, RET_SMALL )
+STRING(stg_unblockAsync_err_str, "unblockAsyncExceptions#_ret")
+
+INFO_TABLE_RET( stg_unblockAsyncExceptionszh_ret, RET_SMALL )
 {
     CInt r;
 
-    // Not true: see comments above
-    // ASSERT(StgTSO_blocked_exceptions(CurrentTSO) != NULL);
-
     StgTSO_flags(CurrentTSO) = StgTSO_flags(CurrentTSO) & 
        ~(TSO_BLOCKEX::I32|TSO_INTERRUPTIBLE::I32);
 
@@ -69,17 +66,12 @@ INFO_TABLE_RET( stg_unblockAsyncExceptionszh_ret,
          * thread, which might result in the thread being killed.
          */
 
-#ifndef REG_R1
-        /*
-         * raiseAsync assumes that the stack is in ThreadRunGHC state,
-         * i.e. with a return address on the top.  In unreg mode, the
-         * return value for IO is on top of the return address, so we
-         * need to make a small adjustment here.
-         */
-        Sp_adj(1);
-#endif
+        STK_CHK_GEN( WDS(2), R1_PTR, stg_unblockAsyncExceptionszh_ret_info);
+        Sp_adj(-2);
+        Sp(1) = R1;
+        Sp(0) = stg_gc_unpt_r1_info;
         SAVE_THREAD_STATE();
-        r = foreign "C" maybePerformBlockedException (MyCapability() "ptr", 
+        (r) = foreign "C" maybePerformBlockedException (MyCapability() "ptr", 
                                                      CurrentTSO "ptr") [R1];
 
         if (r != 0::CInt) {
@@ -91,50 +83,33 @@ INFO_TABLE_RET( stg_unblockAsyncExceptionszh_ret,
                 jump %ENTRY_CODE(Sp(0));
             }
         }
-#ifndef REG_R1
-        /* 
-         * Readjust stack in unregisterised mode if we didn't raise an
-         * exception, see above
-         */
         else {
-            Sp_adj(-1);
+            /*
+               the thread might have been removed from the
+               blocked_exception list by someone else in the meantime.
+               Just restore the stack pointer and continue.  
+            */   
+            Sp_adj(2);
         }
-#endif
     }
 
-#ifdef REG_R1
     Sp_adj(1);
     jump %ENTRY_CODE(Sp(0));
-#else
-    Sp(1) = Sp(0);
-    Sp_adj(1);
-    jump %ENTRY_CODE(Sp(1));
-#endif
 }
 
-INFO_TABLE_RET( stg_blockAsyncExceptionszh_ret,
-               0/*framesize*/, 0/*bitmap*/, RET_SMALL )
+INFO_TABLE_RET( stg_blockAsyncExceptionszh_ret, RET_SMALL )
 {
-    // Not true: see comments above
-    // ASSERT(StgTSO_blocked_exceptions(CurrentTSO) == NULL);
-
     StgTSO_flags(CurrentTSO) = 
        StgTSO_flags(CurrentTSO) | TSO_BLOCKEX::I32 | TSO_INTERRUPTIBLE::I32;
 
-#ifdef REG_R1
     Sp_adj(1);
     jump %ENTRY_CODE(Sp(0));
-#else
-    Sp(1) = Sp(0);
-    Sp_adj(1);
-    jump %ENTRY_CODE(Sp(1));
-#endif
 }
 
-blockAsyncExceptionszh_fast
+stg_blockAsyncExceptionszh
 {
     /* Args: R1 :: IO a */
-    STK_CHK_GEN( WDS(2)/* worst case */, R1_PTR, blockAsyncExceptionszh_fast);
+    STK_CHK_GEN( WDS(2)/* worst case */, R1_PTR, stg_blockAsyncExceptionszh);
 
     if ((TO_W_(StgTSO_flags(CurrentTSO)) & TSO_BLOCKEX) == 0) {
        
@@ -154,27 +129,50 @@ blockAsyncExceptionszh_fast
     jump stg_ap_v_fast;
 }
 
-unblockAsyncExceptionszh_fast
+stg_unblockAsyncExceptionszh
 {
     CInt r;
 
     /* Args: R1 :: IO a */
-    STK_CHK_GEN( WDS(2), R1_PTR, unblockAsyncExceptionszh_fast);
+    STK_CHK_GEN( WDS(4), R1_PTR, stg_unblockAsyncExceptionszh);
+    /* 4 words: one for the unblock frame, 3 for setting up the
+     * stack to call maybePerformBlockedException() below.
+     */
 
+    /* If exceptions are already unblocked, there's nothing to do */
     if ((TO_W_(StgTSO_flags(CurrentTSO)) & TSO_BLOCKEX) != 0) {
 
        StgTSO_flags(CurrentTSO) = StgTSO_flags(CurrentTSO) & 
           ~(TSO_BLOCKEX::I32|TSO_INTERRUPTIBLE::I32);
 
+       /* avoid growing the stack unnecessarily */
+       if (Sp(0) == stg_unblockAsyncExceptionszh_ret_info) {
+           Sp_adj(1);
+       } else {
+           Sp_adj(-1);
+           Sp(0) = stg_blockAsyncExceptionszh_ret_info;
+       }
+
         /* Eagerly raise a blocked exception, if there is one */
         if (StgTSO_blocked_exceptions(CurrentTSO) != END_TSO_QUEUE) {
             /* 
              * We have to be very careful here, as in killThread#, since
              * we are about to raise an async exception in the current
              * thread, which might result in the thread being killed.
+             *
+             * Now, if we are to raise an exception in the current
+             * thread, there might be an update frame above us on the
+             * stack due to unsafePerformIO.  Hence, the stack must
+             * make sense, because it is about to be snapshotted into
+             * an AP_STACK.
              */
+            Sp_adj(-3);
+            Sp(2) = stg_ap_v_info;
+            Sp(1) = R1;
+            Sp(0) = stg_enter_info;
+
             SAVE_THREAD_STATE();
-            r = foreign "C" maybePerformBlockedException (MyCapability() "ptr", 
+            (r) = foreign "C" maybePerformBlockedException (MyCapability() "ptr", 
                                                      CurrentTSO "ptr") [R1];
 
             if (r != 0::CInt) {
@@ -185,24 +183,29 @@ unblockAsyncExceptionszh_fast
                    ASSERT(StgTSO_what_next(CurrentTSO) == ThreadRunGHC::I16);
                    jump %ENTRY_CODE(Sp(0));
                }
+            } else {
+                /* we'll just call R1 directly, below */
+                Sp_adj(3);
             }
         }
 
-       /* avoid growing the stack unnecessarily */
-       if (Sp(0) == stg_unblockAsyncExceptionszh_ret_info) {
-           Sp_adj(1);
-       } else {
-           Sp_adj(-1);
-           Sp(0) = stg_blockAsyncExceptionszh_ret_info;
-       }
     }
     TICK_UNKNOWN_CALL();
     TICK_SLOW_CALL_v();
     jump stg_ap_v_fast;
 }
 
+stg_asyncExceptionsBlockedzh
+{
+    /* args: none */
+    if ((TO_W_(StgTSO_flags(CurrentTSO)) & TSO_BLOCKEX) != 0) {
+        RET_N(1);
+    } else {
+        RET_N(0);
+    }
+}
 
-killThreadzh_fast
+stg_killThreadzh
 {
     /* args: R1 = TSO to kill, R2 = Exception */
 
@@ -213,7 +216,8 @@ killThreadzh_fast
     target = R1;
     exception = R2;
     
-    STK_CHK_GEN( WDS(3), R1_PTR & R2_PTR, killThreadzh_fast);
+    /* Needs 3 words because throwToSingleThreaded uses some stack */
+    STK_CHK_GEN( WDS(3), R1_PTR & R2_PTR, stg_killThreadzh);
 
     /* 
      * We might have killed ourselves.  In which case, better be *very*
@@ -221,7 +225,20 @@ killThreadzh_fast
      * If the exception went to a catch frame, we'll just continue from
      * the handler.
      */
+  loop:
+    if (StgTSO_what_next(target) == ThreadRelocated::I16) {
+        target = StgTSO__link(target);
+        goto loop;
+    }
     if (target == CurrentTSO) {
+        /*
+         * So what should happen if a thread calls "throwTo self" inside
+         * unsafePerformIO, and later the closure is evaluated by another
+         * thread?  Presumably it should behave as if throwTo just returned,
+         * and then continue from there.  See #3279, #3288.  This is what
+         * happens: on resumption, we will just jump to the next frame on
+         * the stack, which is the return point for stg_killThreadzh.
+         */
        SAVE_THREAD_STATE();
        /* ToDo: what if the current thread is blocking exceptions? */
        foreign "C" throwToSingleThreaded(MyCapability() "ptr", 
@@ -236,9 +253,9 @@ killThreadzh_fast
     } else {
        W_ out;
        W_ retcode;
-       out = BaseReg + OFFSET_StgRegTable_rmp_tmp_w;
-       
-       retcode = foreign "C" throwTo(MyCapability() "ptr",
+       out = Sp - WDS(1); /* ok to re-use stack space here */
+
+       (retcode) = foreign "C" throwTo(MyCapability() "ptr",
                                      CurrentTSO "ptr",
                                      target "ptr",
                                      exception "ptr",
@@ -263,42 +280,22 @@ killThreadzh_fast
    Catch frames
    -------------------------------------------------------------------------- */
 
-#ifdef REG_R1
 #define SP_OFF 0
-#else
-#define SP_OFF 1
-#endif
-
-#if defined(PROFILING)
-#define CATCH_FRAME_BITMAP 7
-#define CATCH_FRAME_WORDS  4
-#else
-#define CATCH_FRAME_BITMAP 1
-#define CATCH_FRAME_WORDS  2
-#endif
 
 /* Catch frames are very similar to update frames, but when entering
  * one we just pop the frame off the stack and perform the correct
  * kind of return to the activation record underneath us on the stack.
  */
 
-INFO_TABLE_RET(stg_catch_frame,
-              CATCH_FRAME_WORDS, CATCH_FRAME_BITMAP,
-              CATCH_FRAME)
-#ifdef REG_R1
-   {
-      Sp = Sp + SIZEOF_StgCatchFrame;
-      jump %ENTRY_CODE(Sp(SP_OFF));
-   }
-#else
+INFO_TABLE_RET(stg_catch_frame, CATCH_FRAME,
+#if defined(PROFILING)
+  W_ unused1, W_ unused2,
+#endif
+  W_ unused3, P_ unused4)
    {
-      W_ rval;
-      rval = Sp(0);
       Sp = Sp + SIZEOF_StgCatchFrame;
-      Sp(0) = rval;
       jump %ENTRY_CODE(Sp(SP_OFF));
    }
-#endif
 
 /* -----------------------------------------------------------------------------
  * The catch infotable
@@ -314,13 +311,13 @@ INFO_TABLE(stg_catch,2,0,FUN,"catch","catch")
 {
   R2 = StgClosure_payload(R1,1); /* h */
   R1 = StgClosure_payload(R1,0); /* x */
-  jump catchzh_fast;
+  jump stg_catchzh;
 }
 
-catchzh_fast
+stg_catchzh
 {
     /* args: R1 = m :: IO a, R2 = handler :: Exception -> IO a */
-    STK_CHK_GEN(SIZEOF_StgCatchFrame + WDS(1), R1_PTR & R2_PTR, catchzh_fast);
+    STK_CHK_GEN(SIZEOF_StgCatchFrame + WDS(1), R1_PTR & R2_PTR, stg_catchzh);
   
     /* Set up the catch frame */
     Sp = Sp - SIZEOF_StgCatchFrame;
@@ -343,28 +340,28 @@ catchzh_fast
  *
  *   raise = {err} \n {} -> raise#{err}
  *
- * It is used in raisezh_fast to update thunks on the update list
+ * It is used in stg_raisezh to update thunks on the update list
  * -------------------------------------------------------------------------- */
 
 INFO_TABLE(stg_raise,1,0,THUNK_1_0,"raise","raise")
 {
   R1 = StgThunk_payload(R1,0);
-  jump raisezh_fast;
+  jump stg_raisezh;
 }
 
 section "data" {
   no_break_on_exception: W_[1];
 }
 
-INFO_TABLE_RET(stg_raise_ret, 1, 0, RET_SMALL)
+INFO_TABLE_RET(stg_raise_ret, RET_SMALL, P_ arg1)
 {
   R1 = Sp(1);
   Sp = Sp + WDS(2);
   W_[no_break_on_exception] = 1;  
-  jump raisezh_fast;
+  jump stg_raisezh;
 }
 
-raisezh_fast
+stg_raisezh
 {
     W_ handler;
     W_ frame_type;
@@ -384,12 +381,9 @@ raisezh_fast
     }
 #endif
     
-    /* Inform the Hpc that an exception has been thrown */
-    foreign "C" hs_hpc_raise_event(CurrentTSO "ptr") [];
-
 retry_pop_stack:
     StgTSO_sp(CurrentTSO) = Sp;
-    frame_type = foreign "C" raiseExceptionHelper(BaseReg "ptr", CurrentTSO "ptr", exception "ptr") [];
+    (frame_type) = foreign "C" raiseExceptionHelper(BaseReg "ptr", CurrentTSO "ptr", exception "ptr") [];
     Sp = StgTSO_sp(CurrentTSO);
     if (frame_type == ATOMICALLY_FRAME) {
       /* The exception has reached the edge of a memory transaction.  Check that 
@@ -403,8 +397,8 @@ retry_pop_stack:
       W_ trec, outer;
       W_ r;
       trec = StgTSO_trec(CurrentTSO);
-      r = foreign "C" stmValidateNestOfTransactions(trec "ptr") [];
-      "ptr" outer = foreign "C" stmGetEnclosingTRec(trec "ptr") [];
+      (r) = foreign "C" stmValidateNestOfTransactions(trec "ptr") [];
+      outer  = StgTRecHeader_enclosing_trec(trec);
       foreign "C" stmAbortTransaction(MyCapability() "ptr", trec "ptr") [];
       foreign "C" stmFreeAbortedTRec(MyCapability() "ptr", trec "ptr") [];
 
@@ -421,7 +415,7 @@ retry_pop_stack:
       } else {
         // Transaction was not valid: we retry the exception (otherwise continue
         // with a further call to raiseExceptionHelper)
-        "ptr" trec = foreign "C" stmStartTransaction(MyCapability() "ptr", NO_TREC "ptr") [];
+        ("ptr" trec) = foreign "C" stmStartTransaction(MyCapability() "ptr", NO_TREC "ptr") [];
         StgTSO_trec(CurrentTSO) = trec;
         R1 = StgAtomicallyFrame_code(Sp);
         jump stg_ap_v_fast;
@@ -444,16 +438,17 @@ retry_pop_stack:
             // deadlock if an exception is raised in InteractiveUI,
             // for exmplae.  Perhaps the stop_on_exception flag should
             // be per-thread.
-            W_[rts_stop_on_exception] = 0;
-            "ptr" ioAction = foreign "C" deRefStablePtr (W_[rts_breakpoint_io_action] "ptr") [];
-            Sp = Sp - WDS(6);
-            Sp(5) = exception;
-            Sp(4) = stg_raise_ret_info;
+            CInt[rts_stop_on_exception] = 0;
+            ("ptr" ioAction) = foreign "C" deRefStablePtr (W_[rts_breakpoint_io_action] "ptr") [];
+            Sp = Sp - WDS(7);
+            Sp(6) = exception;
+            Sp(5) = stg_raise_ret_info;
+            Sp(4) = stg_noforceIO_info;    // required for unregisterised
             Sp(3) = exception;             // the AP_STACK
-            Sp(2) = base_GHCziBase_True_closure; // dummy breakpoint info
-            Sp(1) = base_GHCziBase_True_closure; // True <=> a breakpoint
+            Sp(2) = ghczmprim_GHCziBool_True_closure; // dummy breakpoint info
+            Sp(1) = ghczmprim_GHCziBool_True_closure; // True <=> a breakpoint
             R1 = ioAction;
-            jump stg_ap_pppv_info;
+            jump RET_LBL(stg_ap_pppv);
         }
     }
 
@@ -503,7 +498,7 @@ retry_pop_stack:
     } else {
       W_ trec, outer;
       trec = StgTSO_trec(CurrentTSO);
-      "ptr" outer = foreign "C" stmGetEnclosingTRec(trec "ptr") [];
+      outer  = StgTRecHeader_enclosing_trec(trec);
       foreign "C" stmAbortTransaction(MyCapability() "ptr", trec "ptr") [];
       foreign "C" stmFreeAbortedTRec(MyCapability() "ptr", trec "ptr") [];
       StgTSO_trec(CurrentTSO) = outer;
@@ -527,8 +522,8 @@ retry_pop_stack:
     jump RET_LBL(stg_ap_pv);
 }
 
-raiseIOzh_fast
+stg_raiseIOzh
 {
   /* Args :: R1 :: Exception */
-  jump raisezh_fast;
+  jump stg_raisezh;
 }