don't make -ddump-if-trace imply -no-recomp
[ghc-hetmet.git] / rts / Exception.cmm
index 103e0c4..75f2c15 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 )
+INFO_TABLE_RET( stg_unblockAsyncExceptionszh_ret, RET_SMALL )
 {
-    // Not true: see comments above
-    // ASSERT(StgTSO_blocked_exceptions(CurrentTSO) != NULL);
-
-    foreign "C" awakenBlockedExceptionQueue(MyCapability() "ptr", 
-                                           CurrentTSO "ptr") [R1];
+    CInt r;
 
     StgTSO_flags(CurrentTSO) = StgTSO_flags(CurrentTSO) & 
        ~(TSO_BLOCKEX::I32|TSO_INTERRUPTIBLE::I32);
 
+    /* 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.
+         */
+
+#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;
+#ifdef REG_R1
+        Sp(0) = stg_gc_unpt_r1_info;
+#else
+        Sp(0) = stg_ut_1_0_unreg_info;
+#endif
+        SAVE_THREAD_STATE();
+        (r) = foreign "C" maybePerformBlockedException (MyCapability() "ptr", 
+                                                     CurrentTSO "ptr") [R1];
+
+        if (r != 0::CInt) {
+            if (StgTSO_what_next(CurrentTSO) == ThreadKilled::I16) {
+                jump stg_threadFinished;
+            } else {
+                LOAD_THREAD_STATE();
+                ASSERT(StgTSO_what_next(CurrentTSO) == ThreadRunGHC::I16);
+                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);
+        }
+#endif
+    }
+
 #ifdef REG_R1
     Sp_adj(1);
     jump %ENTRY_CODE(Sp(0));
@@ -72,12 +115,8 @@ INFO_TABLE_RET( stg_unblockAsyncExceptionszh_ret,
 #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;
 
@@ -116,16 +155,38 @@ blockAsyncExceptionszh_fast
 
 unblockAsyncExceptionszh_fast
 {
+    CInt r;
+
     /* Args: R1 :: IO a */
     STK_CHK_GEN( WDS(2), R1_PTR, unblockAsyncExceptionszh_fast);
 
     if ((TO_W_(StgTSO_flags(CurrentTSO)) & TSO_BLOCKEX) != 0) {
-       foreign "C" awakenBlockedExceptionQueue(MyCapability() "ptr", 
-                                               CurrentTSO "ptr") [R1];
 
        StgTSO_flags(CurrentTSO) = StgTSO_flags(CurrentTSO) & 
           ~(TSO_BLOCKEX::I32|TSO_INTERRUPTIBLE::I32);
 
+        /* 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.
+             */
+            SAVE_THREAD_STATE();
+            (r) = foreign "C" maybePerformBlockedException (MyCapability() "ptr", 
+                                                     CurrentTSO "ptr") [R1];
+
+            if (r != 0::CInt) {
+                if (StgTSO_what_next(CurrentTSO) == ThreadKilled::I16) {
+                    jump stg_threadFinished;
+               } else {
+                   LOAD_THREAD_STATE();
+                   ASSERT(StgTSO_what_next(CurrentTSO) == ThreadRunGHC::I16);
+                   jump %ENTRY_CODE(Sp(0));
+               }
+            }
+        }
+
        /* avoid growing the stack unnecessarily */
        if (Sp(0) == stg_unblockAsyncExceptionszh_ret_info) {
            Sp_adj(1);
@@ -159,14 +220,18 @@ 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) {
        SAVE_THREAD_STATE();
        /* ToDo: what if the current thread is blocking exceptions? */
        foreign "C" throwToSingleThreaded(MyCapability() "ptr", 
                                          target "ptr", exception "ptr")[R1,R2];
        if (StgTSO_what_next(CurrentTSO) == ThreadKilled::I16) {
-           R1 = ThreadFinished;
-           jump StgReturn;
+            jump stg_threadFinished;
        } else {
            LOAD_THREAD_STATE();
            ASSERT(StgTSO_what_next(CurrentTSO) == ThreadRunGHC::I16);
@@ -177,7 +242,7 @@ killThreadzh_fast
        W_ retcode;
        out = BaseReg + OFFSET_StgRegTable_rmp_tmp_w;
        
-       retcode = foreign "C" throwTo(MyCapability() "ptr",
+       (retcode) = foreign "C" throwTo(MyCapability() "ptr",
                                      CurrentTSO "ptr",
                                      target "ptr",
                                      exception "ptr",
@@ -203,68 +268,35 @@ killThreadzh_fast
    -------------------------------------------------------------------------- */
 
 #ifdef REG_R1
-#define CATCH_FRAME_ENTRY_TEMPLATE(label,ret)  \
-   label                                       \
-   {                                           \
-      Sp = Sp + SIZEOF_StgCatchFrame;          \
-      jump ret;                                        \
-   }
-#else
-#define CATCH_FRAME_ENTRY_TEMPLATE(label,ret)  \
-   label                                       \
-   {                                           \
-      W_ rval;                                 \
-      rval = Sp(0);                            \
-      Sp = Sp + SIZEOF_StgCatchFrame;          \
-      Sp(0) = rval;                            \
-      jump ret;                                        \
-   }
-#endif
-
-#ifdef REG_R1
 #define SP_OFF 0
 #else
 #define SP_OFF 1
 #endif
 
-CATCH_FRAME_ENTRY_TEMPLATE(stg_catch_frame_0_ret,%RET_VEC(Sp(SP_OFF),0))
-CATCH_FRAME_ENTRY_TEMPLATE(stg_catch_frame_1_ret,%RET_VEC(Sp(SP_OFF),1))
-CATCH_FRAME_ENTRY_TEMPLATE(stg_catch_frame_2_ret,%RET_VEC(Sp(SP_OFF),2))
-CATCH_FRAME_ENTRY_TEMPLATE(stg_catch_frame_3_ret,%RET_VEC(Sp(SP_OFF),3))
-CATCH_FRAME_ENTRY_TEMPLATE(stg_catch_frame_4_ret,%RET_VEC(Sp(SP_OFF),4))
-CATCH_FRAME_ENTRY_TEMPLATE(stg_catch_frame_5_ret,%RET_VEC(Sp(SP_OFF),5))
-CATCH_FRAME_ENTRY_TEMPLATE(stg_catch_frame_6_ret,%RET_VEC(Sp(SP_OFF),6))
-CATCH_FRAME_ENTRY_TEMPLATE(stg_catch_frame_7_ret,%RET_VEC(Sp(SP_OFF),7))
-
-#if MAX_VECTORED_RTN > 8
-#error MAX_VECTORED_RTN has changed: please modify stg_catch_frame too.
-#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,
-              stg_catch_frame_0_ret,
-              stg_catch_frame_1_ret,
-              stg_catch_frame_2_ret,
-              stg_catch_frame_3_ret,
-              stg_catch_frame_4_ret,
-              stg_catch_frame_5_ret,
-              stg_catch_frame_6_ret,
-              stg_catch_frame_7_ret)
-CATCH_FRAME_ENTRY_TEMPLATE(,%ENTRY_CODE(Sp(SP_OFF)))
+INFO_TABLE_RET(stg_catch_frame, CATCH_FRAME,
+#if defined(PROFILING)
+  W_ unused1, W_ unused2,
+#endif
+  W_ unused3, "ptr" W_ unused4)
+#ifdef REG_R1
+   {
+      Sp = Sp + SIZEOF_StgCatchFrame;
+      jump %ENTRY_CODE(Sp(SP_OFF));
+   }
+#else
+   {
+      W_ rval;
+      rval = Sp(0);
+      Sp = Sp + SIZEOF_StgCatchFrame;
+      Sp(0) = rval;
+      jump %ENTRY_CODE(Sp(SP_OFF));
+   }
+#endif
 
 /* -----------------------------------------------------------------------------
  * The catch infotable
@@ -318,13 +350,26 @@ INFO_TABLE(stg_raise,1,0,THUNK_1_0,"raise","raise")
   jump raisezh_fast;
 }
 
+section "data" {
+  no_break_on_exception: W_[1];
+}
+
+INFO_TABLE_RET(stg_raise_ret, RET_SMALL, "ptr" W_ arg1)
+{
+  R1 = Sp(1);
+  Sp = Sp + WDS(2);
+  W_[no_break_on_exception] = 1;  
+  jump raisezh_fast;
+}
+
 raisezh_fast
 {
     W_ handler;
-    W_ raise_closure;
     W_ frame_type;
+    W_ exception;
     /* args : R1 :: Exception */
 
+   exception = R1;
 
 #if defined(PROFILING)
     /* Debugging tool: on raising an  exception, show where we are. */
@@ -333,16 +378,13 @@ raisezh_fast
      * the info was only displayed for an *uncaught* exception.
      */
     if (RtsFlags_ProfFlags_showCCSOnException(RtsFlags) != 0::I32) {
-      foreign "C" fprintCCS_stderr(W_[CCCS] "ptr");
+      foreign "C" fprintCCS_stderr(W_[CCCS] "ptr") [];
     }
 #endif
     
-    /* Inform the Hpc that an exception has been thrown */
-    foreign "C" hs_hpc_throw();
-
 retry_pop_stack:
     StgTSO_sp(CurrentTSO) = Sp;
-    frame_type = foreign "C" raiseExceptionHelper(BaseReg "ptr", CurrentTSO "ptr", R1 "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 
@@ -356,14 +398,14 @@ 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") [];
-      foreign "C" stmAbortTransaction(MyCapability() "ptr", trec "ptr");
-      foreign "C" stmFreeAbortedTRec(MyCapability() "ptr", trec "ptr");
+      (r) = foreign "C" stmValidateNestOfTransactions(trec "ptr") [];
+      ("ptr" outer) = foreign "C" stmGetEnclosingTRec(trec "ptr") [];
+      foreign "C" stmAbortTransaction(MyCapability() "ptr", trec "ptr") [];
+      foreign "C" stmFreeAbortedTRec(MyCapability() "ptr", trec "ptr") [];
 
       if (outer != NO_TREC) {
-        foreign "C" stmAbortTransaction(MyCapability() "ptr", outer "ptr");
-        foreign "C" stmFreeAbortedTRec(MyCapability() "ptr", outer "ptr");
+        foreign "C" stmAbortTransaction(MyCapability() "ptr", outer "ptr") [];
+        foreign "C" stmFreeAbortedTRec(MyCapability() "ptr", outer "ptr") [];
       }
 
       StgTSO_trec(CurrentTSO) = NO_TREC;
@@ -374,13 +416,43 @@ 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;
       }          
     }
 
+    // After stripping the stack, see whether we should break here for
+    // GHCi (c.f. the -fbreak-on-exception flag).  We do this after
+    // stripping the stack for a reason: we'll be inspecting values in
+    // GHCi, and it helps if all the thunks under evaluation have
+    // already been updated with the exception, rather than being left
+    // as blackholes.
+    if (W_[no_break_on_exception] != 0) {
+        W_[no_break_on_exception] = 0;
+    } else {
+        if (TO_W_(CInt[rts_stop_on_exception]) != 0) {
+            W_ ioAction;
+            // we don't want any further exceptions to be caught,
+            // until GHCi is ready to handle them.  This prevents
+            // 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(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) = ghczmprim_GHCziBool_True_closure; // dummy breakpoint info
+            Sp(1) = ghczmprim_GHCziBool_True_closure; // True <=> a breakpoint
+            R1 = ioAction;
+            jump RET_LBL(stg_ap_pppv);
+        }
+    }
+
     if (frame_type == STOP_FRAME) {
        /*
         * We've stripped the entire stack, the thread is now dead.
@@ -389,16 +461,12 @@ retry_pop_stack:
         */
        Sp = CurrentTSO + TSO_OFFSET_StgTSO_stack 
                + WDS(TO_W_(StgTSO_stack_size(CurrentTSO))) - WDS(2);
-       Sp(1) = R1;             /* save the exception */
+       Sp(1) = exception;      /* save the exception */
        Sp(0) = stg_enter_info; /* so that GC can traverse this stack */
        StgTSO_what_next(CurrentTSO) = ThreadKilled::I16;
        SAVE_THREAD_STATE();    /* inline! */
 
-       /* The return code goes in BaseReg->rRet, and BaseReg is returned in R1 */
-       StgRegTable_rRet(BaseReg) = ThreadFinished;
-       R1 = BaseReg;
-
-       jump StgReturn;
+        jump stg_threadFinished;
     }
 
     /* Ok, Sp points to the enclosing CATCH_FRAME or CATCH_STM_FRAME.  Pop everything
@@ -431,7 +499,7 @@ retry_pop_stack:
     } else {
       W_ trec, outer;
       trec = StgTSO_trec(CurrentTSO);
-      "ptr" outer = foreign "C" stmGetEnclosingTRec(trec "ptr") [];
+      ("ptr" outer) = foreign "C" stmGetEnclosingTRec(trec "ptr") [];
       foreign "C" stmAbortTransaction(MyCapability() "ptr", trec "ptr") [];
       foreign "C" stmFreeAbortedTRec(MyCapability() "ptr", trec "ptr") [];
       StgTSO_trec(CurrentTSO) = outer;
@@ -447,7 +515,7 @@ retry_pop_stack:
      * token as arguments.
      */
     Sp_adj(-1);
-    Sp(0) = R1;
+    Sp(0) = exception;
     R1 = handler;
     Sp_adj(-1);
     TICK_UNKNOWN_CALL();