+/* -----------------------------------------------------------------------------
+ * $Id: Exception.hc,v 1.1 1999/12/01 14:34:38 simonmar Exp $
+ *
+ * (c) The GHC Team, 1998-1999
+ *
+ * Exception support
+ *
+ * ---------------------------------------------------------------------------*/
+
+#include "Rts.h"
+#include "Exception.h"
+#include "Schedule.h"
+#include "StgRun.h"
+#include "Storage.h"
+#include "RtsUtils.h"
+
+/* -----------------------------------------------------------------------------
+ Exception Primitives
+
+ A thread can request that asynchronous exceptions not be delivered
+ ("blocked") for the duration of an I/O computation. The primitive
+
+ blockAsyncExceptions# :: IO a -> IO a
+
+ is used for this purpose. During a blocked section, asynchronous
+ exceptions may be unblocked again temporarily:
+
+ unblockAsyncExceptions# :: IO a -> IO a
+
+ Furthermore, asynchronous exceptions are blocked automatically during
+ the execution of an exception handler. Both of these primitives
+ leave a continuation on the stack which reverts to the previous
+ state (blocked or unblocked) on exit.
+
+ A thread which wants to raise an exception in another thread (using
+ killThread#) must block until the target thread is ready to receive
+ it. The action of unblocking exceptions in a thread will release all
+ the threads waiting to deliver exceptions to that thread.
+
+ -------------------------------------------------------------------------- */
+
+FN_(blockAsyncExceptionszh_fast)
+{
+ FB_
+ /* Args: R1 :: IO a */
+ STK_CHK_GEN( 2/* worst case */, R1_PTR, blockAsyncExceptionszh_fast, );
+
+ if (CurrentTSO->blocked_exceptions == NULL) {
+ CurrentTSO->blocked_exceptions = END_TSO_QUEUE;
+ Sp--;
+ Sp[0] = (W_)&unblockAsyncExceptionszh_ret_info;
+ }
+ Sp--;
+ Sp[0] = ARG_TAG(0);
+ JMP_(GET_ENTRY(R1.cl));
+ FE_
+}
+
+INFO_TABLE_SRT_BITMAP(unblockAsyncExceptionszh_ret_info, unblockAsyncExceptionszh_ret_entry, 0, 0, 0, 0, RET_SMALL, , EF_, 0, 0);
+FN_(unblockAsyncExceptionszh_ret_entry)
+{
+ FB_
+ ASSERT(CurrentTSO->blocked_exceptions != NULL);
+ awakenBlockedQueue(CurrentTSO->blocked_exceptions);
+ CurrentTSO->blocked_exceptions = NULL;
+ Sp++;
+ JMP_(ENTRY_CODE(Sp[0]));
+ FE_
+}
+
+FN_(unblockAsyncExceptionszh_fast)
+{
+ FB_
+ /* Args: R1 :: IO a */
+ STK_CHK_GEN(2, R1_PTR, unblockAsyncExceptionszh_fast, );
+
+ if (CurrentTSO->blocked_exceptions != NULL) {
+ awakenBlockedQueue(CurrentTSO->blocked_exceptions);
+ CurrentTSO->blocked_exceptions = NULL;
+ Sp--;
+ Sp[0] = (W_)&blockAsyncExceptionszh_ret_info;
+ }
+ Sp--;
+ Sp[0] = ARG_TAG(0);
+ JMP_(GET_ENTRY(R1.cl));
+ FE_
+}
+
+INFO_TABLE_SRT_BITMAP(blockAsyncExceptionszh_ret_info, blockAsyncExceptionszh_ret_entry, 0, 0, 0, 0, RET_SMALL, , EF_, 0, 0);
+FN_(blockAsyncExceptionszh_ret_entry)
+{
+ FB_
+ ASSERT(CurrentTSO->blocked_exceptions == NULL);
+ CurrentTSO->blocked_exceptions = END_TSO_QUEUE;
+ Sp++;
+ JMP_(ENTRY_CODE(Sp[0]));
+ FE_
+}
+
+
+FN_(killThreadzh_fast)
+{
+ FB_
+ /* args: R1.p = TSO to kill, R2.p = Exception */
+
+ /* If the target thread is currently blocking async exceptions,
+ * we'll have to block until it's ready to accept them.
+ */
+ if (R1.t->blocked_exceptions != NULL) {
+
+ /* ToDo (SMP): locking if destination thread is currently
+ * running...
+ */
+ CurrentTSO->link = R1.t->blocked_exceptions;
+ R1.t->blocked_exceptions = CurrentTSO;
+
+ CurrentTSO->why_blocked = BlockedOnException;
+ CurrentTSO->block_info.tso = R1.t;
+
+ BLOCK( R1_PTR | R2_PTR, killThreadzh_fast );
+ }
+
+ /* Killed threads turn into zombies, which might be garbage
+ * collected at a later date. That's why we don't have to
+ * explicitly remove them from any queues they might be on.
+ */
+
+ /* We might have killed ourselves. In which case, better be *very*
+ * careful. If the exception killed us, then return to the scheduler.
+ * If the exception went to a catch frame, we'll just continue from
+ * the handler.
+ */
+ if (R1.t == CurrentTSO) {
+ SaveThreadState(); /* inline! */
+ STGCALL2(raiseAsync, R1.t, R2.cl);
+ if (CurrentTSO->whatNext == ThreadKilled) {
+ R1.w = ThreadYielding;
+ JMP_(StgReturn);
+ }
+ LoadThreadState();
+ if (CurrentTSO->whatNext == ThreadEnterGHC) {
+ R1.w = Sp[0];
+ Sp++;
+ JMP_(GET_ENTRY(R1.cl));
+ } else {
+ barf("killThreadzh_fast");
+ }
+ } else {
+ STGCALL2(raiseAsync, R1.t, R2.cl);
+ }
+
+ JMP_(ENTRY_CODE(Sp[0]));
+ FE_
+}
+
+/* -----------------------------------------------------------------------------
+ Catch frames
+ -------------------------------------------------------------------------- */
+
+#define CATCH_FRAME_ENTRY_TEMPLATE(label,ret) \
+ FN_(label); \
+ FN_(label) \
+ { \
+ FB_ \
+ Su = ((StgCatchFrame *)Sp)->link; \
+ Sp += sizeofW(StgCatchFrame); \
+ JMP_(ret); \
+ FE_ \
+ }
+
+CATCH_FRAME_ENTRY_TEMPLATE(catch_frame_entry,ENTRY_CODE(Sp[0]));
+CATCH_FRAME_ENTRY_TEMPLATE(catch_frame_0_entry,RET_VEC(Sp[0],0));
+CATCH_FRAME_ENTRY_TEMPLATE(catch_frame_1_entry,RET_VEC(Sp[0],1));
+CATCH_FRAME_ENTRY_TEMPLATE(catch_frame_2_entry,RET_VEC(Sp[0],2));
+CATCH_FRAME_ENTRY_TEMPLATE(catch_frame_3_entry,RET_VEC(Sp[0],3));
+CATCH_FRAME_ENTRY_TEMPLATE(catch_frame_4_entry,RET_VEC(Sp[0],4));
+CATCH_FRAME_ENTRY_TEMPLATE(catch_frame_5_entry,RET_VEC(Sp[0],5));
+CATCH_FRAME_ENTRY_TEMPLATE(catch_frame_6_entry,RET_VEC(Sp[0],6));
+CATCH_FRAME_ENTRY_TEMPLATE(catch_frame_7_entry,RET_VEC(Sp[0],7));
+
+#ifdef PROFILING
+#define CATCH_FRAME_BITMAP 7
+#else
+#define CATCH_FRAME_BITMAP 3
+#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.
+ */
+
+VEC_POLY_INFO_TABLE(catch_frame, CATCH_FRAME_BITMAP, NULL/*srt*/, 0/*srt_off*/, 0/*srt_len*/, CATCH_FRAME,, EF_);
+
+/* -----------------------------------------------------------------------------
+ * The catch infotable
+ *
+ * This should be exactly the same as would be generated by this STG code
+ *
+ * catch = {x,h} \n {} -> catch#{x,h}
+ *
+ * It is used in deleteThread when reverting blackholes.
+ * -------------------------------------------------------------------------- */
+
+INFO_TABLE(catch_info,catch_entry,2,0,FUN,,EF_,0,0);
+STGFUN(catch_entry)
+{
+ FB_
+ R2.cl = payloadCPtr(R1.cl,1); /* h */
+ R1.cl = payloadCPtr(R1.cl,0); /* x */
+ JMP_(catchzh_fast);
+ FE_
+}
+
+FN_(catchzh_fast)
+{
+ StgCatchFrame *fp;
+ FB_
+
+ /* args: R1 = m, R2 = handler */
+ STK_CHK_GEN(sizeofW(StgCatchFrame), R1_PTR | R2_PTR, catchzh_fast, );
+ Sp -= sizeofW(StgCatchFrame);
+ fp = (StgCatchFrame *)Sp;
+ SET_HDR(fp,(StgInfoTable *)&catch_frame_info,CCCS);
+ fp -> handler = R2.cl;
+ fp -> exceptions_blocked = (CurrentTSO->blocked_exceptions != NULL);
+ fp -> link = Su;
+ Su = (StgUpdateFrame *)fp;
+ TICK_CATCHF_PUSHED();
+ TICK_ENT_VIA_NODE();
+ JMP_(GET_ENTRY(R1.cl));
+
+ FE_
+}
+
+/* -----------------------------------------------------------------------------
+ * The raise infotable
+ *
+ * This should be exactly the same as would be generated by this STG code
+ *
+ * raise = {err} \n {} -> raise#{err}
+ *
+ * It is used in raisezh_fast to update thunks on the update list
+ * -------------------------------------------------------------------------- */
+
+INFO_TABLE(raise_info,raise_entry,1,0,FUN,,EF_,0,0);
+STGFUN(raise_entry)
+{
+ FB_
+ R1.cl = R1.cl->payload[0];
+ JMP_(raisezh_fast);
+ FE_
+}
+
+FN_(raisezh_fast)
+{
+ StgClosure *handler;
+ StgUpdateFrame *p;
+ StgClosure *raise_closure;
+ FB_
+ /* args : R1 = error */
+
+
+#if defined(PROFILING)
+
+ /* Debugging tool: on raising an exception, show where we are. */
+
+ /* ToDo: currently this is a hack. Would be much better if
+ * the info was only displayed for an *uncaught* exception.
+ */
+ if (RtsFlags.ProfFlags.showCCSOnException) {
+ STGCALL2(print_ccs,stderr,CCCS);
+ }
+
+#endif
+
+ p = Su;
+
+ /* This closure represents the expression 'raise# E' where E
+ * is the exception raise. It is used to overwrite all the
+ * thunks which are currently under evaluataion.
+ */
+ raise_closure = (StgClosure *)RET_STGCALL1(P_,allocate,
+ sizeofW(StgClosure)+1);
+ raise_closure->header.info = &raise_info;
+ raise_closure->payload[0] = R1.cl;
+
+ while (1) {
+
+ switch (get_itbl(p)->type) {
+
+ case UPDATE_FRAME:
+ UPD_IND(p->updatee,raise_closure);
+ p = p->link;
+ continue;
+
+ case SEQ_FRAME:
+ p = ((StgSeqFrame *)p)->link;
+ continue;
+
+ case CATCH_FRAME:
+ /* found it! */
+ break;
+
+ case STOP_FRAME:
+ barf("raisezh_fast: STOP_FRAME");
+
+ default:
+ barf("raisezh_fast: weird activation record");
+ }
+
+ break;
+
+ }
+
+ /* Ok, p points to the enclosing CATCH_FRAME. Pop everything down to
+ * and including this frame, update Su, push R1, and enter the handler.
+ */
+ Su = ((StgCatchFrame *)p)->link;
+ handler = ((StgCatchFrame *)p)->handler;
+
+ Sp = (P_)p + sizeofW(StgCatchFrame) - 1;
+
+ /* Restore the blocked/unblocked state for asynchronous exceptions
+ * at the CATCH_FRAME.
+ *
+ * If exceptions were unblocked, arrange that they are unblocked
+ * again after executing the handler by pushing an
+ * unblockAsyncExceptions_ret stack frame.
+ */
+ if (! ((StgCatchFrame *)p)->exceptions_blocked) {
+ *(Sp--) = (W_)&unblockAsyncExceptionszh_ret_info;
+ }
+
+ /* Ensure that async excpetions are blocked when running the handler.
+ */
+ if (CurrentTSO->blocked_exceptions == NULL) {
+ CurrentTSO->blocked_exceptions = END_TSO_QUEUE;
+ }
+
+ /* Enter the handler, passing the exception value as an argument.
+ */
+ *Sp = R1.w;
+ TICK_ENT_VIA_NODE();
+ R1.cl = handler;
+ JMP_(GET_ENTRY(R1.cl));
+
+ FE_
+}