+++ /dev/null
-/* -----------------------------------------------------------------------------
- *
- * (c) The GHC Team, 1998-2004
- *
- * Exception support
- *
- * This file is written in a subset of C--, extended with various
- * features specific to GHC. It is compiled by GHC directly. For the
- * syntax of .cmm files, see the parser in ghc/compiler/cmm/CmmParse.y.
- *
- * ---------------------------------------------------------------------------*/
-
-#include "Cmm.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.
-
- NB. there's a bug in here. If a thread is inside an
- unsafePerformIO, and inside blockAsyncExceptions# (there is an
- unblockAsyncExceptions_ret on the stack), and it is blocked in an
- interruptible operation, and it receives an exception, then the
- 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().
-
- -------------------------------------------------------------------------- */
-
-INFO_TABLE_RET( stg_unblockAsyncExceptionszh_ret,
- 0/*framesize*/, 0/*bitmap*/, RET_SMALL )
-{
- // Not true: see comments above
- // ASSERT(StgTSO_blocked_exceptions(CurrentTSO) != NULL);
-#if defined(GRAN) || defined(PAR)
- foreign "C" awakenBlockedQueue(MyCapability() "ptr", StgTSO_blocked_exceptions(CurrentTSO) "ptr",
- NULL "ptr");
-#else
- foreign "C" awakenBlockedQueue(MyCapability() "ptr", StgTSO_blocked_exceptions(CurrentTSO) "ptr");
-#endif
- StgTSO_blocked_exceptions(CurrentTSO) = NULL;
-#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 )
-{
- // Not true: see comments above
- // ASSERT(StgTSO_blocked_exceptions(CurrentTSO) == NULL);
- StgTSO_blocked_exceptions(CurrentTSO) = END_TSO_QUEUE;
-#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
-{
- /* Args: R1 :: IO a */
- STK_CHK_GEN( WDS(2)/* worst case */, R1_PTR, blockAsyncExceptionszh_fast);
-
- if (StgTSO_blocked_exceptions(CurrentTSO) == NULL) {
- StgTSO_blocked_exceptions(CurrentTSO) = END_TSO_QUEUE;
- /* avoid growing the stack unnecessarily */
- if (Sp(0) == stg_blockAsyncExceptionszh_ret_info) {
- Sp_adj(1);
- } else {
- Sp_adj(-1);
- Sp(0) = stg_unblockAsyncExceptionszh_ret_info;
- }
- }
- TICK_UNKNOWN_CALL();
- TICK_SLOW_CALL_v();
- jump stg_ap_v_fast;
-}
-
-unblockAsyncExceptionszh_fast
-{
- /* Args: R1 :: IO a */
- STK_CHK_GEN( WDS(2), R1_PTR, unblockAsyncExceptionszh_fast);
-
- if (StgTSO_blocked_exceptions(CurrentTSO) != NULL) {
-#if defined(GRAN) || defined(PAR)
- foreign "C" awakenBlockedQueue(MyCapability() "ptr", StgTSO_blocked_exceptions(CurrentTSO) "ptr",
- StgTSO_block_info(CurrentTSO) "ptr");
-#else
- foreign "C" awakenBlockedQueue(MyCapability() "ptr", StgTSO_blocked_exceptions(CurrentTSO) "ptr");
-#endif
- StgTSO_blocked_exceptions(CurrentTSO) = NULL;
-
- /* 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;
-}
-
-
-#define interruptible(what_next) \
- ( what_next == BlockedOnMVar \
- || what_next == BlockedOnException \
- || what_next == BlockedOnRead \
- || what_next == BlockedOnWrite \
- || what_next == BlockedOnDelay \
- || what_next == BlockedOnDoProc)
-
-killThreadzh_fast
-{
- /* args: R1 = TSO to kill, R2 = Exception */
-
- W_ why_blocked;
-
- /* This thread may have been relocated.
- * (see Schedule.c:threadStackOverflow)
- */
- while:
- if (StgTSO_what_next(R1) == ThreadRelocated::I16) {
- R1 = StgTSO_link(R1);
- goto while;
- }
-
- /* Determine whether this thread is interruptible or not */
-
- /* If the target thread is currently blocking async exceptions,
- * we'll have to block until it's ready to accept them. The
- * exception is interruptible threads - ie. those that are blocked
- * on some resource.
- */
- why_blocked = TO_W_(StgTSO_why_blocked(R1));
- if (StgTSO_blocked_exceptions(R1) != NULL && !interruptible(why_blocked))
- {
- StgTSO_link(CurrentTSO) = StgTSO_blocked_exceptions(R1);
- StgTSO_blocked_exceptions(R1) = CurrentTSO;
-
- StgTSO_why_blocked(CurrentTSO) = BlockedOnException::I16;
- StgTSO_block_info(CurrentTSO) = R1;
-
- 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 == CurrentTSO) {
- SAVE_THREAD_STATE();
- foreign "C" raiseAsync(MyCapability() "ptr", R1 "ptr", R2 "ptr");
- if (StgTSO_what_next(CurrentTSO) == ThreadKilled::I16) {
- R1 = ThreadFinished;
- jump StgReturn;
- } else {
- LOAD_THREAD_STATE();
- ASSERT(StgTSO_what_next(CurrentTSO) == ThreadRunGHC::I16);
- jump %ENTRY_CODE(Sp(0));
- }
- } else {
- foreign "C" raiseAsync(MyCapability() "ptr", R1 "ptr", R2 "ptr");
- }
-
- jump %ENTRY_CODE(Sp(0));
-}
-
-/* -----------------------------------------------------------------------------
- Catch frames
- -------------------------------------------------------------------------- */
-
-#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)))
-
-/* -----------------------------------------------------------------------------
- * 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(stg_catch,2,0,FUN,"catch","catch")
-{
- R2 = StgClosure_payload(R1,1); /* h */
- R1 = StgClosure_payload(R1,0); /* x */
- jump catchzh_fast;
-}
-
-catchzh_fast
-{
- /* args: R1 = m :: IO a, R2 = handler :: Exception -> IO a */
- STK_CHK_GEN(SIZEOF_StgCatchFrame + WDS(1), R1_PTR & R2_PTR, catchzh_fast);
-
- /* Set up the catch frame */
- Sp = Sp - SIZEOF_StgCatchFrame;
- SET_HDR(Sp,stg_catch_frame_info,W_[CCCS]);
-
- StgCatchFrame_handler(Sp) = R2;
- StgCatchFrame_exceptions_blocked(Sp) =
- (StgTSO_blocked_exceptions(CurrentTSO) != NULL);
- TICK_CATCHF_PUSHED();
-
- /* Apply R1 to the realworld token */
- TICK_UNKNOWN_CALL();
- TICK_SLOW_CALL_v();
- jump stg_ap_v_fast;
-}
-
-/* -----------------------------------------------------------------------------
- * 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(stg_raise,1,0,THUNK_1_0,"raise","raise")
-{
- R1 = StgThunk_payload(R1,0);
- jump raisezh_fast;
-}
-
-raisezh_fast
-{
- W_ handler;
- W_ raise_closure;
- W_ frame_type;
- /* args : R1 :: Exception */
-
-
-#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(RtsFlags)) {
- foreign "C" fprintCCS_stderr(W_[CCCS] "ptr");
- }
-#endif
-
-retry_pop_stack:
- StgTSO_sp(CurrentTSO) = Sp;
- frame_type = foreign "C" raiseExceptionHelper(BaseReg "ptr", CurrentTSO "ptr", R1 "ptr");
- Sp = StgTSO_sp(CurrentTSO);
- if (frame_type == ATOMICALLY_FRAME) {
- /* The exception has reached the edge of a memory transaction. Check that
- * the transaction is valid. If not then perhaps the exception should
- * not have been thrown: re-run the transaction */
- W_ trec;
- W_ r;
- trec = StgTSO_trec(CurrentTSO);
- r = foreign "C" stmValidateNestOfTransactions(trec "ptr");
- foreign "C" stmAbortTransaction(MyCapability() "ptr", trec "ptr");
- StgTSO_trec(CurrentTSO) = NO_TREC;
- if (r) {
- // Transaction was valid: continue searching for a catch frame
- Sp = Sp + SIZEOF_StgAtomicallyFrame;
- goto 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");
- StgTSO_trec(CurrentTSO) = trec;
- R1 = StgAtomicallyFrame_code(Sp);
- jump stg_ap_v_fast;
- }
- }
-
- if (frame_type == STOP_FRAME) {
- /*
- * We've stripped the entire stack, the thread is now dead.
- * We will leave the stack in a GC'able state, see the stg_stop_thread
- * entry code in StgStartup.cmm.
- */
- Sp = CurrentTSO + TSO_OFFSET_StgTSO_stack
- + WDS(TO_W_(StgTSO_stack_size(CurrentTSO))) - WDS(2);
- Sp(1) = R1; /* 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;
- }
-
- /* Ok, Sp points to the enclosing CATCH_FRAME or CATCH_STM_FRAME. Pop everything
- * down to and including this frame, update Su, push R1, and enter the handler.
- */
- if (frame_type == CATCH_FRAME) {
- handler = StgCatchFrame_handler(Sp);
- } else {
- handler = StgCatchSTMFrame_handler(Sp);
- }
-
- /* 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.
- */
- W_ frame;
- frame = Sp;
- if (frame_type == CATCH_FRAME) {
- Sp = Sp + SIZEOF_StgCatchFrame;
- if (StgCatchFrame_exceptions_blocked(frame) == 0) {
- Sp_adj(-1);
- Sp(0) = stg_unblockAsyncExceptionszh_ret_info;
- }
- } else {
- Sp = Sp + SIZEOF_StgCatchSTMFrame;
- }
-
- /* Ensure that async excpetions are blocked when running the handler.
- */
- if (StgTSO_blocked_exceptions(CurrentTSO) == NULL) {
- StgTSO_blocked_exceptions(CurrentTSO) = END_TSO_QUEUE;
- }
-
- /* Call the handler, passing the exception value and a realworld
- * token as arguments.
- */
- Sp_adj(-1);
- Sp(0) = R1;
- R1 = handler;
- Sp_adj(-1);
- TICK_UNKNOWN_CALL();
- TICK_SLOW_CALL_pv();
- jump RET_LBL(stg_ap_pv);
-}
-
-raiseIOzh_fast
-{
- /* Args :: R1 :: Exception */
- jump raisezh_fast;
-}
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