/* ----------------------------------------------------------------------------- * Bytecode interpreter * * Copyright (c) The GHC Team, 1994-2002. * ---------------------------------------------------------------------------*/ #include "PosixSource.h" #include "Rts.h" #include "RtsAPI.h" #include "rts/Bytecodes.h" // internal headers #include "sm/Storage.h" #include "sm/Sanity.h" #include "RtsUtils.h" #include "Schedule.h" #include "Updates.h" #include "Prelude.h" #include "Stable.h" #include "Printer.h" #include "Profiling.h" #include "Disassembler.h" #include "Interpreter.h" #include "ThreadPaused.h" #include "Threads.h" #include /* for memcpy */ #if defined(HAVE_ERRNO_H) #include #endif // When building the RTS in the non-dyn way on Windows, we don't // want declspec(__dllimport__) on the front of function prototypes // from libffi. #if defined(mingw32_HOST_OS) #if (defined(i386_HOST_ARCH) && !defined(__PIC__)) || defined(x86_64_HOST_ARCH) # define LIBFFI_NOT_DLL #endif #endif #include "ffi.h" /* -------------------------------------------------------------------------- * The bytecode interpreter * ------------------------------------------------------------------------*/ /* Gather stats about entry, opcode, opcode-pair frequencies. For tuning the interpreter. */ /* #define INTERP_STATS */ /* Sp points to the lowest live word on the stack. */ #define BCO_NEXT instrs[bciPtr++] #define BCO_NEXT_32 (bciPtr += 2) #define BCO_READ_NEXT_32 (BCO_NEXT_32, (((StgWord) instrs[bciPtr-2]) << 16) \ + ( (StgWord) instrs[bciPtr-1])) #define BCO_NEXT_64 (bciPtr += 4) #define BCO_READ_NEXT_64 (BCO_NEXT_64, (((StgWord) instrs[bciPtr-4]) << 48) \ + (((StgWord) instrs[bciPtr-3]) << 32) \ + (((StgWord) instrs[bciPtr-2]) << 16) \ + ( (StgWord) instrs[bciPtr-1])) #if WORD_SIZE_IN_BITS == 32 #define BCO_NEXT_WORD BCO_NEXT_32 #define BCO_READ_NEXT_WORD BCO_READ_NEXT_32 #elif WORD_SIZE_IN_BITS == 64 #define BCO_NEXT_WORD BCO_NEXT_64 #define BCO_READ_NEXT_WORD BCO_READ_NEXT_64 #else #error Cannot cope with WORD_SIZE_IN_BITS being nether 32 nor 64 #endif #define BCO_GET_LARGE_ARG ((bci & bci_FLAG_LARGE_ARGS) ? BCO_READ_NEXT_WORD : BCO_NEXT) #define BCO_PTR(n) (W_)ptrs[n] #define BCO_LIT(n) literals[n] #define LOAD_STACK_POINTERS \ Sp = cap->r.rCurrentTSO->stackobj->sp; \ /* We don't change this ... */ \ SpLim = tso_SpLim(cap->r.rCurrentTSO); #define SAVE_STACK_POINTERS \ cap->r.rCurrentTSO->stackobj->sp = Sp; #if defined(PROFILING) #define LOAD_THREAD_STATE() \ LOAD_STACK_POINTERS \ cap->r.rCCCS = cap->r.rCurrentTSO->prof.cccs; #else #define LOAD_THREAD_STATE() \ LOAD_STACK_POINTERS #endif #if defined(PROFILING) #define SAVE_THREAD_STATE() \ SAVE_STACK_POINTERS \ cap->r.rCurrentTSO->prof.cccs = cap->r.rCCCS; #else #define SAVE_THREAD_STATE() \ SAVE_STACK_POINTERS #endif // Note [Not true: ASSERT(Sp > SpLim)] // // SpLim has some headroom (RESERVED_STACK_WORDS) to allow for saving // any necessary state on the stack when returning to the scheduler // when a stack check fails.. The upshot of this is that Sp could be // less than SpLim both when leaving to return to the scheduler. #define RETURN_TO_SCHEDULER(todo,retcode) \ SAVE_THREAD_STATE(); \ cap->r.rCurrentTSO->what_next = (todo); \ threadPaused(cap,cap->r.rCurrentTSO); \ cap->r.rRet = (retcode); \ return cap; #define RETURN_TO_SCHEDULER_NO_PAUSE(todo,retcode) \ SAVE_THREAD_STATE(); \ cap->r.rCurrentTSO->what_next = (todo); \ cap->r.rRet = (retcode); \ return cap; STATIC_INLINE StgPtr allocate_NONUPD (Capability *cap, int n_words) { return allocate(cap, stg_max(sizeofW(StgHeader)+MIN_PAYLOAD_SIZE, n_words)); } int rts_stop_next_breakpoint = 0; int rts_stop_on_exception = 0; #if defined(INTERP_STATS) /* Hacky stats, for tuning the interpreter ... */ int it_unknown_entries[N_CLOSURE_TYPES]; int it_total_unknown_entries; int it_total_entries; int it_retto_BCO; int it_retto_UPDATE; int it_retto_other; int it_slides; int it_insns; int it_BCO_entries; int it_ofreq[27]; int it_oofreq[27][27]; int it_lastopc; #define INTERP_TICK(n) (n)++ void interp_startup ( void ) { int i, j; it_retto_BCO = it_retto_UPDATE = it_retto_other = 0; it_total_entries = it_total_unknown_entries = 0; for (i = 0; i < N_CLOSURE_TYPES; i++) it_unknown_entries[i] = 0; it_slides = it_insns = it_BCO_entries = 0; for (i = 0; i < 27; i++) it_ofreq[i] = 0; for (i = 0; i < 27; i++) for (j = 0; j < 27; j++) it_oofreq[i][j] = 0; it_lastopc = 0; } void interp_shutdown ( void ) { int i, j, k, o_max, i_max, j_max; debugBelch("%d constrs entered -> (%d BCO, %d UPD, %d ??? )\n", it_retto_BCO + it_retto_UPDATE + it_retto_other, it_retto_BCO, it_retto_UPDATE, it_retto_other ); debugBelch("%d total entries, %d unknown entries \n", it_total_entries, it_total_unknown_entries); for (i = 0; i < N_CLOSURE_TYPES; i++) { if (it_unknown_entries[i] == 0) continue; debugBelch(" type %2d: unknown entries (%4.1f%%) == %d\n", i, 100.0 * ((double)it_unknown_entries[i]) / ((double)it_total_unknown_entries), it_unknown_entries[i]); } debugBelch("%d insns, %d slides, %d BCO_entries\n", it_insns, it_slides, it_BCO_entries); for (i = 0; i < 27; i++) debugBelch("opcode %2d got %d\n", i, it_ofreq[i] ); for (k = 1; k < 20; k++) { o_max = 0; i_max = j_max = 0; for (i = 0; i < 27; i++) { for (j = 0; j < 27; j++) { if (it_oofreq[i][j] > o_max) { o_max = it_oofreq[i][j]; i_max = i; j_max = j; } } } debugBelch("%d: count (%4.1f%%) %6d is %d then %d\n", k, ((double)o_max) * 100.0 / ((double)it_insns), o_max, i_max, j_max ); it_oofreq[i_max][j_max] = 0; } } #else // !INTERP_STATS #define INTERP_TICK(n) /* nothing */ #endif #if defined(PROFILING) // // Build a zero-argument PAP with the current CCS // See Note [Evaluating functions with profiling] in Apply.cmm // STATIC_INLINE StgClosure * newEmptyPAP (Capability *cap, StgClosure *tagged_obj, // a FUN or a BCO uint32_t arity) { StgPAP *pap = (StgPAP *)allocate(cap, sizeofW(StgPAP)); SET_HDR(pap, &stg_PAP_info, cap->r.rCCCS); pap->arity = arity; pap->n_args = 0; pap->fun = tagged_obj; return (StgClosure *)pap; } // // Make an exact copy of a PAP, except that we combine the current CCS with the // CCS in the PAP. See Note [Evaluating functions with profiling] in Apply.cmm // STATIC_INLINE StgClosure * copyPAP (Capability *cap, StgPAP *oldpap) { uint32_t size = PAP_sizeW(oldpap->n_args); StgPAP *pap = (StgPAP *)allocate(cap, size); enterFunCCS(&cap->r, oldpap->header.prof.ccs); SET_HDR(pap, &stg_PAP_info, cap->r.rCCCS); pap->arity = oldpap->arity; pap->n_args = oldpap->n_args; pap->fun = oldpap->fun; uint32_t i; for (i = 0; i < ((StgPAP *)pap)->n_args; i++) { pap->payload[i] = oldpap->payload[i]; } return (StgClosure *)pap; } #endif static StgWord app_ptrs_itbl[] = { (W_)&stg_ap_p_info, (W_)&stg_ap_pp_info, (W_)&stg_ap_ppp_info, (W_)&stg_ap_pppp_info, (W_)&stg_ap_ppppp_info, (W_)&stg_ap_pppppp_info, }; HsStablePtr rts_breakpoint_io_action; // points to the IO action which is executed on a breakpoint // it is set in main/GHC.hs:runStmt Capability * interpretBCO (Capability* cap) { // Use of register here is primarily to make it clear to compilers // that these entities are non-aliasable. register StgPtr Sp; // local state -- stack pointer register StgPtr SpLim; // local state -- stack lim pointer register StgClosure *tagged_obj = 0, *obj; uint32_t n, m; LOAD_THREAD_STATE(); cap->r.rHpLim = (P_)1; // HpLim is the context-switch flag; when it // goes to zero we must return to the scheduler. IF_DEBUG(interpreter, debugBelch( "\n---------------------------------------------------------------\n"); debugBelch("Entering the interpreter, Sp = %p\n", Sp); #if defined(PROFILING) fprintCCS(stderr, cap->r.rCCCS); debugBelch("\n"); #endif debugBelch("\n"); printStackChunk(Sp,cap->r.rCurrentTSO->stackobj->stack+cap->r.rCurrentTSO->stackobj->stack_size); debugBelch("\n\n"); ); // ------------------------------------------------------------------------ // Case 1: // // We have a closure to evaluate. Stack looks like: // // | XXXX_info | // +---------------+ // Sp | -------------------> closure // +---------------+ // | stg_enter | // +---------------+ // if (Sp[0] == (W_)&stg_enter_info) { Sp++; goto eval; } // ------------------------------------------------------------------------ // Case 2: // // We have a BCO application to perform. Stack looks like: // // | .... | // +---------------+ // | arg1 | // +---------------+ // | BCO | // +---------------+ // Sp | RET_BCO | // +---------------+ // else if (Sp[0] == (W_)&stg_apply_interp_info) { obj = UNTAG_CLOSURE((StgClosure *)Sp[1]); Sp += 2; goto run_BCO_fun; } // ------------------------------------------------------------------------ // Case 3: // // We have an unboxed value to return. See comment before // do_return_unboxed, below. // else { goto do_return_unboxed; } // Evaluate the object on top of the stack. eval: tagged_obj = (StgClosure*)Sp[0]; Sp++; eval_obj: obj = UNTAG_CLOSURE(tagged_obj); INTERP_TICK(it_total_evals); IF_DEBUG(interpreter, debugBelch( "\n---------------------------------------------------------------\n"); debugBelch("Evaluating: "); printObj(obj); debugBelch("Sp = %p\n", Sp); #if defined(PROFILING) fprintCCS(stderr, cap->r.rCCCS); debugBelch("\n"); #endif debugBelch("\n" ); printStackChunk(Sp,cap->r.rCurrentTSO->stackobj->stack+cap->r.rCurrentTSO->stackobj->stack_size); debugBelch("\n\n"); ); // IF_DEBUG(sanity,checkStackChunk(Sp, cap->r.rCurrentTSO->stack+cap->r.rCurrentTSO->stack_size)); IF_DEBUG(sanity,checkStackFrame(Sp)); switch ( get_itbl(obj)->type ) { case IND: case IND_STATIC: { tagged_obj = ((StgInd*)obj)->indirectee; goto eval_obj; } case CONSTR: case CONSTR_1_0: case CONSTR_0_1: case CONSTR_2_0: case CONSTR_1_1: case CONSTR_0_2: case CONSTR_NOCAF: break; case FUN: case FUN_1_0: case FUN_0_1: case FUN_2_0: case FUN_1_1: case FUN_0_2: case FUN_STATIC: #if defined(PROFILING) if (cap->r.rCCCS != obj->header.prof.ccs) { tagged_obj = newEmptyPAP(cap, tagged_obj, get_fun_itbl(obj)->f.arity); } #endif break; case PAP: #if defined(PROFILING) if (cap->r.rCCCS != obj->header.prof.ccs) { tagged_obj = copyPAP(cap, (StgPAP *)obj); } #endif break; case BCO: ASSERT(((StgBCO *)obj)->arity > 0); #if defined(PROFILING) if (cap->r.rCCCS != obj->header.prof.ccs) { tagged_obj = newEmptyPAP(cap, tagged_obj, ((StgBCO *)obj)->arity); } #endif break; case AP: /* Copied from stg_AP_entry. */ { uint32_t i, words; StgAP *ap; ap = (StgAP*)obj; words = ap->n_args; // Stack check if (Sp - (words+sizeofW(StgUpdateFrame)+2) < SpLim) { Sp -= 2; Sp[1] = (W_)tagged_obj; Sp[0] = (W_)&stg_enter_info; RETURN_TO_SCHEDULER(ThreadInterpret, StackOverflow); } #if defined(PROFILING) // restore the CCCS after evaluating the AP Sp -= 2; Sp[1] = (W_)cap->r.rCCCS; Sp[0] = (W_)&stg_restore_cccs_eval_info; #endif Sp -= sizeofW(StgUpdateFrame); { StgUpdateFrame *__frame; __frame = (StgUpdateFrame *)Sp; SET_INFO((StgClosure *)__frame, (StgInfoTable *)&stg_upd_frame_info); __frame->updatee = (StgClosure *)(ap); } ENTER_CCS_THUNK(cap,ap); /* Reload the stack */ Sp -= words; for (i=0; i < words; i++) { Sp[i] = (W_)ap->payload[i]; } obj = UNTAG_CLOSURE((StgClosure*)ap->fun); ASSERT(get_itbl(obj)->type == BCO); goto run_BCO_fun; } default: #if defined(INTERP_STATS) { int j; j = get_itbl(obj)->type; ASSERT(j >= 0 && j < N_CLOSURE_TYPES); it_unknown_entries[j]++; it_total_unknown_entries++; } #endif { // Can't handle this object; yield to scheduler IF_DEBUG(interpreter, debugBelch("evaluating unknown closure -- yielding to sched\n"); printObj(obj); ); #if defined(PROFILING) // restore the CCCS after evaluating the closure Sp -= 2; Sp[1] = (W_)cap->r.rCCCS; Sp[0] = (W_)&stg_restore_cccs_eval_info; #endif Sp -= 2; Sp[1] = (W_)tagged_obj; Sp[0] = (W_)&stg_enter_info; RETURN_TO_SCHEDULER_NO_PAUSE(ThreadRunGHC, ThreadYielding); } } // ------------------------------------------------------------------------ // We now have an evaluated object (tagged_obj). The next thing to // do is return it to the stack frame on top of the stack. do_return: obj = UNTAG_CLOSURE(tagged_obj); ASSERT(closure_HNF(obj)); IF_DEBUG(interpreter, debugBelch( "\n---------------------------------------------------------------\n"); debugBelch("Returning: "); printObj(obj); debugBelch("Sp = %p\n", Sp); #if defined(PROFILING) fprintCCS(stderr, cap->r.rCCCS); debugBelch("\n"); #endif debugBelch("\n"); printStackChunk(Sp,cap->r.rCurrentTSO->stackobj->stack+cap->r.rCurrentTSO->stackobj->stack_size); debugBelch("\n\n"); ); IF_DEBUG(sanity,checkStackChunk(Sp, cap->r.rCurrentTSO->stackobj->stack+cap->r.rCurrentTSO->stackobj->stack_size)); switch (get_itbl((StgClosure *)Sp)->type) { case RET_SMALL: { const StgInfoTable *info; // NOTE: not using get_itbl(). info = ((StgClosure *)Sp)->header.info; if (info == (StgInfoTable *)&stg_restore_cccs_info || info == (StgInfoTable *)&stg_restore_cccs_eval_info) { cap->r.rCCCS = (CostCentreStack*)Sp[1]; Sp += 2; goto do_return; } if (info == (StgInfoTable *)&stg_ap_v_info) { n = 1; m = 0; goto do_apply; } if (info == (StgInfoTable *)&stg_ap_f_info) { n = 1; m = 1; goto do_apply; } if (info == (StgInfoTable *)&stg_ap_d_info) { n = 1; m = sizeofW(StgDouble); goto do_apply; } if (info == (StgInfoTable *)&stg_ap_l_info) { n = 1; m = sizeofW(StgInt64); goto do_apply; } if (info == (StgInfoTable *)&stg_ap_n_info) { n = 1; m = 1; goto do_apply; } if (info == (StgInfoTable *)&stg_ap_p_info) { n = 1; m = 1; goto do_apply; } if (info == (StgInfoTable *)&stg_ap_pp_info) { n = 2; m = 2; goto do_apply; } if (info == (StgInfoTable *)&stg_ap_ppp_info) { n = 3; m = 3; goto do_apply; } if (info == (StgInfoTable *)&stg_ap_pppp_info) { n = 4; m = 4; goto do_apply; } if (info == (StgInfoTable *)&stg_ap_ppppp_info) { n = 5; m = 5; goto do_apply; } if (info == (StgInfoTable *)&stg_ap_pppppp_info) { n = 6; m = 6; goto do_apply; } goto do_return_unrecognised; } case UPDATE_FRAME: // Returning to an update frame: do the update, pop the update // frame, and continue with the next stack frame. // // NB. we must update with the *tagged* pointer. Some tags // are not optional, and if we omit the tag bits when updating // then bad things can happen (albeit very rarely). See #1925. // What happened was an indirection was created with an // untagged pointer, and this untagged pointer was propagated // to a PAP by the GC, violating the invariant that PAPs // always contain a tagged pointer to the function. INTERP_TICK(it_retto_UPDATE); updateThunk(cap, cap->r.rCurrentTSO, ((StgUpdateFrame *)Sp)->updatee, tagged_obj); Sp += sizeofW(StgUpdateFrame); goto do_return; case RET_BCO: // Returning to an interpreted continuation: put the object on // the stack, and start executing the BCO. INTERP_TICK(it_retto_BCO); Sp--; Sp[0] = (W_)obj; // NB. return the untagged object; the bytecode expects it to // be untagged. XXX this doesn't seem right. obj = (StgClosure*)Sp[2]; ASSERT(get_itbl(obj)->type == BCO); goto run_BCO_return; default: do_return_unrecognised: { // Can't handle this return address; yield to scheduler INTERP_TICK(it_retto_other); IF_DEBUG(interpreter, debugBelch("returning to unknown frame -- yielding to sched\n"); printStackChunk(Sp,cap->r.rCurrentTSO->stackobj->stack+cap->r.rCurrentTSO->stackobj->stack_size); ); Sp -= 2; Sp[1] = (W_)tagged_obj; Sp[0] = (W_)&stg_enter_info; RETURN_TO_SCHEDULER_NO_PAUSE(ThreadRunGHC, ThreadYielding); } } // ------------------------------------------------------------------------- // Returning an unboxed value. The stack looks like this: // // | .... | // +---------------+ // | fv2 | // +---------------+ // | fv1 | // +---------------+ // | BCO | // +---------------+ // | stg_ctoi_ret_ | // +---------------+ // | retval | // +---------------+ // | XXXX_info | // +---------------+ // // where XXXX_info is one of the stg_ret_*_info family. // // We're only interested in the case when the real return address // is a BCO; otherwise we'll return to the scheduler. do_return_unboxed: { int offset; ASSERT( Sp[0] == (W_)&stg_ret_v_info || Sp[0] == (W_)&stg_ret_p_info || Sp[0] == (W_)&stg_ret_n_info || Sp[0] == (W_)&stg_ret_f_info || Sp[0] == (W_)&stg_ret_d_info || Sp[0] == (W_)&stg_ret_l_info ); IF_DEBUG(interpreter, debugBelch( "\n---------------------------------------------------------------\n"); debugBelch("Returning: "); printObj(obj); debugBelch("Sp = %p\n", Sp); #if defined(PROFILING) fprintCCS(stderr, cap->r.rCCCS); debugBelch("\n"); #endif debugBelch("\n"); printStackChunk(Sp,cap->r.rCurrentTSO->stackobj->stack+cap->r.rCurrentTSO->stackobj->stack_size); debugBelch("\n\n"); ); // get the offset of the stg_ctoi_ret_XXX itbl offset = stack_frame_sizeW((StgClosure *)Sp); switch (get_itbl((StgClosure*)((StgPtr)Sp+offset))->type) { case RET_BCO: // Returning to an interpreted continuation: put the object on // the stack, and start executing the BCO. INTERP_TICK(it_retto_BCO); obj = (StgClosure*)Sp[offset+1]; ASSERT(get_itbl(obj)->type == BCO); goto run_BCO_return_unboxed; default: { // Can't handle this return address; yield to scheduler INTERP_TICK(it_retto_other); IF_DEBUG(interpreter, debugBelch("returning to unknown frame -- yielding to sched\n"); printStackChunk(Sp,cap->r.rCurrentTSO->stackobj->stack+cap->r.rCurrentTSO->stackobj->stack_size); ); RETURN_TO_SCHEDULER_NO_PAUSE(ThreadRunGHC, ThreadYielding); } } } // not reached. // ------------------------------------------------------------------------- // Application... do_apply: ASSERT(obj == UNTAG_CLOSURE(tagged_obj)); // we have a function to apply (obj), and n arguments taking up m // words on the stack. The info table (stg_ap_pp_info or whatever) // is on top of the arguments on the stack. { switch (get_itbl(obj)->type) { case PAP: { StgPAP *pap; uint32_t i, arity; pap = (StgPAP *)obj; // we only cope with PAPs whose function is a BCO if (get_itbl(UNTAG_CLOSURE(pap->fun))->type != BCO) { goto defer_apply_to_sched; } // Stack check: we're about to unpack the PAP onto the // stack. The (+1) is for the (arity < n) case, where we // also need space for an extra info pointer. if (Sp - (pap->n_args + 1) < SpLim) { Sp -= 2; Sp[1] = (W_)tagged_obj; Sp[0] = (W_)&stg_enter_info; RETURN_TO_SCHEDULER(ThreadInterpret, StackOverflow); } Sp++; arity = pap->arity; ASSERT(arity > 0); if (arity < n) { // n must be greater than 1, and the only kinds of // application we support with more than one argument // are all pointers... // // Shuffle the args for this function down, and put // the appropriate info table in the gap. for (i = 0; i < arity; i++) { Sp[(int)i-1] = Sp[i]; // ^^^^^ careful, i-1 might be negative, but i is unsigned } Sp[arity-1] = app_ptrs_itbl[n-arity-1]; Sp--; // unpack the PAP's arguments onto the stack Sp -= pap->n_args; for (i = 0; i < pap->n_args; i++) { Sp[i] = (W_)pap->payload[i]; } obj = UNTAG_CLOSURE(pap->fun); #if defined(PROFILING) enterFunCCS(&cap->r, pap->header.prof.ccs); #endif goto run_BCO_fun; } else if (arity == n) { Sp -= pap->n_args; for (i = 0; i < pap->n_args; i++) { Sp[i] = (W_)pap->payload[i]; } obj = UNTAG_CLOSURE(pap->fun); #if defined(PROFILING) enterFunCCS(&cap->r, pap->header.prof.ccs); #endif goto run_BCO_fun; } else /* arity > n */ { // build a new PAP and return it. StgPAP *new_pap; new_pap = (StgPAP *)allocate(cap, PAP_sizeW(pap->n_args + m)); SET_HDR(new_pap,&stg_PAP_info,cap->r.rCCCS); new_pap->arity = pap->arity - n; new_pap->n_args = pap->n_args + m; new_pap->fun = pap->fun; for (i = 0; i < pap->n_args; i++) { new_pap->payload[i] = pap->payload[i]; } for (i = 0; i < m; i++) { new_pap->payload[pap->n_args + i] = (StgClosure *)Sp[i]; } tagged_obj = (StgClosure *)new_pap; Sp += m; goto do_return; } } case BCO: { uint32_t arity, i; Sp++; arity = ((StgBCO *)obj)->arity; ASSERT(arity > 0); if (arity < n) { // n must be greater than 1, and the only kinds of // application we support with more than one argument // are all pointers... // // Shuffle the args for this function down, and put // the appropriate info table in the gap. for (i = 0; i < arity; i++) { Sp[(int)i-1] = Sp[i]; // ^^^^^ careful, i-1 might be negative, but i is unsigned } Sp[arity-1] = app_ptrs_itbl[n-arity-1]; Sp--; goto run_BCO_fun; } else if (arity == n) { goto run_BCO_fun; } else /* arity > n */ { // build a PAP and return it. StgPAP *pap; uint32_t i; pap = (StgPAP *)allocate(cap, PAP_sizeW(m)); SET_HDR(pap, &stg_PAP_info,cap->r.rCCCS); pap->arity = arity - n; pap->fun = obj; pap->n_args = m; for (i = 0; i < m; i++) { pap->payload[i] = (StgClosure *)Sp[i]; } tagged_obj = (StgClosure *)pap; Sp += m; goto do_return; } } // No point in us applying machine-code functions default: defer_apply_to_sched: IF_DEBUG(interpreter, debugBelch("Cannot apply compiled function; yielding to scheduler\n")); Sp -= 2; Sp[1] = (W_)tagged_obj; Sp[0] = (W_)&stg_enter_info; RETURN_TO_SCHEDULER_NO_PAUSE(ThreadRunGHC, ThreadYielding); } // ------------------------------------------------------------------------ // Ok, we now have a bco (obj), and its arguments are all on the // stack. We can start executing the byte codes. // // The stack is in one of two states. First, if this BCO is a // function: // // | .... | // +---------------+ // | arg2 | // +---------------+ // | arg1 | // +---------------+ // // Second, if this BCO is a continuation: // // | .... | // +---------------+ // | fv2 | // +---------------+ // | fv1 | // +---------------+ // | BCO | // +---------------+ // | stg_ctoi_ret_ | // +---------------+ // | retval | // +---------------+ // // where retval is the value being returned to this continuation. // In the event of a stack check, heap check, or context switch, // we need to leave the stack in a sane state so the garbage // collector can find all the pointers. // // (1) BCO is a function: the BCO's bitmap describes the // pointerhood of the arguments. // // (2) BCO is a continuation: BCO's bitmap describes the // pointerhood of the free variables. // // Sadly we have three different kinds of stack/heap/cswitch check // to do: run_BCO_return: // Heap check if (doYouWantToGC(cap)) { Sp--; Sp[0] = (W_)&stg_enter_info; RETURN_TO_SCHEDULER(ThreadInterpret, HeapOverflow); } // Stack checks aren't necessary at return points, the stack use // is aggregated into the enclosing function entry point. goto run_BCO; run_BCO_return_unboxed: // Heap check if (doYouWantToGC(cap)) { RETURN_TO_SCHEDULER(ThreadInterpret, HeapOverflow); } // Stack checks aren't necessary at return points, the stack use // is aggregated into the enclosing function entry point. goto run_BCO; run_BCO_fun: IF_DEBUG(sanity, Sp -= 2; Sp[1] = (W_)obj; Sp[0] = (W_)&stg_apply_interp_info; checkStackChunk(Sp,SpLim); Sp += 2; ); // Heap check if (doYouWantToGC(cap)) { Sp -= 2; Sp[1] = (W_)obj; Sp[0] = (W_)&stg_apply_interp_info; // placeholder, really RETURN_TO_SCHEDULER(ThreadInterpret, HeapOverflow); } // Stack check if (Sp - INTERP_STACK_CHECK_THRESH < SpLim) { Sp -= 2; Sp[1] = (W_)obj; Sp[0] = (W_)&stg_apply_interp_info; // placeholder, really RETURN_TO_SCHEDULER(ThreadInterpret, StackOverflow); } goto run_BCO; // Now, actually interpret the BCO... (no returning to the // scheduler again until the stack is in an orderly state). run_BCO: INTERP_TICK(it_BCO_entries); { register int bciPtr = 0; /* instruction pointer */ register StgWord16 bci; register StgBCO* bco = (StgBCO*)obj; register StgWord16* instrs = (StgWord16*)(bco->instrs->payload); register StgWord* literals = (StgWord*)(&bco->literals->payload[0]); register StgPtr* ptrs = (StgPtr*)(&bco->ptrs->payload[0]); #if defined(DEBUG) int bcoSize; bcoSize = bco->instrs->bytes / sizeof(StgWord16); #endif IF_DEBUG(interpreter,debugBelch("bcoSize = %d\n", bcoSize)); #if defined(INTERP_STATS) it_lastopc = 0; /* no opcode */ #endif nextInsn: ASSERT(bciPtr < bcoSize); IF_DEBUG(interpreter, //if (do_print_stack) { //debugBelch("\n-- BEGIN stack\n"); //printStack(Sp,cap->r.rCurrentTSO->stack+cap->r.rCurrentTSO->stack_size,iSu); //debugBelch("-- END stack\n\n"); //} debugBelch("Sp = %p pc = %-4d ", Sp, bciPtr); disInstr(bco,bciPtr); if (0) { int i; debugBelch("\n"); for (i = 8; i >= 0; i--) { debugBelch("%d %p\n", i, (StgPtr)(*(Sp+i))); } debugBelch("\n"); } //if (do_print_stack) checkStack(Sp,cap->r.rCurrentTSO->stack+cap->r.rCurrentTSO->stack_size,iSu); ); INTERP_TICK(it_insns); #if defined(INTERP_STATS) ASSERT( (int)instrs[bciPtr] >= 0 && (int)instrs[bciPtr] < 27 ); it_ofreq[ (int)instrs[bciPtr] ] ++; it_oofreq[ it_lastopc ][ (int)instrs[bciPtr] ] ++; it_lastopc = (int)instrs[bciPtr]; #endif bci = BCO_NEXT; /* We use the high 8 bits for flags, only the highest of which is * currently allocated */ ASSERT((bci & 0xFF00) == (bci & 0x8000)); switch (bci & 0xFF) { /* check for a breakpoint on the beginning of a let binding */ case bci_BRK_FUN: { int arg1_brk_array, arg2_array_index, arg3_module_uniq; #if defined(PROFILING) int arg4_cc; #endif StgArrBytes *breakPoints; int returning_from_break; // the io action to run at a breakpoint StgClosure *ioAction; // a closure to save the top stack frame on the heap StgAP_STACK *new_aps; int i; int size_words; arg1_brk_array = BCO_GET_LARGE_ARG; arg2_array_index = BCO_NEXT; arg3_module_uniq = BCO_GET_LARGE_ARG; #if defined(PROFILING) arg4_cc = BCO_GET_LARGE_ARG; #else BCO_GET_LARGE_ARG; #endif // check if we are returning from a breakpoint - this info // is stored in the flags field of the current TSO. If true, // then don't break this time around. returning_from_break = cap->r.rCurrentTSO->flags & TSO_STOPPED_ON_BREAKPOINT; #if defined(PROFILING) cap->r.rCCCS = pushCostCentre(cap->r.rCCCS, (CostCentre*)BCO_LIT(arg4_cc)); #endif // if we are returning from a break then skip this section // and continue executing if (!returning_from_break) { breakPoints = (StgArrBytes *) BCO_PTR(arg1_brk_array); // stop the current thread if either the // "rts_stop_next_breakpoint" flag is true OR if the // breakpoint flag for this particular expression is // true if (rts_stop_next_breakpoint == true || ((StgWord8*)breakPoints->payload)[arg2_array_index] == true) { // make sure we don't automatically stop at the // next breakpoint rts_stop_next_breakpoint = false; // allocate memory for a new AP_STACK, enough to // store the top stack frame plus an // stg_apply_interp_info pointer and a pointer to // the BCO size_words = BCO_BITMAP_SIZE(obj) + 2; new_aps = (StgAP_STACK *) allocate(cap, AP_STACK_sizeW(size_words)); SET_HDR(new_aps,&stg_AP_STACK_info,cap->r.rCCCS); new_aps->size = size_words; new_aps->fun = &stg_dummy_ret_closure; // fill in the payload of the AP_STACK new_aps->payload[0] = (StgClosure *)&stg_apply_interp_info; new_aps->payload[1] = (StgClosure *)obj; // copy the contents of the top stack frame into the AP_STACK for (i = 2; i < size_words; i++) { new_aps->payload[i] = (StgClosure *)Sp[i-2]; } // Arrange the stack to call the breakpoint IO action, and // continue execution of this BCO when the IO action returns. // // ioAction :: Bool -- exception? // -> HValue -- the AP_STACK, or exception // -> Int -- the breakpoint index (arg2) // -> Int -- the module uniq (arg3) // -> IO () // ioAction = (StgClosure *) deRefStablePtr ( rts_breakpoint_io_action); Sp -= 11; Sp[10] = (W_)obj; Sp[9] = (W_)&stg_apply_interp_info; Sp[8] = (W_)new_aps; Sp[7] = (W_)False_closure; // True <=> a breakpoint Sp[6] = (W_)&stg_ap_ppv_info; Sp[5] = (W_)BCO_LIT(arg3_module_uniq); Sp[4] = (W_)&stg_ap_n_info; Sp[3] = (W_)arg2_array_index; Sp[2] = (W_)&stg_ap_n_info; Sp[1] = (W_)ioAction; Sp[0] = (W_)&stg_enter_info; // set the flag in the TSO to say that we are now // stopping at a breakpoint so that when we resume // we don't stop on the same breakpoint that we // already stopped at just now cap->r.rCurrentTSO->flags |= TSO_STOPPED_ON_BREAKPOINT; // stop this thread and return to the scheduler - // eventually we will come back and the IO action on // the top of the stack will be executed RETURN_TO_SCHEDULER_NO_PAUSE(ThreadRunGHC, ThreadYielding); } } // record that this thread is not stopped at a breakpoint anymore cap->r.rCurrentTSO->flags &= ~TSO_STOPPED_ON_BREAKPOINT; // continue normal execution of the byte code instructions goto nextInsn; } case bci_STKCHECK: { // Explicit stack check at the beginning of a function // *only* (stack checks in case alternatives are // propagated to the enclosing function). StgWord stk_words_reqd = BCO_GET_LARGE_ARG + 1; if (Sp - stk_words_reqd < SpLim) { Sp -= 2; Sp[1] = (W_)obj; Sp[0] = (W_)&stg_apply_interp_info; RETURN_TO_SCHEDULER(ThreadInterpret, StackOverflow); } else { goto nextInsn; } } case bci_PUSH_L: { int o1 = BCO_NEXT; Sp[-1] = Sp[o1]; Sp--; goto nextInsn; } case bci_PUSH_LL: { int o1 = BCO_NEXT; int o2 = BCO_NEXT; Sp[-1] = Sp[o1]; Sp[-2] = Sp[o2]; Sp -= 2; goto nextInsn; } case bci_PUSH_LLL: { int o1 = BCO_NEXT; int o2 = BCO_NEXT; int o3 = BCO_NEXT; Sp[-1] = Sp[o1]; Sp[-2] = Sp[o2]; Sp[-3] = Sp[o3]; Sp -= 3; goto nextInsn; } case bci_PUSH_G: { int o1 = BCO_GET_LARGE_ARG; Sp[-1] = BCO_PTR(o1); Sp -= 1; goto nextInsn; } case bci_PUSH_ALTS: { int o_bco = BCO_GET_LARGE_ARG; Sp -= 2; Sp[1] = BCO_PTR(o_bco); Sp[0] = (W_)&stg_ctoi_R1p_info; #if defined(PROFILING) Sp -= 2; Sp[1] = (W_)cap->r.rCCCS; Sp[0] = (W_)&stg_restore_cccs_info; #endif goto nextInsn; } case bci_PUSH_ALTS_P: { int o_bco = BCO_GET_LARGE_ARG; Sp[-2] = (W_)&stg_ctoi_R1unpt_info; Sp[-1] = BCO_PTR(o_bco); Sp -= 2; #if defined(PROFILING) Sp -= 2; Sp[1] = (W_)cap->r.rCCCS; Sp[0] = (W_)&stg_restore_cccs_info; #endif goto nextInsn; } case bci_PUSH_ALTS_N: { int o_bco = BCO_GET_LARGE_ARG; Sp[-2] = (W_)&stg_ctoi_R1n_info; Sp[-1] = BCO_PTR(o_bco); Sp -= 2; #if defined(PROFILING) Sp -= 2; Sp[1] = (W_)cap->r.rCCCS; Sp[0] = (W_)&stg_restore_cccs_info; #endif goto nextInsn; } case bci_PUSH_ALTS_F: { int o_bco = BCO_GET_LARGE_ARG; Sp[-2] = (W_)&stg_ctoi_F1_info; Sp[-1] = BCO_PTR(o_bco); Sp -= 2; #if defined(PROFILING) Sp -= 2; Sp[1] = (W_)cap->r.rCCCS; Sp[0] = (W_)&stg_restore_cccs_info; #endif goto nextInsn; } case bci_PUSH_ALTS_D: { int o_bco = BCO_GET_LARGE_ARG; Sp[-2] = (W_)&stg_ctoi_D1_info; Sp[-1] = BCO_PTR(o_bco); Sp -= 2; #if defined(PROFILING) Sp -= 2; Sp[1] = (W_)cap->r.rCCCS; Sp[0] = (W_)&stg_restore_cccs_info; #endif goto nextInsn; } case bci_PUSH_ALTS_L: { int o_bco = BCO_GET_LARGE_ARG; Sp[-2] = (W_)&stg_ctoi_L1_info; Sp[-1] = BCO_PTR(o_bco); Sp -= 2; #if defined(PROFILING) Sp -= 2; Sp[1] = (W_)cap->r.rCCCS; Sp[0] = (W_)&stg_restore_cccs_info; #endif goto nextInsn; } case bci_PUSH_ALTS_V: { int o_bco = BCO_GET_LARGE_ARG; Sp[-2] = (W_)&stg_ctoi_V_info; Sp[-1] = BCO_PTR(o_bco); Sp -= 2; #if defined(PROFILING) Sp -= 2; Sp[1] = (W_)cap->r.rCCCS; Sp[0] = (W_)&stg_restore_cccs_info; #endif goto nextInsn; } case bci_PUSH_APPLY_N: Sp--; Sp[0] = (W_)&stg_ap_n_info; goto nextInsn; case bci_PUSH_APPLY_V: Sp--; Sp[0] = (W_)&stg_ap_v_info; goto nextInsn; case bci_PUSH_APPLY_F: Sp--; Sp[0] = (W_)&stg_ap_f_info; goto nextInsn; case bci_PUSH_APPLY_D: Sp--; Sp[0] = (W_)&stg_ap_d_info; goto nextInsn; case bci_PUSH_APPLY_L: Sp--; Sp[0] = (W_)&stg_ap_l_info; goto nextInsn; case bci_PUSH_APPLY_P: Sp--; Sp[0] = (W_)&stg_ap_p_info; goto nextInsn; case bci_PUSH_APPLY_PP: Sp--; Sp[0] = (W_)&stg_ap_pp_info; goto nextInsn; case bci_PUSH_APPLY_PPP: Sp--; Sp[0] = (W_)&stg_ap_ppp_info; goto nextInsn; case bci_PUSH_APPLY_PPPP: Sp--; Sp[0] = (W_)&stg_ap_pppp_info; goto nextInsn; case bci_PUSH_APPLY_PPPPP: Sp--; Sp[0] = (W_)&stg_ap_ppppp_info; goto nextInsn; case bci_PUSH_APPLY_PPPPPP: Sp--; Sp[0] = (W_)&stg_ap_pppppp_info; goto nextInsn; case bci_PUSH_UBX: { int i; int o_lits = BCO_GET_LARGE_ARG; int n_words = BCO_NEXT; Sp -= n_words; for (i = 0; i < n_words; i++) { Sp[i] = (W_)BCO_LIT(o_lits+i); } goto nextInsn; } case bci_SLIDE: { int n = BCO_NEXT; int by = BCO_NEXT; /* a_1, .. a_n, b_1, .. b_by, s => a_1, .. a_n, s */ while(--n >= 0) { Sp[n+by] = Sp[n]; } Sp += by; INTERP_TICK(it_slides); goto nextInsn; } case bci_ALLOC_AP: { StgAP* ap; int n_payload = BCO_NEXT; ap = (StgAP*)allocate(cap, AP_sizeW(n_payload)); Sp[-1] = (W_)ap; ap->n_args = n_payload; SET_HDR(ap, &stg_AP_info, cap->r.rCCCS) Sp --; goto nextInsn; } case bci_ALLOC_AP_NOUPD: { StgAP* ap; int n_payload = BCO_NEXT; ap = (StgAP*)allocate(cap, AP_sizeW(n_payload)); Sp[-1] = (W_)ap; ap->n_args = n_payload; SET_HDR(ap, &stg_AP_NOUPD_info, cap->r.rCCCS) Sp --; goto nextInsn; } case bci_ALLOC_PAP: { StgPAP* pap; int arity = BCO_NEXT; int n_payload = BCO_NEXT; pap = (StgPAP*)allocate(cap, PAP_sizeW(n_payload)); Sp[-1] = (W_)pap; pap->n_args = n_payload; pap->arity = arity; SET_HDR(pap, &stg_PAP_info, cap->r.rCCCS) Sp --; goto nextInsn; } case bci_MKAP: { int i; int stkoff = BCO_NEXT; int n_payload = BCO_NEXT; StgAP* ap = (StgAP*)Sp[stkoff]; ASSERT((int)ap->n_args == n_payload); ap->fun = (StgClosure*)Sp[0]; // The function should be a BCO, and its bitmap should // cover the payload of the AP correctly. ASSERT(get_itbl(ap->fun)->type == BCO && BCO_BITMAP_SIZE(ap->fun) == ap->n_args); for (i = 0; i < n_payload; i++) ap->payload[i] = (StgClosure*)Sp[i+1]; Sp += n_payload+1; IF_DEBUG(interpreter, debugBelch("\tBuilt "); printObj((StgClosure*)ap); ); goto nextInsn; } case bci_MKPAP: { int i; int stkoff = BCO_NEXT; int n_payload = BCO_NEXT; StgPAP* pap = (StgPAP*)Sp[stkoff]; ASSERT((int)pap->n_args == n_payload); pap->fun = (StgClosure*)Sp[0]; // The function should be a BCO if (get_itbl(pap->fun)->type != BCO) { #if defined(DEBUG) printClosure(pap->fun); #endif barf("bci_MKPAP"); } for (i = 0; i < n_payload; i++) pap->payload[i] = (StgClosure*)Sp[i+1]; Sp += n_payload+1; IF_DEBUG(interpreter, debugBelch("\tBuilt "); printObj((StgClosure*)pap); ); goto nextInsn; } case bci_UNPACK: { /* Unpack N ptr words from t.o.s constructor */ int i; int n_words = BCO_NEXT; StgClosure* con = (StgClosure*)Sp[0]; Sp -= n_words; for (i = 0; i < n_words; i++) { Sp[i] = (W_)con->payload[i]; } goto nextInsn; } case bci_PACK: { int i; int o_itbl = BCO_GET_LARGE_ARG; int n_words = BCO_NEXT; StgInfoTable* itbl = INFO_PTR_TO_STRUCT((StgInfoTable *)BCO_LIT(o_itbl)); int request = CONSTR_sizeW( itbl->layout.payload.ptrs, itbl->layout.payload.nptrs ); StgClosure* con = (StgClosure*)allocate_NONUPD(cap,request); ASSERT( itbl->layout.payload.ptrs + itbl->layout.payload.nptrs > 0); SET_HDR(con, (StgInfoTable*)BCO_LIT(o_itbl), cap->r.rCCCS); for (i = 0; i < n_words; i++) { con->payload[i] = (StgClosure*)Sp[i]; } Sp += n_words; Sp --; Sp[0] = (W_)con; IF_DEBUG(interpreter, debugBelch("\tBuilt "); printObj((StgClosure*)con); ); goto nextInsn; } case bci_TESTLT_P: { unsigned int discr = BCO_NEXT; int failto = BCO_GET_LARGE_ARG; StgClosure* con = (StgClosure*)Sp[0]; if (GET_TAG(con) >= discr) { bciPtr = failto; } goto nextInsn; } case bci_TESTEQ_P: { unsigned int discr = BCO_NEXT; int failto = BCO_GET_LARGE_ARG; StgClosure* con = (StgClosure*)Sp[0]; if (GET_TAG(con) != discr) { bciPtr = failto; } goto nextInsn; } case bci_TESTLT_I: { // There should be an Int at Sp[1], and an info table at Sp[0]. int discr = BCO_GET_LARGE_ARG; int failto = BCO_GET_LARGE_ARG; I_ stackInt = (I_)Sp[1]; if (stackInt >= (I_)BCO_LIT(discr)) bciPtr = failto; goto nextInsn; } case bci_TESTEQ_I: { // There should be an Int at Sp[1], and an info table at Sp[0]. int discr = BCO_GET_LARGE_ARG; int failto = BCO_GET_LARGE_ARG; I_ stackInt = (I_)Sp[1]; if (stackInt != (I_)BCO_LIT(discr)) { bciPtr = failto; } goto nextInsn; } case bci_TESTLT_W: { // There should be an Int at Sp[1], and an info table at Sp[0]. int discr = BCO_GET_LARGE_ARG; int failto = BCO_GET_LARGE_ARG; W_ stackWord = (W_)Sp[1]; if (stackWord >= (W_)BCO_LIT(discr)) bciPtr = failto; goto nextInsn; } case bci_TESTEQ_W: { // There should be an Int at Sp[1], and an info table at Sp[0]. int discr = BCO_GET_LARGE_ARG; int failto = BCO_GET_LARGE_ARG; W_ stackWord = (W_)Sp[1]; if (stackWord != (W_)BCO_LIT(discr)) { bciPtr = failto; } goto nextInsn; } case bci_TESTLT_D: { // There should be a Double at Sp[1], and an info table at Sp[0]. int discr = BCO_GET_LARGE_ARG; int failto = BCO_GET_LARGE_ARG; StgDouble stackDbl, discrDbl; stackDbl = PK_DBL( & Sp[1] ); discrDbl = PK_DBL( & BCO_LIT(discr) ); if (stackDbl >= discrDbl) { bciPtr = failto; } goto nextInsn; } case bci_TESTEQ_D: { // There should be a Double at Sp[1], and an info table at Sp[0]. int discr = BCO_GET_LARGE_ARG; int failto = BCO_GET_LARGE_ARG; StgDouble stackDbl, discrDbl; stackDbl = PK_DBL( & Sp[1] ); discrDbl = PK_DBL( & BCO_LIT(discr) ); if (stackDbl != discrDbl) { bciPtr = failto; } goto nextInsn; } case bci_TESTLT_F: { // There should be a Float at Sp[1], and an info table at Sp[0]. int discr = BCO_GET_LARGE_ARG; int failto = BCO_GET_LARGE_ARG; StgFloat stackFlt, discrFlt; stackFlt = PK_FLT( & Sp[1] ); discrFlt = PK_FLT( & BCO_LIT(discr) ); if (stackFlt >= discrFlt) { bciPtr = failto; } goto nextInsn; } case bci_TESTEQ_F: { // There should be a Float at Sp[1], and an info table at Sp[0]. int discr = BCO_GET_LARGE_ARG; int failto = BCO_GET_LARGE_ARG; StgFloat stackFlt, discrFlt; stackFlt = PK_FLT( & Sp[1] ); discrFlt = PK_FLT( & BCO_LIT(discr) ); if (stackFlt != discrFlt) { bciPtr = failto; } goto nextInsn; } // Control-flow ish things case bci_ENTER: // Context-switch check. We put it here to ensure that // the interpreter has done at least *some* work before // context switching: sometimes the scheduler can invoke // the interpreter with context_switch == 1, particularly // if the -C0 flag has been given on the cmd line. if (cap->r.rHpLim == NULL) { Sp--; Sp[0] = (W_)&stg_enter_info; RETURN_TO_SCHEDULER(ThreadInterpret, ThreadYielding); } goto eval; case bci_RETURN: tagged_obj = (StgClosure *)Sp[0]; Sp++; goto do_return; case bci_RETURN_P: Sp--; Sp[0] = (W_)&stg_ret_p_info; goto do_return_unboxed; case bci_RETURN_N: Sp--; Sp[0] = (W_)&stg_ret_n_info; goto do_return_unboxed; case bci_RETURN_F: Sp--; Sp[0] = (W_)&stg_ret_f_info; goto do_return_unboxed; case bci_RETURN_D: Sp--; Sp[0] = (W_)&stg_ret_d_info; goto do_return_unboxed; case bci_RETURN_L: Sp--; Sp[0] = (W_)&stg_ret_l_info; goto do_return_unboxed; case bci_RETURN_V: Sp--; Sp[0] = (W_)&stg_ret_v_info; goto do_return_unboxed; case bci_SWIZZLE: { int stkoff = BCO_NEXT; signed short n = (signed short)(BCO_NEXT); Sp[stkoff] += (W_)n; goto nextInsn; } case bci_CCALL: { void *tok; int stk_offset = BCO_NEXT; int o_itbl = BCO_GET_LARGE_ARG; int interruptible = BCO_NEXT; void(*marshall_fn)(void*) = (void (*)(void*))BCO_LIT(o_itbl); /* the stack looks like this: | | <- Sp + stk_offset +-------------+ | | | args | | | <- Sp + ret_size + 1 +-------------+ | C fun | <- Sp + ret_size +-------------+ | ret | <- Sp +-------------+ ret is a placeholder for the return address, and may be up to 2 words. We need to copy the args out of the TSO, because when we call suspendThread() we no longer own the TSO stack, and it may move at any time - indeed suspendThread() itself may do stack squeezing and move our args. So we make a copy of the argument block. */ #define ROUND_UP_WDS(p) ((((StgWord)(p)) + sizeof(W_)-1)/sizeof(W_)) ffi_cif *cif = (ffi_cif *)marshall_fn; uint32_t nargs = cif->nargs; uint32_t ret_size; uint32_t i; int j; StgPtr p; W_ ret[2]; // max needed W_ *arguments[stk_offset]; // max needed void *argptrs[nargs]; void (*fn)(void); if (cif->rtype->type == FFI_TYPE_VOID) { // necessary because cif->rtype->size == 1 for void, // but the bytecode generator has not pushed a // placeholder in this case. ret_size = 0; } else { ret_size = ROUND_UP_WDS(cif->rtype->size); } memcpy(arguments, Sp+ret_size+1, sizeof(W_) * (stk_offset-1-ret_size)); // libffi expects the args as an array of pointers to // values, so we have to construct this array before making // the call. p = (StgPtr)arguments; for (i = 0; i < nargs; i++) { argptrs[i] = (void *)p; // get the size from the cif p += ROUND_UP_WDS(cif->arg_types[i]->size); } // this is the function we're going to call fn = (void(*)(void))Sp[ret_size]; // Restore the Haskell thread's current value of errno errno = cap->r.rCurrentTSO->saved_errno; // There are a bunch of non-ptr words on the stack (the // ccall args, the ccall fun address and space for the // result), which we need to cover with an info table // since we might GC during this call. // // We know how many (non-ptr) words there are before the // next valid stack frame: it is the stk_offset arg to the // CCALL instruction. So we overwrite this area of the // stack with empty stack frames (stg_ret_v_info); // for (j = 0; j < stk_offset; j++) { Sp[j] = (W_)&stg_ret_v_info; /* an empty stack frame */ } // save obj (pointer to the current BCO), since this // might move during the call. We push an stg_ret_p frame // for this. Sp -= 2; Sp[1] = (W_)obj; Sp[0] = (W_)&stg_ret_p_info; SAVE_THREAD_STATE(); tok = suspendThread(&cap->r, interruptible); // We already made a copy of the arguments above. ffi_call(cif, fn, ret, argptrs); // And restart the thread again, popping the stg_ret_p frame. cap = (Capability *)((void *)((unsigned char*)resumeThread(tok) - STG_FIELD_OFFSET(Capability,r))); LOAD_THREAD_STATE(); if (Sp[0] != (W_)&stg_ret_p_info) { // the stack is not how we left it. This probably // means that an exception got raised on exit from the // foreign call, so we should just continue with // whatever is on top of the stack now. RETURN_TO_SCHEDULER_NO_PAUSE(ThreadRunGHC, ThreadYielding); } // Re-load the pointer to the BCO from the stg_ret_p frame, // it might have moved during the call. Also reload the // pointers to the components of the BCO. obj = (StgClosure*)Sp[1]; bco = (StgBCO*)obj; instrs = (StgWord16*)(bco->instrs->payload); literals = (StgWord*)(&bco->literals->payload[0]); ptrs = (StgPtr*)(&bco->ptrs->payload[0]); Sp += 2; // pop the stg_ret_p frame // Save the Haskell thread's current value of errno cap->r.rCurrentTSO->saved_errno = errno; // Copy the return value back to the TSO stack. It is at // most 2 words large, and resides at arguments[0]. memcpy(Sp, ret, sizeof(W_) * stg_min(stk_offset,ret_size)); goto nextInsn; } case bci_JMP: { /* BCO_NEXT modifies bciPtr, so be conservative. */ int nextpc = BCO_GET_LARGE_ARG; bciPtr = nextpc; goto nextInsn; } case bci_CASEFAIL: barf("interpretBCO: hit a CASEFAIL"); // Errors default: barf("interpretBCO: unknown or unimplemented opcode %d", (int)(bci & 0xFF)); } /* switch on opcode */ } } barf("interpretBCO: fell off end of the interpreter"); }