path: root/rts/PrimOps.cmm

/* -----------------------------------------------------------------------------
 *
 * (c) The GHC Team, 1998-2004
 *
 * Out-of-line primitive operations
 *
 * This file contains the implementations of all the primitive
 * operations ("primops") which are not expanded inline.  See
 * ghc/compiler/prelude/primops.txt.pp for a list of all the primops;
 * this file contains code for most of those with the attribute
 * out_of_line=True.
 *
 * Entry convention: the entry convention for a primop is that all the
 * args are in Stg registers (R1, R2, etc.).  This is to make writing
 * the primops easier.  (see compiler/codeGen/CgCallConv.hs).
 *
 * Return convention: results from a primop are generally returned
 * using the ordinary unboxed tuple return convention.  The C-- parser
 * implements the RET_xxxx() macros to perform unboxed-tuple returns
 * based on the prevailing return convention.
 *
 * 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"

#ifdef __PIC__
import __gmpz_init;
import __gmpz_add;
import __gmpz_sub;
import __gmpz_mul;
import __gmpz_gcd;
import __gmpn_gcd_1;
import __gmpn_cmp;
import __gmpz_tdiv_q;
import __gmpz_tdiv_r;
import __gmpz_tdiv_qr;
import __gmpz_fdiv_qr;
import __gmpz_divexact;
import __gmpz_and;
import __gmpz_xor;
import __gmpz_ior;
import __gmpz_com;
import base_GHCziIOBase_NestedAtomically_closure;
import pthread_mutex_lock;
import pthread_mutex_unlock;
#endif
import EnterCriticalSection;
import LeaveCriticalSection;

/*-----------------------------------------------------------------------------
  Array Primitives

  Basically just new*Array - the others are all inline macros.

  The size arg is always passed in R1, and the result returned in R1.

  The slow entry point is for returning from a heap check, the saved
  size argument must be re-loaded from the stack.
  -------------------------------------------------------------------------- */

/* for objects that are *less* than the size of a word, make sure we
 * round up to the nearest word for the size of the array.
 */

newByteArrayzh_fast
{
    W_ words, payload_words, n, p;
    MAYBE_GC(NO_PTRS,newByteArrayzh_fast);
    n = R1;
    payload_words = ROUNDUP_BYTES_TO_WDS(n);
    words = BYTES_TO_WDS(SIZEOF_StgArrWords) + payload_words;
    ("ptr" p) = foreign "C" allocateLocal(MyCapability() "ptr",words) [];
    TICK_ALLOC_PRIM(SIZEOF_StgArrWords,WDS(payload_words),0);
    SET_HDR(p, stg_ARR_WORDS_info, W_[CCCS]);
    StgArrWords_words(p) = payload_words;
    RET_P(p);
}

newPinnedByteArrayzh_fast
{
    W_ words, payload_words, n, p;

    MAYBE_GC(NO_PTRS,newPinnedByteArrayzh_fast);
    n = R1;
    payload_words = ROUNDUP_BYTES_TO_WDS(n);

    // We want an 8-byte aligned array.  allocatePinned() gives us
    // 8-byte aligned memory by default, but we want to align the
    // *goods* inside the ArrWords object, so we have to check the
    // size of the ArrWords header and adjust our size accordingly.
    words = BYTES_TO_WDS(SIZEOF_StgArrWords) + payload_words;
    if ((SIZEOF_StgArrWords & 7) != 0) {
	words = words + 1;
    }

    ("ptr" p) = foreign "C" allocatePinned(words) [];
    TICK_ALLOC_PRIM(SIZEOF_StgArrWords,WDS(payload_words),0);

    // Again, if the ArrWords header isn't a multiple of 8 bytes, we
    // have to push the object forward one word so that the goods
    // fall on an 8-byte boundary.
    if ((SIZEOF_StgArrWords & 7) != 0) {
	p = p + WDS(1);
    }

    SET_HDR(p, stg_ARR_WORDS_info, W_[CCCS]);
    StgArrWords_words(p) = payload_words;
    RET_P(p);
}

newArrayzh_fast
{
    W_ words, n, init, arr, p;
    /* Args: R1 = words, R2 = initialisation value */

    n = R1;
    MAYBE_GC(R2_PTR,newArrayzh_fast);

    words = BYTES_TO_WDS(SIZEOF_StgMutArrPtrs) + n;
    ("ptr" arr) = foreign "C" allocateLocal(MyCapability() "ptr",words) [R2];
    TICK_ALLOC_PRIM(SIZEOF_StgMutArrPtrs, WDS(n), 0);

    SET_HDR(arr, stg_MUT_ARR_PTRS_DIRTY_info, W_[CCCS]);
    StgMutArrPtrs_ptrs(arr) = n;

    // Initialise all elements of the the array with the value in R2
    init = R2;
    p = arr + SIZEOF_StgMutArrPtrs;
  for:
    if (p < arr + WDS(words)) {
	W_[p] = init;
	p = p + WDS(1);
	goto for;
    }

    RET_P(arr);
}

unsafeThawArrayzh_fast
{
  // SUBTLETY TO DO WITH THE OLD GEN MUTABLE LIST
  //
  // A MUT_ARR_PTRS lives on the mutable list, but a MUT_ARR_PTRS_FROZEN 
  // normally doesn't.  However, when we freeze a MUT_ARR_PTRS, we leave
  // it on the mutable list for the GC to remove (removing something from
  // the mutable list is not easy, because the mut_list is only singly-linked).
  // 
  // So that we can tell whether a MUT_ARR_PTRS_FROZEN is on the mutable list,
  // when we freeze it we set the info ptr to be MUT_ARR_PTRS_FROZEN0
  // to indicate that it is still on the mutable list.
  //
  // So, when we thaw a MUT_ARR_PTRS_FROZEN, we must cope with two cases:
  // either it is on a mut_list, or it isn't.  We adopt the convention that
  // the closure type is MUT_ARR_PTRS_FROZEN0 if it is on the mutable list,
  // and MUT_ARR_PTRS_FROZEN otherwise.  In fact it wouldn't matter if
  // we put it on the mutable list more than once, but it would get scavenged
  // multiple times during GC, which would be unnecessarily slow.
  //
  if (StgHeader_info(R1) != stg_MUT_ARR_PTRS_FROZEN0_info) {
	SET_INFO(R1,stg_MUT_ARR_PTRS_DIRTY_info);
	recordMutable(R1, R1);
	// must be done after SET_INFO, because it ASSERTs closure_MUTABLE()
	RET_P(R1);
  } else {
	SET_INFO(R1,stg_MUT_ARR_PTRS_DIRTY_info);
	RET_P(R1);
  }
}

/* -----------------------------------------------------------------------------
   MutVar primitives
   -------------------------------------------------------------------------- */

newMutVarzh_fast
{
    W_ mv;
    /* Args: R1 = initialisation value */

    ALLOC_PRIM( SIZEOF_StgMutVar, R1_PTR, newMutVarzh_fast);

    mv = Hp - SIZEOF_StgMutVar + WDS(1);
    SET_HDR(mv,stg_MUT_VAR_DIRTY_info,W_[CCCS]);
    StgMutVar_var(mv) = R1;
    
    RET_P(mv);
}

atomicModifyMutVarzh_fast
{
    W_ mv, z, x, y, r;
    /* Args: R1 :: MutVar#,  R2 :: a -> (a,b) */

    /* If x is the current contents of the MutVar#, then 
       We want to make the new contents point to

         (sel_0 (f x))
 
       and the return value is
	 
	 (sel_1 (f x))

        obviously we can share (f x).

         z = [stg_ap_2 f x]  (max (HS + 2) MIN_UPD_SIZE)
	 y = [stg_sel_0 z]   (max (HS + 1) MIN_UPD_SIZE)
         r = [stg_sel_1 z]   (max (HS + 1) MIN_UPD_SIZE)
    */

#if MIN_UPD_SIZE > 1
#define THUNK_1_SIZE (SIZEOF_StgThunkHeader + WDS(MIN_UPD_SIZE))
#define TICK_ALLOC_THUNK_1() TICK_ALLOC_UP_THK(WDS(1),WDS(MIN_UPD_SIZE-1))
#else
#define THUNK_1_SIZE (SIZEOF_StgThunkHeader + WDS(1))
#define TICK_ALLOC_THUNK_1() TICK_ALLOC_UP_THK(WDS(1),0)
#endif

#if MIN_UPD_SIZE > 2
#define THUNK_2_SIZE (SIZEOF_StgThunkHeader + WDS(MIN_UPD_SIZE))
#define TICK_ALLOC_THUNK_2() TICK_ALLOC_UP_THK(WDS(2),WDS(MIN_UPD_SIZE-2))
#else
#define THUNK_2_SIZE (SIZEOF_StgThunkHeader + WDS(2))
#define TICK_ALLOC_THUNK_2() TICK_ALLOC_UP_THK(WDS(2),0)
#endif

#define SIZE (THUNK_2_SIZE + THUNK_1_SIZE + THUNK_1_SIZE)

   HP_CHK_GEN_TICKY(SIZE, R1_PTR & R2_PTR, atomicModifyMutVarzh_fast);

#if defined(THREADED_RTS)
    ACQUIRE_LOCK(atomic_modify_mutvar_mutex "ptr") [R1,R2];
#endif

   x = StgMutVar_var(R1);

   TICK_ALLOC_THUNK_2();
   CCCS_ALLOC(THUNK_2_SIZE);
   z = Hp - THUNK_2_SIZE + WDS(1);
   SET_HDR(z, stg_ap_2_upd_info, W_[CCCS]);
   LDV_RECORD_CREATE(z);
   StgThunk_payload(z,0) = R2;
   StgThunk_payload(z,1) = x;

   TICK_ALLOC_THUNK_1();
   CCCS_ALLOC(THUNK_1_SIZE);
   y = z - THUNK_1_SIZE;
   SET_HDR(y, stg_sel_0_upd_info, W_[CCCS]);
   LDV_RECORD_CREATE(y);
   StgThunk_payload(y,0) = z;

   StgMutVar_var(R1) = y;
   foreign "C" dirty_MUT_VAR(BaseReg "ptr", R1 "ptr") [R1];

   TICK_ALLOC_THUNK_1();
   CCCS_ALLOC(THUNK_1_SIZE);
   r = y - THUNK_1_SIZE;
   SET_HDR(r, stg_sel_1_upd_info, W_[CCCS]);
   LDV_RECORD_CREATE(r);
   StgThunk_payload(r,0) = z;

#if defined(THREADED_RTS)
    RELEASE_LOCK(atomic_modify_mutvar_mutex "ptr") [];
#endif

   RET_P(r);
}

/* -----------------------------------------------------------------------------
   Weak Pointer Primitives
   -------------------------------------------------------------------------- */

STRING(stg_weak_msg,"New weak pointer at %p\n")

mkWeakzh_fast
{
  /* R1 = key
     R2 = value
     R3 = finalizer (or NULL)
  */
  W_ w;

  if (R3 == NULL) {
    R3 = stg_NO_FINALIZER_closure;
  }

  ALLOC_PRIM( SIZEOF_StgWeak, R1_PTR & R2_PTR & R3_PTR, mkWeakzh_fast );

  w = Hp - SIZEOF_StgWeak + WDS(1);
  SET_HDR(w, stg_WEAK_info, W_[CCCS]);

  StgWeak_key(w)       = R1;
  StgWeak_value(w)     = R2;
  StgWeak_finalizer(w) = R3;

  StgWeak_link(w)	= W_[weak_ptr_list];
  W_[weak_ptr_list] 	= w;

  IF_DEBUG(weak, foreign "C" debugBelch(stg_weak_msg,w) []);

  RET_P(w);
}


finalizzeWeakzh_fast
{
  /* R1 = weak ptr
   */
  W_ w, f;

  w = R1;

  // already dead?
  if (GET_INFO(w) == stg_DEAD_WEAK_info) {
      RET_NP(0,stg_NO_FINALIZER_closure);
  }

  // kill it
#ifdef PROFILING
  // @LDV profiling
  // A weak pointer is inherently used, so we do not need to call
  // LDV_recordDead_FILL_SLOP_DYNAMIC():
  //    LDV_recordDead_FILL_SLOP_DYNAMIC((StgClosure *)w);
  // or, LDV_recordDead():
  //    LDV_recordDead((StgClosure *)w, sizeofW(StgWeak) - sizeofW(StgProfHeader));
  // Furthermore, when PROFILING is turned on, dead weak pointers are exactly as 
  // large as weak pointers, so there is no need to fill the slop, either.
  // See stg_DEAD_WEAK_info in StgMiscClosures.hc.
#endif

  //
  // Todo: maybe use SET_HDR() and remove LDV_recordCreate()?
  //
  SET_INFO(w,stg_DEAD_WEAK_info);
  LDV_RECORD_CREATE(w);

  f = StgWeak_finalizer(w);
  StgDeadWeak_link(w) = StgWeak_link(w);

  /* return the finalizer */
  if (f == stg_NO_FINALIZER_closure) {
      RET_NP(0,stg_NO_FINALIZER_closure);
  } else {
      RET_NP(1,f);
  }
}

deRefWeakzh_fast
{
  /* R1 = weak ptr */
  W_ w, code, val;

  w = R1;
  if (GET_INFO(w) == stg_WEAK_info) {
    code = 1;
    val = StgWeak_value(w);
  } else {
    code = 0;
    val = w;
  }
  RET_NP(code,val);
}

/* -----------------------------------------------------------------------------
   Arbitrary-precision Integer operations.

   There are some assumptions in this code that mp_limb_t == W_.  This is
   the case for all the platforms that GHC supports, currently.
   -------------------------------------------------------------------------- */

int2Integerzh_fast
{
   /* arguments: R1 = Int# */

   W_ val, s, p;	/* to avoid aliasing */

   val = R1;
   ALLOC_PRIM( SIZEOF_StgArrWords + WDS(1), NO_PTRS, int2Integerzh_fast );

   p = Hp - SIZEOF_StgArrWords;
   SET_HDR(p, stg_ARR_WORDS_info, W_[CCCS]);
   StgArrWords_words(p) = 1;

   /* mpz_set_si is inlined here, makes things simpler */
   if (%lt(val,0)) { 
	s  = -1;
	Hp(0) = -val;
   } else { 
     if (%gt(val,0)) {
	s = 1;
	Hp(0) = val;
     } else {
	s = 0;
     }
  }

   /* returns (# size  :: Int#, 
		 data  :: ByteArray# 
	       #)
   */
   RET_NP(s,p);
}

word2Integerzh_fast
{
   /* arguments: R1 = Word# */

   W_ val, s, p;	/* to avoid aliasing */

   val = R1;

   ALLOC_PRIM( SIZEOF_StgArrWords + WDS(1), NO_PTRS, word2Integerzh_fast);

   p = Hp - SIZEOF_StgArrWords;
   SET_HDR(p, stg_ARR_WORDS_info, W_[CCCS]);
   StgArrWords_words(p) = 1;

   if (val != 0) {
	s = 1;
	W_[Hp] = val;
   } else {
	s = 0;
   }

   /* returns (# size  :: Int#, 
		 data  :: ByteArray# #)
   */
   RET_NP(s,p);
}


/*
 * 'long long' primops for converting to/from Integers.
 */

#ifdef SUPPORT_LONG_LONGS

int64ToIntegerzh_fast
{
   /* arguments: L1 = Int64# */

   L_ val;
   W_ hi, lo, s, neg, words_needed, p;

   val = L1;
   neg = 0;

   hi = TO_W_(val >> 32);
   lo = TO_W_(val);

   if ( hi != 0 && hi != 0xFFFFFFFF )  { 
       words_needed = 2;
   } else { 
       // minimum is one word
       words_needed = 1;
   }

   ALLOC_PRIM( SIZEOF_StgArrWords + WDS(words_needed),
	       NO_PTRS, int64ToIntegerzh_fast );

   p = Hp - SIZEOF_StgArrWords - WDS(words_needed) + WDS(1);
   SET_HDR(p, stg_ARR_WORDS_info, W_[CCCS]);
   StgArrWords_words(p) = words_needed;

   if ( %lt(hi,0) ) {
     neg = 1;
     lo = -lo;
     if(lo == 0) {
       hi = -hi;
     } else {
       hi = -hi - 1;
     }
   }

   if ( words_needed == 2 )  { 
      s = 2;
      Hp(-1) = lo;
      Hp(0) = hi;
   } else { 
       if ( lo != 0 ) {
	   s = 1;
	   Hp(0) = lo;
       } else /* val==0 */  {
	   s = 0;
       }
   }
   if ( neg != 0 ) {
	s = -s;
   }

   /* returns (# size  :: Int#, 
		 data  :: ByteArray# #)
   */
   RET_NP(s,p);
}
word64ToIntegerzh_fast
{
   /* arguments: L1 = Word64# */

   L_ val;
   W_ hi, lo, s, words_needed, p;

   val = L1;
   hi = TO_W_(val >> 32);
   lo = TO_W_(val);

   if ( hi != 0 ) {
      words_needed = 2;
   } else {
      words_needed = 1;
   }

   ALLOC_PRIM( SIZEOF_StgArrWords + WDS(words_needed),
	       NO_PTRS, word64ToIntegerzh_fast );

   p = Hp - SIZEOF_StgArrWords - WDS(words_needed) + WDS(1);
   SET_HDR(p, stg_ARR_WORDS_info, W_[CCCS]);
   StgArrWords_words(p) = words_needed;

   if ( hi != 0 ) { 
     s = 2;
     Hp(-1) = lo;
     Hp(0)  = hi;
   } else {
      if ( lo != 0 ) {
        s = 1;
        Hp(0) = lo;
     } else /* val==0 */  {
      s = 0;
     }
  }

   /* returns (# size  :: Int#, 
		 data  :: ByteArray# #)
   */
   RET_NP(s,p);
}



#endif /* SUPPORT_LONG_LONGS */

/* ToDo: this is shockingly inefficient */

#ifndef THREADED_RTS
section "bss" {
  mp_tmp1:
    bits8 [SIZEOF_MP_INT];
}

section "bss" {
  mp_tmp2:
    bits8 [SIZEOF_MP_INT];
}

section "bss" {
  mp_result1:
    bits8 [SIZEOF_MP_INT];
}

section "bss" {
  mp_result2:
    bits8 [SIZEOF_MP_INT];
}
#endif

#ifdef THREADED_RTS
#define FETCH_MP_TEMP(X) \
W_ X; \
X = BaseReg + (OFFSET_StgRegTable_r ## X);
#else
#define FETCH_MP_TEMP(X) /* Nothing */
#endif

#define GMP_TAKE2_RET1(name,mp_fun)                                     \
name                                                                    \
{                                                                       \
  CInt s1, s2;                                                          \
  W_ d1, d2;                                                            \
  FETCH_MP_TEMP(mp_tmp1);                                               \
  FETCH_MP_TEMP(mp_tmp2);                                               \
  FETCH_MP_TEMP(mp_result1)                                             \
  FETCH_MP_TEMP(mp_result2);                                            \
                                                                        \
  /* call doYouWantToGC() */                                            \
  MAYBE_GC(R2_PTR & R4_PTR, name);                                      \
                                                                        \
  s1 = W_TO_INT(R1);                                                    \
  d1 = R2;                                                              \
  s2 = W_TO_INT(R3);                                                    \
  d2 = R4;                                                              \
                                                                        \
  MP_INT__mp_alloc(mp_tmp1) = W_TO_INT(StgArrWords_words(d1));          \
  MP_INT__mp_size(mp_tmp1)  = (s1);                                     \
  MP_INT__mp_d(mp_tmp1)	    = BYTE_ARR_CTS(d1);                         \
  MP_INT__mp_alloc(mp_tmp2) = W_TO_INT(StgArrWords_words(d2));          \
  MP_INT__mp_size(mp_tmp2)  = (s2);                                     \
  MP_INT__mp_d(mp_tmp2)	    = BYTE_ARR_CTS(d2);                         \
                                                                        \
  foreign "C" __gmpz_init(mp_result1 "ptr") [];                            \
                                                                        \
  /* Perform the operation */                                           \
  foreign "C" mp_fun(mp_result1 "ptr",mp_tmp1  "ptr",mp_tmp2  "ptr") []; \
                                                                        \
  RET_NP(TO_W_(MP_INT__mp_size(mp_result1)),                            \
         MP_INT__mp_d(mp_result1) - SIZEOF_StgArrWords);                \
}

#define GMP_TAKE1_RET1(name,mp_fun)                                     \
name                                                                    \
{                                                                       \
  CInt s1;                                                              \
  W_ d1;                                                                \
  FETCH_MP_TEMP(mp_tmp1);                                               \
  FETCH_MP_TEMP(mp_result1)                                             \
                                                                        \
  /* call doYouWantToGC() */                                            \
  MAYBE_GC(R2_PTR, name);                                               \
                                                                        \
  d1 = R2;                                                              \
  s1 = W_TO_INT(R1);                                                    \
                                                                        \
  MP_INT__mp_alloc(mp_tmp1)	= W_TO_INT(StgArrWords_words(d1));      \
  MP_INT__mp_size(mp_tmp1)	= (s1);                                 \
  MP_INT__mp_d(mp_tmp1)		= BYTE_ARR_CTS(d1);                     \
                                                                        \
  foreign "C" __gmpz_init(mp_result1 "ptr") [];                            \
                                                                        \
  /* Perform the operation */                                           \
  foreign "C" mp_fun(mp_result1 "ptr",mp_tmp1 "ptr") [];                \
                                                                        \
  RET_NP(TO_W_(MP_INT__mp_size(mp_result1)),                            \
         MP_INT__mp_d(mp_result1) - SIZEOF_StgArrWords);                \
}

#define GMP_TAKE2_RET2(name,mp_fun)                                                     \
name                                                                                    \
{                                                                                       \
  CInt s1, s2;                                                                          \
  W_ d1, d2;                                                                            \
  FETCH_MP_TEMP(mp_tmp1);                                                               \
  FETCH_MP_TEMP(mp_tmp2);                                                               \
  FETCH_MP_TEMP(mp_result1)                                                             \
  FETCH_MP_TEMP(mp_result2)                                                             \
                                                                                        \
  /* call doYouWantToGC() */                                                            \
  MAYBE_GC(R2_PTR & R4_PTR, name);                                                      \
                                                                                        \
  s1 = W_TO_INT(R1);                                                                    \
  d1 = R2;                                                                              \
  s2 = W_TO_INT(R3);                                                                    \
  d2 = R4;                                                                              \
                                                                                        \
  MP_INT__mp_alloc(mp_tmp1)	= W_TO_INT(StgArrWords_words(d1));                      \
  MP_INT__mp_size(mp_tmp1)	= (s1);                                                 \
  MP_INT__mp_d(mp_tmp1)		= BYTE_ARR_CTS(d1);                                     \
  MP_INT__mp_alloc(mp_tmp2)	= W_TO_INT(StgArrWords_words(d2));                      \
  MP_INT__mp_size(mp_tmp2)	= (s2);                                                 \
  MP_INT__mp_d(mp_tmp2)		= BYTE_ARR_CTS(d2);                                     \
                                                                                        \
  foreign "C" __gmpz_init(mp_result1 "ptr") [];                                               \
  foreign "C" __gmpz_init(mp_result2 "ptr") [];                                               \
                                                                                        \
  /* Perform the operation */                                                           \
  foreign "C" mp_fun(mp_result1 "ptr",mp_result2 "ptr",mp_tmp1 "ptr",mp_tmp2 "ptr") [];    \
                                                                                        \
  RET_NPNP(TO_W_(MP_INT__mp_size(mp_result1)),                                          \
           MP_INT__mp_d(mp_result1) - SIZEOF_StgArrWords,                               \
	   TO_W_(MP_INT__mp_size(mp_result2)),                                          \
           MP_INT__mp_d(mp_result2) - SIZEOF_StgArrWords);                              \
}

GMP_TAKE2_RET1(plusIntegerzh_fast,     __gmpz_add)
GMP_TAKE2_RET1(minusIntegerzh_fast,    __gmpz_sub)
GMP_TAKE2_RET1(timesIntegerzh_fast,    __gmpz_mul)
GMP_TAKE2_RET1(gcdIntegerzh_fast,      __gmpz_gcd)
GMP_TAKE2_RET1(quotIntegerzh_fast,     __gmpz_tdiv_q)
GMP_TAKE2_RET1(remIntegerzh_fast,      __gmpz_tdiv_r)
GMP_TAKE2_RET1(divExactIntegerzh_fast, __gmpz_divexact)
GMP_TAKE2_RET1(andIntegerzh_fast,      __gmpz_and)
GMP_TAKE2_RET1(orIntegerzh_fast,       __gmpz_ior)
GMP_TAKE2_RET1(xorIntegerzh_fast,      __gmpz_xor)
GMP_TAKE1_RET1(complementIntegerzh_fast, __gmpz_com)

GMP_TAKE2_RET2(quotRemIntegerzh_fast, __gmpz_tdiv_qr)
GMP_TAKE2_RET2(divModIntegerzh_fast,  __gmpz_fdiv_qr)

#ifndef THREADED_RTS
section "bss" {
  mp_tmp_w:  W_; // NB. mp_tmp_w is really an here mp_limb_t
}
#endif

gcdIntzh_fast
{
    /* R1 = the first Int#; R2 = the second Int# */
    W_ r; 
    FETCH_MP_TEMP(mp_tmp_w);

    W_[mp_tmp_w] = R1;
    (r) = foreign "C" __gmpn_gcd_1(mp_tmp_w "ptr", 1, R2) [];

    R1 = r;
    /* Result parked in R1, return via info-pointer at TOS */
    jump %ENTRY_CODE(Sp(0));
}


gcdIntegerIntzh_fast
{
    /* R1 = s1; R2 = d1; R3 = the int */
    W_ s1;
    (s1) = foreign "C" __gmpn_gcd_1( BYTE_ARR_CTS(R2) "ptr", R1, R3) [];
    R1 = s1;
    
    /* Result parked in R1, return via info-pointer at TOS */
    jump %ENTRY_CODE(Sp(0));
}


cmpIntegerIntzh_fast
{
    /* R1 = s1; R2 = d1; R3 = the int */
    W_ usize, vsize, v_digit, u_digit;

    usize = R1;
    vsize = 0;
    v_digit = R3;

    // paraphrased from __gmpz_cmp_si() in the GMP sources
    if (%gt(v_digit,0)) {
	vsize = 1;
    } else { 
	if (%lt(v_digit,0)) {
	    vsize = -1;
	    v_digit = -v_digit;
	}
    }

    if (usize != vsize) {
	R1 = usize - vsize; 
	jump %ENTRY_CODE(Sp(0));
    }

    if (usize == 0) {
	R1 = 0; 
	jump %ENTRY_CODE(Sp(0));
    }

    u_digit = W_[BYTE_ARR_CTS(R2)];

    if (u_digit == v_digit) {
	R1 = 0; 
	jump %ENTRY_CODE(Sp(0));
    }

    if (%gtu(u_digit,v_digit)) { // NB. unsigned: these are mp_limb_t's
	R1 = usize; 
    } else {
	R1 = -usize; 
    }

    jump %ENTRY_CODE(Sp(0));
}

cmpIntegerzh_fast
{
    /* R1 = s1; R2 = d1; R3 = s2; R4 = d2 */
    W_ usize, vsize, size, up, vp;
    CInt cmp;

    // paraphrased from __gmpz_cmp() in the GMP sources
    usize = R1;
    vsize = R3;

    if (usize != vsize) {
	R1 = usize - vsize; 
	jump %ENTRY_CODE(Sp(0));
    }

    if (usize == 0) {
	R1 = 0; 
	jump %ENTRY_CODE(Sp(0));
    }

    if (%lt(usize,0)) { // NB. not <, which is unsigned
	size = -usize;
    } else {
	size = usize;
    }

    up = BYTE_ARR_CTS(R2);
    vp = BYTE_ARR_CTS(R4);

    (cmp) = foreign "C" __gmpn_cmp(up "ptr", vp "ptr", size) [];

    if (cmp == 0 :: CInt) {
	R1 = 0; 
	jump %ENTRY_CODE(Sp(0));
    }

    if (%lt(cmp,0 :: CInt) == %lt(usize,0)) {
	R1 = 1;
    } else {
	R1 = (-1); 
    }
    /* Result parked in R1, return via info-pointer at TOS */
    jump %ENTRY_CODE(Sp(0));
}

integer2Intzh_fast
{
    /* R1 = s; R2 = d */
    W_ r, s;

    s = R1;
    if (s == 0) {
	r = 0;
    } else {
	r = W_[R2 + SIZEOF_StgArrWords];
	if (%lt(s,0)) {
	    r = -r;
	}
    }
    /* Result parked in R1, return via info-pointer at TOS */
    R1 = r;
    jump %ENTRY_CODE(Sp(0));
}

integer2Wordzh_fast
{
  /* R1 = s; R2 = d */
  W_ r, s;

  s = R1;
  if (s == 0) {
    r = 0;
  } else {
    r = W_[R2 + SIZEOF_StgArrWords];
    if (%lt(s,0)) {
	r = -r;
    }
  }
  /* Result parked in R1, return via info-pointer at TOS */
  R1 = r;
  jump %ENTRY_CODE(Sp(0));
}

decodeFloatzh_fast
{ 
    W_ p;
    F_ arg;
    FETCH_MP_TEMP(mp_tmp1);
    FETCH_MP_TEMP(mp_tmp_w);
    
    /* arguments: F1 = Float# */
    arg = F1;
    
    ALLOC_PRIM( SIZEOF_StgArrWords + WDS(1), NO_PTRS, decodeFloatzh_fast );
    
    /* Be prepared to tell Lennart-coded __decodeFloat
       where mantissa._mp_d can be put (it does not care about the rest) */
    p = Hp - SIZEOF_StgArrWords;
    SET_HDR(p,stg_ARR_WORDS_info,W_[CCCS]);
    StgArrWords_words(p) = 1;
    MP_INT__mp_d(mp_tmp1) = BYTE_ARR_CTS(p);
    
    /* Perform the operation */
    foreign "C" __decodeFloat(mp_tmp1 "ptr",mp_tmp_w "ptr" ,arg) [];
    
    /* returns: (Int# (expn), Int#, ByteArray#) */
    RET_NNP(W_[mp_tmp_w], TO_W_(MP_INT__mp_size(mp_tmp1)), p);
}

#define DOUBLE_MANTISSA_SIZE SIZEOF_DOUBLE
#define ARR_SIZE (SIZEOF_StgArrWords + DOUBLE_MANTISSA_SIZE)

decodeDoublezh_fast
{ 
    D_ arg;
    W_ p;
    FETCH_MP_TEMP(mp_tmp1);
    FETCH_MP_TEMP(mp_tmp_w);

    /* arguments: D1 = Double# */
    arg = D1;

    ALLOC_PRIM( ARR_SIZE, NO_PTRS, decodeDoublezh_fast );
    
    /* Be prepared to tell Lennart-coded __decodeDouble
       where mantissa.d can be put (it does not care about the rest) */
    p = Hp - ARR_SIZE + WDS(1);
    SET_HDR(p, stg_ARR_WORDS_info, W_[CCCS]);
    StgArrWords_words(p) = BYTES_TO_WDS(DOUBLE_MANTISSA_SIZE);
    MP_INT__mp_d(mp_tmp1) = BYTE_ARR_CTS(p);

    /* Perform the operation */
    foreign "C" __decodeDouble(mp_tmp1 "ptr", mp_tmp_w "ptr",arg) [];
    
    /* returns: (Int# (expn), Int#, ByteArray#) */
    RET_NNP(W_[mp_tmp_w], TO_W_(MP_INT__mp_size(mp_tmp1)), p);
}

/* -----------------------------------------------------------------------------
 * Concurrency primitives
 * -------------------------------------------------------------------------- */

forkzh_fast
{
  /* args: R1 = closure to spark */

  MAYBE_GC(R1_PTR, forkzh_fast);

  W_ closure;
  W_ threadid;
  closure = R1;

  ("ptr" threadid) = foreign "C" createIOThread( MyCapability() "ptr", 
				RtsFlags_GcFlags_initialStkSize(RtsFlags), 
				closure "ptr") [];
  foreign "C" scheduleThread(MyCapability() "ptr", threadid "ptr") [];

  // switch at the earliest opportunity
  CInt[context_switch] = 1 :: CInt;
  
  RET_P(threadid);
}

forkOnzh_fast
{
  /* args: R1 = cpu, R2 = closure to spark */

  MAYBE_GC(R2_PTR, forkOnzh_fast);

  W_ cpu;
  W_ closure;
  W_ threadid;
  cpu = R1;
  closure = R2;

  ("ptr" threadid) = foreign "C" createIOThread( MyCapability() "ptr", 
				RtsFlags_GcFlags_initialStkSize(RtsFlags), 
				closure "ptr") [];
  foreign "C" scheduleThreadOn(MyCapability() "ptr", cpu, threadid "ptr") [];

  // switch at the earliest opportunity
  CInt[context_switch] = 1 :: CInt;
  
  RET_P(threadid);
}

yieldzh_fast
{
  jump stg_yield_noregs;
}

myThreadIdzh_fast
{
  /* no args. */
  RET_P(CurrentTSO);
}

labelThreadzh_fast
{
  /* args: 
	R1 = ThreadId#
	R2 = Addr# */
#ifdef DEBUG
  foreign "C" labelThread(R1 "ptr", R2 "ptr") [];
#endif
  jump %ENTRY_CODE(Sp(0));
}

isCurrentThreadBoundzh_fast
{
  /* no args */
  W_ r;
  (r) = foreign "C" isThreadBound(CurrentTSO) [];
  RET_N(r);
}


/* -----------------------------------------------------------------------------
 * TVar primitives
 * -------------------------------------------------------------------------- */

#ifdef REG_R1
#define SP_OFF 0
#define IF_NOT_REG_R1(x) 
#else
#define SP_OFF 1
#define IF_NOT_REG_R1(x) x
#endif

// Catch retry frame ------------------------------------------------------------

INFO_TABLE_RET(stg_catch_retry_frame, CATCH_RETRY_FRAME,
#if defined(PROFILING)
  W_ unused1, W_ unused2,
#endif
  W_ unused3, "ptr" W_ unused4, "ptr" W_ unused5)
{
   W_ r, frame, trec, outer;
   IF_NOT_REG_R1(W_ rval;  rval = Sp(0);  Sp_adj(1); )

   frame = Sp;
   trec = StgTSO_trec(CurrentTSO);
   ("ptr" outer) = foreign "C" stmGetEnclosingTRec(trec "ptr") [];
   (r) = foreign "C" stmCommitNestedTransaction(MyCapability() "ptr", trec "ptr") [];
   if (r != 0) {
     /* Succeeded (either first branch or second branch) */
     StgTSO_trec(CurrentTSO) = outer;
     Sp = Sp + SIZEOF_StgCatchRetryFrame;
     IF_NOT_REG_R1(Sp_adj(-1); Sp(0) = rval;)
     jump %ENTRY_CODE(Sp(SP_OFF));
   } else {
     /* Did not commit: re-execute */
     W_ new_trec;
     ("ptr" new_trec) = foreign "C" stmStartTransaction(MyCapability() "ptr", outer "ptr") [];
     StgTSO_trec(CurrentTSO) = new_trec;
     if (StgCatchRetryFrame_running_alt_code(frame) != 0::I32) {
       R1 = StgCatchRetryFrame_alt_code(frame);
     } else {
       R1 = StgCatchRetryFrame_first_code(frame);
     }
     jump stg_ap_v_fast;
   }
}


// Atomically frame ------------------------------------------------------------

INFO_TABLE_RET(stg_atomically_frame, ATOMICALLY_FRAME,
#if defined(PROFILING)
  W_ unused1, W_ unused2,
#endif
  "ptr" W_ unused3, "ptr" W_ unused4)
{
  W_ frame, trec, valid, next_invariant, q, outer;
  IF_NOT_REG_R1(W_ rval;  rval = Sp(0);  Sp_adj(1); )

  frame = Sp;
  trec = StgTSO_trec(CurrentTSO);
  ("ptr" outer) = foreign "C" stmGetEnclosingTRec(trec "ptr") [];

  if (outer == NO_TREC) {
    /* First time back at the atomically frame -- pick up invariants */
    ("ptr" q) = foreign "C" stmGetInvariantsToCheck(MyCapability() "ptr", trec "ptr") [];
    StgAtomicallyFrame_next_invariant_to_check(frame) = q;

  } else {
    /* Second/subsequent time back at the atomically frame -- abort the
     * tx that's checking the invariant and move on to the next one */
    StgTSO_trec(CurrentTSO) = outer;
    q = StgAtomicallyFrame_next_invariant_to_check(frame);
    StgInvariantCheckQueue_my_execution(q) = trec;
    foreign "C" stmAbortTransaction(MyCapability() "ptr", trec "ptr") [];
    /* Don't free trec -- it's linked from q and will be stashed in the
     * invariant if we eventually commit. */
    q = StgInvariantCheckQueue_next_queue_entry(q);
    StgAtomicallyFrame_next_invariant_to_check(frame) = q;
    trec = outer;
  }

  q = StgAtomicallyFrame_next_invariant_to_check(frame);

  if (q != END_INVARIANT_CHECK_QUEUE) {
    /* We can't commit yet: another invariant to check */
    ("ptr" trec) = foreign "C" stmStartTransaction(MyCapability() "ptr", trec "ptr") [];
    StgTSO_trec(CurrentTSO) = trec;

    next_invariant = StgInvariantCheckQueue_invariant(q);
    R1 = StgAtomicInvariant_code(next_invariant);
    jump stg_ap_v_fast;

  } else {

    /* We've got no more invariants to check, try to commit */
    (valid) = foreign "C" stmCommitTransaction(MyCapability() "ptr", trec "ptr") [];
    if (valid != 0) {
      /* Transaction was valid: commit succeeded */
      StgTSO_trec(CurrentTSO) = NO_TREC;
      Sp = Sp + SIZEOF_StgAtomicallyFrame;
      IF_NOT_REG_R1(Sp_adj(-1); Sp(0) = rval;)
      jump %ENTRY_CODE(Sp(SP_OFF));
    } else {
      /* Transaction was not valid: try again */
      ("ptr" trec) = foreign "C" stmStartTransaction(MyCapability() "ptr", NO_TREC "ptr") [];
      StgTSO_trec(CurrentTSO) = trec;
      StgAtomicallyFrame_next_invariant_to_check(frame) = END_INVARIANT_CHECK_QUEUE;
      R1 = StgAtomicallyFrame_code(frame);
      jump stg_ap_v_fast;
    }
  }
}

INFO_TABLE_RET(stg_atomically_waiting_frame, ATOMICALLY_FRAME,
#if defined(PROFILING)
  W_ unused1, W_ unused2,
#endif
  "ptr" W_ unused3, "ptr" W_ unused4)
{
  W_ frame, trec, valid;
  IF_NOT_REG_R1(W_ rval;  rval = Sp(0);  Sp_adj(1); )

  frame = Sp;

  /* The TSO is currently waiting: should we stop waiting? */
  (valid) = foreign "C" stmReWait(MyCapability() "ptr", CurrentTSO "ptr") [];
  if (valid != 0) {
    /* Previous attempt is still valid: no point trying again yet */
	  IF_NOT_REG_R1(Sp_adj(-2);
			Sp(1) = stg_NO_FINALIZER_closure;
		  	Sp(0) = stg_ut_1_0_unreg_info;)
    jump stg_block_noregs;
  } else {
    /* Previous attempt is no longer valid: try again */
    ("ptr" trec) = foreign "C" stmStartTransaction(MyCapability() "ptr", NO_TREC "ptr") [];
    StgTSO_trec(CurrentTSO) = trec;
    StgHeader_info(frame) = stg_atomically_frame_info;
    R1 = StgAtomicallyFrame_code(frame);
    jump stg_ap_v_fast;
  }
}

// STM catch frame --------------------------------------------------------------

#ifdef REG_R1
#define SP_OFF 0
#else
#define SP_OFF 1
#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_stm_frame, CATCH_STM_FRAME,
#if defined(PROFILING)
  W_ unused1, W_ unused2,
#endif
  "ptr" W_ unused3, "ptr" W_ unused4)
   {
      IF_NOT_REG_R1(W_ rval;  rval = Sp(0);  Sp_adj(1); )
      W_ r, frame, trec, outer;
      frame = Sp;
      trec = StgTSO_trec(CurrentTSO);
      ("ptr" outer) = foreign "C" stmGetEnclosingTRec(trec "ptr") [];
      (r) = foreign "C" stmCommitNestedTransaction(MyCapability() "ptr", trec "ptr") [];
      if (r != 0) {
        /* Commit succeeded */
        StgTSO_trec(CurrentTSO) = outer;
        Sp = Sp + SIZEOF_StgCatchSTMFrame;
        IF_NOT_REG_R1(Sp_adj(-1); Sp(0) = rval;)
        jump Sp(SP_OFF);
      } else {
        /* Commit failed */
        W_ new_trec;
        ("ptr" new_trec) = foreign "C" stmStartTransaction(MyCapability() "ptr", outer "ptr") [];
        StgTSO_trec(CurrentTSO) = new_trec;
        R1 = StgCatchSTMFrame_code(frame);
        jump stg_ap_v_fast;
      }
   }


// Primop definition ------------------------------------------------------------

atomicallyzh_fast
{
  W_ frame;
  W_ old_trec;
  W_ new_trec;
  
  // stmStartTransaction may allocate
  MAYBE_GC (R1_PTR, atomicallyzh_fast); 

  /* Args: R1 = m :: STM a */
  STK_CHK_GEN(SIZEOF_StgAtomicallyFrame + WDS(1), R1_PTR, atomicallyzh_fast);

  old_trec = StgTSO_trec(CurrentTSO);

  /* Nested transactions are not allowed; raise an exception */
  if (old_trec != NO_TREC) {
     R1 = base_GHCziIOBase_NestedAtomically_closure;
     jump raisezh_fast;
  }

  /* Set up the atomically frame */
  Sp = Sp - SIZEOF_StgAtomicallyFrame;
  frame = Sp;

  SET_HDR(frame,stg_atomically_frame_info, W_[CCCS]);
  StgAtomicallyFrame_code(frame) = R1;
  StgAtomicallyFrame_next_invariant_to_check(frame) = END_INVARIANT_CHECK_QUEUE;

  /* Start the memory transcation */
  ("ptr" new_trec) = foreign "C" stmStartTransaction(MyCapability() "ptr", old_trec "ptr") [R1];
  StgTSO_trec(CurrentTSO) = new_trec;

  /* Apply R1 to the realworld token */
  jump stg_ap_v_fast;
}


catchSTMzh_fast
{
  W_ frame;
  
  /* Args: R1 :: STM a */
  /* Args: R2 :: Exception -> STM a */
  STK_CHK_GEN(SIZEOF_StgCatchSTMFrame + WDS(1), R1_PTR & R2_PTR, catchSTMzh_fast);

  /* Set up the catch frame */
  Sp = Sp - SIZEOF_StgCatchSTMFrame;
  frame = Sp;

  SET_HDR(frame, stg_catch_stm_frame_info, W_[CCCS]);
  StgCatchSTMFrame_handler(frame) = R2;
  StgCatchSTMFrame_code(frame) = R1;

  /* Start a nested transaction to run the body of the try block in */
  W_ cur_trec;  
  W_ new_trec;
  cur_trec = StgTSO_trec(CurrentTSO);
  ("ptr" new_trec) = foreign "C" stmStartTransaction(MyCapability() "ptr", cur_trec "ptr");
  StgTSO_trec(CurrentTSO) = new_trec;

  /* Apply R1 to the realworld token */
  jump stg_ap_v_fast;
}


catchRetryzh_fast
{
  W_ frame;
  W_ new_trec;
  W_ trec;

  // stmStartTransaction may allocate
  MAYBE_GC (R1_PTR & R2_PTR, catchRetryzh_fast); 

  /* Args: R1 :: STM a */
  /* Args: R2 :: STM a */
  STK_CHK_GEN(SIZEOF_StgCatchRetryFrame + WDS(1), R1_PTR & R2_PTR, catchRetryzh_fast);

  /* Start a nested transaction within which to run the first code */
  trec = StgTSO_trec(CurrentTSO);
  ("ptr" new_trec) = foreign "C" stmStartTransaction(MyCapability() "ptr", trec "ptr") [R1,R2];
  StgTSO_trec(CurrentTSO) = new_trec;

  /* Set up the catch-retry frame */
  Sp = Sp - SIZEOF_StgCatchRetryFrame;
  frame = Sp;
  
  SET_HDR(frame, stg_catch_retry_frame_info, W_[CCCS]);
  StgCatchRetryFrame_running_alt_code(frame) = 0 :: CInt; // false;
  StgCatchRetryFrame_first_code(frame) = R1;
  StgCatchRetryFrame_alt_code(frame) = R2;

  /* Apply R1 to the realworld token */
  jump stg_ap_v_fast;
}


retryzh_fast
{
  W_ frame_type;
  W_ frame;
  W_ trec;
  W_ outer;
  W_ r;

  MAYBE_GC (NO_PTRS, retryzh_fast); // STM operations may allocate

  // Find the enclosing ATOMICALLY_FRAME or CATCH_RETRY_FRAME
retry_pop_stack:
  StgTSO_sp(CurrentTSO) = Sp;
  (frame_type) = foreign "C" findRetryFrameHelper(CurrentTSO "ptr") [];
  Sp = StgTSO_sp(CurrentTSO);
  frame = Sp;
  trec = StgTSO_trec(CurrentTSO);
  ("ptr" outer) = foreign "C" stmGetEnclosingTRec(trec "ptr") [];

  if (frame_type == CATCH_RETRY_FRAME) {
    // The retry reaches a CATCH_RETRY_FRAME before the atomic frame
    ASSERT(outer != NO_TREC);
    // Abort the transaction attempting the current branch
    foreign "C" stmAbortTransaction(MyCapability() "ptr", trec "ptr") [];
    foreign "C" stmFreeAbortedTRec(MyCapability() "ptr", trec "ptr") [];
    if (!StgCatchRetryFrame_running_alt_code(frame) != 0::I32) {
      // Retry in the first branch: try the alternative
      ("ptr" trec) = foreign "C" stmStartTransaction(MyCapability() "ptr", outer "ptr") [];
      StgTSO_trec(CurrentTSO) = trec;
      StgCatchRetryFrame_running_alt_code(frame) = 1 :: CInt; // true;
      R1 = StgCatchRetryFrame_alt_code(frame);
      jump stg_ap_v_fast;
    } else {
      // Retry in the alternative code: propagate the retry
      StgTSO_trec(CurrentTSO) = outer;
      Sp = Sp + SIZEOF_StgCatchRetryFrame;
      goto retry_pop_stack;
    }
  }

  // We've reached the ATOMICALLY_FRAME: attempt to wait 
  ASSERT(frame_type == ATOMICALLY_FRAME);
  if (outer != NO_TREC) {
    // We called retry while checking invariants, so abort the current
    // invariant check (merging its TVar accesses into the parents read
    // set so we'll wait on them)
    foreign "C" stmAbortTransaction(MyCapability() "ptr", trec "ptr") [];
    foreign "C" stmFreeAbortedTRec(MyCapability() "ptr", trec "ptr") [];
    trec = outer;
    StgTSO_trec(CurrentTSO) = trec;
    ("ptr" outer) = foreign "C" stmGetEnclosingTRec(trec "ptr") [];
  }
  ASSERT(outer == NO_TREC);

  (r) = foreign "C" stmWait(MyCapability() "ptr", CurrentTSO "ptr", trec "ptr") [];
  if (r != 0) {
    // Transaction was valid: stmWait put us on the TVars' queues, we now block
    StgHeader_info(frame) = stg_atomically_waiting_frame_info;
    Sp = frame;
    // Fix up the stack in the unregisterised case: the return convention is different.
    IF_NOT_REG_R1(Sp_adj(-2); 
		  Sp(1) = stg_NO_FINALIZER_closure;
		  Sp(0) = stg_ut_1_0_unreg_info;)
    R3 = trec; // passing to stmWaitUnblock()
    jump stg_block_stmwait;
  } else {
    // Transaction was not valid: retry immediately
    ("ptr" trec) = foreign "C" stmStartTransaction(MyCapability() "ptr", outer "ptr") [];
    StgTSO_trec(CurrentTSO) = trec;
    R1 = StgAtomicallyFrame_code(frame);
    Sp = frame;
    jump stg_ap_v_fast;
  }
}


checkzh_fast
{
  W_ trec, closure;

  /* Args: R1 = invariant closure */
  MAYBE_GC (R1_PTR, checkzh_fast); 

  trec = StgTSO_trec(CurrentTSO);
  closure = R1;
  foreign "C" stmAddInvariantToCheck(MyCapability() "ptr", 
                                     trec "ptr",
                                     closure "ptr") [];

  jump %ENTRY_CODE(Sp(0));
}


newTVarzh_fast
{
  W_ tv;
  W_ new_value;

  /* Args: R1 = initialisation value */

  MAYBE_GC (R1_PTR, newTVarzh_fast); 
  new_value = R1;
  ("ptr" tv) = foreign "C" stmNewTVar(MyCapability() "ptr", new_value "ptr") [];
  RET_P(tv);
}


readTVarzh_fast
{
  W_ trec;
  W_ tvar;
  W_ result;

  /* Args: R1 = TVar closure */

  MAYBE_GC (R1_PTR, readTVarzh_fast); // Call to stmReadTVar may allocate
  trec = StgTSO_trec(CurrentTSO);
  tvar = R1;
  ("ptr" result) = foreign "C" stmReadTVar(MyCapability() "ptr", trec "ptr", tvar "ptr") [];

  RET_P(result);
}


writeTVarzh_fast
{
  W_ trec;
  W_ tvar;
  W_ new_value;
  
  /* Args: R1 = TVar closure */
  /*       R2 = New value    */

  MAYBE_GC (R1_PTR & R2_PTR, writeTVarzh_fast); // Call to stmWriteTVar may allocate
  trec = StgTSO_trec(CurrentTSO);
  tvar = R1;
  new_value = R2;
  foreign "C" stmWriteTVar(MyCapability() "ptr", trec "ptr", tvar "ptr", new_value "ptr") [];

  jump %ENTRY_CODE(Sp(0));
}


/* -----------------------------------------------------------------------------
 * MVar primitives
 *
 * take & putMVar work as follows.  Firstly, an important invariant:
 *
 *    If the MVar is full, then the blocking queue contains only
 *    threads blocked on putMVar, and if the MVar is empty then the
 *    blocking queue contains only threads blocked on takeMVar.
 *
 * takeMvar:
 *    MVar empty : then add ourselves to the blocking queue
 *    MVar full  : remove the value from the MVar, and
 *                 blocking queue empty     : return
 *                 blocking queue non-empty : perform the first blocked putMVar
 *                                            from the queue, and wake up the
 *                                            thread (MVar is now full again)
 *
 * putMVar is just the dual of the above algorithm.
 *
 * How do we "perform a putMVar"?  Well, we have to fiddle around with
 * the stack of the thread waiting to do the putMVar.  See
 * stg_block_putmvar and stg_block_takemvar in HeapStackCheck.c for
 * the stack layout, and the PerformPut and PerformTake macros below.
 *
 * It is important that a blocked take or put is woken up with the
 * take/put already performed, because otherwise there would be a
 * small window of vulnerability where the thread could receive an
 * exception and never perform its take or put, and we'd end up with a
 * deadlock.
 *
 * -------------------------------------------------------------------------- */

isEmptyMVarzh_fast
{
    /* args: R1 = MVar closure */

    if (GET_INFO(R1) == stg_EMPTY_MVAR_info) {
	RET_N(1);
    } else {
	RET_N(0);
    }
}

newMVarzh_fast
{
    /* args: none */
    W_ mvar;

    ALLOC_PRIM ( SIZEOF_StgMVar, NO_PTRS, newMVarzh_fast );
  
    mvar = Hp - SIZEOF_StgMVar + WDS(1);
    SET_HDR(mvar,stg_EMPTY_MVAR_info,W_[CCCS]);
    StgMVar_head(mvar)  = stg_END_TSO_QUEUE_closure;
    StgMVar_tail(mvar)  = stg_END_TSO_QUEUE_closure;
    StgMVar_value(mvar) = stg_END_TSO_QUEUE_closure;
    RET_P(mvar);
}


/* If R1 isn't available, pass it on the stack */
#ifdef REG_R1
#define PerformTake(tso, value)				\
    W_[StgTSO_sp(tso) + WDS(1)] = value;		\
    W_[StgTSO_sp(tso) + WDS(0)] = stg_gc_unpt_r1_info;
#else
#define PerformTake(tso, value)					\
    W_[StgTSO_sp(tso) + WDS(1)] = value;			\
    W_[StgTSO_sp(tso) + WDS(0)] = stg_ut_1_0_unreg_info;
#endif

#define PerformPut(tso,lval)			\
    StgTSO_sp(tso) = StgTSO_sp(tso) + WDS(3);	\
    lval = W_[StgTSO_sp(tso) - WDS(1)];

takeMVarzh_fast
{
    W_ mvar, val, info, tso;

    /* args: R1 = MVar closure */
    mvar = R1;

#if defined(THREADED_RTS)
    ("ptr" info) = foreign "C" lockClosure(mvar "ptr") [];
#else
    info = GET_INFO(mvar);
#endif

    /* If the MVar is empty, put ourselves on its blocking queue,
     * and wait until we're woken up.
     */
    if (info == stg_EMPTY_MVAR_info) {
	if (StgMVar_head(mvar) == stg_END_TSO_QUEUE_closure) {
	    StgMVar_head(mvar) = CurrentTSO;
	} else {
	    StgTSO_link(StgMVar_tail(mvar)) = CurrentTSO;
	}
	StgTSO_link(CurrentTSO)        = stg_END_TSO_QUEUE_closure;
	StgTSO_why_blocked(CurrentTSO) = BlockedOnMVar::I16;
	StgTSO_block_info(CurrentTSO)  = mvar;
	StgMVar_tail(mvar) = CurrentTSO;
	
	jump stg_block_takemvar;
  }

  /* we got the value... */
  val = StgMVar_value(mvar);

  if (StgMVar_head(mvar) != stg_END_TSO_QUEUE_closure)
  {
      /* There are putMVar(s) waiting... 
       * wake up the first thread on the queue
       */
      ASSERT(StgTSO_why_blocked(StgMVar_head(mvar)) == BlockedOnMVar::I16);

      /* actually perform the putMVar for the thread that we just woke up */
      tso = StgMVar_head(mvar);
      PerformPut(tso,StgMVar_value(mvar));
      dirtyTSO(tso);

#if defined(GRAN) || defined(PAR)
      /* ToDo: check 2nd arg (mvar) is right */
      ("ptr" tso) = foreign "C" unblockOne(StgMVar_head(mvar),mvar) [];
      StgMVar_head(mvar) = tso;
#else
      ("ptr" tso) = foreign "C" unblockOne(MyCapability() "ptr", 
				         StgMVar_head(mvar) "ptr") [];
      StgMVar_head(mvar) = tso;
#endif

      if (StgMVar_head(mvar) == stg_END_TSO_QUEUE_closure) {
	  StgMVar_tail(mvar) = stg_END_TSO_QUEUE_closure;
      }

#if defined(THREADED_RTS)
      unlockClosure(mvar, stg_FULL_MVAR_info);
#endif
      RET_P(val);
  } 
  else
  {
      /* No further putMVars, MVar is now empty */
      StgMVar_value(mvar) = stg_END_TSO_QUEUE_closure;
 
#if defined(THREADED_RTS)
      unlockClosure(mvar, stg_EMPTY_MVAR_info);
#else
      SET_INFO(mvar,stg_EMPTY_MVAR_info);
#endif

      RET_P(val);
  }
}


tryTakeMVarzh_fast
{
    W_ mvar, val, info, tso;

    /* args: R1 = MVar closure */

    mvar = R1;

#if defined(THREADED_RTS)
    ("ptr" info) = foreign "C" lockClosure(mvar "ptr") [];
#else
    info = GET_INFO(mvar);
#endif

    if (info == stg_EMPTY_MVAR_info) {
#if defined(THREADED_RTS)
        unlockClosure(mvar, stg_EMPTY_MVAR_info);
#endif
	/* HACK: we need a pointer to pass back, 
	 * so we abuse NO_FINALIZER_closure
	 */
	RET_NP(0, stg_NO_FINALIZER_closure);
    }

    /* we got the value... */
    val = StgMVar_value(mvar);

    if (StgMVar_head(mvar) != stg_END_TSO_QUEUE_closure) {

	/* There are putMVar(s) waiting... 
	 * wake up the first thread on the queue
	 */
	ASSERT(StgTSO_why_blocked(StgMVar_head(mvar)) == BlockedOnMVar::I16);

	/* actually perform the putMVar for the thread that we just woke up */
	tso = StgMVar_head(mvar);
	PerformPut(tso,StgMVar_value(mvar));
        dirtyTSO(tso);

#if defined(GRAN) || defined(PAR)
	/* ToDo: check 2nd arg (mvar) is right */
	("ptr" tso) = foreign "C" unblockOne(StgMVar_head(mvar) "ptr", mvar "ptr") [];
	StgMVar_head(mvar) = tso;
#else
	("ptr" tso) = foreign "C" unblockOne(MyCapability() "ptr",
					   StgMVar_head(mvar) "ptr") [];
	StgMVar_head(mvar) = tso;
#endif

	if (StgMVar_head(mvar) == stg_END_TSO_QUEUE_closure) {
	    StgMVar_tail(mvar) = stg_END_TSO_QUEUE_closure;
	}
#if defined(THREADED_RTS)
        unlockClosure(mvar, stg_FULL_MVAR_info);
#endif
    }
    else 
    {
	/* No further putMVars, MVar is now empty */
	StgMVar_value(mvar) = stg_END_TSO_QUEUE_closure;
#if defined(THREADED_RTS)
    	unlockClosure(mvar, stg_EMPTY_MVAR_info);
#else
	SET_INFO(mvar,stg_EMPTY_MVAR_info);
#endif
    }
    
    RET_NP(1, val);
}


putMVarzh_fast
{
    W_ mvar, info, tso;

    /* args: R1 = MVar, R2 = value */
    mvar = R1;

#if defined(THREADED_RTS)
    ("ptr" info) = foreign "C" lockClosure(mvar "ptr") [R2];
#else
    info = GET_INFO(mvar);
#endif

    if (info == stg_FULL_MVAR_info) {
	if (StgMVar_head(mvar) == stg_END_TSO_QUEUE_closure) {
	    StgMVar_head(mvar) = CurrentTSO;
	} else {
	    StgTSO_link(StgMVar_tail(mvar)) = CurrentTSO;
	}
	StgTSO_link(CurrentTSO)        = stg_END_TSO_QUEUE_closure;
	StgTSO_why_blocked(CurrentTSO) = BlockedOnMVar::I16;
	StgTSO_block_info(CurrentTSO)  = mvar;
	StgMVar_tail(mvar) = CurrentTSO;
	
	jump stg_block_putmvar;
    }
  
    if (StgMVar_head(mvar) != stg_END_TSO_QUEUE_closure) {

	/* There are takeMVar(s) waiting: wake up the first one
	 */
	ASSERT(StgTSO_why_blocked(StgMVar_head(mvar)) == BlockedOnMVar::I16);

	/* actually perform the takeMVar */
	tso = StgMVar_head(mvar);
	PerformTake(tso, R2);
        dirtyTSO(tso);
      
#if defined(GRAN) || defined(PAR)
	/* ToDo: check 2nd arg (mvar) is right */
	("ptr" tso) = foreign "C" unblockOne(MyCapability() "ptr", StgMVar_head(mvar) "ptr",mvar "ptr") [];
	StgMVar_head(mvar) = tso;
#else
	("ptr" tso) = foreign "C" unblockOne(MyCapability() "ptr", StgMVar_head(mvar) "ptr") [];
	StgMVar_head(mvar) = tso;
#endif

	if (StgMVar_head(mvar) == stg_END_TSO_QUEUE_closure) {
	    StgMVar_tail(mvar) = stg_END_TSO_QUEUE_closure;
	}

#if defined(THREADED_RTS)
    	unlockClosure(mvar, stg_EMPTY_MVAR_info);
#endif
	jump %ENTRY_CODE(Sp(0));
    }
    else
    {
	/* No further takes, the MVar is now full. */
	StgMVar_value(mvar) = R2;

#if defined(THREADED_RTS)
    	unlockClosure(mvar, stg_FULL_MVAR_info);
#else
	SET_INFO(mvar,stg_FULL_MVAR_info);
#endif
	jump %ENTRY_CODE(Sp(0));
    }
    
    /* ToDo: yield afterward for better communication performance? */
}


tryPutMVarzh_fast
{
    W_ mvar, info, tso;

    /* args: R1 = MVar, R2 = value */
    mvar = R1;

#if defined(THREADED_RTS)
    ("ptr" info) = foreign "C" lockClosure(mvar "ptr") [R2];
#else
    info = GET_INFO(mvar);
#endif

    if (info == stg_FULL_MVAR_info) {
#if defined(THREADED_RTS)
    	unlockClosure(mvar, stg_FULL_MVAR_info);
#endif
	RET_N(0);
    }
  
    if (StgMVar_head(mvar) != stg_END_TSO_QUEUE_closure) {

	/* There are takeMVar(s) waiting: wake up the first one
	 */
	ASSERT(StgTSO_why_blocked(StgMVar_head(mvar)) == BlockedOnMVar::I16);
	
	/* actually perform the takeMVar */
	tso = StgMVar_head(mvar);
	PerformTake(tso, R2);
        dirtyTSO(tso);
      
#if defined(GRAN) || defined(PAR)
	/* ToDo: check 2nd arg (mvar) is right */
	("ptr" tso) = foreign "C" unblockOne(MyCapability() "ptr", StgMVar_head(mvar) "ptr",mvar "ptr") [];
	StgMVar_head(mvar) = tso;
#else
	("ptr" tso) = foreign "C" unblockOne(MyCapability() "ptr", StgMVar_head(mvar) "ptr") [];
	StgMVar_head(mvar) = tso;
#endif

	if (StgMVar_head(mvar) == stg_END_TSO_QUEUE_closure) {
	    StgMVar_tail(mvar) = stg_END_TSO_QUEUE_closure;
	}

#if defined(THREADED_RTS)
    	unlockClosure(mvar, stg_EMPTY_MVAR_info);
#endif
    }
    else
    {
	/* No further takes, the MVar is now full. */
	StgMVar_value(mvar) = R2;

#if defined(THREADED_RTS)
    	unlockClosure(mvar, stg_FULL_MVAR_info);
#else
	SET_INFO(mvar,stg_FULL_MVAR_info);
#endif
    }
    
    RET_N(1);
    /* ToDo: yield afterward for better communication performance? */
}


/* -----------------------------------------------------------------------------
   Stable pointer primitives
   -------------------------------------------------------------------------  */

makeStableNamezh_fast
{
    W_ index, sn_obj;

    ALLOC_PRIM( SIZEOF_StgStableName, R1_PTR, makeStableNamezh_fast );
  
    (index) = foreign "C" lookupStableName(R1 "ptr") [];

    /* Is there already a StableName for this heap object?
     *  stable_ptr_table is a pointer to an array of snEntry structs.
     */
    if ( snEntry_sn_obj(W_[stable_ptr_table] + index*SIZEOF_snEntry) == NULL ) {
	sn_obj = Hp - SIZEOF_StgStableName + WDS(1);
	SET_HDR(sn_obj, stg_STABLE_NAME_info, W_[CCCS]);
	StgStableName_sn(sn_obj) = index;
	snEntry_sn_obj(W_[stable_ptr_table] + index*SIZEOF_snEntry) = sn_obj;
    } else {
	sn_obj = snEntry_sn_obj(W_[stable_ptr_table] + index*SIZEOF_snEntry);
    }
    
    RET_P(sn_obj);
}


makeStablePtrzh_fast
{
    /* Args: R1 = a */
    W_ sp;
    MAYBE_GC(R1_PTR, makeStablePtrzh_fast);
    ("ptr" sp) = foreign "C" getStablePtr(R1 "ptr") [];
    RET_N(sp);
}

deRefStablePtrzh_fast
{
    /* Args: R1 = the stable ptr */
    W_ r, sp;
    sp = R1;
    r = snEntry_addr(W_[stable_ptr_table] + sp*SIZEOF_snEntry);
    RET_P(r);
}

/* -----------------------------------------------------------------------------
   Bytecode object primitives
   -------------------------------------------------------------------------  */

newBCOzh_fast
{
    /* R1 = instrs
       R2 = literals
       R3 = ptrs
       R4 = arity
       R5 = bitmap array
    */
    W_ bco, bitmap_arr, bytes, words;
    
    bitmap_arr = R5;

    words = BYTES_TO_WDS(SIZEOF_StgBCO) + StgArrWords_words(bitmap_arr);
    bytes = WDS(words);

    ALLOC_PRIM( bytes, R1_PTR&R2_PTR&R3_PTR&R5_PTR, newBCOzh_fast );

    bco = Hp - bytes + WDS(1);
    SET_HDR(bco, stg_BCO_info, W_[CCCS]);
    
    StgBCO_instrs(bco)     = R1;
    StgBCO_literals(bco)   = R2;
    StgBCO_ptrs(bco)       = R3;
    StgBCO_arity(bco)      = HALF_W_(R4);
    StgBCO_size(bco)       = HALF_W_(words);
    
    // Copy the arity/bitmap info into the BCO
    W_ i;
    i = 0;
for:
    if (i < StgArrWords_words(bitmap_arr)) {
	StgBCO_bitmap(bco,i) = StgArrWords_payload(bitmap_arr,i);
	i = i + 1;
	goto for;
    }
    
    RET_P(bco);
}


mkApUpd0zh_fast
{
    // R1 = the BCO# for the AP
    //	
    W_ ap;

    // This function is *only* used to wrap zero-arity BCOs in an
    // updatable wrapper (see ByteCodeLink.lhs).  An AP thunk is always
    // saturated and always points directly to a FUN or BCO.
    ASSERT(%INFO_TYPE(%GET_STD_INFO(R1)) == HALF_W_(BCO) &&
	   StgBCO_arity(R1) == HALF_W_(0));

    HP_CHK_GEN_TICKY(SIZEOF_StgAP, R1_PTR, mkApUpd0zh_fast);
    TICK_ALLOC_UP_THK(0, 0);
    CCCS_ALLOC(SIZEOF_StgAP);

    ap = Hp - SIZEOF_StgAP + WDS(1);
    SET_HDR(ap, stg_AP_info, W_[CCCS]);
    
    StgAP_n_args(ap) = HALF_W_(0);
    StgAP_fun(ap) = R1;
    
    RET_P(ap);
}

unpackClosurezh_fast
{
/* args: R1 = closure to analyze */
// TODO: Consider the absence of ptrs or nonptrs as a special case ?

    W_ info, ptrs, nptrs, p, ptrs_arr, nptrs_arr;
    info  = %GET_STD_INFO(UNTAG(R1));

    // Some closures have non-standard layout, so we omit those here.
    W_ type;
    type = TO_W_(%INFO_TYPE(info));
    switch [0 .. N_CLOSURE_TYPES] type {
    case THUNK_SELECTOR : {
        ptrs = 1;
        nptrs = 0;
        goto out;
    }
    case THUNK, THUNK_1_0, THUNK_0_1, THUNK_2_0, THUNK_1_1, 
         THUNK_0_2, THUNK_STATIC, AP, PAP, AP_STACK, BCO : {
        ptrs = 0;
        nptrs = 0;
        goto out;
    }
    default: {
        ptrs  = TO_W_(%INFO_PTRS(info)); 
        nptrs = TO_W_(%INFO_NPTRS(info));
        goto out;
    }}
out:

    W_ ptrs_arr_sz, nptrs_arr_sz;
    nptrs_arr_sz = SIZEOF_StgArrWords   + WDS(nptrs);
    ptrs_arr_sz  = SIZEOF_StgMutArrPtrs + WDS(ptrs);

    ALLOC_PRIM (ptrs_arr_sz + nptrs_arr_sz, R1_PTR, unpackClosurezh_fast);

    W_ clos;
    clos = UNTAG(R1);

    ptrs_arr  = Hp - nptrs_arr_sz - ptrs_arr_sz + WDS(1);
    nptrs_arr = Hp - nptrs_arr_sz + WDS(1);

    SET_HDR(ptrs_arr, stg_MUT_ARR_PTRS_FROZEN_info, W_[CCCS]);
    StgMutArrPtrs_ptrs(ptrs_arr) = ptrs;
    p = 0;
for:
    if(p < ptrs) {
    	 W_[ptrs_arr + SIZEOF_StgMutArrPtrs + WDS(p)] = StgClosure_payload(clos,p);
	 p = p + 1;
	 goto for;
    }
    
    SET_HDR(nptrs_arr, stg_ARR_WORDS_info, W_[CCCS]);
    StgArrWords_words(nptrs_arr) = nptrs;
    p = 0;
for2:
    if(p < nptrs) {
    	 W_[BYTE_ARR_CTS(nptrs_arr) + WDS(p)] = StgClosure_payload(clos, p+ptrs);
    	 p = p + 1;
	 goto for2;
    }
    RET_NPP(info, ptrs_arr, nptrs_arr);
}

/* -----------------------------------------------------------------------------
   Thread I/O blocking primitives
   -------------------------------------------------------------------------- */

/* Add a thread to the end of the blocked queue. (C-- version of the C
 * macro in Schedule.h).
 */
#define APPEND_TO_BLOCKED_QUEUE(tso)			\
    ASSERT(StgTSO_link(tso) == END_TSO_QUEUE);		\
    if (W_[blocked_queue_hd] == END_TSO_QUEUE) {	\
      W_[blocked_queue_hd] = tso;			\
    } else {						\
      StgTSO_link(W_[blocked_queue_tl]) = tso;		\
    }							\
    W_[blocked_queue_tl] = tso;

waitReadzh_fast
{
    /* args: R1 */
#ifdef THREADED_RTS
    foreign "C" barf("waitRead# on threaded RTS") never returns;
#else

    ASSERT(StgTSO_why_blocked(CurrentTSO) == NotBlocked::I16);
    StgTSO_why_blocked(CurrentTSO) = BlockedOnRead::I16;
    StgTSO_block_info(CurrentTSO) = R1;
    // No locking - we're not going to use this interface in the
    // threaded RTS anyway.
    APPEND_TO_BLOCKED_QUEUE(CurrentTSO);
    jump stg_block_noregs;
#endif
}

waitWritezh_fast
{
    /* args: R1 */
#ifdef THREADED_RTS
    foreign "C" barf("waitWrite# on threaded RTS") never returns;
#else

    ASSERT(StgTSO_why_blocked(CurrentTSO) == NotBlocked::I16);
    StgTSO_why_blocked(CurrentTSO) = BlockedOnWrite::I16;
    StgTSO_block_info(CurrentTSO) = R1;
    // No locking - we're not going to use this interface in the
    // threaded RTS anyway.
    APPEND_TO_BLOCKED_QUEUE(CurrentTSO);
    jump stg_block_noregs;
#endif
}


STRING(stg_delayzh_malloc_str, "delayzh_fast")
delayzh_fast
{
#ifdef mingw32_HOST_OS
    W_ ares;
    CInt reqID;
#else
    W_ t, prev, target;
#endif

#ifdef THREADED_RTS
    foreign "C" barf("delay# on threaded RTS") never returns;
#else

    /* args: R1 (microsecond delay amount) */
    ASSERT(StgTSO_why_blocked(CurrentTSO) == NotBlocked::I16);
    StgTSO_why_blocked(CurrentTSO) = BlockedOnDelay::I16;

#ifdef mingw32_HOST_OS

    /* could probably allocate this on the heap instead */
    ("ptr" ares) = foreign "C" stgMallocBytes(SIZEOF_StgAsyncIOResult,
					    stg_delayzh_malloc_str);
    (reqID) = foreign "C" addDelayRequest(R1);
    StgAsyncIOResult_reqID(ares)   = reqID;
    StgAsyncIOResult_len(ares)     = 0;
    StgAsyncIOResult_errCode(ares) = 0;
    StgTSO_block_info(CurrentTSO)  = ares;

    /* Having all async-blocked threads reside on the blocked_queue
     * simplifies matters, so change the status to OnDoProc put the
     * delayed thread on the blocked_queue.
     */
    StgTSO_why_blocked(CurrentTSO) = BlockedOnDoProc::I16;
    APPEND_TO_BLOCKED_QUEUE(CurrentTSO);
    jump stg_block_async_void;

#else

    W_ time;
    W_ divisor;
    (time) = foreign "C" getourtimeofday() [R1];
    divisor = TO_W_(RtsFlags_MiscFlags_tickInterval(RtsFlags))*1000;
    target = ((R1 + divisor - 1) / divisor) /* divide rounding up */
           + time + 1; /* Add 1 as getourtimeofday rounds down */
    StgTSO_block_info(CurrentTSO) = target;

    /* Insert the new thread in the sleeping queue. */
    prev = NULL;
    t = W_[sleeping_queue];
while:
    if (t != END_TSO_QUEUE && StgTSO_block_info(t) < target) {
	prev = t;
	t = StgTSO_link(t);
	goto while;
    }

    StgTSO_link(CurrentTSO) = t;
    if (prev == NULL) {
	W_[sleeping_queue] = CurrentTSO;
    } else {
	StgTSO_link(prev) = CurrentTSO;
    }
    jump stg_block_noregs;
#endif
#endif /* !THREADED_RTS */
}


#ifdef mingw32_HOST_OS
STRING(stg_asyncReadzh_malloc_str, "asyncReadzh_fast")
asyncReadzh_fast
{
    W_ ares;
    CInt reqID;

#ifdef THREADED_RTS
    foreign "C" barf("asyncRead# on threaded RTS") never returns;
#else

    /* args: R1 = fd, R2 = isSock, R3 = len, R4 = buf */
    ASSERT(StgTSO_why_blocked(CurrentTSO) == NotBlocked::I16);
    StgTSO_why_blocked(CurrentTSO) = BlockedOnRead::I16;

    /* could probably allocate this on the heap instead */
    ("ptr" ares) = foreign "C" stgMallocBytes(SIZEOF_StgAsyncIOResult,
					    stg_asyncReadzh_malloc_str)
			[R1,R2,R3,R4];
    (reqID) = foreign "C" addIORequest(R1, 0/*FALSE*/,R2,R3,R4 "ptr") [];
    StgAsyncIOResult_reqID(ares)   = reqID;
    StgAsyncIOResult_len(ares)     = 0;
    StgAsyncIOResult_errCode(ares) = 0;
    StgTSO_block_info(CurrentTSO)  = ares;
    APPEND_TO_BLOCKED_QUEUE(CurrentTSO);
    jump stg_block_async;
#endif
}

STRING(stg_asyncWritezh_malloc_str, "asyncWritezh_fast")
asyncWritezh_fast
{
    W_ ares;
    CInt reqID;

#ifdef THREADED_RTS
    foreign "C" barf("asyncWrite# on threaded RTS") never returns;
#else

    /* args: R1 = fd, R2 = isSock, R3 = len, R4 = buf */
    ASSERT(StgTSO_why_blocked(CurrentTSO) == NotBlocked::I16);
    StgTSO_why_blocked(CurrentTSO) = BlockedOnWrite::I16;

    ("ptr" ares) = foreign "C" stgMallocBytes(SIZEOF_StgAsyncIOResult,
					    stg_asyncWritezh_malloc_str)
			[R1,R2,R3,R4];
    (reqID) = foreign "C" addIORequest(R1, 1/*TRUE*/,R2,R3,R4 "ptr") [];

    StgAsyncIOResult_reqID(ares)   = reqID;
    StgAsyncIOResult_len(ares)     = 0;
    StgAsyncIOResult_errCode(ares) = 0;
    StgTSO_block_info(CurrentTSO)  = ares;
    APPEND_TO_BLOCKED_QUEUE(CurrentTSO);
    jump stg_block_async;
#endif
}

STRING(stg_asyncDoProczh_malloc_str, "asyncDoProczh_fast")
asyncDoProczh_fast
{
    W_ ares;
    CInt reqID;

#ifdef THREADED_RTS
    foreign "C" barf("asyncDoProc# on threaded RTS") never returns;
#else

    /* args: R1 = proc, R2 = param */
    ASSERT(StgTSO_why_blocked(CurrentTSO) == NotBlocked::I16);
    StgTSO_why_blocked(CurrentTSO) = BlockedOnDoProc::I16;

    /* could probably allocate this on the heap instead */
    ("ptr" ares) = foreign "C" stgMallocBytes(SIZEOF_StgAsyncIOResult,
					    stg_asyncDoProczh_malloc_str) 
				[R1,R2];
    (reqID) = foreign "C" addDoProcRequest(R1 "ptr",R2 "ptr") [];
    StgAsyncIOResult_reqID(ares)   = reqID;
    StgAsyncIOResult_len(ares)     = 0;
    StgAsyncIOResult_errCode(ares) = 0;
    StgTSO_block_info(CurrentTSO) = ares;
    APPEND_TO_BLOCKED_QUEUE(CurrentTSO);
    jump stg_block_async;
#endif
}
#endif

// noDuplicate# tries to ensure that none of the thunks under
// evaluation by the current thread are also under evaluation by
// another thread.  It relies on *both* threads doing noDuplicate#;
// the second one will get blocked if they are duplicating some work.
noDuplicatezh_fast
{
    SAVE_THREAD_STATE();
    ASSERT(StgTSO_what_next(CurrentTSO) == ThreadRunGHC::I16);
    foreign "C" threadPaused (MyCapability() "ptr", CurrentTSO "ptr") [];
    
    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));
    }
}

getApStackValzh_fast
{
   W_ ap_stack, offset, val, ok;

   /* args: R1 = AP_STACK, R2 = offset */
   ap_stack = R1;
   offset   = R2;

   if (%INFO_PTR(ap_stack) == stg_AP_STACK_info) {
        ok = 1;
        val = StgAP_STACK_payload(ap_stack,offset); 
   } else {
        ok = 0;
        val = R1;
   }
   RET_NP(ok,val);
}