PrimOps.cmm 52.3 KB
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/* -----------------------------------------------------------------------------
 *
 * (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"

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#ifdef __PIC__
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import pthread_mutex_lock;
import pthread_mutex_unlock;
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#endif
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import base_ControlziExceptionziBase_nestedAtomically_closure;
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import EnterCriticalSection;
import LeaveCriticalSection;
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import ghczmprim_GHCziBool_False_closure;
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/*-----------------------------------------------------------------------------
  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.
 */

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stg_newByteArrayzh
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{
    W_ words, payload_words, n, p;
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    MAYBE_GC(NO_PTRS,stg_newByteArrayzh);
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    n = R1;
    payload_words = ROUNDUP_BYTES_TO_WDS(n);
    words = BYTES_TO_WDS(SIZEOF_StgArrWords) + payload_words;
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    ("ptr" p) = foreign "C" allocate(MyCapability() "ptr",words) [];
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    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);
}

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#define BA_ALIGN 16
#define BA_MASK  (BA_ALIGN-1)

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stg_newPinnedByteArrayzh
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{
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    W_ words, bytes, payload_words, p;
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    MAYBE_GC(NO_PTRS,stg_newPinnedByteArrayzh);
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    bytes = R1;
    /* payload_words is what we will tell the profiler we had to allocate */
    payload_words = ROUNDUP_BYTES_TO_WDS(bytes);
    /* When we actually allocate memory, we need to allow space for the
       header: */
    bytes = bytes + SIZEOF_StgArrWords;
    /* And we want to align to BA_ALIGN bytes, so we need to allow space
       to shift up to BA_ALIGN - 1 bytes: */
    bytes = bytes + BA_ALIGN - 1;
    /* Now we convert to a number of words: */
    words = ROUNDUP_BYTES_TO_WDS(bytes);
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    ("ptr" p) = foreign "C" allocatePinned(MyCapability() "ptr", words) [];
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    TICK_ALLOC_PRIM(SIZEOF_StgArrWords,WDS(payload_words),0);

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    /* Now we need to move p forward so that the payload is aligned
       to BA_ALIGN bytes: */
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    p = p + ((-p - SIZEOF_StgArrWords) & BA_MASK);

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

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stg_newAlignedPinnedByteArrayzh
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{
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    W_ words, bytes, payload_words, p, alignment;
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    MAYBE_GC(NO_PTRS,stg_newAlignedPinnedByteArrayzh);
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    bytes = R1;
    alignment = R2;
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    /* payload_words is what we will tell the profiler we had to allocate */
    payload_words = ROUNDUP_BYTES_TO_WDS(bytes);
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    /* When we actually allocate memory, we need to allow space for the
       header: */
    bytes = bytes + SIZEOF_StgArrWords;
    /* And we want to align to <alignment> bytes, so we need to allow space
       to shift up to <alignment - 1> bytes: */
    bytes = bytes + alignment - 1;
    /* Now we convert to a number of words: */
    words = ROUNDUP_BYTES_TO_WDS(bytes);
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    ("ptr" p) = foreign "C" allocatePinned(MyCapability() "ptr", words) [];
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    TICK_ALLOC_PRIM(SIZEOF_StgArrWords,WDS(payload_words),0);

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    /* Now we need to move p forward so that the payload is aligned
       to <alignment> bytes. Note that we are assuming that
       <alignment> is a power of 2, which is technically not guaranteed */
    p = p + ((-p - SIZEOF_StgArrWords) & (alignment - 1));
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    SET_HDR(p, stg_ARR_WORDS_info, W_[CCCS]);
    StgArrWords_words(p) = payload_words;
    RET_P(p);
}

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

    n = R1;
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    MAYBE_GC(R2_PTR,stg_newArrayzh);
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    words = BYTES_TO_WDS(SIZEOF_StgMutArrPtrs) + n;
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    ("ptr" arr) = foreign "C" allocate(MyCapability() "ptr",words) [R2];
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    TICK_ALLOC_PRIM(SIZEOF_StgMutArrPtrs, WDS(n), 0);

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    SET_HDR(arr, stg_MUT_ARR_PTRS_DIRTY_info, W_[CCCS]);
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    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);
}

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stg_unsafeThawArrayzh
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{
  // 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).
  // 
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  // So that we can tell whether a MUT_ARR_PTRS_FROZEN is on the mutable list,
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  // 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.
  //
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  // 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
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  // the closure type is MUT_ARR_PTRS_FROZEN0 if it is on the mutable list,
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  // 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.
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  //
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  if (StgHeader_info(R1) != stg_MUT_ARR_PTRS_FROZEN0_info) {
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	SET_INFO(R1,stg_MUT_ARR_PTRS_DIRTY_info);
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	recordMutable(R1, R1);
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	// must be done after SET_INFO, because it ASSERTs closure_MUTABLE()
	RET_P(R1);
  } else {
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	SET_INFO(R1,stg_MUT_ARR_PTRS_DIRTY_info);
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	RET_P(R1);
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  }
}

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

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

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    ALLOC_PRIM( SIZEOF_StgMutVar, R1_PTR, stg_newMutVarzh);
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    mv = Hp - SIZEOF_StgMutVar + WDS(1);
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    SET_HDR(mv,stg_MUT_VAR_DIRTY_info,W_[CCCS]);
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    StgMutVar_var(mv) = R1;
    
    RET_P(mv);
}

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stg_atomicModifyMutVarzh
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{
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    W_ mv, f, z, x, y, r, h;
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    /* 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
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#define THUNK_1_SIZE (SIZEOF_StgThunkHeader + WDS(MIN_UPD_SIZE))
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#define TICK_ALLOC_THUNK_1() TICK_ALLOC_UP_THK(WDS(1),WDS(MIN_UPD_SIZE-1))
#else
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#define THUNK_1_SIZE (SIZEOF_StgThunkHeader + WDS(1))
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#define TICK_ALLOC_THUNK_1() TICK_ALLOC_UP_THK(WDS(1),0)
#endif

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

#define SIZE (THUNK_2_SIZE + THUNK_1_SIZE + THUNK_1_SIZE)

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   HP_CHK_GEN_TICKY(SIZE, R1_PTR & R2_PTR, stg_atomicModifyMutVarzh);
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   mv = R1;
   f = R2;
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   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);
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   StgThunk_payload(z,0) = f;
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   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);
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   StgThunk_payload(y,0) = z;
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   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);
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   StgThunk_payload(r,0) = z;

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 retry:
   x = StgMutVar_var(mv);
   StgThunk_payload(z,1) = x;
#ifdef THREADED_RTS
   (h) = foreign "C" cas(mv + SIZEOF_StgHeader + OFFSET_StgMutVar_var, x, y) [];
   if (h != x) { goto retry; }
#else
   StgMutVar_var(mv) = y;
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#endif
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   if (GET_INFO(mv) == stg_MUT_VAR_CLEAN_info) {
     foreign "C" dirty_MUT_VAR(BaseReg "ptr", mv "ptr") [];
   }

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   RET_P(r);
}

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

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

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

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

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  ALLOC_PRIM( SIZEOF_StgWeak, R1_PTR & R2_PTR & R3_PTR, stg_mkWeakzh );
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  w = Hp - SIZEOF_StgWeak + WDS(1);
  SET_HDR(w, stg_WEAK_info, W_[CCCS]);

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  // We don't care about cfinalizer here.
  // Should StgWeak_cfinalizer(w) be stg_NO_FINALIZER_closure or
  // something else?

  StgWeak_key(w)        = R1;
  StgWeak_value(w)      = R2;
  StgWeak_finalizer(w)  = R3;
  StgWeak_cfinalizer(w) = stg_NO_FINALIZER_closure;
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  StgWeak_link(w)	= W_[weak_ptr_list];
  W_[weak_ptr_list] 	= w;

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

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stg_mkWeakForeignEnvzh
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{
  /* R1 = key
     R2 = value
     R3 = finalizer
     R4 = pointer
     R5 = has environment (0 or 1)
     R6 = environment
  */
  W_ w, payload_words, words, p;

  W_ key, val, fptr, ptr, flag, eptr;

  key  = R1;
  val  = R2;
  fptr = R3;
  ptr  = R4;
  flag = R5;
  eptr = R6;

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  ALLOC_PRIM( SIZEOF_StgWeak, R1_PTR & R2_PTR, stg_mkWeakForeignEnvzh );
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  w = Hp - SIZEOF_StgWeak + WDS(1);
  SET_HDR(w, stg_WEAK_info, W_[CCCS]);

  payload_words = 4;
  words         = BYTES_TO_WDS(SIZEOF_StgArrWords) + payload_words;
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  ("ptr" p)     = foreign "C" allocate(MyCapability() "ptr", words) [];
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  TICK_ALLOC_PRIM(SIZEOF_StgArrWords,WDS(payload_words),0);
  SET_HDR(p, stg_ARR_WORDS_info, W_[CCCS]);

  StgArrWords_words(p)     = payload_words;
  StgArrWords_payload(p,0) = fptr;
  StgArrWords_payload(p,1) = ptr;
  StgArrWords_payload(p,2) = eptr;
  StgArrWords_payload(p,3) = flag;

  // We don't care about the value here.
  // Should StgWeak_value(w) be stg_NO_FINALIZER_closure or something else?

  StgWeak_key(w)        = key;
  StgWeak_value(w)      = val;
  StgWeak_finalizer(w)  = stg_NO_FINALIZER_closure;
  StgWeak_cfinalizer(w) = p;

  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);
}
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stg_finalizzeWeakzh
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{
  /* R1 = weak ptr
   */
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  W_ w, f, arr;
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  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);

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  f   = StgWeak_finalizer(w);
  arr = StgWeak_cfinalizer(w);

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  StgDeadWeak_link(w) = StgWeak_link(w);
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  if (arr != stg_NO_FINALIZER_closure) {
    foreign "C" runCFinalizer(StgArrWords_payload(arr,0),
                              StgArrWords_payload(arr,1),
                              StgArrWords_payload(arr,2),
                              StgArrWords_payload(arr,3)) [];
  }

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

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stg_deRefWeakzh
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{
  /* 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);
}

/* -----------------------------------------------------------------------------
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   Floating point operations.
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   -------------------------------------------------------------------------- */

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stg_decodeFloatzuIntzh
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{ 
    W_ p;
    F_ arg;
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    W_ mp_tmp1;
    W_ mp_tmp_w;

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    STK_CHK_GEN( WDS(2), NO_PTRS, stg_decodeFloatzuIntzh );
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    mp_tmp1  = Sp - WDS(1);
    mp_tmp_w = Sp - WDS(2);
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    /* arguments: F1 = Float# */
    arg = F1;
    
    /* Perform the operation */
    foreign "C" __decodeFloat_Int(mp_tmp1 "ptr", mp_tmp_w "ptr", arg) [];
    
    /* returns: (Int# (mantissa), Int# (exponent)) */
    RET_NN(W_[mp_tmp1], W_[mp_tmp_w]);
}

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stg_decodeDoublezu2Intzh
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{ 
    D_ arg;
    W_ p;
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    W_ mp_tmp1;
    W_ mp_tmp2;
    W_ mp_result1;
    W_ mp_result2;

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    STK_CHK_GEN( WDS(4), NO_PTRS, stg_decodeDoublezu2Intzh );
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    mp_tmp1    = Sp - WDS(1);
    mp_tmp2    = Sp - WDS(2);
    mp_result1 = Sp - WDS(3);
    mp_result2 = Sp - WDS(4);
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    /* arguments: D1 = Double# */
    arg = D1;

    /* Perform the operation */
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    foreign "C" __decodeDouble_2Int(mp_tmp1 "ptr", mp_tmp2 "ptr",
                                    mp_result1 "ptr", mp_result2 "ptr",
                                    arg) [];

    /* returns:
       (Int# (mant sign), Word# (mant high), Word# (mant low), Int# (expn)) */
    RET_NNNN(W_[mp_tmp1], W_[mp_tmp2], W_[mp_result1], W_[mp_result2]);
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}

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

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stg_forkzh
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{
  /* args: R1 = closure to spark */
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  MAYBE_GC(R1_PTR, stg_forkzh);
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  W_ closure;
  W_ threadid;
  closure = R1;

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  ("ptr" threadid) = foreign "C" createIOThread( MyCapability() "ptr", 
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				RtsFlags_GcFlags_initialStkSize(RtsFlags), 
				closure "ptr") [];
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  /* start blocked if the current thread is blocked */
  StgTSO_flags(threadid) = 
     StgTSO_flags(threadid) |  (StgTSO_flags(CurrentTSO) & 
                                (TSO_BLOCKEX::I32 | TSO_INTERRUPTIBLE::I32));

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  foreign "C" scheduleThread(MyCapability() "ptr", threadid "ptr") [];

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  // context switch soon, but not immediately: we don't want every
  // forkIO to force a context-switch.
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  Capability_context_switch(MyCapability()) = 1 :: CInt;
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  RET_P(threadid);
}

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

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  MAYBE_GC(R2_PTR, stg_forkOnzh);
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  W_ cpu;
  W_ closure;
  W_ threadid;
  cpu = R1;
  closure = R2;

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  ("ptr" threadid) = foreign "C" createIOThread( MyCapability() "ptr", 
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				RtsFlags_GcFlags_initialStkSize(RtsFlags), 
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				closure "ptr") [];
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  /* start blocked if the current thread is blocked */
  StgTSO_flags(threadid) = 
     StgTSO_flags(threadid) |  (StgTSO_flags(CurrentTSO) & 
                                (TSO_BLOCKEX::I32 | TSO_INTERRUPTIBLE::I32));

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  foreign "C" scheduleThreadOn(MyCapability() "ptr", cpu, threadid "ptr") [];
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  // context switch soon, but not immediately: we don't want every
  // forkIO to force a context-switch.
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  Capability_context_switch(MyCapability()) = 1 :: CInt;
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  RET_P(threadid);
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}

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stg_yieldzh
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{
  jump stg_yield_noregs;
}

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

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

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

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stg_threadStatuszh
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{
    /* args: R1 :: ThreadId# */
    W_ tso;
    W_ why_blocked;
    W_ what_next;
    W_ ret;

    tso = R1;
    loop:
      if (TO_W_(StgTSO_what_next(tso)) == ThreadRelocated) {
          tso = StgTSO__link(tso);
          goto loop;
      }

    what_next   = TO_W_(StgTSO_what_next(tso));
    why_blocked = TO_W_(StgTSO_why_blocked(tso));
    // Note: these two reads are not atomic, so they might end up
    // being inconsistent.  It doesn't matter, since we
    // only return one or the other.  If we wanted to return the
    // contents of block_info too, then we'd have to do some synchronisation.

    if (what_next == ThreadComplete) {
        ret = 16;  // NB. magic, matches up with GHC.Conc.threadStatus
    } else {
        if (what_next == ThreadKilled) {
            ret = 17;
        } else {
            ret = why_blocked;
        }
    }
    RET_N(ret);
}
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/* -----------------------------------------------------------------------------
 * TVar primitives
 * -------------------------------------------------------------------------- */

#define SP_OFF 0

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

643
INFO_TABLE_RET(stg_catch_retry_frame, CATCH_RETRY_FRAME,
644
#if defined(PROFILING)
645
  W_ unused1, W_ unused2,
646
#endif
647
  W_ unused3, P_ unused4, P_ unused5)
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{
   W_ r, frame, trec, outer;

   frame = Sp;
   trec = StgTSO_trec(CurrentTSO);
653
   outer  = StgTRecHeader_enclosing_trec(trec);
654
   (r) = foreign "C" stmCommitNestedTransaction(MyCapability() "ptr", trec "ptr") [];
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   if (r != 0) {
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     /* Succeeded (either first branch or second branch) */
     StgTSO_trec(CurrentTSO) = outer;
     Sp = Sp + SIZEOF_StgCatchRetryFrame;
     jump %ENTRY_CODE(Sp(SP_OFF));
   } else {
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     /* Did not commit: re-execute */
662
     W_ new_trec;
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     ("ptr" new_trec) = foreign "C" stmStartTransaction(MyCapability() "ptr", outer "ptr") [];
664
     StgTSO_trec(CurrentTSO) = new_trec;
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     if (StgCatchRetryFrame_running_alt_code(frame) != 0::I32) {
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       R1 = StgCatchRetryFrame_alt_code(frame);
     } else {
       R1 = StgCatchRetryFrame_first_code(frame);
     }
670
     jump stg_ap_v_fast;
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   }
}
673 674


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// Atomically frame ------------------------------------------------------------
676

677
INFO_TABLE_RET(stg_atomically_frame, ATOMICALLY_FRAME,
678
#if defined(PROFILING)
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  W_ unused1, W_ unused2,
680
#endif
681
  P_ code, P_ next_invariant_to_check, P_ result)
682
{
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  W_ frame, trec, valid, next_invariant, q, outer;
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  frame  = Sp;
  trec   = StgTSO_trec(CurrentTSO);
  result = R1;
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  outer  = StgTRecHeader_enclosing_trec(trec);
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  if (outer == NO_TREC) {
    /* First time back at the atomically frame -- pick up invariants */
692
    ("ptr" q) = foreign "C" stmGetInvariantsToCheck(MyCapability() "ptr", trec "ptr") [];
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    StgAtomicallyFrame_next_invariant_to_check(frame) = q;
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    StgAtomicallyFrame_result(frame) = result;
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  } else {
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    /* 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 */
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    ("ptr" trec) = foreign "C" stmStartTransaction(MyCapability() "ptr", trec "ptr") [];
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    StgTSO_trec(CurrentTSO) = trec;
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    next_invariant = StgInvariantCheckQueue_invariant(q);
    R1 = StgAtomicInvariant_code(next_invariant);
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    jump stg_ap_v_fast;
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  } else {

    /* We've got no more invariants to check, try to commit */
724
    (valid) = foreign "C" stmCommitTransaction(MyCapability() "ptr", trec "ptr") [];
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    if (valid != 0) {
      /* Transaction was valid: commit succeeded */
      StgTSO_trec(CurrentTSO) = NO_TREC;
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      R1 = StgAtomicallyFrame_result(frame);
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      Sp = Sp + SIZEOF_StgAtomicallyFrame;
      jump %ENTRY_CODE(Sp(SP_OFF));
    } else {
      /* Transaction was not valid: try again */
733
      ("ptr" trec) = foreign "C" stmStartTransaction(MyCapability() "ptr", NO_TREC "ptr") [];
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      StgTSO_trec(CurrentTSO) = trec;
      StgAtomicallyFrame_next_invariant_to_check(frame) = END_INVARIANT_CHECK_QUEUE;
      R1 = StgAtomicallyFrame_code(frame);
      jump stg_ap_v_fast;
    }
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  }
}

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INFO_TABLE_RET(stg_atomically_waiting_frame, ATOMICALLY_FRAME,
#if defined(PROFILING)
  W_ unused1, W_ unused2,
#endif
746
  P_ code, P_ next_invariant_to_check, P_ result)
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{
  W_ frame, trec, valid;

  frame = Sp;

  /* The TSO is currently waiting: should we stop waiting? */
753
  (valid) = foreign "C" stmReWait(MyCapability() "ptr", CurrentTSO "ptr") [];
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  if (valid != 0) {
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    /* Previous attempt is still valid: no point trying again yet */
    jump stg_block_noregs;
  } else {
    /* Previous attempt is no longer valid: try again */
759
    ("ptr" trec) = foreign "C" stmStartTransaction(MyCapability() "ptr", NO_TREC "ptr") [];
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    StgTSO_trec(CurrentTSO) = trec;
    StgHeader_info(frame) = stg_atomically_frame_info;
    R1 = StgAtomicallyFrame_code(frame);
763
    jump stg_ap_v_fast;
764
  }
765
}
766 767 768 769 770 771 772 773 774 775

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

#define SP_OFF 0

/* 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.
 */

776 777 778 779
INFO_TABLE_RET(stg_catch_stm_frame, CATCH_STM_FRAME,
#if defined(PROFILING)
  W_ unused1, W_ unused2,
#endif
780
  P_ unused3, P_ unused4)
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   {
      W_ r, frame, trec, outer;
      frame = Sp;
      trec = StgTSO_trec(CurrentTSO);
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      outer  = StgTRecHeader_enclosing_trec(trec);
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      (r) = foreign "C" stmCommitNestedTransaction(MyCapability() "ptr", trec "ptr") [];
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      if (r != 0) {
        /* Commit succeeded */
        StgTSO_trec(CurrentTSO) = outer;
        Sp = Sp + SIZEOF_StgCatchSTMFrame;
        jump Sp(SP_OFF);
      } else {
        /* Commit failed */
        W_ new_trec;
795
        ("ptr" new_trec) = foreign "C" stmStartTransaction(MyCapability() "ptr", outer "ptr") [];
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        StgTSO_trec(CurrentTSO) = new_trec;
        R1 = StgCatchSTMFrame_code(frame);
        jump stg_ap_v_fast;
      }
   }
801 802 803 804


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

805
stg_atomicallyzh
806 807 808 809 810
{
  W_ frame;
  W_ old_trec;
  W_ new_trec;
  
811
  // stmStartTransaction may allocate
812
  MAYBE_GC (R1_PTR, stg_atomicallyzh); 
813

814
  /* Args: R1 = m :: STM a */
815
  STK_CHK_GEN(SIZEOF_StgAtomicallyFrame + WDS(1), R1_PTR, stg_atomicallyzh);
816

817 818 819 820
  old_trec = StgTSO_trec(CurrentTSO);

  /* Nested transactions are not allowed; raise an exception */
  if (old_trec != NO_TREC) {
821
     R1 = base_ControlziExceptionziBase_nestedAtomically_closure;
822
     jump stg_raisezh;
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  }

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

829
  SET_HDR(frame,stg_atomically_frame_info, W_[CCCS]);
830
  StgAtomicallyFrame_code(frame) = R1;
831
  StgAtomicallyFrame_result(frame) = NO_TREC;
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  StgAtomicallyFrame_next_invariant_to_check(frame) = END_INVARIANT_CHECK_QUEUE;
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  /* Start the memory transcation */
835
  ("ptr" new_trec) = foreign "C" stmStartTransaction(MyCapability() "ptr", old_trec "ptr") [R1];
836 837 838
  StgTSO_trec(CurrentTSO) = new_trec;

  /* Apply R1 to the realworld token */
839
  jump stg_ap_v_fast;
840 841 842
}


843
stg_catchSTMzh
844 845 846 847 848
{
  W_ frame;
  
  /* Args: R1 :: STM a */
  /* Args: R2 :: Exception -> STM a */
849
  STK_CHK_GEN(SIZEOF_StgCatchSTMFrame + WDS(1), R1_PTR & R2_PTR, stg_catchSTMzh);
850 851 852 853 854

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

855
  SET_HDR(frame, stg_catch_stm_frame_info, W_[CCCS]);
856
  StgCatchSTMFrame_handler(frame) = R2;
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  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);
863
  ("ptr" new_trec) = foreign "C" stmStartTransaction(MyCapability() "ptr", cur_trec "ptr");
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  StgTSO_trec(CurrentTSO) = new_trec;
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  /* Apply R1 to the realworld token */
867
  jump stg_ap_v_fast;
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}


871
stg_catchRetryzh
872 873 874 875 876
{
  W_ frame;
  W_ new_trec;
  W_ trec;

877
  // stmStartTransaction may allocate
878
  MAYBE_GC (R1_PTR & R2_PTR, stg_catchRetryzh); 
879

880 881
  /* Args: R1 :: STM a */
  /* Args: R2 :: STM a */
882
  STK_CHK_GEN(SIZEOF_StgCatchRetryFrame + WDS(1), R1_PTR & R2_PTR, stg_catchRetryzh);
883 884 885

  /* Start a nested transaction within which to run the first code */
  trec = StgTSO_trec(CurrentTSO);
886
  ("ptr" new_trec) = foreign "C" stmStartTransaction(MyCapability() "ptr", trec "ptr") [R1,R2];
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  StgTSO_trec(CurrentTSO) = new_trec;

  /* Set up the catch-retry frame */
  Sp = Sp - SIZEOF_StgCatchRetryFrame;
  frame = Sp;
  
893
  SET_HDR(frame, stg_catch_retry_frame_info, W_[CCCS]);
894
  StgCatchRetryFrame_running_alt_code(frame) = 0 :: CInt; // false;
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  StgCatchRetryFrame_first_code(frame) = R1;
  StgCatchRetryFrame_alt_code(frame) = R2;

  /* Apply R1 to the realworld token */
899
  jump stg_ap_v_fast;
900 901 902
}


903
stg_retryzh
904 905 906 907 908 909 910
{
  W_ frame_type;
  W_ frame;
  W_ trec;
  W_ outer;
  W_ r;

911
  MAYBE_GC (NO_PTRS, stg_retryzh); // STM operations may allocate
912 913 914 915

  // Find the enclosing ATOMICALLY_FRAME or CATCH_RETRY_FRAME
retry_pop_stack:
  StgTSO_sp(CurrentTSO) = Sp;
916
  (frame_type) = foreign "C" findRetryFrameHelper(CurrentTSO "ptr") [];
917 918
  Sp = StgTSO_sp(CurrentTSO);
  frame = Sp;
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  trec = StgTSO_trec(CurrentTSO);
920
  outer  = StgTRecHeader_enclosing_trec(trec);
921 922 923 924

  if (frame_type == CATCH_RETRY_FRAME) {
    // The retry reaches a CATCH_RETRY_FRAME before the atomic frame
    ASSERT(outer != NO_TREC);
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    // Abort the transaction attempting the current branch
    foreign "C" stmAbortTransaction(MyCapability() "ptr", trec "ptr") [];
    foreign "C" stmFreeAbortedTRec(MyCapability() "ptr", trec "ptr") [];
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    if (!StgCatchRetryFrame_running_alt_code(frame) != 0::I32) {
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      // Retry in the first branch: try the alternative
930
      ("ptr" trec) = foreign "C" stmStartTransaction(MyCapability() "ptr", outer "ptr") [];
931
      StgTSO_trec(CurrentTSO) = trec;
932
      StgCatchRetryFrame_running_alt_code(frame) = 1 :: CInt; // true;
933
      R1 = StgCatchRetryFrame_alt_code(frame);
934
      jump stg_ap_v_fast;
935
    } else {
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      // Retry in the alternative code: propagate the retry
      StgTSO_trec(CurrentTSO) = outer;
      Sp = Sp + SIZEOF_StgCatchRetryFrame;
      goto retry_pop_stack;
940 941 942 943 944
    }
  }

  // We've reached the ATOMICALLY_FRAME: attempt to wait 
  ASSERT(frame_type == ATOMICALLY_FRAME);
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  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;
952
    StgTSO_trec(CurrentTSO) = trec;
953
    outer  = StgTRecHeader_enclosing_trec(trec);
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  }
955
  ASSERT(outer == NO_TREC);
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957
  (r) = foreign "C" stmWait(MyCapability() "ptr", CurrentTSO "ptr", trec "ptr") [];
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  if (r != 0) {
959
    // Transaction was valid: stmWait put us on the TVars' queues, we now block
960
    StgHeader_info(frame) = stg_atomically_waiting_frame_info;
961
    Sp = frame;
962
    // Fix up the stack in the unregisterised case: the return convention is different.
963 964
    R3 = trec; // passing to stmWaitUnblock()
    jump stg_block_stmwait;
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  } else {
    // Transaction was not valid: retry immediately
967
    ("ptr" trec) = foreign "C" stmStartTransaction(MyCapability() "ptr", outer "ptr") [];
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    StgTSO_trec(CurrentTSO) = trec;
    R1 = StgAtomicallyFrame_code(frame);
    Sp = frame;
971
    jump stg_ap_v_fast;
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  }
}


976
stg_checkzh
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{
  W_ trec, closure;

  /* Args: R1 = invariant closure */
981
  MAYBE_GC (R1_PTR, stg_checkzh); 
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  trec = StgTSO_trec(CurrentTSO);
  closure = R1;
  foreign "C" stmAddInvariantToCheck(MyCapability() "ptr", 
                                     trec "ptr",
                                     closure "ptr") [];

  jump %ENTRY_CODE(Sp(0));
}


993
stg_newTVarzh
994 995
{
  W_ tv;
996
  W_ new_value;
997 998 999

  /* Args: R1 = initialisation value */

1000
  MAYBE_GC (R1_PTR, stg_newTVarzh); 
1001
  new_value = R1;
1002
  ("ptr" tv) = foreign "C" stmNewTVar(MyCapability() "ptr", new_value "ptr") [];
1003 1004 1005 1006
  RET_P(tv);
}


1007
stg_readTVarzh
1008 1009 1010 1011 1012 1013 1014
{
  W_ trec;
  W_ tvar;
  W_ result;

  /* Args: R1 = TVar closure */

1015
  MAYBE_GC (R1_PTR, stg_readTVarzh); // Call to stmReadTVar may allocate
1016 1017
  trec = StgTSO_trec(CurrentTSO);
  tvar = R1;
1018
  ("ptr" result) = foreign "C" stmReadTVar(MyCapability() "ptr", trec "ptr", tvar "ptr") [];
1019 1020 1021 1022

  RET_P(result);
}

1023
stg_readTVarIOzh
1024 1025 1026 1027 1028 1029 1030 1031 1032 1033
{
    W_ result;

again:
    result = StgTVar_current_value(R1);
    if (%INFO_PTR(result) == stg_TREC_HEADER_info) {
        goto again;
    }
    RET_P(result);
}
1034

1035
stg_writeTVarzh
1036 1037 1038 1039 1040 1041 1042 1043
{
  W_ trec;
  W_ tvar;
  W_ new_value;
  
  /* Args: R1 = TVar closure */
  /*       R2 = New value    */

1044
  MAYBE_GC (R1_PTR & R2_PTR, stg_writeTVarzh); // Call to stmWriteTVar may allocate
1045 1046 1047
  trec = StgTSO_trec(CurrentTSO);
  tvar = R1;
  new_value = R2;
1048
  foreign "C" stmWriteTVar(MyCapability() "ptr", trec "ptr", tvar "ptr", new_value "ptr") [];
1049 1050 1051 1052 1053

  jump %ENTRY_CODE(Sp(0));
}


1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085
/* -----------------------------------------------------------------------------
 * 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.
 *
 * -------------------------------------------------------------------------- */

1086
stg_isEmptyMVarzh
1087 1088 1089
{
    /* args: R1 = MVar closure */

1090
    if (StgMVar_value(R1) == stg_END_TSO_QUEUE_closure) {
1091
	RET_N(1);
1092 1093
    } else {
	RET_N(0);
1094 1095 1096
    }
}

1097
stg_newMVarzh
1098 1099 1100 1101
{
    /* args: none */
    W_ mvar;

1102
    ALLOC_PRIM ( SIZEOF_StgMVar, NO_PTRS, stg_newMVarzh );
1103 1104
  
    mvar = Hp - SIZEOF_StgMVar + WDS(1);
1105 1106
    SET_HDR(mvar,stg_MVAR_DIRTY_info,W_[CCCS]);
        // MVARs start dirty: generation 0 has no mutable list
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    StgMVar_head(mvar)  = stg_END_TSO_QUEUE_closure;
    StgMVar_tail(mvar)  = stg_END_TSO_QUEUE_closure;
    StgM