path: root/ghc/runtime/c-as-asm/StgDebug.lc

\section[StgDebug]{Useful debugging routines for the STG machine}

Call these functions directly from a debugger to print Nodes,
registers, stacks, etc.

(An invocation such as 

  make EXTRA_HC_OPTS='-optl-u -optl_DEBUG_LoadSymbols' ghci

 is usually required to get this code included in the object code.)

Nota Bene: in a registerised build, you have to save all the registers
in their appropriate SAVE locations before calling any code that needs
register contents.  (This has to be repeated every time you emerge
from the STG world.)

On a sparc, this can be done by the following gdb script

define saveRegs

  set *(&MainRegTable+8) = $l1
  set *(&MainRegTable+9) = $l2
  set *(&MainRegTable+10) = $l3
  set *(&MainRegTable+11) = $l4
  set *(&MainRegTable+12) = $l5
  set *(&MainRegTable+13) = $l6
  set *(&MainRegTable+14) = $l7
  set *(&MainRegTable+4) = $f2
  set *(&MainRegTable+5) = $f3
  set *(&MainRegTable+6) = $f4
  set *(&MainRegTable+7) = $f5

  set *((double *) &MainRegTable+0) = (double) $f6
  set *((double *) &MainRegTable+2) = (double) $f8
  set *(&MainRegTable+23) = $l0
  set *(&MainRegTable+16) = $i0
  set *(&MainRegTable+17) = $i1
  set *(&MainRegTable+18) = $i2
  set *(&MainRegTable+19) = $i3
  set *(&StorageMgrInfo+0) = $i4
  set *(&StorageMgrInfo+1) = $i5

end


New code (attempts to interpret heap/stack contents)
  DEBUG_LoadSymbols( filename ) Load symbol table from object file
                                (not essential but useful initialisation)
  DEBUG_PrintA( depth, size )   Print "depth" entries from A stack
  DEBUG_PrintB( depth, size )   ditto
  DEBUG_Where( depth, size )    Ambitious attempt to print stacks
                                symbolically.  Result is a little inaccurate
                                but often good enough to do the job.
  DEBUG_NODE( closure, size )   Print a closure on the heap
  DEBUG_INFO_TABLE(closure)     Print info-table of a closure
  DEBUG_SPT( size )             Print the Stable Pointer Table

(Use variable DEBUG_details to set level of detail shown.)

Older code (less fancy ==> more reliable)
  DEBUG_ASTACK(lines)		Print "lines" lines of the A Stack
  DEBUG_BSTACK(lines)		Print "lines" lines of the B Stack
  DEBUG_UPDATES(frames)		Print "frames" update frames
  DEBUG_REGS()			Print register values
  DEBUG_MP()                    Print the MallocPtr Lists

\begin{code}
#if defined(RUNTIME_DEBUGGING)

#include "rtsdefs.h"
\end{code}

\subsection[StgDebug_Symbol_Tables]{Loading Symbol Tables}

NB: this assumes a.out files - won't work on Alphas.
ToDo: At least add some #ifdefs

\begin{code}
#include <a.out.h>
#include <stab.h>
/* #include <nlist.h> */

#include <stdio.h>

#define FROM_START 0  /* for fseek */

/* Simple lookup table */

/* Current implementation is pretty dumb! */

struct entry {
  unsigned value;
  int index;
  char *name;
};

static int table_uninitialised = 1;
static int max_table_size;
static int table_size;
static struct entry* table;

static
void reset_table( int size )
{
  max_table_size = size;
  table_size = 0;
  table = (struct entry *) malloc( size * sizeof( struct entry ) );
}

static
void prepare_table()
{
  /* Could sort it... */
}

static
void insert( unsigned value, int index, char *name )
{
  if ( table_size >= max_table_size ) {
    fprintf( stderr, "Symbol table overflow\n" );
    exit( 1 );
  }
  table[table_size].value = value;
  table[table_size].index = index;
  table[table_size].name = name;
  table_size = table_size + 1;
}

static
int lookup( unsigned value, int *result )
{
  int i;
  for( i = 0; i < table_size && table[i].value != value; ++i ) {
  }
  if (i < table_size) {
    *result = table[i].index;
    return 1;
  } else {
    return 0;
  }
}

static int lookup_name( char *name, unsigned *result )
{
  int i;
  for( i = 0; i < table_size && strcmp(name,table[i].name) != 0; ++i ) {
  }
  if (i < table_size) {
    *result = table[i].value;
    return 1;
  } else {
    return 0;
  }
}
\end{code}

* Z-escapes:
    "std"++xs -> "Zstd"++xs
    char_to_c 'Z'  = "ZZ"
    char_to_c '&'  = "Za"
    char_to_c '|'  = "Zb"
    char_to_c ':'  = "Zc"
    char_to_c '/'  = "Zd"
    char_to_c '='  = "Ze"
    char_to_c '>'  = "Zg"
    char_to_c '#'  = "Zh"
    char_to_c '<'  = "Zl"
    char_to_c '-'  = "Zm"
    char_to_c '!'  = "Zn"
    char_to_c '.'  = "Zo"
    char_to_c '+'  = "Zp"
    char_to_c '\'' = "Zq"
    char_to_c '*'  = "Zt"
    char_to_c '_'  = "Zu"
    char_to_c c    = "Z" ++ show (ord c)

\begin{code}
static char unZcode( char ch )
{
  switch (ch) {
  case 'Z' :
  case '\0' : 
    return ('Z');
  case 'a' :
    return ('&');
  case 'b' :
    return ('|');
  case 'c' :
    return (':');
  case 'd' :
    return ('/');
  case 'e' :
    return ('=');
  case 'g' :
    return ('>');
  case 'h' :
    return ('#');
  case 'l' :
    return ('<');
  case 'm' :
    return ('-');
  case 'n' :
    return ('!');
  case 'o' :
    return ('.');
  case 'p' :
    return ('+');
  case 'q' :
    return ('\'');
  case 't' :
    return ('*');
  case 'u' :
    return ('_');
  default : 
    return (ch);
  }
}

/* Precondition: out big enough to handle output (about twice length of in) */
static void enZcode( char *in, char *out )
{
  int i, j;

  j = 0;
  out[ j++ ] = '_';
  for( i = 0; in[i] != '\0'; ++i ) {
    switch (in[i]) {
    case 'Z'  : 
      out[j++] = 'Z';
      out[j++] = 'Z';
      break;
    case '&'  : 
      out[j++] = 'Z';
      out[j++] = 'a';
      break;
    case '|'  : 
      out[j++] = 'Z';
      out[j++] = 'b';
      break;
    case ':'  : 
      out[j++] = 'Z';
      out[j++] = 'c';
      break;
    case '/'  : 
      out[j++] = 'Z';
      out[j++] = 'd';
      break;
    case '='  : 
      out[j++] = 'Z';
      out[j++] = 'e';
      break;
    case '>'  : 
      out[j++] = 'Z';
      out[j++] = 'g';
      break;
    case '#'  : 
      out[j++] = 'Z';
      out[j++] = 'h';
      break;
    case '<'  : 
      out[j++] = 'Z';
      out[j++] = 'l';
      break;
    case '-'  : 
      out[j++] = 'Z';
      out[j++] = 'm';
      break;
    case '!'  : 
      out[j++] = 'Z';
      out[j++] = 'n';
      break;
    case '.'  : 
      out[j++] = 'Z';
      out[j++] = 'o';
      break;
    case '+'  : 
      out[j++] = 'Z';
      out[j++] = 'p';
      break;
    case '\'' : 
      out[j++] = 'Z';
      out[j++] = 'q';
      break;
    case '*'  : 
      out[j++] = 'Z';
      out[j++] = 't';
      break;
    case '_'  : 
      out[j++] = 'Z';
      out[j++] = 'u';
      break;
    default :
      out[j++] = in[i];
      break;
    }
  }
  out[j] = '\0';
}
\end{code}

\begin{code}
static int lookupForName( P_ addr, char **result )
{
  int i;
  for( i = 0; i < table_size && table[i].value != (unsigned) addr; ++i ) {
  }
  if (i < table_size) {
    *result = table[i].name;
    return 1;
  } else {
    return 0;
  }
}

static void printZcoded( char *raw )
{
  int j;
  
  /* start at 1 to skip the leading "_" */
  for( j = 1; raw[j] != '\0'; /* explicit */) {
    if (raw[j] == 'Z') {
      putchar(unZcode(raw[j+1]));
      j = j + 2;
    } else {
      putchar(raw[j]);
      j = j + 1;
    }
  }
}

static void printName( P_ addr )
{
  char *raw;

  if (lookupForName( addr, &raw )) {
    printZcoded(raw);
  } else {
    printf("0x%x", addr);
  }
}
  
/* Fairly ad-hoc piece of code that seems to filter out a lot of
   rubbish like the obj-splitting symbols */

static
int isReal( unsigned char type, char *name )
{
  int external = type & N_EXT;
  int tp = type & N_TYPE;

  if (tp == N_TEXT || tp == N_DATA) {
    return( name[0] == '_' && name[1] != '_' );
  } else {
    return( 0 );
  }
}

void DEBUG_LoadSymbols( char *name )
{
  FILE *binary;

  struct exec header;

  long sym_offset;
  long sym_size;
  long num_syms;
  long num_real_syms;
  struct nlist *symbol_table;

  long str_offset;
  long str_size; /* assumed 4 bytes.... */
  char *string_table;

  long i;
  
  binary = fopen( name, "r" );
  if (binary == NULL) {
    fprintf( stderr, "Can't open symbol table file \"%s\".\n", name );
  }


  if (fread( &header,  sizeof( struct exec ), 1, binary ) != 1) { 
    fprintf( stderr, "Can't read symbol table header.\n" );
    exit( 1 );
  }
  if ( N_BADMAG( header ) ) {
    fprintf( stderr, "Bad magic number in symbol table header.\n" );
    exit( 1 );
  }



  sym_offset = N_SYMOFF( header );
  sym_size = header.a_syms;
  num_syms = sym_size / sizeof( struct nlist );
  fseek( binary, sym_offset, FROM_START );

  symbol_table = (struct nlist *) malloc( sym_size );
  if (symbol_table == NULL) {
    fprintf( stderr, "Can't allocate symbol table of size %d\n", sym_size );
    exit( 1 );
  }

  printf("Reading %d symbols\n", num_syms);

  if (fread( symbol_table, sym_size, 1, binary ) != 1) {
    fprintf( stderr, "Can't read symbol table\n");
    exit( 1 );
  }



  str_offset = N_STROFF( header );
  fseek( binary, str_offset, FROM_START );

  if (fread( &str_size, 4, 1, binary ) != 1) {
    fprintf( stderr, "Can't read string table size\n");
    exit( 1 );
  }

  /* apparently the size of the string table includes the 4 bytes that
   * store the size...
   */
  string_table = (char *) malloc( str_size );
  if (string_table == NULL) {
    fprintf( stderr, "Can't allocate string table of size %d\n", str_size );
    exit( 1 );
  }

  if (fread( string_table+4, str_size-4, 1, binary ) != 1) {
    fprintf( stderr, "Can't read string table\n");
    exit( 1 );
  }

  num_real_syms = 0;
  for( i = 0; i != num_syms; ++i ) {
    unsigned char type = symbol_table[i].n_type;
    unsigned value = symbol_table[i].n_value;
    char *str = &string_table[symbol_table[i].n_un.n_strx];

    if ( isReal( type, str ) ) {
      num_real_syms = num_real_syms + 1;
    }
  }

  printf("Of which %d are real symbols\n", num_real_syms);

/*
  for( i = 0; i != num_syms; ++i ) {
    unsigned char type = symbol_table[i].n_type;
    unsigned value = symbol_table[i].n_value;
    char *str = &string_table[symbol_table[i].n_un.n_strx];

    if ( isReal(type, str) ) {
      printf("Symbol %d. Extern? %c. Type: %c. Value: 0x%x. Name: %s\n",
	     i,
	     (external ? 'y' : 'n'),
	     type,
	     value,
	     str
	     );
    }
  }
*/

  reset_table( num_real_syms );

  for( i = 0; i != num_syms; ++i ) {
    unsigned char type = symbol_table[i].n_type;
    unsigned value = symbol_table[i].n_value;
    char *str = &string_table[symbol_table[i].n_un.n_strx];

    if ( isReal( type, str ) ) {
      insert( value, i, str );
    }

  }

  prepare_table();
}
\end{code}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
\subsection[StgDebug_PrettyPrinting]{Pretty printing internal structures}
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\begin{code}
#include "../storage/SMinternal.h"

#ifdef GCap
#define HP_BOT appelInfo.oldbase
#elif GCdu
#define HP_BOT dualmodeInfo.modeinfo[dualmodeInfo.mode].base
#elif GC2s
#define HP_BOT semispaceInfo[semispace].base
#elif GC1s
#define HP_BOT compactingInfo.base
#else
  unknown garbage collector - help, help!
#endif
\end{code}

\begin{code}
/* range: 0..NUM_LEVELS_OF_DETAIL-1.  Level of machine-related detail shown */
#define NUM_LEVELS_OF_DETAIL 3
static int DEBUG_details = 2; 
\end{code}

\begin{code}
/* Determine the size and number of pointers for this kind of closure */
static
void 
getClosureShape( P_ node, int *vhs, int *size, int *ptrs, char **type )
{
  /* The result is used for printing out closure contents.  If the
     info-table is mince, we'd better conservatively guess there's
     nothing in the closure to avoid chasing non-ptrs. */
  *vhs = 0;
  *size = 0;
  *ptrs = 0;
  *type = "*unknown info type*";

    /* ToDo: if in garbage collector, consider subtracting some weird offset which some GCs add to infoptr */

  /* The order here precisely reflects that in SMInfoTables.lh to make
     it easier to check that this list is complete. */
  switch(INFO_TYPE(INFO_PTR(node)))
    {
      case INFO_SPEC_U_TYPE:
        *vhs = 0; /* by decree */
        *size = SPEC_CLOSURE_SIZE(node);
	*ptrs = SPEC_CLOSURE_NoPTRS(node);
        *type = "SPECU";
	break;
      case INFO_SPEC_N_TYPE:
        *vhs = 0; /* by decree */
        *size = SPEC_CLOSURE_SIZE(node);
	*ptrs = SPEC_CLOSURE_NoPTRS(node);
        *type = "SPECN";
	break;

      case INFO_GEN_U_TYPE:
	*vhs = GEN_VHS;
        *size = GEN_CLOSURE_SIZE(node);
	*ptrs = GEN_CLOSURE_NoPTRS(node);
        *type = "GENU";
	break;
      case INFO_GEN_N_TYPE:
	*vhs = GEN_VHS;
        *size = GEN_CLOSURE_SIZE(node);
	*ptrs = GEN_CLOSURE_NoPTRS(node);
        *type = "GENN";
	break;

      case INFO_DYN_TYPE:
	*vhs = DYN_VHS;
        *size = DYN_CLOSURE_SIZE(node);
	*ptrs = DYN_CLOSURE_NoPTRS(node);
	*type = "DYN";
	break;

      case INFO_TUPLE_TYPE:
	*vhs = TUPLE_VHS;
        *size = TUPLE_CLOSURE_SIZE(node);
	*ptrs = TUPLE_CLOSURE_NoPTRS(node);
	*type = "TUPLE";
	break;

      case INFO_DATA_TYPE:
	*vhs = DATA_VHS;
        *size = DATA_CLOSURE_SIZE(node);
	*ptrs = DATA_CLOSURE_NoPTRS(node);
	*type = "DATA";
	break;

      case INFO_MUTUPLE_TYPE:
	*vhs = MUTUPLE_VHS;
        *size = MUTUPLE_CLOSURE_SIZE(node);
	*ptrs = MUTUPLE_CLOSURE_NoPTRS(node);
	*type = "MUTUPLE";
	break;

      case INFO_IMMUTUPLE_TYPE:
	*vhs = MUTUPLE_VHS;
        *size = MUTUPLE_CLOSURE_SIZE(node);
	*ptrs = MUTUPLE_CLOSURE_NoPTRS(node);
	*type = "IMMUTUPLE";
	break;

      case INFO_STATIC_TYPE:
	*vhs = STATIC_VHS;
        *size = INFO_SIZE(INFO_PTR(node));
	*ptrs = INFO_NoPTRS(INFO_PTR(node));
	*type = "STATIC";
	break;

      case INFO_CONST_TYPE:
	*vhs = 0;
        *size = 0;
	*ptrs = 0;
	*type = "CONST";
	break;

      case INFO_CHARLIKE_TYPE:
	*vhs = 0;
        *size = 1;
	*ptrs = 0;
	*type = "CHAR";
	break;

      case INFO_INTLIKE_TYPE:
	*vhs = 0;
        *size = 1;
	*ptrs = 0;
	*type = "INT";
	break;

      case INFO_BH_TYPE:
	*vhs = 0;
        *size = INFO_SIZE(INFO_PTR(node));
	*ptrs = 0;
	*type = "BHOLE";
	break;

/* most of the following are plausible guesses (particularily VHSs) ADR */
      case INFO_BQ_TYPE:
#ifdef CONCURRENT
	*vhs = 0;
        *size = BQ_CLOSURE_SIZE(node);
	*ptrs = BQ_CLOSURE_NoPTRS(node);
	*type = "BQ";
#else
	printf("Panic: found BQ Infotable in non-threaded system.\n");
#endif
	break;

      case INFO_IND_TYPE:
	*vhs = 0;
        *size = IND_CLOSURE_SIZE(node);
	*ptrs = IND_CLOSURE_NoPTRS(node);
	*type = "IND";
	break;

      case INFO_CAF_TYPE:
	*vhs = 0; /* ?? ADR */
        *size = INFO_SIZE(INFO_PTR(node));
	*ptrs = 0;
	*type = "CAF";
	break;

      case INFO_FETCHME_TYPE:
#ifdef PAR
	*vhs = FETCHME_VHS;
	*size = FETCHME_CLOSURE_SIZE(node);
	*ptrs = FETCHME_CLOSURE_PTRS(node);
	*type = "FETCHME";
#else
	printf("Panic: found FETCHME Infotable in sequential system.\n");
#endif
	break;

      case INFO_FMBQ_TYPE:
#ifdef PAR
	*vhs = FMBQ_VHS;
	*size = FMBQ_CLOSURE_SIZE(node);
	*ptrs = FMBQ_CLOSURE_PTRS(node);
	*type = "FMBQ";
#else
	printf("Panic: found FMBQ Infotable in sequential system.\n");
#endif
	break;

      case INFO_BF_TYPE:
#ifdef PAR
	*vhs = 0;
        *size = 0;
	*ptrs = 0;
	*type = "BlockedFetch";
#else
	printf("Panic: found BlockedFetch Infotable in sequential system.\n");
#endif
	break;

      case INFO_TSO_TYPE:
	/* Conservative underestimate: this will contain a regtable
           which comes nowhere near fitting the standard "p ptrs; s-p
           non-ptrs" format. ADR */
#ifdef CONCURRENT
	*vhs = TSO_VHS;
        *size = 0;
	*ptrs = 0;
	*type = "TSO";
#else
	printf("Panic: found TSO Infotable in non-threaded system.\n");
#endif
	break;

      case INFO_STKO_TYPE:
	/* Conservative underestimate: this will contain stuff
           which comes nowhere near fitting the standard "p ptrs; s-p
           non-ptrs" format. JSM */
#ifdef CONCURRENT
	*vhs = STKO_VHS;
        *size = 0;
	*ptrs = 0;
	*type = "STKO";
#else
	printf("Panic: found STKO Infotable in non-threaded system.\n");
#endif
	break;

      /* There are no others in SMInfoTables.lh 11/5/94 ADR*/
      default:
	printf("Invalid/unknown info type %d\n", INFO_TYPE(INFO_PTR(node)));
	break;
    }
}  

static
void 
printWord( W_ word )
{
  printf("0x%08lx", word);
}

static
void
printAddress( P_ address )
{
#ifdef PAR
  PP_ SpA  = STKO_SpA(SAVE_StkO);
  PP_ SuA  = STKO_SuA(SAVE_StkO);
  P_  SpB  = STKO_SpB(SAVE_StkO);
  P_  SuB  = STKO_SuB(SAVE_StkO);
#else
  PP_ SpA  = SAVE_SpA;
  PP_ SuA  = SAVE_SuA;
  P_  SpB  = SAVE_SpB;
  P_  SuB  = SAVE_SuB;
#endif
  P_  Hp   = SAVE_Hp;

  PP_ botA = stackInfo.botA;
  P_ botB  = stackInfo.botB;
  P_ HpBot = HP_BOT;

  char *name;

  /* ToDo: check if it's in text or data segment. */

  /* The @-1@s in stack comparisions are because we sometimes use the
     address of just below the stack... */

  if (lookupForName( address, &name )) {
    printZcoded( name );
  } else {
    if (DEBUG_details > 1) {
      printWord( (W_) address );
      printf(" : ");
    }
    if (HpBot <= address && address < Hp) {
      printf("Hp[%d]", address - HpBot);
    } else if (SUBTRACT_A_STK((PP_)address, botA) >= -1 && SUBTRACT_A_STK(SpA, (PP_)address) >= 0) {
      printf("SpA[%d]", SUBTRACT_A_STK((PP_)address, botA));
    } else if (SUBTRACT_B_STK(address, botB) >= -1 && SUBTRACT_B_STK(SpB, address) >= 0) {
      /* ToDo: check if it's an update frame */
      printf("SpB[%d]", SUBTRACT_B_STK(address, botB));
    } else {
      printWord( (W_) address );
    }
  }
}

static
void
printIndentation( int indentation )
{
  int i;
  for (i = 0; i < indentation; ++i) { printf("  "); }
}

/* The weight parameter is used to (eventually) break cycles */
static 
void 
printStandardShapeClosure( 
      int indentation, 
      int weight, 
      P_ closure, int vhs, int size, int noPtrs
)
{
#ifdef PAR
  PP_ SpA  = STKO_SpA(SAVE_StkO);
  PP_ SuA  = STKO_SuA(SAVE_StkO);
  P_  SpB  = STKO_SpB(SAVE_StkO);
  P_  SuB  = STKO_SuB(SAVE_StkO);
#else
  PP_ SpA  = SAVE_SpA;
  PP_ SuA  = SAVE_SuA;
  P_  SpB  = SAVE_SpB;
  P_  SuB  = SAVE_SuB;
#endif
  P_ Hp    = SAVE_Hp;

  extern void printClosure PROTO( (P_, int, int) );
  int numValues = size - vhs;
  P_ HpBot = HP_BOT;

  if (DEBUG_details > 1) {
    printAddress( closure );
    printf(": ");
  }
  printName((P_)INFO_PTR(closure));

  if ( numValues > 0 ) {
    int newWeight = weight-1 ;
        /* I've tried dividing the weight by size to share it out amongst
           sub-closures - but that didn't work too well. */

    if (newWeight > 0) {
      int i=0;
      printf("(\n");
      while (i < numValues) {
	P_ data = (P_) closure[_FHS + vhs + i];

	printIndentation(indentation+1);
	if (i < noPtrs) {
	  printClosure( data, indentation+1, newWeight);
	} else {
	  printAddress( data );
	}
	i = i + 1;
	if (i < numValues) printf(",\n");
      }
      printf(")");
    } else {
      int i;
      printf("(_");
      for( i = 1; i < size; ++i ) {
	printf(",_");
      }
      printf(")");
    }
  }
}

/* Should be static but has to be extern to allow mutual recursion */
void 
printClosure( P_ closure, int indentation, int weight )
{
  int vhs, size, ptrs;
  char *type;

  /* I'd love to put a test here that this actually _is_ a closure -
     but testing that it is in the heap is overly strong. */

  getClosureShape(closure, &vhs, &size, &ptrs, &type);

  /* The order here precisely reflects that in SMInfoTables.lh to make
     it easier to check that this list is complete. */
  switch(INFO_TYPE(INFO_PTR(closure))) {
  case INFO_SPEC_U_TYPE:
  case INFO_SPEC_N_TYPE:
  case INFO_GEN_U_TYPE:
  case INFO_GEN_N_TYPE:
  case INFO_DYN_TYPE:
  case INFO_TUPLE_TYPE:
  case INFO_DATA_TYPE:
  case INFO_MUTUPLE_TYPE:
  case INFO_IMMUTUPLE_TYPE:
    printStandardShapeClosure(indentation, weight, closure, 
			      vhs, size, ptrs);
    break;

  case INFO_STATIC_TYPE:
    /* If the STATIC contains Floats or Doubles, we can't print it. */
    /* And we can't always rely on the size/ptrs info either */
    printAddress( closure );
    printf(" STATIC");
    break;

  case INFO_CONST_TYPE:
    if (DEBUG_details > 1) {
      printAddress( closure );
      printf(": ");
    }
    printName((P_)INFO_PTR(closure));
    break;

  case INFO_CHARLIKE_TYPE:
    /* ToDo: check for non-printable characters */
    if (DEBUG_details > 1) printf("CHARLIKE ");
    printf("\'%c\'", (unsigned char) CHARLIKE_VALUE(closure));
    break;

  case INFO_INTLIKE_TYPE:
    if (DEBUG_details > 1) printf("INTLIKE ");
    printf("%d",INTLIKE_VALUE(closure));
    break;

  case INFO_BH_TYPE:
    /* Is there anything to say here> */
    if (DEBUG_details > 1) {
      printAddress( closure );
      printf(": ");
    }
    printName((P_)INFO_PTR(closure));
    break;

/* most of the following are just plausible guesses (particularily VHSs) ADR */

  case INFO_BQ_TYPE:
#ifdef CONCURRENT
    printStandardShapeClosure(indentation, weight, closure, 
			      vhs, size, ptrs);
#else
    printf("Panic: found BQ Infotable in non-threaded system.\n");
#endif
    break;

  case INFO_IND_TYPE:
    if (DEBUG_details > 0) {
      printAddress( closure );
      printf(" IND: ");
    }
    printClosure( (P_) IND_CLOSURE_PTR(closure), indentation, weight );
    break;

  case INFO_CAF_TYPE:
    if (DEBUG_details > 0) {
      printAddress( closure );
      printf(" CAF: ");
    }
    printClosure( (P_) IND_CLOSURE_PTR(closure), indentation, weight );
    break;

  case INFO_FETCHME_TYPE:
#ifdef PAR
    printStandardShapeClosure(indentation, weight, closure, 
			      vhs, size, ptrs);
#else
    printf("Panic: found FETCHME Infotable in sequential system.\n");
#endif
    break;

  case INFO_FMBQ_TYPE:
#ifdef PAR
    printStandardShapeClosure(indentation, weight, closure, 
			      vhs, size, ptrs);
#else
    printf("Panic: found FMBQ Infotable in sequential system.\n");
#endif
    break;

  case INFO_BF_TYPE:
#ifdef PAR
    printStandardShapeClosure(indentation, weight, closure, 
			      vhs, size, ptrs);
#else
    printf("Panic: found BlockedFetch Infotable in sequential system.\n");
#endif
    break;

  case INFO_TSO_TYPE:
#ifdef CONCURRENT
    /* A TSO contains a regtable... */
    printAddress( closure );
    printf(" TSO: ...");
#else
    printf("Panic: found TSO Infotable in non-threaded system.\n");
#endif
    break;

    case INFO_STKO_TYPE:
#ifdef CONCURRENT
    /* A STKO contains parts of the A and B stacks... */
    printAddress( closure );
    printf(" STKO: ...");
#else
    printf("Panic: found STKO Infotable in non-threaded system.\n");
#endif
    break;

  /* There are no others in SMInfoTables.lh 11/5/94 ADR*/
  default:
    printf("Invalid/unknown info type %d\n", INFO_TYPE(INFO_PTR(closure)));
    break;
  }
}    

void
DEBUG_NODE( P_ closure, int size )
{
  printClosure( closure, 0, size );
  printf("\n");
}
\end{code}

Now some stuff for printing stacks - almost certainly doesn't work
under threads which keep the stack on the heap.

\begin{code}
#ifndef CONCURRENT

static int
minimum(int a, int b)
{
  if (a < b) {
    return a;
  } else {
    return b;
  }
}

void DEBUG_PrintA( int depth, int weight )
{
  PP_ SpA  = SAVE_SpA;
  PP_ SuA  = SAVE_SuA;
  P_  SpB  = SAVE_SpB;
  P_  SuB  = SAVE_SuB;
  P_ Hp    = SAVE_Hp;

  int i;
  I_ size = minimum(depth, SUBTRACT_A_STK(SpA, stackInfo.botA)+1);
     
  printf("Dump of the Address Stack (SpA = 0x%x, SuA = 0x%x)\n", SpA, SuA);

  for( i = 0; i < size; ++i ) {
    printIndentation(1);
    printf("SpA[%ld] (0x%08lx):", i, SpA + AREL(i));
    printClosure((P_)*(SpA + AREL(i)), 2, weight);
    printf("\n");
  }
}

void DEBUG_PrintB( int depth, int weight )
{
  PP_ SpA  = SAVE_SpA;
  PP_ SuA  = SAVE_SuA;
  P_  SpB  = SAVE_SpB;
  P_  SuB  = SAVE_SuB;
  P_ Hp    = SAVE_Hp;
  
  I_ i;
  I_ size = minimum(depth, SUBTRACT_B_STK(SpB, stackInfo.botB)+1);

  P_ updateFramePtr;
  I_ update_count;
     
  printf("Dump of the Value Stack (SpB = 0x%x, SuB = 0x%x)\n", SpB, SuB);
  
  updateFramePtr = SuB;
  update_count = 0;
  i = 0;
  while (i < size) {
    if (updateFramePtr == SpB + BREL(i)) {
      
      printIndentation(1);
      printf("SpB[%ld] (0x%08lx): UpdateFrame[%d](", 
	     i, 
	     updateFramePtr, 
	     update_count 
	     );
      printName( (P_) *(SpB + BREL(i)) );
      printf(", UF[%d] (= SpB[%ld]), SpA[%ld], ",
	     update_count+1, 
	     SUBTRACT_B_STK(SpB, GRAB_SuB(updateFramePtr)),
	     SUBTRACT_A_STK(SpA, GRAB_SuA(updateFramePtr))
	     );
      printAddress( GRAB_UPDATEE(updateFramePtr) );
      printf(")\n");

      printIndentation(2);
      printClosure( GRAB_UPDATEE(updateFramePtr), 3, weight );
      printf("\n");

      updateFramePtr = GRAB_SuB(updateFramePtr);
      update_count = update_count + 1;

      /* ToDo: GhcConstants.lh reveals that there are two other sizes possible */
      i = i + STD_UF_SIZE;
    } else {
      printIndentation(1);
      printf("SpB[%ld] (0x%08lx): ", i, SpB + BREL(i) );
      printName((P_) *(SpB + BREL(i)) );
      printf("\n");
      i = i + 1;
    }
  }
}
#endif /* not CONCURRENT */
\end{code}

ToDo: 

   All the following code incorrectly assumes that the only return
   addresses are those associated with update frames.
   
   To do a proper job of printing the environment we need to:

   1) Recognise vectored and non-vectored returns on the B stack.

   2) Know where the local variables are in the A and B stacks for
      each return situation.

   Until then, we'll just need to look suspiciously at the
   "environment" being printed out.

   ADR 

\begin{code}
/* How many real stacks are there on SpA and SpB? */
static
int numStacks( )
{
#ifdef PAR
  PP_ SpA  = STKO_SpA(SAVE_StkO);
  PP_ SuA  = STKO_SuA(SAVE_StkO);
  P_  SpB  = STKO_SpB(SAVE_StkO);
  P_  SuB  = STKO_SuB(SAVE_StkO);
#else
  PP_ SpA  = SAVE_SpA;
  PP_ SuA  = SAVE_SuA;
  P_  SpB  = SAVE_SpB;
  P_  SuB  = SAVE_SuB;
#endif
  P_  Hp   = SAVE_Hp;
  
  int depth = 1; /* There's always at least one stack */

  while (SUBTRACT_B_STK(SuB, stackInfo.botB) >= 0) {
    SuB = GRAB_SuB( SuB );
    depth = depth + 1;
  }
  return depth;
}

static
void printLocalAStack( int depth, int indentation, int weight, PP_ SpA, int size )
{
  int i;

  ASSERT( size >= 0 );

  for( i = size-1; i >= 0; --i ) {
    printIndentation( indentation );
    printf("A[%ld][%ld]", depth, i);
    if (DEBUG_details > 1) printf(" (0x%08lx) ", SpA + AREL(i) );
    printf("=");
    printClosure( *(SpA + AREL(i)), indentation+2, weight );
    printf("\n");
  }
}

static
void printLocalBStack( int depth, int indentation, int weight, P_ SpB, int size )
{
  int i;

  ASSERT( size >= 0 );

  for( i = size-1; i >= 0; --i) {
    printIndentation( indentation );
    printf("B[%ld][%ld]", depth, i);
    if (DEBUG_details > 1) printf(" (0x%08lx) ", SpB + BREL(i) );
    printf("=");
    printAddress( (P_) *(SpB + BREL(i)) );
    printf("\n");
  }
}

static
void printEnvironment( int depth, int indentation, int weight, PP_ SpA, PP_ SuA, P_ SpB, P_ SuB )
{
  int sizeA = SUBTRACT_A_STK(SpA, SuA);
  int sizeB = SUBTRACT_B_STK(SpB, SuB);

  if (sizeA + sizeB > 0) {
    printIndentation( indentation );
    printf("let\n");

    printLocalAStack( depth, indentation+1, weight, SpA, sizeA );
    printLocalBStack( depth, indentation+1, weight, SpB, sizeB );

    printIndentation( indentation );
    printf("in\n");
  }
}
\end{code}

Printing the current context is a little tricky.

Ideally, we would work from the bottom of the stack up to the top
recursively printing the stuff nearer the top.

In practice, we have to work from the top down because the top
contains info about how much data is below the current return address.

The result is that we have two recursive passes over the stacks: the
first one prints the "cases" and the second one prints the
continuations (vector tables, etc.)

Note that because we compress chains of update frames, the depth and
indentation do not always change in step.

ToDo: 

* detecting non-updating cases too
* printing continuations (from vector tables) properly
* printing sensible names in environment.
* fix bogus nature of lets


\begin{code}
static int maxDepth = 5;

static
int printCases( int depth, int weight, PP_ SpA, PP_ SuA, P_ SpB, P_ SuB )
{
  int indentation;

  if (depth < maxDepth && SUBTRACT_B_STK(SuB, stackInfo.botB) >= 0) {
    PP_ nextSpA, nextSuA;
    P_  nextSpB, nextSuB;

    /* ToDo: GhcConstants.lh reveals that there are two other sizes of
       update frame possible */
    /* ToDo: botB is probably wrong in THREAD system */

    nextSpB = SuB + BREL(STD_UF_SIZE);
    nextSuB = GRAB_SuB( SuB );
    nextSpA = SuA;
    nextSuA = GRAB_SuA( nextSuB );

    indentation = printCases( depth+1, weight, nextSpA, nextSuA, nextSpB, nextSuB );

    if (DEBUG_details > 1 || nextSpB != nextSuB) { /* show frame (even if adjacent to another) */
      printIndentation( indentation );
      printf("case\n");
      indentation = indentation + 1;
    }
    if (SpB != SuB) { 
      /* next thing on stack is a return vector - no need to show it here. */
      SpB = SpB + BREL(1);
    }
    printEnvironment( depth, indentation, weight, SpA, SuA, SpB, SuB );
  } else {
    printf("...\n");
    indentation = 1;
  }
  
  return indentation;
}

/* ToDo: pay more attention to format of vector tables in SMupdate.lh */

static
int isVTBLEntry( P_ entry )
{
  char *raw;

  if (lookupForName( entry, &raw )) {
    if ( strncmp( "_ret", raw, 4 ) == 0 ) {
      return 1;
    } else if ( strncmp( "_djn", raw, 4 ) == 0) {
      return 1;
    } else {
      return 0;
    }
  } else {
    return 0;
  }
}

static
void printVectorTable( int indentation, PP_ vtbl )
{
  if (isVTBLEntry( (P_) vtbl )) { /* Direct return */
    printName( (P_) vtbl );
  } else {
    int i = 0;
    while( isVTBLEntry( vtbl[RVREL(i)] )) {
      printIndentation( indentation );
      printf( "%d -> ", i );
      printName( vtbl[RVREL(i)] );
      printf( "\n" );
      i = i + 1;
    }
  }
}

static
void printContinuations( int depth, int indentation, int weight, PP_ SpA, PP_ SuA, P_ SpB, P_ SuB )
{
  if (depth < maxDepth && SUBTRACT_B_STK(SuB, stackInfo.botB) >= 0) {
    PP_ nextSpA, nextSuA;
    P_  nextSpB, nextSuB;
    int nextIndent = indentation; /* Indentation to print next frame at */

    /* ToDo: GhcConstants.lh reveals that there are two other sizes of
       update frame possible */
    /* ToDo: botB is probably wrong in THREAD system */

    /* ToDo: ASSERT that SuA == nextSuA */

    nextSpB = SuB + BREL(STD_UF_SIZE);
    nextSuB = GRAB_SuB( SuB );
    nextSpA = SuA;
    nextSuA = GRAB_SuA( nextSuB );

    if (DEBUG_details > 0) { /* print update information */

      if (SpB != SuB) { /* start of chain of update frames */
	printIndentation( indentation );
	printf("of updatePtr ->\n");
	printIndentation( indentation+1 );
	printf("update\n");
      }
      printIndentation( indentation+2 );
      printClosure( (P_)*(SuB + BREL(UF_UPDATEE)), indentation+2, weight );
      printf(" := ");
      printName( (P_) *(SuB + BREL(UF_RET)) );
      printf("(updatePtr)\n");

      if (nextSpB != nextSuB) { /* end of chain of update frames */
	nextIndent = nextIndent-1;
	printVectorTable( indentation+1, (PP_) *(nextSpB) );
      }
    } else {
      if (nextSpB != nextSuB) { /* end of chain of update frames */
	nextIndent = nextIndent-1;
	printVectorTable( indentation, (PP_) *(nextSpB) );
      }
    }
    printContinuations( depth+1, nextIndent, weight, nextSpA, nextSuA, nextSpB, nextSuB );

  } else {
    printf("...\n");
  }
}


void DEBUG_Where( int depth, int weight )
{
#ifdef PAR
  PP_ SpA  = STKO_SpA(SAVE_StkO);
  PP_ SuA  = STKO_SuA(SAVE_StkO);
  P_  SpB  = STKO_SpB(SAVE_StkO);
  P_  SuB  = STKO_SuB(SAVE_StkO);
#else
  PP_ SpA  = SAVE_SpA;
  PP_ SuA  = SAVE_SuA;
  P_  SpB  = SAVE_SpB;
  P_  SuB  = SAVE_SuB;
#endif
  P_ Hp    = SAVE_Hp;
  StgRetAddr RetReg = SAVE_Ret;
  P_ Node  = SAVE_R1.p;

  int indentation;

  maxDepth = depth;

  printf("WARNING: Non-updating cases may be incorrectly displayed\n");

  indentation = printCases( 1, weight, SpA, SuA, SpB, SuB );

  printIndentation( indentation );
  printf("CASE\n");

  printIndentation( indentation+1 );
  printName( Node );
  printf("\n");
  printVectorTable( indentation+1, (PP_) RetReg );

  printContinuations( depth, indentation, weight, SpA, SuA, SpB, SuB );
}  
\end{code}


\begin{code}
#if defined(RUNTIME_DEBUGGING)

void
DEBUG_INFO_TABLE(node)
P_ node;
{
  int vhs, size, ptrs; /* not used */
  char *ip_type;
  StgPtr info_ptr = (StgPtr) INFO_PTR(node);

  getClosureShape(node, &vhs, &size, &ptrs, &ip_type);

  fprintf(stderr,
	  "%s Info Ptr 0x%lx; Entry: 0x%lx; Update: 0x%lx\n",
	  ip_type, info_ptr,
	  (W_) ENTRY_CODE(info_ptr), (W_) UPDATE_CODE(info_ptr));
  fprintf(stderr,
	  "Tag: %d; Type: %d; Size: %lu; Ptrs: %lu\n\n",
	  INFO_TAG(info_ptr), INFO_TYPE(info_ptr),
	  INFO_SIZE(info_ptr),INFO_NoPTRS(info_ptr));
#if defined(PAR)
  fprintf(stderr,"Enter Flush Entry: 0x%lx;\tExit Flush Entry: 0x%lx\n",INFO_FLUSHENT(info_ptr),INFO_FLUSH(info_ptr));
#endif /* PAR */

#if defined(USE_COST_CENTRES)
  fprintf(stderr,"Cost Centre:       0x%lx\n",INFO_CAT(info_ptr));
#endif /* USE_COST_CENTRES */

#if defined(_INFO_COPYING)
  fprintf(stderr,"Evacuate Entry:    0x%lx;\tScavenge Entry: 0x%lx\n",
	  INFO_EVAC_2S(info_ptr),INFO_SCAV_2S(info_ptr));
#endif /* INFO_COPYING */

#if defined(_INFO_COMPACTING)
  fprintf(stderr,"Scan Link:         0x%lx;\tScan Move:      0x%lx\n",
	  (W_) INFO_SCAN_LINK_1S(info_ptr), (W_) INFO_SCAN_MOVE_1S(info_ptr));
  fprintf(stderr,"Mark:              0x%lx;\tMarked:         0x%lx;\n",
	  (W_) INFO_MARK_1S(info_ptr), (W_) INFO_MARKED_1S(info_ptr));
  if(BASE_INFO_TYPE(info_ptr)==INFO_SPEC_TYPE)
    fprintf(stderr,"plus specialised code\n");
  else
    fprintf(stderr,"Marking:           0x%lx\n",(W_) INFO_MARKING_1S(info_ptr));
#endif /* INFO_COMPACTING */
}

void
DEBUG_REGS()
{
#ifdef PAR
  PP_ SpA  = STKO_SpA(SAVE_StkO);
  PP_ SuA  = STKO_SuA(SAVE_StkO);
  P_  SpB  = STKO_SpB(SAVE_StkO);
  P_  SuB  = STKO_SuB(SAVE_StkO);
#else
  PP_ SpA  = SAVE_SpA;
  PP_ SuA  = SAVE_SuA;
  P_  SpB  = SAVE_SpB;
  P_  SuB  = SAVE_SuB;
#endif
  P_  Hp   = SAVE_Hp;
  P_  HpLim= SAVE_HpLim;
  I_  TagReg= SAVE_Tag;
  StgRetAddr RetReg = SAVE_Ret;
  P_  Node = SAVE_R1.p;
  StgUnion  R1   = SAVE_R1;
  StgUnion  R2   = SAVE_R2;
  StgUnion  R3   = SAVE_R3;
  StgUnion  R4   = SAVE_R4;
  StgUnion  R5   = SAVE_R5;
  StgUnion  R6   = SAVE_R6;
  StgUnion  R7   = SAVE_R7;
  StgUnion  R8   = SAVE_R8;
  StgFloat FltReg1 = SAVE_Flt1;
  StgFloat FltReg2 = SAVE_Flt2;
  StgFloat FltReg3 = SAVE_Flt3;
  StgFloat FltReg4 = SAVE_Flt4;
  StgDouble DblReg1 = SAVE_Dbl1;
  StgDouble DblReg2 = SAVE_Dbl2;

  fprintf(stderr,"STG-Machine Register Values:\n\n");
  fprintf(stderr,"Node:  %08lx;  Hp:    %08lx;  HpLim: %08lx;  Tag:   %8lu\n",Node,(W_)Hp,(W_)HpLim,TagReg);
  fprintf(stderr,"SpA:   %08lx;  SpB:   %08lx;  SuA:   %08lx;  SuB:   %08lx\n",(W_)SpA,(W_)SpB,(W_)SuA,(W_)SuB);
  fprintf(stderr,"RetReg: %08lx\n",RetReg);

#if 0
/* These bits need to have the FLUSH_REG_MAP, whereas the surrounding bits
   use the MAIN_REG_MAP */

  fprintf(stderr, "\n");
  fprintf(stderr,"LiveR: %08lx\n", LivenessReg);
  fprintf(stderr,"Flush: %08lx;  FStk:  %08lx;  FStkB: %08lx;  FTmp:  %08lx\n",(W_)FlushP,(W_)FStack,(W_)FStackBase,(W_)Temp);
#endif /* 0 */

  fprintf(stderr, "\n");

  fprintf(stderr,"Gen:   %8lu, %8lu, %8lu, %8lu\n",R1.i,R2.i,R3.i,R4.i);
  fprintf(stderr,"       %8lu, %8lu, %8lu, %8lu\n",R5.i,R6.i,R7.i,R8.i);
  fprintf(stderr,"Float: %8g, %8g, %8g, %8g\n",FltReg1,FltReg2,FltReg3,FltReg4);
  fprintf(stderr,"Dble:  %8g, %8g\n",DblReg1,DblReg2);
}

void
DEBUG_MP()
{
  StgPtr mp;
  StgInt i;

  fprintf(stderr,"MallocPtrList\n\n");

  for(mp = StorageMgrInfo.MallocPtrList; 
      mp != NULL; 
      mp = MallocPtr_CLOSURE_LINK(mp)) {

    fprintf(stderr, "MallocPtr(0x%lx) = 0x%lx\n", mp, MallocPtr_CLOSURE_DATA(mp));

/*
    DEBUG_PRINT_NODE(mp);
*/
  }

#if defined(GCap) || defined(GCgn)
  fprintf(stderr,"\nOldMallocPtr List\n\n");

  for(mp = StorageMgrInfo.OldMallocPtrList; 
      mp != NULL; 
      mp = MallocPtr_CLOSURE_LINK(mp)) {

    fprintf(stderr, "  MallocPtr(0x%lx) = 0x%lx\n", mp, MallocPtr_CLOSURE_DATA(mp));
/*  
   DEBUG_PRINT_NODE(mp);
*/
  }
#endif /* GCap || GCgn */

  fprintf(stderr, "\n");
}

#ifndef PAR
void
DEBUG_SPT(int weight)
{ 
  StgPtr SPTable = StorageMgrInfo.StablePointerTable;
  StgInt size = SPT_SIZE(SPTable);
  StgInt ptrs = SPT_NoPTRS(SPTable);
  StgInt top = SPT_TOP(SPTable);

  StgInt i;

/*
  DEBUG_PRINT_NODE(SPTable);
*/

  fprintf(stderr,"SPTable@0x%lx:\n", SPTable);
  fprintf(stderr,"  InfoPtr = 0x%lx\n", INFO_PTR(SPTable));
  fprintf(stderr,"  size = %d, ptrs = %d, top = %d\n",
	            size,      ptrs,      top
	 );
  for( i=0; i < ptrs; i++ ) {
    if (i % 10 == 0) {
      fprintf(stderr,"\n  ");
    }
    printClosure(SPT_SPTR(SPTable, i),1,weight);
    fprintf(stderr, "\n");
  }
  fprintf(stderr, "\n");
  for( i=0; i < top; i++) {
    if (i % 10 == 0) {
      fprintf(stderr,"\n  ");
    }
    fprintf(stderr, " %3d", SPT_FREE(SPTable, i));
  }
  
  fprintf(stderr, "\n\n");

}
#endif /* !PAR */       


/*
  These routines crawl over the A and B stacks, printing
  a maximum "lines" lines at the top of the stack.
*/


#define	STACK_VALUES_PER_LINE	5

#if !defined(PAR)
/* (stack stuff is really different on parallel machines) */

void
DEBUG_ASTACK(lines)
I_ lines;
{
  PP_ SpA  = SAVE_SpA;
  PP_ SuA  = SAVE_SuA;
  P_  SpB  = SAVE_SpB;
  P_  SuB  = SAVE_SuB;

  PP_	stackptr;
  I_ count = 0;

  fprintf(stderr,"Dump of the Address Stack, SpA: 0x%08lx, BOS: 0x%08lx\n",
		    (W_) SpA, (W_) stackInfo.botA);
  
  for (stackptr = SpA;
       SUBTRACT_A_STK(stackptr, stackInfo.botA) >= 0;
       stackptr = stackptr + AREL(1)) 
    {
      if( count++ % STACK_VALUES_PER_LINE == 0)
	{
	  if(count >= lines * STACK_VALUES_PER_LINE)
	    break;
	  fprintf(stderr,"\nSpA[%ld] (0x%08lx): ",count-1,stackptr);
	}
      fprintf(stderr,"0x%08lx ",(W_) *stackptr);
    }
  fprintf(stderr, "\n");
}


void
DEBUG_BSTACK(lines)
I_ lines;
{
  PP_ SpA  = SAVE_SpA;
  PP_ SuA  = SAVE_SuA;
  P_  SpB  = SAVE_SpB;
  P_  SuB  = SAVE_SuB;

  P_	stackptr;
  I_ count = 0;

  fprintf(stderr,"Dump of the Value Stack, SpB: 0x%08lx, BOS: 0x%08lx\n",
		(W_) SpB, (W_) stackInfo.botB);
  
  for (stackptr = SpB;
	 SUBTRACT_B_STK(stackptr, stackInfo.botB) > 0;
	 stackptr = stackptr + BREL(1)) 
      {
	if( count++ % STACK_VALUES_PER_LINE == 0)
	  {
	    if(count >= lines * STACK_VALUES_PER_LINE)
	      break;
	    fprintf(stderr,"\nSpB[%ld] (0x%08lx): ",count-1,stackptr);
	  }
	fprintf(stderr,"0x%08lx ",(W_) *stackptr);
      }
  fprintf(stderr, "\n");
}
#endif /* not parallel */

/*
  This should disentangle update frames from both stacks.
*/

#if ! defined(PAR)
void
DEBUG_UPDATES(limit)
I_ limit;
{
  PP_ SpA  = SAVE_SpA;
  PP_ SuA  = SAVE_SuA;
  P_  SpB  = SAVE_SpB;
  P_  SuB  = SAVE_SuB;

  P_ updatee, retreg;
  PP_ sua;
  P_ sub;
  PP_ spa = SuA;
  P_ spb = SuB;
  I_ count = 0;

  fprintf(stderr,"Update Frame Stack Dump:\n\n");
  
  for(spb = SuB;
      SUBTRACT_B_STK(spb, stackInfo.botB) > 0 && count++ < limit;
      /* re-init given explicitly */)
    {
      updatee = GRAB_UPDATEE(spb); 	   /* Thing to be updated  */
      retreg  = (P_) GRAB_RET(spb); 	   /* Return vector below */

      fprintf(stderr,"SuA: 0x%08lx, SuB: 0x%08lx, Updatee 0x%08lx, RetReg 0x%x\n",
	             (W_) spa, (W_) spb,
		     (W_) updatee, (W_) retreg);

      spa = GRAB_SuA(spb);                 /* Next SuA, SuB */
      spb = GRAB_SuB(spb);
    }
}
#endif /* not parallel */

#endif /* RUNTIME_DEBUGGING */

#endif /* PAR || RUNTIME_DEBUGGING */
\end{code}