runtime/libtrace/tracelib.c

/*===-- Libraries/tracelib.c - Runtime routines for tracing -----*- C++ -*--===
 *
 * Runtime routines for supporting tracing of execution
 * for code generated by LLVM.
 *
 *===---------------------------------------------------------------------===*/

#include "tracelib.h"
#include <assert.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>


/*===---------------------------------------------------------------------=====
 * HASH FUNCTIONS
 *===---------------------------------------------------------------------===*/

/* use #defines until we have inlining */

typedef int64_t Generic;
typedef uint64_t Index;
typedef ptrdiff_t Pointer;

/* Index IntegerHashFunc(const Generic value, const Index size) */
#define IntegerHashFunc(value, size) \
  (value % size)

/* Index IntegerRehashFunc(const Generic oldHashValue, const Index size) */
#define IntegerRehashFunc(oldHashValue, size) \
  ((oldHashValue+16) % size) /* 16 is relatively prime to a Mersenne prime! */

/* Index PointerHashFunc(const void* value, const Index size) */
#define PointerHashFunc(value, size) \
  IntegerHashFunc((Pointer) value, size)

/* Index PointerRehashFunc(const void* value, const Index size) */
#define PointerRehashFunc(value, size) \
  IntegerRehashFunc((Pointer) value, size)


/*===---------------------------------------------------------------------=====
 * POINTER-TO-GENERIC HASH TABLE.
 * These should be moved to a separate location: HashTable.[ch]
 *===---------------------------------------------------------------------===*/

typedef enum { FIND, ENTER } ACTION;
typedef char FULLEMPTY;
const FULLEMPTY EMPTY = '\0';
const FULLEMPTY FULL  = '\1';

const uint MAX_NUM_PROBES = 4;

typedef struct PtrValueHashEntry_struct {
  void*   key;
  Generic value;
} PtrValueHashEntry;

typedef struct PtrValueHashTable_struct {
  PtrValueHashEntry* table;
  FULLEMPTY* fullEmptyFlags;
  Index capacity;
  Index size;
} PtrValueHashTable;


extern Generic LookupOrInsertPtr(PtrValueHashTable* ptrTable,
                                 void* ptr, ACTION action);

extern void Insert(PtrValueHashTable* ptrTable, void* ptr, Generic value);

extern void Delete(PtrValueHashTable* ptrTable, void* ptr);


void
InitializeTable(PtrValueHashTable* ptrTable, Index newSize)
{
  ptrTable->table = (PtrValueHashEntry*) malloc(newSize *
                                                sizeof(PtrValueHashEntry));
  ptrTable->fullEmptyFlags = (FULLEMPTY*) malloc(newSize * sizeof(FULLEMPTY));
  memset(ptrTable->fullEmptyFlags, '\0', newSize * sizeof(FULLEMPTY));
  ptrTable->capacity = newSize;
  ptrTable->size = 0;
}

PtrValueHashTable*
CreateTable(Index initialSize)
{
  PtrValueHashTable* ptrTable =
    (PtrValueHashTable*) malloc(sizeof(PtrValueHashTable));
  InitializeTable(ptrTable, initialSize);
  return ptrTable;
}

void
ReallocTable(PtrValueHashTable* ptrTable, Index newSize)
{
  if (newSize > ptrTable->capacity)
    {
      unsigned int i;
      
      PtrValueHashEntry* oldTable = ptrTable->table;
      FULLEMPTY* oldFlags = ptrTable->fullEmptyFlags; 
      Index oldSize = ptrTable->size;
      
      /* allocate the new storage and flags and re-insert the old entries */
      InitializeTable(ptrTable, newSize);
      for (i=0; i < oldSize; ++i) 
        Insert(ptrTable, oldTable[i].key, oldTable[i].value);
      assert(ptrTable->size == oldSize);
      
      free(oldTable);
      free(oldFlags);
    }
}

void
DeleteTable(PtrValueHashTable* ptrTable)
{
  free(ptrTable->table);
  free(ptrTable->fullEmptyFlags);
  memset(ptrTable, '\0', sizeof(PtrValueHashTable));
  free(ptrTable);
}

void
InsertAtIndex(PtrValueHashTable* ptrTable, void* ptr, Generic value, Index index)
{
  assert(ptrTable->fullEmptyFlags[index] == EMPTY && "Slot is in use!");
  ptrTable->table[index].key = ptr; 
  ptrTable->table[index].value = value; 
  ptrTable->fullEmptyFlags[index] = FULL;
  ptrTable->size++;
}

void
DeleteAtIndex(PtrValueHashTable* ptrTable, Index index)
{
  assert(ptrTable->fullEmptyFlags[index] == FULL && "Deleting empty slot!");
  ptrTable->table[index].key = NULL; 
  ptrTable->table[index].value = (Generic) NULL; 
  ptrTable->fullEmptyFlags[index] = EMPTY;
  ptrTable->size--;
}

Index
FindIndex(PtrValueHashTable* ptrTable, void* ptr)
{
  uint numProbes = 1;
  Index index = PointerHashFunc(ptr, ptrTable->capacity);
  if (ptrTable->fullEmptyFlags[index] == FULL)
    {
      if (ptrTable->table[index].key == ptr)
        return index;
      
      /* First lookup failed on non-empty slot: probe further */
      while (numProbes < MAX_NUM_PROBES)
        {
          index = PointerRehashFunc(index, ptrTable->capacity);
          if (ptrTable->fullEmptyFlags[index] == EMPTY)
            break;
          else if (ptrTable->table[index].key == ptr)
            return index;
          ++numProbes;
        }
    }
  
  /* Lookup failed: item is not in the table. */
  /* If last slot is empty, use that slot. */
  /* Otherwise, table must have been reallocated, so search again. */
  
  if (numProbes == MAX_NUM_PROBES)
    { /* table is too full: reallocate and search again */
      ReallocTable(ptrTable, 1 + 2*ptrTable->capacity);
      return FindIndex(ptrTable, ptr);
    }
  else
    {
      assert(ptrTable->fullEmptyFlags[index] == EMPTY &&
             "Stopped before finding an empty slot and before MAX probes!");
      return index;
    }
}

Generic
LookupOrInsertPtr(PtrValueHashTable* ptrTable, void* ptr, ACTION action)
{
  Index index = FindIndex(ptrTable, ptr);
  if (ptrTable->fullEmptyFlags[index] == FULL &&
      ptrTable->table[index].key == ptr)
    return ptrTable->table[index].value;
  
  /* Lookup failed: item is not in the table */
  if (action != ENTER)
    return (Generic) NULL;
  
  /* Insert item into the table and return its index */
  InsertAtIndex(ptrTable, ptr, (Generic) NULL, index);
  return (Generic) NULL;
}

/* Returns NULL if the item is not found. */
/* void* LookupPtr(PtrValueHashTable* ptrTable, void* ptr) */
#define LookupPtr(ptrTable, ptr) \
  LookupOrInsertPtr(ptrTable, ptr, FIND)

void
Insert(PtrValueHashTable* ptrTable, void* ptr, Generic value)
{
  Index index = FindIndex(ptrTable, ptr);
  assert(ptrTable->fullEmptyFlags[index] == EMPTY &&
         "ptr is already in the table: delete it first!");
  InsertAtIndex(ptrTable, ptr, value, index);
}

void
Delete(PtrValueHashTable* ptrTable, void* ptr)
{
  Index index = FindIndex(ptrTable, ptr);
  if (ptrTable->fullEmptyFlags[index] == FULL &&
      ptrTable->table[index].key == ptr)
    {
      DeleteAtIndex(ptrTable, index);
    }
}

/*===---------------------------------------------------------------------=====
 * RUNTIME ROUTINES TO MAP POINTERS TO SEQUENCE NUMBERS
 *===---------------------------------------------------------------------===*/

PtrValueHashTable* SequenceNumberTable = NULL;
Index INITIAL_SIZE = 1 << 18;

#define MAX_NUM_SAVED 1024

typedef struct PointerSet_struct {
  char* savedPointers[MAX_NUM_SAVED];   /* 1024 alloca'd ptrs shd suffice */
  unsigned int numSaved;
  struct PointerSet_struct* nextOnStack;     /* implement a cheap stack */ 
} PointerSet;

PointerSet* topOfStack = NULL;

SequenceNumber
HashPointerToSeqNum(char* ptr)
{
  static SequenceNumber count = 0;
  SequenceNumber seqnum;
  if (SequenceNumberTable == NULL) {
    assert(MAX_NUM_PROBES < INITIAL_SIZE+1 && "Initial size too small");
    SequenceNumberTable = CreateTable(INITIAL_SIZE);
  }
  seqnum = (SequenceNumber) LookupPtr(SequenceNumberTable, ptr);
  if (seqnum == 0)
    {
      Insert(SequenceNumberTable, ptr, ++count);
      seqnum = count;
    }
  return seqnum;
}

void
ReleasePointerSeqNum(char* ptr)
{ /* if a sequence number was assigned to this ptr, release it */
  SequenceNumber seqnum;
  if (SequenceNumberTable != NULL)
    Delete(SequenceNumberTable, ptr);
}

void
PushPointerSet()
{
  PointerSet* newSet = (PointerSet*) malloc(sizeof(PointerSet));
  newSet->numSaved = 0;
  newSet->nextOnStack = topOfStack;
  topOfStack = newSet;
}

void
PopPointerSet()
{
  PointerSet* oldSet;
  assert(topOfStack != NULL && "popping from empty stack!");
  oldSet = topOfStack; 
  topOfStack = oldSet->nextOnStack;
  assert(oldSet->numSaved == 0);
  free(oldSet);
}

/* free the pointers! */
static void
ReleaseRecordedPointers(char* savedPointers[MAX_NUM_SAVED],
                        unsigned int numSaved)
{
  unsigned int i;
  for (i=0; i < topOfStack->numSaved; ++i)
    ReleasePointerSeqNum(topOfStack->savedPointers[i]);  
}

void
ReleasePointersPopSet()
{
  ReleaseRecordedPointers(topOfStack->savedPointers, topOfStack->numSaved);
  topOfStack->numSaved = 0;
  PopPointerSet();
}

void
RecordPointer(char* ptr)
{ /* record pointers for release later */
  if (topOfStack->numSaved == MAX_NUM_SAVED) {
    printf("***\n*** WARNING: OUT OF ROOM FOR SAVED POINTERS."
           " ALL POINTERS ARE BEING FREED.\n"
           "*** THE SEQUENCE NUMBERS OF SAVED POINTERS WILL CHANGE!\n*** \n");
    ReleaseRecordedPointers(topOfStack->savedPointers, topOfStack->numSaved);
    topOfStack->numSaved = 0;
  }
  topOfStack->savedPointers[topOfStack->numSaved++] = ptr;
}

/*===---------------------------------------------------------------------=====
 * TEST DRIVER FOR INSTRUMENTATION LIBRARY
 *===---------------------------------------------------------------------===*/

#ifndef TEST_INSTRLIB
#undef  TEST_INSTRLIB /* #define this to turn on by default */
#endif

#ifdef TEST_INSTRLIB
int
main(int argc, char** argv)
{
  int i, j;
  int doRelease = 0;

  INITIAL_SIZE = 5; /* start with small table to test realloc's*/
  
  if (argc > 1 && ! strcmp(argv[1], "-r"))
    {
      PushPointerSet();
      doRelease = 1;
    }
  
  for (i=0; i < argc; ++i)
    for (j=0; argv[i][j]; ++j)
      {
        printf("Sequence number for argc[%d][%d] (%c) = Hash(%p) = %d\n",
               i, j, argv[i][j], argv[i]+j, HashPointerToSeqNum(argv[i]+j));
        
        if (doRelease)
          RecordPointer(argv[i]+j);
      }
  
  if (doRelease)
    ReleasePointersPopSet();     
  
  /* print sequence numbers out again to compare with (-r) and w/o release */
  for (i=argc-1; i >= 0; --i)
    for (j=0; argv[i][j]; ++j)
      printf("Sequence number for argc[%d][%d] (%c) = Hash(%p) = %d\n",
             i, j, argv[i][j], argv[i]+j, HashPointerToSeqNum(argv[i]+j));
  
  return 0;
}
#endif