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Overview
Comment:Rearrange fields in the Parse object to reduce the amount of initialization required.
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SHA1: 361940b44dd17bf2b39fc0e0716c0de6b2b7f4f7
User & Date: drh 2016-10-01 21:43:37.888
Context
2016-10-01
23:55
Add SQLITE_USE_ALLOCA to the --lean configuration in speed-check.sh. (check-in: fe07609efc user: drh tags: trunk)
21:43
Rearrange fields in the Parse object to reduce the amount of initialization required. (check-in: 361940b44d user: drh tags: trunk)
20:43
Reduce the width of a memset() to avoid double-initializing some variables. (check-in: 34edbfd12d user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/sqliteInt.h.
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  u8 nTempReg;         /* Number of temporary registers in aTempReg[] */
  u8 isMultiWrite;     /* True if statement may modify/insert multiple rows */
  u8 mayAbort;         /* True if statement may throw an ABORT exception */
  u8 hasCompound;      /* Need to invoke convertCompoundSelectToSubquery() */
  u8 okConstFactor;    /* OK to factor out constants */
  u8 disableLookaside; /* Number of times lookaside has been disabled */
  u8 nColCache;        /* Number of entries in aColCache[] */
  int aTempReg[8];     /* Holding area for temporary registers */
  int nRangeReg;       /* Size of the temporary register block */
  int iRangeReg;       /* First register in temporary register block */
  int nErr;            /* Number of errors seen */
  int nTab;            /* Number of previously allocated VDBE cursors */
  int nMem;            /* Number of memory cells used so far */
  int nOpAlloc;        /* Number of slots allocated for Vdbe.aOp[] */
  int szOpAlloc;       /* Bytes of memory space allocated for Vdbe.aOp[] */







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  u8 nTempReg;         /* Number of temporary registers in aTempReg[] */
  u8 isMultiWrite;     /* True if statement may modify/insert multiple rows */
  u8 mayAbort;         /* True if statement may throw an ABORT exception */
  u8 hasCompound;      /* Need to invoke convertCompoundSelectToSubquery() */
  u8 okConstFactor;    /* OK to factor out constants */
  u8 disableLookaside; /* Number of times lookaside has been disabled */
  u8 nColCache;        /* Number of entries in aColCache[] */

  int nRangeReg;       /* Size of the temporary register block */
  int iRangeReg;       /* First register in temporary register block */
  int nErr;            /* Number of errors seen */
  int nTab;            /* Number of previously allocated VDBE cursors */
  int nMem;            /* Number of memory cells used so far */
  int nOpAlloc;        /* Number of slots allocated for Vdbe.aOp[] */
  int szOpAlloc;       /* Bytes of memory space allocated for Vdbe.aOp[] */
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  int nSelectIndent;   /* How far to indent SELECTTRACE() output */
#endif
#ifndef SQLITE_OMIT_SHARED_CACHE
  int nTableLock;        /* Number of locks in aTableLock */
  TableLock *aTableLock; /* Required table locks for shared-cache mode */
#endif
  AutoincInfo *pAinc;  /* Information about AUTOINCREMENT counters */

  /* Information used while coding trigger programs. */
  Parse *pToplevel;    /* Parse structure for main program (or NULL) */
  Table *pTriggerTab;  /* Table triggers are being coded for */
  int addrCrTab;       /* Address of OP_CreateTable opcode on CREATE TABLE */
  u32 nQueryLoop;      /* Est number of iterations of a query (10*log2(N)) */
  u32 oldmask;         /* Mask of old.* columns referenced */
  u32 newmask;         /* Mask of new.* columns referenced */
  u8 eTriggerOp;       /* TK_UPDATE, TK_INSERT or TK_DELETE */
  u8 eOrconf;          /* Default ON CONFLICT policy for trigger steps */
  u8 disableTriggers;  /* True to disable triggers */



  /* The column cache comes at the end of the recursive section
  ** When initializing a new Parse object, the header above, and


  ** the non-recursive part that follows the column cache both need
  ** to be zeroed.  But the column cache itself does not need zeroing
  */
  struct yColCache {
    int iTable;           /* Table cursor number */
    i16 iColumn;          /* Table column number */
    u8 tempReg;           /* iReg is a temp register that needs to be freed */
    int iLevel;           /* Nesting level */
    int iReg;             /* Reg with value of this column. 0 means none. */
    int lru;              /* Least recently used entry has the smallest value */
  } aColCache[SQLITE_N_COLCACHE];  /* One for each column cache entry */




  /************************************************************************
  ** Above is constant between recursions.  Below is reset before and after
  ** each recursion.  The boundary between these two regions is determined
  ** using offsetof(Parse,nVar) so the nVar field must be the first field
  ** in the recursive region.
  ************************************************************************/







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  int nSelectIndent;   /* How far to indent SELECTTRACE() output */
#endif
#ifndef SQLITE_OMIT_SHARED_CACHE
  int nTableLock;        /* Number of locks in aTableLock */
  TableLock *aTableLock; /* Required table locks for shared-cache mode */
#endif
  AutoincInfo *pAinc;  /* Information about AUTOINCREMENT counters */


  Parse *pToplevel;    /* Parse structure for main program (or NULL) */
  Table *pTriggerTab;  /* Table triggers are being coded for */
  int addrCrTab;       /* Address of OP_CreateTable opcode on CREATE TABLE */
  u32 nQueryLoop;      /* Est number of iterations of a query (10*log2(N)) */
  u32 oldmask;         /* Mask of old.* columns referenced */
  u32 newmask;         /* Mask of new.* columns referenced */
  u8 eTriggerOp;       /* TK_UPDATE, TK_INSERT or TK_DELETE */
  u8 eOrconf;          /* Default ON CONFLICT policy for trigger steps */
  u8 disableTriggers;  /* True to disable triggers */

  /**************************************************************************
  ** Fields above must be initialized to zero.  The fields that follow,
  ** down to the beginning of the recursive section, do not need to be
  ** initialized as they will be set before being used.  The boundary is
  ** determined by offsetof(Parse,aColCache).
  **************************************************************************/



  struct yColCache {
    int iTable;           /* Table cursor number */
    i16 iColumn;          /* Table column number */
    u8 tempReg;           /* iReg is a temp register that needs to be freed */
    int iLevel;           /* Nesting level */
    int iReg;             /* Reg with value of this column. 0 means none. */
    int lru;              /* Least recently used entry has the smallest value */
  } aColCache[SQLITE_N_COLCACHE];  /* One for each column cache entry */
  int aTempReg[8];        /* Holding area for temporary registers */
  Token sNameToken;       /* Token with unqualified schema object name */
  Token sLastToken;       /* The last token parsed */

  /************************************************************************
  ** Above is constant between recursions.  Below is reset before and after
  ** each recursion.  The boundary between these two regions is determined
  ** using offsetof(Parse,nVar) so the nVar field must be the first field
  ** in the recursive region.
  ************************************************************************/
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#endif
  char **azVar;             /* Pointers to names of parameters */
  Vdbe *pReprepare;         /* VM being reprepared (sqlite3Reprepare()) */
  const char *zTail;        /* All SQL text past the last semicolon parsed */
  Table *pNewTable;         /* A table being constructed by CREATE TABLE */
  Trigger *pNewTrigger;     /* Trigger under construct by a CREATE TRIGGER */
  const char *zAuthContext; /* The 6th parameter to db->xAuth callbacks */
  Token sNameToken;         /* Token with unqualified schema object name */
  Token sLastToken;         /* The last token parsed */
#ifndef SQLITE_OMIT_VIRTUALTABLE
  Token sArg;               /* Complete text of a module argument */
  Table **apVtabLock;       /* Pointer to virtual tables needing locking */
#endif
  Table *pZombieTab;        /* List of Table objects to delete after code gen */
  TriggerPrg *pTriggerPrg;  /* Linked list of coded triggers */
  With *pWith;              /* Current WITH clause, or NULL */







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#endif
  char **azVar;             /* Pointers to names of parameters */
  Vdbe *pReprepare;         /* VM being reprepared (sqlite3Reprepare()) */
  const char *zTail;        /* All SQL text past the last semicolon parsed */
  Table *pNewTable;         /* A table being constructed by CREATE TABLE */
  Trigger *pNewTrigger;     /* Trigger under construct by a CREATE TRIGGER */
  const char *zAuthContext; /* The 6th parameter to db->xAuth callbacks */


#ifndef SQLITE_OMIT_VIRTUALTABLE
  Token sArg;               /* Complete text of a module argument */
  Table **apVtabLock;       /* Pointer to virtual tables needing locking */
#endif
  Table *pZombieTab;        /* List of Table objects to delete after code gen */
  TriggerPrg *pTriggerPrg;  /* Linked list of coded triggers */
  With *pWith;              /* Current WITH clause, or NULL */