SQLite

Check-in [3b3e32d4cd]
Login

Many hyperlinks are disabled.
Use anonymous login to enable hyperlinks.

Overview
Comment:Small size and performance optimization in the bytecode engine.
Downloads: Tarball | ZIP archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA3-256: 3b3e32d4cd07a1d2d1708fffa47819345ae6b39205a9f548280d499c8f481d64
User & Date: drh 2017-09-20 17:49:12.127
References
2017-09-21
01:04
Revert one performance improvement changes from check-in [3b3e32d4cd07] as it was causing a reference to an uninitialized value. (check-in: f8b1c64d3e user: drh tags: trunk)
Context
2017-09-20
18:07
The BLOB returned by sqlite3VdbeMemFromBtree() does not need to be zero-terminated. (check-in: e0af9a9040 user: drh tags: trunk)
17:49
Small size and performance optimization in the bytecode engine. (check-in: 3b3e32d4cd user: drh tags: trunk)
10:47
Improved resolution of large integer values in "CAST(x AS NUMERIC)". (check-in: 7f2bd4ff45 user: drh tags: trunk)
Changes
Side-by-Side Diff Ignore Whitespace Patch
Changes to src/vdbemem.c.
︙
110
111
112
113
114
115
116
117

118
119
120
121
122
123
124

110
111
112
113
114
115
116

117
118
119
120
121
122
123
124








-
+








int sqlite3VdbeChangeEncoding(Mem *pMem, int desiredEnc){
#ifndef SQLITE_OMIT_UTF16
  int rc;
#endif
  assert( (pMem->flags&MEM_RowSet)==0 );
  assert( desiredEnc==SQLITE_UTF8 || desiredEnc==SQLITE_UTF16LE
           || desiredEnc==SQLITE_UTF16BE );
  if( !(pMem->flags&MEM_Str) || pMem->enc==desiredEnc ){
  if( pMem->enc==desiredEnc || !(pMem->flags&MEM_Str) ){
    return SQLITE_OK;
  }
  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
#ifdef SQLITE_OMIT_UTF16
  return SQLITE_ERROR;
#else
︙
204
205
206
207
208
209
210














211
212
213
214
215
216
217
218
219
220
221
222
223
224
225


226
227
228
229
230
231
232
233
234
235
236

204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237


238
239




240
241
242
243
244
245
246








+
+
+
+
+
+
+
+
+
+
+
+
+
+













-
-
+
+
-
-
-
-








    return sqlite3VdbeMemGrow(pMem, szNew, 0);
  }
  assert( (pMem->flags & MEM_Dyn)==0 );
  pMem->z = pMem->zMalloc;
  pMem->flags &= (MEM_Null|MEM_Int|MEM_Real);
  return SQLITE_OK;
}

/*
** It is already known that pMem contains an unterminated string.
** Add the zero terminator.
*/
static SQLITE_NOINLINE int vdbeMemAddTerminator(Mem *pMem){
  if( sqlite3VdbeMemGrow(pMem, pMem->n+2, 1) ){
    return SQLITE_NOMEM_BKPT;
  }
  pMem->z[pMem->n] = 0;
  pMem->z[pMem->n+1] = 0;
  pMem->flags |= MEM_Term;
  return SQLITE_OK;
}

/*
** Change pMem so that its MEM_Str or MEM_Blob value is stored in
** MEM.zMalloc, where it can be safely written.
**
** Return SQLITE_OK on success or SQLITE_NOMEM if malloc fails.
*/
int sqlite3VdbeMemMakeWriteable(Mem *pMem){
  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
  assert( (pMem->flags&MEM_RowSet)==0 );
  if( (pMem->flags & (MEM_Str|MEM_Blob))!=0 ){
    if( ExpandBlob(pMem) ) return SQLITE_NOMEM;
    if( pMem->szMalloc==0 || pMem->z!=pMem->zMalloc ){
      if( sqlite3VdbeMemGrow(pMem, pMem->n + 2, 1) ){
        return SQLITE_NOMEM_BKPT;
      int rc = vdbeMemAddTerminator(pMem);
      if( rc ) return rc;
      }
      pMem->z[pMem->n] = 0;
      pMem->z[pMem->n+1] = 0;
      pMem->flags |= MEM_Term;
    }
  }
  pMem->flags &= ~MEM_Ephem;
#ifdef SQLITE_DEBUG
  pMem->pScopyFrom = 0;
#endif
︙
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288

271
272
273
274
275
276
277














278
279
280
281
282
283
284








-
-
-
-
-
-
-
-
-
-
-
-
-
-








  memset(&pMem->z[pMem->n], 0, pMem->u.nZero);
  pMem->n += pMem->u.nZero;
  pMem->flags &= ~(MEM_Zero|MEM_Term);
  return SQLITE_OK;
}
#endif

/*
** It is already known that pMem contains an unterminated string.
** Add the zero terminator.
*/
static SQLITE_NOINLINE int vdbeMemAddTerminator(Mem *pMem){
  if( sqlite3VdbeMemGrow(pMem, pMem->n+2, 1) ){
    return SQLITE_NOMEM_BKPT;
  }
  pMem->z[pMem->n] = 0;
  pMem->z[pMem->n+1] = 0;
  pMem->flags |= MEM_Term;
  return SQLITE_OK;
}

/*
** Make sure the given Mem is \u0000 terminated.
*/
int sqlite3VdbeMemNulTerminate(Mem *pMem){
  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
  testcase( (pMem->flags & (MEM_Term|MEM_Str))==(MEM_Term|MEM_Str) );
  testcase( (pMem->flags & (MEM_Term|MEM_Str))==0 );
︙