Add the Mempage.aDataOfst field and use it in sqlite3BtreeMovetoUnpacked()

for about a 2 million cycle gain.

FossilOrigin-Name: bee94dc3510745ba2efa044e8f3299793cfc7e34

manifest

@@ -1,5 +1,5 @@
-C Treat\scompilation\sof\sFTS5\sfor\sthe\sloadable\sextension\sspecially\swith\sMSVC.
-D 2015-06-26T20:45:43.839
+C Add\sthe\sMempage.aDataOfst\sfield\sand\suse\sit\sin\ssqlite3BtreeMovetoUnpacked()\nfor\sabout\sa\s2\smillion\scycle\sgain.
+D 2015-06-27T03:58:15.601
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 285a0a234ed7610d431d91671c136098c2bd86a9
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -269,9 +269,9 @@ F src/auth.c b56c78ebe40a2110fd361379f7e8162d23f92240
 F src/backup.c ff743689c4d6c5cb55ad42ed9d174b2b3e71f1e3
 F src/bitvec.c 5eb7958c3bf65210211cbcfc44eff86d0ded7c9d
 F src/btmutex.c 45a968cc85afed9b5e6cf55bf1f42f8d18107f79
-F src/btree.c c113f73fc4048038529cc30ed7147b24c34c2c5d
+F src/btree.c 2a7554d5607f8ded06bf282c8e9e609a32d9ce55
 F src/btree.h 969adc948e89e449220ff0ff724c94bb2a52e9f1
-F src/btreeInt.h fdd1aff02fb2a63812bd95716e7f579fc3759107
+F src/btreeInt.h 426d1e0d1a15d06b3ad2304f4bedc5bb71e5b4a2
 F src/build.c b3f15255d5b16e42dafeaa638fd4f8a47c94ed70
 F src/callback.c 7b44ce59674338ad48b0e84e7b72f935ea4f68b0
 F src/complete.c a5cf5b4b56390cfb7b8636e8f7ddef90258dd575
@@ -1364,7 +1364,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh 48bd54594752d5be3337f12c72f28d2080cb630b
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P d27d9965b5404cd32be1113215fd9feeb5b66acc
-R 3acd5e6aa6095e21a23b200982f0e53b
-U mistachkin
-Z ca7f05b6600c190f8e4e9359f2b7edca
+P 7c610276bb41dbc80fe169d35fe9a3a3f6525635
+R 762529df533e804d7973bafd804366fc
+U drh
+Z 0b74e27756355a1dbfb2275608b79e03

manifest.uuid

@@ -1 +1 @@
-7c610276bb41dbc80fe169d35fe9a3a3f6525635
+bee94dc3510745ba2efa044e8f3299793cfc7e34

src/btree.c

@@ -954,10 +954,16 @@ static int ptrmapGet(BtShared *pBt, Pgno key, u8 *pEType, Pgno *pPgno){
 ** the page, 1 means the second cell, and so forth) return a pointer
 ** to the cell content.
 **
+** findCellPastPtr() does the same except it skips past the initial
+** 4-byte child pointer found on interior pages, if there is one.
+**
 ** This routine works only for pages that do not contain overflow cells.
 */
 #define findCell(P,I) \
   ((P)->aData + ((P)->maskPage & get2byte(&(P)->aCellIdx[2*(I)])))
+#define findCellPastPtr(P,I) \
+  ((P)->aDataOfst + ((P)->maskPage & get2byte(&(P)->aCellIdx[2*(I)])))
+
 
 /*
 ** This is common tail processing for btreeParseCellPtr() and
@@ -1703,6 +1709,7 @@ static int btreeInitPage(MemPage *pPage){
     pPage->cellOffset = cellOffset = hdr + 8 + pPage->childPtrSize;
     pPage->aDataEnd = &data[usableSize];
     pPage->aCellIdx = &data[cellOffset];
+    pPage->aDataOfst = &data[pPage->childPtrSize];
     /* EVIDENCE-OF: R-58015-48175 The two-byte integer at offset 5 designates
     ** the start of the cell content area. A zero value for this integer is
     ** interpreted as 65536. */
@@ -1822,6 +1829,7 @@ static void zeroPage(MemPage *pPage, int flags){
   pPage->cellOffset = first;
   pPage->aDataEnd = &data[pBt->usableSize];
   pPage->aCellIdx = &data[first];
+  pPage->aDataOfst = &data[pPage->childPtrSize];
   pPage->nOverflow = 0;
   assert( pBt->pageSize>=512 && pBt->pageSize<=65536 );
   pPage->maskPage = (u16)(pBt->pageSize - 1);
@@ -5014,7 +5022,7 @@ int sqlite3BtreeMovetoUnpacked(
     if( xRecordCompare==0 ){
       for(;;){
         i64 nCellKey;
-        pCell = findCell(pPage, idx) + pPage->childPtrSize;
+        pCell = findCellPastPtr(pPage, idx);
         if( pPage->intKeyLeaf ){
           while( 0x80 <= *(pCell++) ){
             if( pCell>=pPage->aDataEnd ) return SQLITE_CORRUPT_BKPT;
@@ -5047,7 +5055,7 @@ int sqlite3BtreeMovetoUnpacked(
     }else{
       for(;;){
         int nCell;  /* Size of the pCell cell in bytes */
-        pCell = findCell(pPage, idx) + pPage->childPtrSize;
+        pCell = findCellPastPtr(pPage, idx);
 
         /* The maximum supported page-size is 65536 bytes. This means that
         ** the maximum number of record bytes stored on an index B-Tree

src/btreeInt.h

@@ -295,6 +295,7 @@ struct MemPage {
   u8 *aData;           /* Pointer to disk image of the page data */
   u8 *aDataEnd;        /* One byte past the end of usable data */
   u8 *aCellIdx;        /* The cell index area */
+  u8 *aDataOfst;       /* Same as aData for leaves.  aData+4 for interior */
   DbPage *pDbPage;     /* Pager page handle */
   u16 (*xCellSize)(MemPage*,u8*);             /* cellSizePtr method */
   void (*xParseCell)(MemPage*,u8*,CellInfo*); /* btreeParseCell method */