Performance improvements in btreeParseCell() by inlining the varint decoder.

FossilOrigin-Name: 172a864d14fd9f0e3e97d2a13b22222ae0fedd39

1 files changed, 43 insertions, 4 deletions

diff --git a/src/btree.c b/src/btree.c
index bc3c13437..e64139b80 100644
--- a/src/btree.c
+++ b/src/btree.c
@@ -1054,6 +1054,7 @@ static void btreeParseCellPtr(
 ){
   u8 *pIter;              /* For scanning through pCell */
   u32 nPayload;           /* Number of bytes of cell payload */
+  u64 iKey;               /* Extracted Key value */
 
   assert( sqlite3_mutex_held(pPage->pBt->mutex) );
   assert( pPage->leaf==0 || pPage->leaf==1 );
@@ -1061,8 +1062,46 @@ static void btreeParseCellPtr(
   assert( pPage->noPayload==0 );
   assert( pPage->intKeyLeaf );
   assert( pPage->childPtrSize==0 );
-  pIter = pCell + getVarint32(pCell, nPayload);
-  pIter += getVarint(pIter, (u64*)&pInfo->nKey);
+  pIter = pCell;
+
+  /* The next block of code is equivalent to:
+  **
+  **     pIter += getVarint32(pIter, nPayload);
+  **
+  ** The code is inlined to avoid a function call.
+  */
+  nPayload = *pIter;
+  if( nPayload>=0x80 ){
+    u8 *pEnd = &pIter[8];
+    nPayload &= 0x7f;
+    do{
+      nPayload = (nPayload<<7) | (*++pIter & 0x7f);
+    }while( (*pIter)>=0x80 && pIter<pEnd );
+  }
+  pIter++;
+
+  /* The next block of code is equivalent to:
+  **
+  **     pIter += getVarint(pIter, (u64*)&pInfo->nKey);
+  **
+  ** The code is inlined to avoid a function call.
+  */
+  iKey = *pIter;
+  if( iKey>=0x80 ){
+    u8 *pEnd = &pIter[7];
+    iKey &= 0x7f;
+    while(1){
+      iKey = (iKey<<7) | (*++pIter & 0x7f);
+      if( (*pIter)<0x80 ) break;
+      if( pIter>=pEnd ){
+        iKey = (iKey<<8) | *++pIter;
+        break;
+      }
+    }
+  }
+  pIter++;
+
+  pInfo->nKey = *(i64*)&iKey;
   pInfo->nPayload = nPayload;
   pInfo->pPayload = pIter;
   testcase( nPayload==pPage->maxLocal );
@@ -1094,7 +1133,7 @@ static void btreeParseCellPtrIndex(
   pIter = pCell + pPage->childPtrSize;
   nPayload = *pIter;
   if( nPayload>=0x80 ){
-    u8 *pEnd = &pIter[9];
+    u8 *pEnd = &pIter[8];
     nPayload &= 0x7f;
     do{
       nPayload = (nPayload<<7) | (*++pIter & 0x7f);
@@ -1155,7 +1194,7 @@ static u16 cellSizePtr(MemPage *pPage, u8 *pCell){
   assert( pPage->noPayload==0 );
   nSize = *pIter;
   if( nSize>=0x80 ){
-    pEnd = &pIter[9];
+    pEnd = &pIter[8];
     nSize &= 0x7f;
     do{
       nSize = (nSize<<7) | (*++pIter & 0x7f);