Avoid unnecessary calls to ExpandBlob() for smaller and faster code.

FossilOrigin-Name: 5e196fd18169e84806cd45dd1a8190339323e772

3 files changed, 26 insertions, 18 deletions

diff --git a/src/vdbe.c b/src/vdbe.c
index 13c20c462..0cd0147f5 100644
--- a/src/vdbe.c
+++ b/src/vdbe.c
@@ -3872,7 +3872,6 @@ case OP_SeekGT: {       /* jump, in3 */
 #ifdef SQLITE_DEBUG
     { int i; for(i=0; i<r.nField; i++) assert( memIsValid(&r.aMem[i]) ); }
 #endif
-    (void)ExpandBlob(r.aMem);
     r.eqSeen = 0;
     rc = sqlite3BtreeMovetoUnpacked(pC->uc.pCursor, &r, 0, 0, &res);
     if( rc!=SQLITE_OK ){
@@ -4013,13 +4012,13 @@ case OP_Found: {        /* jump, in3 */
     r.pKeyInfo = pC->pKeyInfo;
     r.nField = (u16)pOp->p4.i;
     r.aMem = pIn3;
+#ifdef SQLITE_DEBUG
     for(ii=0; ii<r.nField; ii++){
       assert( memIsValid(&r.aMem[ii]) );
-      (void)ExpandBlob(&r.aMem[ii]);
-#ifdef SQLITE_DEBUG
+      assert( (r.aMem[ii].flags & MEM_Zero)==0 || r.aMem[ii].n==0 );
       if( ii ) REGISTER_TRACE(pOp->p3+ii, &r.aMem[ii]);
-#endif
     }
+#endif
     pIdxKey = &r;
   }else{
     pIdxKey = sqlite3VdbeAllocUnpackedRecord(
diff --git a/src/vdbeaux.c b/src/vdbeaux.c
index 838a8f044..43f235c7b 100644
--- a/src/vdbeaux.c
+++ b/src/vdbeaux.c
@@ -3712,10 +3712,12 @@ static int vdbeCompareMemString(
 ** The input pBlob is guaranteed to be a Blob that is not marked
 ** with MEM_Zero.  Return true if it could be a zero-blob.
 */
-static int isZeroBlob(const Mem *pBlob){
+static int isAllZero(const char *z, int n){
   int i;
-  for(i=0; i<pBlob->n && pBlob->z[i]==0; i++){}
-  return i==pBlob->n;
+  for(i=0; i<n; i++){
+    if( z[i] ) return 0;
+  }
+  return 1;
 }
 
 /*
@@ -3739,10 +3741,10 @@ static SQLITE_NOINLINE int sqlite3BlobCompare(const Mem *pB1, const Mem *pB2){
     if( pB1->flags & pB2->flags & MEM_Zero ){
       return pB1->u.nZero - pB2->u.nZero;
     }else if( pB1->flags & MEM_Zero ){
-      if( !isZeroBlob(pB2) ) return -1;
+      if( !isAllZero(pB2->z, pB2->n) ) return -1;
       return pB1->u.nZero - n2;
     }else{
-      if( !isZeroBlob(pB1) ) return +1;
+      if( !isAllZero(pB1->z, pB1->n) ) return +1;
       return n1 - pB2->u.nZero;
     }
   }
@@ -4054,6 +4056,7 @@ int sqlite3VdbeRecordCompareWithSkip(
 
     /* RHS is a blob */
     else if( pRhs->flags & MEM_Blob ){
+      assert( (pRhs->flags & MEM_Zero)==0 || pRhs->n==0 );
       getVarint32(&aKey1[idx1], serial_type);
       testcase( serial_type==12 );
       if( serial_type<12 || (serial_type & 0x01) ){
@@ -4065,6 +4068,12 @@ int sqlite3VdbeRecordCompareWithSkip(
         if( (d1+nStr) > (unsigned)nKey1 ){
           pPKey2->errCode = (u8)SQLITE_CORRUPT_BKPT;
           return 0;                /* Corruption */
+        }else if( pRhs->flags & MEM_Zero ){
+          if( !isAllZero((const char*)&aKey1[d1],nStr) ){
+            rc = 1;
+          }else{
+            rc = nStr - pRhs->u.nZero;
+          }
         }else{
           int nCmp = MIN(nStr, pRhs->n);
           rc = memcmp(&aKey1[d1], pRhs->z, nCmp);
diff --git a/src/vdbemem.c b/src/vdbemem.c
index ca6e480d1..efc4a9722 100644
--- a/src/vdbemem.c
+++ b/src/vdbemem.c
@@ -189,18 +189,18 @@ int sqlite3VdbeMemClearAndResize(Mem *pMem, int szNew){
 ** Return SQLITE_OK on success or SQLITE_NOMEM if malloc fails.
 */
 int sqlite3VdbeMemMakeWriteable(Mem *pMem){
-  int f;
   assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
   assert( (pMem->flags&MEM_RowSet)==0 );
-  (void)ExpandBlob(pMem);
-  f = pMem->flags;
-  if( (f&(MEM_Str|MEM_Blob)) && (pMem->szMalloc==0 || pMem->z!=pMem->zMalloc) ){
-    if( sqlite3VdbeMemGrow(pMem, pMem->n + 2, 1) ){
-      return SQLITE_NOMEM_BKPT;
+  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;
+      }
+      pMem->z[pMem->n] = 0;
+      pMem->z[pMem->n+1] = 0;
+      pMem->flags |= MEM_Term;
     }
-    pMem->z[pMem->n] = 0;
-    pMem->z[pMem->n+1] = 0;
-    pMem->flags |= MEM_Term;
   }
   pMem->flags &= ~MEM_Ephem;
 #ifdef SQLITE_DEBUG