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Remove the use of 64-bit math in the offset computations of

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the OP_Column opcode for a small performance improvement.

FossilOrigin-Name: 61a2c8d4d64c28119e9f06eb42f9c0437ba7a7bd
This commit is contained in:
drh
2010-02-05 14:12:53 +00:00
parent a963896796
commit 6658cd9a74
3 changed files with 20 additions and 16 deletions
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16
src/vdbe.c
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@@ -2068,7 +2068,7 @@ case OP_Column: {
u8 *zIdx; /* Index into header */
u8 *zEndHdr; /* Pointer to first byte after the header */
u32 offset; /* Offset into the data */
u64 offset64; /* 64-bit offset. 64 bits needed to catch overflow */
u32 szField; /* Number of bytes in the content of a field */
int szHdr; /* Size of the header size field at start of record */
int avail; /* Number of bytes of available data */
Mem *pReg; /* PseudoTable input register */
@@ -2243,12 +2243,16 @@ case OP_Column: {
** column and aOffset[i] will contain the offset from the beginning
** of the record to the start of the data for the i-th column
*/
offset64 = offset;
for(i=0; i<nField; i++){
if( zIdx<zEndHdr ){
aOffset[i] = (u32)offset64;
aOffset[i] = offset;
zIdx += getVarint32(zIdx, aType[i]);
offset64 += sqlite3VdbeSerialTypeLen(aType[i]);
szField = sqlite3VdbeSerialTypeLen(aType[i]);
offset += szField;
if( offset<szField ){ /* True if offset overflows */
zIdx = &zEndHdr[1]; /* Forces SQLITE_CORRUPT return below */
break;
}
}else{
/* If i is less that nField, then there are less fields in this
** record than SetNumColumns indicated there are columns in the
@@ -2268,8 +2272,8 @@ case OP_Column: {
** of the record (when all fields present), then we must be dealing
** with a corrupt database.
*/
if( (zIdx > zEndHdr)|| (offset64 > payloadSize)
|| (zIdx==zEndHdr && offset64!=(u64)payloadSize) ){
if( (zIdx > zEndHdr) || (offset > payloadSize)
|| (zIdx==zEndHdr && offset!=payloadSize) ){
rc = SQLITE_CORRUPT_BKPT;
goto op_column_out;
}