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

the OP_Column opcode for a small performance improvement.

FossilOrigin-Name: 61a2c8d4d64c28119e9f06eb42f9c0437ba7a7bd

manifest

@@ -1,8 +1,8 @@
 -----BEGIN PGP SIGNED MESSAGE-----
 Hash: SHA1
 
-C Fix\sa\sperformance\sglitch\sthat\sappears\sfor\slarge\stransactions.
-D 2010-02-04T17:38:32
+C Remove\sthe\suse\sof\s64-bit\smath\sin\sthe\soffset\scomputations\sof\s\nthe\sOP_Column\sopcode\sfor\sa\ssmall\sperformance\simprovement.
+D 2010-02-05T14:12:54
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in c5827ead754ab32b9585487177c93bb00b9497b3
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -212,7 +212,7 @@ F src/update.c c0dc6b75ad28b76b619042d934f337b02acee208
 F src/utf.c dad16adcc0c35ef2437dca125a4b07419d361052
 F src/util.c aa0b1da8f71edff84b4b41dbe05fe6ac75d819c6
 F src/vacuum.c 28ee5a4963d16cf2477075d85966c0f461cd79de
-F src/vdbe.c b0c18b5c5ab4745a09b8f164e5db36413d98872e
+F src/vdbe.c 78f2167915a8a9611e79eeaf13318d247abed185
 F src/vdbe.h bea1f0cd530775bdb58a340265f3cf3ee920e9b2
 F src/vdbeInt.h e276691b6835da5c0008cc5beaaecedcd7bdba8e
 F src/vdbeapi.c a8b6a6617fc9a0492e4f7d6626d3afe994ddd3f2
@@ -789,14 +789,14 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
-P 1b6e6094c88214e02c9e3638932997ac20bfe413
-R a169746145d95681a0eb74b572825817
+P 26cb1df73504d5d883cf0967e57b46aa062d0b00
+R 1958cacd7f583aec4ab73bfa77d04590
 U drh
-Z 2e5d2a4ce8f32874758dbc577421eb49
+Z fc01b4de0eee88e8eb53af6f3beff67e
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manifest.uuid

@@ -1 +1 @@
-26cb1df73504d5d883cf0967e57b46aa062d0b00
+61a2c8d4d64c28119e9f06eb42f9c0437ba7a7bd

src/vdbe.c

@@ -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;
     }