Optimizations to the sqlite3VdbeRecordCompare() routine help it to run 12.5%

faster for some traces.

FossilOrigin-Name: 74c76f0bf946d184275de478ec72220d76342493

diff --git a/manifest b/manifest
index 8823f66e92bb85c71db7382cd63539082a6d50e7..e8549cb56b7fde846a3de0aa0497cbe76907d4d8 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,8 +1,8 @@
 -----BEGIN PGP SIGNED MESSAGE-----
 Hash: SHA1
 
-C Optimizations\sto\sthe\smain\sloop\sinside\ssqlite3VdbeExec()\sto\shelp\sVDBE\sbyte\scode\nrun\sa\sfew\spercent\sfaster.
-D 2009-11-14T23:22:23
+C Optimizations\sto\sthe\ssqlite3VdbeRecordCompare()\sroutine\shelp\sit\sto\srun\s12.5%\nfaster\sfor\ssome\straces.
+D 2009-11-16T02:14:01
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in 53f3dfa49f28ab5b80cb083fb7c9051e596bcfa1
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -214,7 +214,7 @@ F src/vdbe.c 0bc1c3aaa0c5c13240c2e39ce3b9ae92586fc30b
 F src/vdbe.h 5f35750615163d1064052785b4a9f0eb004a720d
 F src/vdbeInt.h d7ea821ac7813c9bea0fe87558c35e07b2c7c44d
 F src/vdbeapi.c 17680ab7a75ec938c5ba039a6c87489d01faf2cb
-F src/vdbeaux.c 45d1e150d811da2bafe820136b1c21616b2e5fd4
+F src/vdbeaux.c d86062c20dd11f76d7e84148eb90ad2e67c692bd
 F src/vdbeblob.c 84f924700a7a889152aeebef77ca5f4e3875ffb4
 F src/vdbemem.c 1e16e3a16e55f4c3452834f0e041726021aa66e0
 F src/vtab.c 456fc226614569f0e46f216e33265bea268bd917
@@ -771,14 +771,14 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
-P 8bd3cc82720ac7e8a9d4a03a882b6f8226867b0d
-R cb3a1da29955733378e76881557b866a
+P d622ac6ac7a297754494d3a33dbaeea02836272e
+R 8a77d446e8971c8c821f82b0e714ed44
 U drh
-Z afa90cd668940f60ced698df17c38b7b
+Z 16e3d159b2fe2d607c2cd029c6925807
 -----BEGIN PGP SIGNATURE-----
 Version: GnuPG v1.4.6 (GNU/Linux)
 
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-=cEZ3
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diff --git a/manifest.uuid b/manifest.uuid
index 1d5ac89eade6f621361c1d575af115ddf83c881d..b6942d0e4fe7731c5ee52a94d242b8505d02f93c 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-d622ac6ac7a297754494d3a33dbaeea02836272e
\ No newline at end of file
+74c76f0bf946d184275de478ec72220d76342493
\ No newline at end of file

diff --git a/src/vdbeaux.c b/src/vdbeaux.c
index 8dc4cf12d1d687e489b0b4923659915427fbf60a..e8142f90584bd70a5e7f244a9761577a87ea5cdd 100644 (file)
--- a/src/vdbeaux.c
+++ b/src/vdbeaux.c
@@ -2788,8 +2788,16 @@ int sqlite3VdbeRecordCompare(
   mem1.enc = pKeyInfo->enc;
   mem1.db = pKeyInfo->db;
   mem1.flags = 0;
-  mem1.u.i = 0;  /* not needed, here to silence compiler warning */
-  mem1.zMalloc = 0;
+  VVA_ONLY( mem1.zMalloc = 0; ) /* Only used by assert() statements */
+
+  /* Compilers may complain that mem1.u.i is potentially uninitialized.
+  ** We could initialize it, as shown here, to silence those complaints.
+  ** But in fact, mem1.u.i will never actually be used initialized, and doing 
+  ** the unnecessary initialization has a measurable negative performance
+  ** impact, since this routine is a very high runner.  And so, we choose
+  ** to ignore the compiler warnings and leave this variable uninitialized.
+  */
+  /*  mem1.u.i = 0;  // not needed, here to silence compiler warning */
   
   idx1 = getVarint32(aKey1, szHdr1);
   d1 = szHdr1;
@@ -2813,47 +2821,52 @@ int sqlite3VdbeRecordCompare(
     rc = sqlite3MemCompare(&mem1, &pPKey2->aMem[i],
                            i<nField ? pKeyInfo->aColl[i] : 0);
     if( rc!=0 ){
-      break;
+      assert( mem1.zMalloc==0 );  /* See comment below */
+
+      /* Invert the result if we are using DESC sort order. */
+      if( pKeyInfo->aSortOrder && i<nField && pKeyInfo->aSortOrder[i] ){
+        rc = -rc;
+      }
+    
+      /* If the PREFIX_SEARCH flag is set and all fields except the final
+      ** rowid field were equal, then clear the PREFIX_SEARCH flag and set 
+      ** pPKey2->rowid to the value of the rowid field in (pKey1, nKey1).
+      ** This is used by the OP_IsUnique opcode.
+      */
+      if( (pPKey2->flags & UNPACKED_PREFIX_SEARCH) && i==(pPKey2->nField-1) ){
+        assert( idx1==szHdr1 && rc );
+        assert( mem1.flags & MEM_Int );
+        pPKey2->flags &= ~UNPACKED_PREFIX_SEARCH;
+        pPKey2->rowid = mem1.u.i;
+      }
+    
+      return rc;
     }
     i++;
   }
 
-  /* No memory allocation is ever used on mem1. */
-  if( NEVER(mem1.zMalloc) ) sqlite3VdbeMemRelease(&mem1);
-
-  /* If the PREFIX_SEARCH flag is set and all fields except the final
-  ** rowid field were equal, then clear the PREFIX_SEARCH flag and set 
-  ** pPKey2->rowid to the value of the rowid field in (pKey1, nKey1).
-  ** This is used by the OP_IsUnique opcode.
+  /* No memory allocation is ever used on mem1.  Prove this using
+  ** the following assert().  If the assert() fails, it indicates a
+  ** memory leak and a need to call sqlite3VdbeMemRelease(&mem1).
   */
-  if( (pPKey2->flags & UNPACKED_PREFIX_SEARCH) && i==(pPKey2->nField-1) ){
-    assert( idx1==szHdr1 && rc );
-    assert( mem1.flags & MEM_Int );
-    pPKey2->flags &= ~UNPACKED_PREFIX_SEARCH;
-    pPKey2->rowid = mem1.u.i;
-  }
-
-  if( rc==0 ){
-    /* rc==0 here means that one of the keys ran out of fields and
-    ** all the fields up to that point were equal. If the UNPACKED_INCRKEY
-    ** flag is set, then break the tie by treating key2 as larger.
-    ** If the UPACKED_PREFIX_MATCH flag is set, then keys with common prefixes
-    ** are considered to be equal.  Otherwise, the longer key is the 
-    ** larger.  As it happens, the pPKey2 will always be the longer
-    ** if there is a difference.
-    */
-    if( pPKey2->flags & UNPACKED_INCRKEY ){
-      rc = -1;
-    }else if( pPKey2->flags & UNPACKED_PREFIX_MATCH ){
-      /* Leave rc==0 */
-    }else if( idx1<szHdr1 ){
-      rc = 1;
-    }
-  }else if( pKeyInfo->aSortOrder && i<pKeyInfo->nField
-               && pKeyInfo->aSortOrder[i] ){
-    rc = -rc;
+  assert( mem1.zMalloc==0 );
+
+  /* rc==0 here means that one of the keys ran out of fields and
+  ** all the fields up to that point were equal. If the UNPACKED_INCRKEY
+  ** flag is set, then break the tie by treating key2 as larger.
+  ** If the UPACKED_PREFIX_MATCH flag is set, then keys with common prefixes
+  ** are considered to be equal.  Otherwise, the longer key is the 
+  ** larger.  As it happens, the pPKey2 will always be the longer
+  ** if there is a difference.
+  */
+  assert( rc==0 );
+  if( pPKey2->flags & UNPACKED_INCRKEY ){
+    rc = -1;
+  }else if( pPKey2->flags & UNPACKED_PREFIX_MATCH ){
+    /* Leave rc==0 */
+  }else if( idx1<szHdr1 ){
+    rc = 1;
   }
-
   return rc;
 }