Code generator tries to avoid pointless OP_IsNull and OP_Affinity opcodes.

FossilOrigin-Name: ebb0c8a3e977dc741704e733b5a5d931d9b27028

manifest

@@ -1,8 +1,8 @@
 -----BEGIN PGP SIGNED MESSAGE-----
 Hash: SHA1
 
-C Make\ssure\sthe\soutput\sof\ssqlite3OsFullPathname\sis\sinitialized\seven\sif\sthe\nfails\sdue\sto\sI/O\sor\sOOM\serrors.
+C Code\sgenerator\stries\sto\savoid\spointless\sOP_IsNull\sand\sOP_Affinity\sopcodes.
-D 2009-11-16T23:36:34
+D 2009-11-17T18:31:48
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in 53f3dfa49f28ab5b80cb083fb7c9051e596bcfa1
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -117,7 +117,7 @@ F src/callback.c 908f3e0172c3d4058f4ca0acd42c637c52e9669f
 F src/complete.c 417df1ef5ea798532bb6290b0cc4265fef82980a
 F src/date.c a79c0a8f219370b972e320741f995a3bef9df33f
 F src/delete.c ec04635d152debdab70d4b30c5516b59282075ea
-F src/expr.c 94f3086a342a1d151fb9d17ef1c33bff4cc768f0
+F src/expr.c cc086099c3afbc10bfdb506a0b5b298b0547c956
 F src/fault.c 160a0c015b6c2629d3899ed2daf63d75754a32bb
 F src/fkey.c e2116672a6bd610dc888e27df292ebc7999c9bb0
 F src/func.c bf54e1202cbfb28bf4b1fd9b58899009ae76716f
@@ -167,7 +167,7 @@ F src/select.c a727f61f3267bfa20ce1c3e85d38dc2132db1060
 F src/shell.c f4948cb6d30665d755a6b5e0ec313d1094aab828
 F src/sqlite.h.in 4464e9772122f0447305d425e04d122b6f1bffec
 F src/sqlite3ext.h 69dfb8116af51b84a029cddb3b35062354270c89
-F src/sqliteInt.h 961a7a3c1428fdc9c18df63ee34c91c7425c47af
+F src/sqliteInt.h 1d6795e4d56c55cff86d9b9968eab37c67307f95
 F src/sqliteLimit.h 3afab2291762b5d09ae20c18feb8e9fa935a60a6
 F src/status.c e651be6b30d397d86384c6867bc016e4913bcac7
 F src/table.c 2cd62736f845d82200acfa1287e33feb3c15d62e
@@ -210,7 +210,7 @@ F src/update.c 8efeb09822886e33c265dd96d29a3d865ea6dcf2
 F src/utf.c dad16adcc0c35ef2437dca125a4b07419d361052
 F src/util.c ad4f03079ba0fe83590d1cc9197e8e4844e38592
 F src/vacuum.c 03309a08d549f9389cc3a3589afd4fadbdaf0679
-F src/vdbe.c 0bc1c3aaa0c5c13240c2e39ce3b9ae92586fc30b
+F src/vdbe.c 678dc437014c654707b7980e5a1a76b7dea5fecd
 F src/vdbe.h 5f35750615163d1064052785b4a9f0eb004a720d
 F src/vdbeInt.h d7ea821ac7813c9bea0fe87558c35e07b2c7c44d
 F src/vdbeapi.c 17680ab7a75ec938c5ba039a6c87489d01faf2cb
@@ -219,7 +219,7 @@ F src/vdbeblob.c 84f924700a7a889152aeebef77ca5f4e3875ffb4
 F src/vdbemem.c 1e16e3a16e55f4c3452834f0e041726021aa66e0
 F src/vtab.c 456fc226614569f0e46f216e33265bea268bd917
 F src/walker.c 3112bb3afe1d85dc52317cb1d752055e9a781f8f
-F src/where.c 5a8ed38834465e47c9e28ea5462f3ad8b90000c7
+F src/where.c ef0dbd3963087e9caecf175e4669d2ef2a5735a1
 F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2
 F test/alias.test 4529fbc152f190268a15f9384a5651bbbabc9d87
 F test/all.test 14165b3e32715b700b5f0cbf8f6e3833dda0be45
@@ -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 929b6047391411c6f539e47afe6b63d16e352ccb
+P e4943adb83819dee06e2e9da25ff6d967ca170de
-R 13facd3cb5b58e8321f51a81ba26b282
+R 537d50eb63e21c879029e20006a4ef86
 U drh
-Z 5557a9bdd7c9ffd1ef2b1b912759377d
+Z 25f5f894370572ec60a402b96fc8f463
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+c0IYZzkLkFY6S76oMkFaA2k=
-=JRXc
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manifest.uuid

@@ -1 +1 @@
-e4943adb83819dee06e2e9da25ff6d967ca170de
+ebb0c8a3e977dc741704e733b5a5d931d9b27028

src/expr.c

@@ -1258,6 +1258,71 @@ int sqlite3ExprIsInteger(Expr *p, int *pValue){
   return rc;
 }
 
+/*
+** Return FALSE if there is no chance that the expression can be NULL.
+**
+** If the expression might be NULL or if the expression is too complex
+** to tell return TRUE.  
+**
+** This routine is used as an optimization, to skip OP_IsNull opcodes
+** when we know that a value cannot be NULL.  Hence, a false positive
+** (returning TRUE when in fact the expression can never be NULL) might
+** be a small performance hit but is otherwise harmless.  On the other
+** hand, a false negative (returning FALSE when the result could be NULL)
+** will likely result in an incorrect answer.  So when in doubt, return
+** TRUE.
+*/
+int sqlite3ExprCanBeNull(const Expr *p){
+  u8 op;
+  while( p->op==TK_UPLUS || p->op==TK_MINUS ){ p = p->pLeft; }
+  op = p->op;
+  if( op==TK_REGISTER ) op = p->op2;
+  switch( op ){
+    case TK_INTEGER:
+    case TK_STRING:
+    case TK_FLOAT:
+    case TK_BLOB:
+      return 0;
+    default:
+      return 1;
+  }
+}
+
+/*
+** Return TRUE if the given expression is a constant which would be
+** unchanged by OP_Affinity with the affinity given in the second
+** argument.
+**
+** This routine is used to determine if the OP_Affinity operation
+** can be omitted.  When in doubt return FALSE.  A false negative
+** is harmless.  A false positive, however, can result in the wrong
+** answer.
+*/
+int sqlite3ExprNeedsNoAffinityChange(const Expr *p, char aff){
+  u8 op;
+  if( aff==SQLITE_AFF_NONE ) return 1;
+  while( p->op==TK_UPLUS || p->op==TK_MINUS ){ p = p->pLeft; }
+  op = p->op;
+  if( op==TK_REGISTER ) op = p->op2;
+  switch( op ){
+    case TK_INTEGER: {
+      return aff==SQLITE_AFF_INTEGER || aff==SQLITE_AFF_NUMERIC;
+    }
+    case TK_FLOAT: {
+      return aff==SQLITE_AFF_REAL || aff==SQLITE_AFF_NUMERIC;
+    }
+    case TK_STRING: {
+      return aff==SQLITE_AFF_TEXT;
+    }
+    case TK_BLOB: {
+      return 1;
+    }
+    default: {
+      return 0;
+    }
+  }
+}
+
 /*
 ** Return TRUE if the given string is a row-id column name.
 */

src/sqliteInt.h

@@ -2674,6 +2674,8 @@ int sqlite3ExprIsConstant(Expr*);
 int sqlite3ExprIsConstantNotJoin(Expr*);
 int sqlite3ExprIsConstantOrFunction(Expr*);
 int sqlite3ExprIsInteger(Expr*, int*);
+int sqlite3ExprCanBeNull(const Expr*);
+int sqlite3ExprNeedsNoAffinityChange(const Expr*, char);
 int sqlite3IsRowid(const char*);
 void sqlite3GenerateRowDelete(Parse*, Table*, int, int, int, Trigger *, int);
 void sqlite3GenerateRowIndexDelete(Parse*, Table*, int, int*);

src/vdbe.c

@@ -2292,17 +2292,18 @@ op_column_out:
 ** memory cell in the range.
 */
 case OP_Affinity: {
-  char *zAffinity;   /* The affinity to be applied */
+  const char *zAffinity;   /* The affinity to be applied */
-  Mem *pData0;       /* First register to which to apply affinity */
+  char cAff;               /* A single character of affinity */
-  Mem *pLast;        /* Last register to which to apply affinity */
-  Mem *pRec;         /* Current register */
 
   zAffinity = pOp->p4.z;
-  pData0 = &aMem[pOp->p1];
+  assert( zAffinity!=0 );
-  pLast = &pData0[pOp->p2-1];
+  assert( zAffinity[pOp->p2]==0 );
-  for(pRec=pData0; pRec<=pLast; pRec++){
+  pIn1 = &aMem[pOp->p1];
-    ExpandBlob(pRec);
+  while( (cAff = *(zAffinity++))!=0 ){
-    applyAffinity(pRec, zAffinity[pRec-pData0], encoding);
+    assert( pIn1 <= &p->aMem[p->nMem] );
+    ExpandBlob(pIn1);
+    applyAffinity(pIn1, cAff, encoding);
+    pIn1++;
   }
   break;
 }
@@ -3255,6 +3256,7 @@ case OP_SeekGt: {       /* jump, in3 */
       assert( oc!=OP_SeekLt || r.flags==0 );
 
       r.aMem = &aMem[pOp->p3];
+      ExpandBlob(r.aMem);
       rc = sqlite3BtreeMovetoUnpacked(pC->pCursor, &r, 0, 0, &res);
       if( rc!=SQLITE_OK ){
         goto abort_due_to_error;

src/where.c

@@ -2594,15 +2594,40 @@ static void disableTerm(WhereLevel *pLevel, WhereTerm *pTerm){
 ** Code an OP_Affinity opcode to apply the column affinity string zAff
 ** to the n registers starting at base. 
 **
-** This routine assumes that zAff is dynamic and makes its own copy.
+** As an optimization, SQLITE_AFF_NONE entries (which are no-ops) at the
+** beginning and end of zAff are ignored.  If all entries in zAff are
+** SQLITE_AFF_NONE, then no code gets generated.
+**
+** This routine makes its own copy of zAff so that the caller is free
+** to modify zAff after this routine returns.
 */
 static void codeApplyAffinity(Parse *pParse, int base, int n, char *zAff){
   Vdbe *v = pParse->pVdbe;
+  if( zAff==0 ){
+    assert( pParse->db->mallocFailed );
+    return;
+  }
   assert( v!=0 );
+
+  /* Adjust base and n to skip over SQLITE_AFF_NONE entries at the beginning
+  ** and end of the affinity string.
+  */
+  while( n>0 && zAff[0]==SQLITE_AFF_NONE ){
+    n--;
+    base++;
+    zAff++;
+  }
+  while( n>1 && zAff[n-1]==SQLITE_AFF_NONE ){
+    n--;
+  }
+
+  /* Code the OP_Affinity opcode if there is anything left to do. */
+  if( n>0 ){
     sqlite3VdbeAddOp2(v, OP_Affinity, base, n);
-  sqlite3VdbeChangeP4(v, -1, zAff, 0);
+    sqlite3VdbeChangeP4(v, -1, zAff, n);
     sqlite3ExprCacheAffinityChange(pParse, base, n);
   }
+}
 
 
 /*
@@ -2672,7 +2697,7 @@ static int codeEqualityTerm(
 
 /*
 ** Generate code that will evaluate all == and IN constraints for an
-** index.  The values for all constraints are left on the stack.
+** index.
 **
 ** For example, consider table t1(a,b,c,d,e,f) with index i1(a,b,c).
 ** Suppose the WHERE clause is this:  a==5 AND b IN (1,2,3) AND c>5 AND c<10
@@ -2684,7 +2709,8 @@ static int codeEqualityTerm(
 **
 ** In the example above nEq==2.  But this subroutine works for any value
 ** of nEq including 0.  If nEq==0, this routine is nearly a no-op.
-** The only thing it does is allocate the pLevel->iMem memory cell.
+** The only thing it does is allocate the pLevel->iMem memory cell and
+** compute the affinity string.
 **
 ** This routine always allocates at least one memory cell and returns
 ** the index of that memory cell. The code that
@@ -2762,12 +2788,18 @@ static int codeAllEqualityTerms(
     testcase( pTerm->eOperator & WO_ISNULL );
     testcase( pTerm->eOperator & WO_IN );
     if( (pTerm->eOperator & (WO_ISNULL|WO_IN))==0 ){
+      Expr *pRight = pTerm->pExpr->pRight;
+      if( sqlite3ExprCanBeNull(pRight) ){
         sqlite3VdbeAddOp2(v, OP_IsNull, regBase+j, pLevel->addrBrk);
-      if( zAff 
+      }
-       && sqlite3CompareAffinity(pTerm->pExpr->pRight, zAff[j])==SQLITE_AFF_NONE
+      if( zAff ){
-      ){
+        if( sqlite3CompareAffinity(pRight, zAff[j])==SQLITE_AFF_NONE ){
           zAff[j] = SQLITE_AFF_NONE;
         }
+        if( sqlite3ExprNeedsNoAffinityChange(pRight, zAff[j]) ){
+          zAff[j] = SQLITE_AFF_NONE;
+        }
+      }
     }
   }
   *pzAff = zAff;
@@ -3093,14 +3125,17 @@ static Bitmask codeOneLoopStart(
       Expr *pRight = pRangeStart->pExpr->pRight;
       sqlite3ExprCode(pParse, pRight, regBase+nEq);
       sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, addrNxt);
-      if( zAff 
+      if( zAff ){
-       && sqlite3CompareAffinity(pRight, zAff[nConstraint])==SQLITE_AFF_NONE
+        if( sqlite3CompareAffinity(pRight, zAff[nConstraint])==SQLITE_AFF_NONE){
-      ){
+          /* Since the comparison is to be performed with no conversions
-        /* Since the comparison is to be performed with no conversions applied
+          ** applied to the operands, set the affinity to apply to pRight to 
-        ** to the operands, set the affinity to apply to pRight to 
           ** SQLITE_AFF_NONE.  */
           zAff[nConstraint] = SQLITE_AFF_NONE;
         }
+        if( sqlite3ExprNeedsNoAffinityChange(pRight, zAff[nConstraint]) ){
+          zAff[nConstraint] = SQLITE_AFF_NONE;
+        }
+      }  
       nConstraint++;
     }else if( isMinQuery ){
       sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq);
@@ -3128,14 +3163,17 @@ static Bitmask codeOneLoopStart(
       sqlite3ExprCacheRemove(pParse, regBase+nEq);
       sqlite3ExprCode(pParse, pRight, regBase+nEq);
       sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, addrNxt);
-      if( zAff 
+      if( zAff ){
-       && sqlite3CompareAffinity(pRight, zAff[nConstraint])==SQLITE_AFF_NONE
+        if( sqlite3CompareAffinity(pRight, zAff[nConstraint])==SQLITE_AFF_NONE){
-      ){
+          /* Since the comparison is to be performed with no conversions
-        /* Since the comparison is to be performed with no conversions applied
+          ** applied to the operands, set the affinity to apply to pRight to 
-        ** to the operands, set the affinity to apply to pRight to 
           ** SQLITE_AFF_NONE.  */
           zAff[nConstraint] = SQLITE_AFF_NONE;
         }
+        if( sqlite3ExprNeedsNoAffinityChange(pRight, zAff[nConstraint]) ){
+          zAff[nConstraint] = SQLITE_AFF_NONE;
+        }
+      }  
       codeApplyAffinity(pParse, regBase, nEq+1, zAff);
       nConstraint++;
     }