Improvements to the way the LIKE optimization is implemented, resulting in

slightly smaller and faster code that is easier to test.

FossilOrigin-Name: 54c63b329288729031f45b7778752552cd90e226

manifest

@@ -1,5 +1,5 @@
-C Change\sthe\sway\stester.tcl\shandes\s$argv\sso\sthat\sin\s"permutations.test\s<permutation>\s<filename>"\s<filename>\smay\sbe\sthe\sname\sof\sany\sfile\sin\sthe\stest/\sdirectory.
-D 2016-04-30T19:23:10.056
+C Improvements\sto\sthe\sway\sthe\sLIKE\soptimization\sis\simplemented,\sresulting\sin\nslightly\ssmaller\sand\sfaster\scode\sthat\sis\seasier\sto\stest.
+D 2016-05-02T10:25:42.392
 F Makefile.in 9e816d0323e418fbc0f8b2c05fc14e0b3763d9e8
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc 71b8b16cf9393f68e2e2035486ca104872558836
@@ -443,7 +443,7 @@ F src/update.c 3e67ab3c0814635f355fb1f8ab010a2b9e016e7d
 F src/utf.c 699001c79f28e48e9bcdf8a463da029ea660540c
 F src/util.c 810ec3f22e2d1b62e66c30fe3621ebdedd23584d
 F src/vacuum.c feb1eabb20987983d9350cad98299b21fa811f52
-F src/vdbe.c 465bb820f9760602959ba8d279cdae621206d696
+F src/vdbe.c 4bad04212736526845fda9ca674afafb10078b2b
 F src/vdbe.h 5591b5add447096e31288b5a0a78ec5d7b5c5170
 F src/vdbeInt.h ddb157974436d87652de7dc641f7191496d9a8cd
 F src/vdbeapi.c ba85b78fe08dc4a9ce747e62c89a2b4a4547e74c
@@ -457,9 +457,9 @@ F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
 F src/wal.c 4db22ed7e77bcf672b1a685d6ddeffba8d5be302
 F src/wal.h 2f7c831cf3b071fa548bf2d5cac640846a7ff19c
 F src/walker.c 0f142b5bd3ed2041fc52d773880748b212e63354
-F src/where.c bae50f2f18f9e8584549a77363858623b07e4915
-F src/whereInt.h 7de94b751f088fe3fdc8cc04a491376f0900a059
-F src/wherecode.c 8fdad9fbba723df1c1e8d07e7ea8507572040340
+F src/where.c 019e5b10dedcf54ef077ce23dd8fce38d614dcf4
+F src/whereInt.h 3b1fc240e322613ba4e9dc857ca9c7c3390acc74
+F src/wherecode.c 28951741be3974701186281ced0564e9586a0db3
 F src/whereexpr.c eacc0e60d029a082b4fc0cc42ea98544add1319e
 F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
 F test/affinity2.test a6d901b436328bd67a79b41bb0ac2663918fe3bd
@@ -1486,7 +1486,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 459a0b456da69112605b37adc9af27d79e35a4d7
-R 23212a22e435d3100aef78ab9c45b327
-U dan
-Z 034fcb062ad20342a7b230d87b3ffc20
+P 820c57bb24ad3d8663ca512e4022268b940bb2ee
+R c58e65d0f2e2d03ddd82d7f66bccab45
+U drh
+Z 38f3015d7db64980369a2f7c9273004f

manifest.uuid

@@ -1 +1 @@
-820c57bb24ad3d8663ca512e4022268b940bb2ee
+54c63b329288729031f45b7778752552cd90e226

src/vdbe.c

@@ -1091,10 +1091,12 @@ case OP_String8: {         /* same as TK_STRING, out2 */
 **
 ** The string value P4 of length P1 (bytes) is stored in register P2.
 **
-** If P5!=0 and the content of register P3 is greater than zero, then
+** If P3 is not zero and the content of register P3 is equal to P5, then
 ** the datatype of the register P2 is converted to BLOB.  The content is
 ** the same sequence of bytes, it is merely interpreted as a BLOB instead
-** of a string, as if it had been CAST.
+** of a string, as if it had been CAST.  In other words:
+**
+** if( P3!=0 and reg[P3]==P5 ) reg[P2] := CAST(reg[P2] as BLOB)
 */
 case OP_String: {          /* out2 */
   assert( pOp->p4.z!=0 );
@@ -1105,12 +1107,11 @@ case OP_String: {          /* out2 */
   pOut->enc = encoding;
   UPDATE_MAX_BLOBSIZE(pOut);
 #ifndef SQLITE_LIKE_DOESNT_MATCH_BLOBS
-  if( pOp->p5 ){
-    assert( pOp->p3>0 );
+  if( pOp->p3>0 ){
     assert( pOp->p3<=(p->nMem+1 - p->nCursor) );
     pIn3 = &aMem[pOp->p3];
     assert( pIn3->flags & MEM_Int );
-    if( pIn3->u.i ) pOut->flags = MEM_Blob|MEM_Static|MEM_Term;
+    if( pIn3->u.i==pOp->p5 ) pOut->flags = MEM_Blob|MEM_Static|MEM_Term;
   }
 #endif
   break;
@@ -5966,21 +5967,6 @@ case OP_DecrJumpZero: {      /* jump, in1 */
 }
 
 
-/* Opcode: JumpZeroIncr P1 P2 * * *
-** Synopsis: if (r[P1]++)==0 ) goto P2
-**
-** The register P1 must contain an integer.  If register P1 is initially
-** zero, then jump to P2.  Increment register P1 regardless of whether or
-** not the jump is taken.
-*/
-case OP_JumpZeroIncr: {        /* jump, in1 */
-  pIn1 = &aMem[pOp->p1];
-  assert( pIn1->flags&MEM_Int );
-  VdbeBranchTaken(pIn1->u.i==0, 2);
-  if( (pIn1->u.i++)==0 ) goto jump_to_p2;
-  break;
-}
-
 /* Opcode: AggStep0 * P2 P3 P4 P5
 ** Synopsis: accum=r[P3] step(r[P2@P5])
 **

src/where.c

@@ -4607,13 +4607,8 @@ void sqlite3WhereEnd(WhereInfo *pWInfo){
     }
 #ifndef SQLITE_LIKE_DOESNT_MATCH_BLOBS
     if( pLevel->addrLikeRep ){
-      int op;
-      if( sqlite3VdbeGetOp(v, pLevel->addrLikeRep-1)->p1 ){
-        op = OP_DecrJumpZero;
-      }else{
-        op = OP_JumpZeroIncr;
-      }
-      sqlite3VdbeAddOp2(v, op, pLevel->iLikeRepCntr, pLevel->addrLikeRep);
+      sqlite3VdbeAddOp2(v, OP_DecrJumpZero, (int)(pLevel->iLikeRepCntr>>1),
+                        pLevel->addrLikeRep);
       VdbeCoverage(v);
     }
 #endif

src/whereInt.h

@@ -70,7 +70,7 @@ struct WhereLevel {
   int addrFirst;        /* First instruction of interior of the loop */
   int addrBody;         /* Beginning of the body of this loop */
 #ifndef SQLITE_LIKE_DOESNT_MATCH_BLOBS
-  int iLikeRepCntr;     /* LIKE range processing counter register */
+  u32 iLikeRepCntr;     /* LIKE range processing counter register (times 2) */
   int addrLikeRep;      /* LIKE range processing address */
 #endif
   u8 iFrom;             /* Which entry in the FROM clause */

src/wherecode.c

@@ -560,9 +560,10 @@ static int codeAllEqualityTerms(
 
 #ifndef SQLITE_LIKE_DOESNT_MATCH_BLOBS
 /*
-** If the most recently coded instruction is a constant range contraint
-** that originated from the LIKE optimization, then change the P3 to be
-** pLoop->iLikeRepCntr and set P5.
+** If the most recently coded instruction is a constant range constraint
+** (a string literal) that originated from the LIKE optimization, then 
+** set P3 and P5 on the OP_String opcode so that the string will be cast
+** to a BLOB at appropriate times.
 **
 ** The LIKE optimization trys to evaluate "x LIKE 'abc%'" as a range
 ** expression: "x>='ABC' AND x<'abd'".  But this requires that the range
@@ -587,8 +588,8 @@ static void whereLikeOptimizationStringFixup(
     assert( pOp!=0 );
     assert( pOp->opcode==OP_String8 
             || pTerm->pWC->pWInfo->pParse->db->mallocFailed );
-    pOp->p3 = pLevel->iLikeRepCntr;
-    pOp->p5 = 1;
+    pOp->p3 = (int)(pLevel->iLikeRepCntr>>1);  /* Register holding counter */
+    pOp->p5 = (u8)(pLevel->iLikeRepCntr&1);    /* ASC or DESC */
   }
 }
 #else
@@ -1175,14 +1176,17 @@ Bitmask sqlite3WhereCodeOneLoopStart(
       if( (pRangeEnd->wtFlags & TERM_LIKEOPT)!=0 ){
         assert( pRangeStart!=0 );                     /* LIKE opt constraints */
         assert( pRangeStart->wtFlags & TERM_LIKEOPT );   /* occur in pairs */
-        pLevel->iLikeRepCntr = ++pParse->nMem;
-        testcase( bRev );
-        testcase( pIdx->aSortOrder[nEq]==SQLITE_SO_DESC );
-        sqlite3VdbeAddOp2(v, OP_Integer,
-                          bRev ^ (pIdx->aSortOrder[nEq]==SQLITE_SO_DESC),
-                          pLevel->iLikeRepCntr);
+        pLevel->iLikeRepCntr = (u32)++pParse->nMem;
+        sqlite3VdbeAddOp2(v, OP_Integer, 1, (int)pLevel->iLikeRepCntr);
         VdbeComment((v, "LIKE loop counter"));
         pLevel->addrLikeRep = sqlite3VdbeCurrentAddr(v);
+        /* iLikeRepCntr actually stores 2x the counter register number.  The
+        ** bottom bit indicates whether the search order is ASC or DESC. */
+        testcase( bRev );
+        testcase( pIdx->aSortOrder[nEq]==SQLITE_SO_DESC );
+        assert( (bRev & ~1)==0 );
+        pLevel->iLikeRepCntr <<=1;
+        pLevel->iLikeRepCntr |= bRev ^ (pIdx->aSortOrder[nEq]==SQLITE_SO_DESC);
       }
 #endif
       if( pRangeStart==0
@@ -1696,11 +1700,17 @@ Bitmask sqlite3WhereCodeOneLoopStart(
       continue;
     }
     if( pTerm->wtFlags & TERM_LIKECOND ){
+      /* If the TERM_LIKECOND flag is set, that means that the range search
+      ** is sufficient to guarantee that the LIKE operator is true, so we
+      ** can skip the call to the like(A,B) function.  But this only works
+      ** for strings.  So do not skip the call to the function on the pass
+      ** that compares BLOBs. */
 #ifdef SQLITE_LIKE_DOESNT_MATCH_BLOBS
       continue;
 #else
-      assert( pLevel->iLikeRepCntr>0 );
-      skipLikeAddr = sqlite3VdbeAddOp1(v, OP_IfNot, pLevel->iLikeRepCntr);
+      u32 x = pLevel->iLikeRepCntr;
+      assert( x>0 );
+      skipLikeAddr = sqlite3VdbeAddOp1(v, (x&1)? OP_IfNot : OP_If, (int)(x>>1));
       VdbeCoverage(v);
 #endif
     }