Attempt to factor out constant functions from the interior of table scans,

since functions can often be expensive to compute.

FossilOrigin-Name: 62e9270a8057d758621da33adb27fad14225f95d

manifest

@@ -1,5 +1,5 @@
-C Use\scompiler\sintrinsic\sfunctions\sfor\ssigned\sinteger\smath\swhen\soverflow\ndetection\sis\sneeded.
-D 2017-01-03T21:57:11.355
+C Attempt\sto\sfactor\sout\sconstant\sfunctions\sfrom\sthe\sinterior\sof\stable\sscans,\nsince\sfunctions\scan\soften\sbe\sexpensive\sto\scompute.
+D 2017-01-04T01:07:24.603
 F Makefile.in 41bd4cad981487345c4a84081074bcdb876e4b2e
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc b8ca53350ae545e3562403d5da2a69cec79308da
@@ -341,7 +341,7 @@ F src/ctime.c 9f2296a4e5d26ebf0e0d95a0af4628f1ea694e7a
 F src/date.c dc3f1391d9297f8c748132813aaffcb117090d6e
 F src/dbstat.c 19ee7a4e89979d4df8e44cfac7a8f905ec89b77d
 F src/delete.c c8bc10d145c9666a34ae906250326fdaa8d58fa5
-F src/expr.c 449cbb8b9857ff8eb685b72555086818a178858c
+F src/expr.c 8ba6e4ee13cab031bab897d871cf51678cbdd57e
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
 F src/fkey.c 2e9aabe1aee76273aff8a84ee92c464e095400ae
 F src/func.c c67273e1ec08abbdcc14c189892a3ff6eeece86b
@@ -393,7 +393,7 @@ F src/shell.c 6095531aa900decdaa765e0f3993fba7153c92c1
 F src/sqlite.h.in e8e2d108d82647f0a812fdb74accf91c1ec08ddc
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h 8648034aa702469afb553231677306cc6492a1ae
-F src/sqliteInt.h f3450b70cfd99b434304225cf3b95de9cb4a9536
+F src/sqliteInt.h ba08d9eb983697be3eb7ee8d41d1121177694f59
 F src/sqliteLimit.h c0373387c287c8d0932510b5547ecde31b5da247
 F src/status.c a9e66593dfb28a9e746cba7153f84d49c1ddc4b1
 F src/table.c 5226df15ab9179b9ed558d89575ea0ce37b03fc9
@@ -1541,8 +1541,10 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P bed0eaa5f50112e64fc97a2afdc9d56cf8f5026a 4c2efd4239bf07eb4b92d4af54edd68ee6312670
-R 4be5114c40ec1b8757eebb3b6a7e4284
-T +closed 4c2efd4239bf07eb4b92d4af54edd68ee6312670
+P d3ac32a6e7f1823450feb3d1089802542090d164
+R c8a0edce7fe1361197ea989faff6405e
+T *branch * factor-constant-funcs
+T *sym-factor-constant-funcs *
+T -sym-trunk *
 U drh
-Z 6bd6e679c9840443d9b2f38c8bc4573f
+Z 75605860ea44512895bed0398cfff7b7

manifest.uuid

@@ -1 +1 @@
-d3ac32a6e7f1823450feb3d1089802542090d164
+62e9270a8057d758621da33adb27fad14225f95d

src/expr.c

@@ -3612,6 +3612,9 @@ int sqlite3ExprCodeTarget(Parse *pParse, Expr *pExpr, int target){
       u8 enc = ENC(db);      /* The text encoding used by this database */
       CollSeq *pColl = 0;    /* A collating sequence */
 
+      if( ConstFactorOk(pParse) && sqlite3ExprIsConstantNotJoin(pExpr) ){
+        return sqlite3ExprCodeAtInit(pParse, pExpr, -1, 1);
+      }
       assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
       if( ExprHasProperty(pExpr, EP_TokenOnly) ){
         pFarg = 0;
@@ -3992,8 +3995,16 @@ int sqlite3ExprCodeTarget(Parse *pParse, Expr *pExpr, int target){
 
 /*
 ** Factor out the code of the given expression to initialization time.
+**
+** If regDest>=0 then the result is always stored in that register.
+** If regDest<0 then this routine is free to store the value whereever
+** it wants.  The register where the expression is stored is returned.
+**
+** If regDest<0 and an equivalent expression already exists elsewhere
+** in the initialization expressions, then routine just returns the
+** register of the prior occurrance.
 */
-void sqlite3ExprCodeAtInit(
+int sqlite3ExprCodeAtInit(
   Parse *pParse,    /* Parsing context */
   Expr *pExpr,      /* The expression to code when the VDBE initializes */
   int regDest,      /* Store the value in this register */
@@ -4002,6 +4013,18 @@ void sqlite3ExprCodeAtInit(
   ExprList *p;
   assert( ConstFactorOk(pParse) );
   p = pParse->pConstExpr;
+  if( regDest<0 ){
+    if( p && reusable ){
+      struct ExprList_item *pItem;
+      int i;
+      for(pItem=p->a, i=p->nExpr; i>0; pItem++, i--){
+        if( pItem->reusable && sqlite3ExprCompare(pItem->pExpr,pExpr,-1)==0 ){
+          return pItem->u.iConstExprReg;
+        }
+      }
+    }
+    regDest = ++pParse->nMem;
+  }
   pExpr = sqlite3ExprDup(pParse->db, pExpr, 0);
   p = sqlite3ExprListAppend(pParse, p, pExpr);
   if( p ){
@@ -4010,6 +4033,7 @@ void sqlite3ExprCodeAtInit(
      pItem->reusable = reusable;
   }
   pParse->pConstExpr = p;
+  return regDest;
 }
 
 /*
@@ -4032,19 +4056,8 @@ int sqlite3ExprCodeTemp(Parse *pParse, Expr *pExpr, int *pReg){
    && pExpr->op!=TK_REGISTER
    && sqlite3ExprIsConstantNotJoin(pExpr)
   ){
-    ExprList *p = pParse->pConstExpr;
-    int i;
     *pReg  = 0;
-    if( p ){
-      struct ExprList_item *pItem;
-      for(pItem=p->a, i=p->nExpr; i>0; pItem++, i--){
-        if( pItem->reusable && sqlite3ExprCompare(pItem->pExpr,pExpr,-1)==0 ){
-          return pItem->u.iConstExprReg;
-        }
-      }
-    }
-    r2 = ++pParse->nMem;
-    sqlite3ExprCodeAtInit(pParse, pExpr, r2, 1);
+    r2 = sqlite3ExprCodeAtInit(pParse, pExpr, -1, 1);
   }else{
     int r1 = sqlite3GetTempReg(pParse);
     r2 = sqlite3ExprCodeTarget(pParse, pExpr, r1);

src/sqliteInt.h

@@ -3716,7 +3716,7 @@ void sqlite3ExprCacheAffinityChange(Parse*, int, int);
 void sqlite3ExprCode(Parse*, Expr*, int);
 void sqlite3ExprCodeCopy(Parse*, Expr*, int);
 void sqlite3ExprCodeFactorable(Parse*, Expr*, int);
-void sqlite3ExprCodeAtInit(Parse*, Expr*, int, u8);
+int sqlite3ExprCodeAtInit(Parse*, Expr*, int, u8);
 int sqlite3ExprCodeTemp(Parse*, Expr*, int*);
 int sqlite3ExprCodeTarget(Parse*, Expr*, int);
 void sqlite3ExprCodeAndCache(Parse*, Expr*, int);