Trim NULL values off the end of records when the SQLITE_ENABLE_TRIM_NULLS

compile-time option is used.  Increase the size of the P5 operand to 16 bits.
Fix a problem with short records in the sessions extension.

FossilOrigin-Name: 4801bd59a01dcc11a3eb9e776e7599b36f162d2a

diff --cc manifest
index edea9fbb44cb289db17e011a94ffd436be2e364a,e160f9e3f69ff1cc7e6ad83ccccfa9751eccb594..b6cd8613f424d08d94b591814d19ca33c8461056
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Ensure\sthat\ssqlite3_blob_reopen()\scorrectly\shandles\sshort\srows.\s\nFix\sfor\sticket\s[e6e962d6b0f06f46e].
- D 2017-01-25T14:38:19.847
 -C Fix\sanother\spre-update\shook\sissue,\sthis\stime\sin\ssqlite3preupdate_old().
 -D 2017-01-25T18:53:27.729
++C Trim\sNULL\svalues\soff\sthe\send\sof\srecords\swhen\sthe\sSQLITE_ENABLE_TRIM_NULLS\ncompile-time\soption\sis\sused.\s\sIncrease\sthe\ssize\sof\sthe\sP5\soperand\sto\s16\sbits.\nFix\sa\sproblem\swith\sshort\srecords\sin\sthe\ssessions\sextension.
++D 2017-01-25T20:55:11.502
  F Makefile.in 5f415e7867296d678fed2e6779aea10c1318b4bc
  F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
  F Makefile.msc b8ca53350ae545e3562403d5da2a69cec79308da
@@@ -352,7 -352,7 +352,7 @@@ F src/hash.c 63d0ee752a3b92d4695b2b1f52
  F src/hash.h ab34c5c54a9e9de2e790b24349ba5aab3dbb4fd4
  F src/hwtime.h 747c1bbe9df21a92e9c50f3bbec1de841dc5e5da
  F src/in-operator.md 10cd8f4bcd225a32518407c2fb2484089112fd71
- F src/insert.c 05e47e2de7b712a3a4148cd469e5f60873f5ef13
 -F src/insert.c 07ccec2c1fb32dd2c5fbfd63426e98dc2a79a0fa
++F src/insert.c 8183e1778ec42d26732bec8c98aeffa8af13038f
  F src/legacy.c 75d3023be8f0d2b99d60f905090341a03358c58e
  F src/loadext.c a68d8d1d14cf7488bb29dc5311cb1ce9a4404258
  F src/main.c e207b81542d13b9f13d61e78ca441f9781f055b0
@@@ -395,7 -395,7 +395,7 @@@ F src/shell.c 59de9acab4423a536277653f2
  F src/sqlite.h.in 1971ab9709e010d52a02a1a6276d5a2f9b947476
  F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
  F src/sqlite3ext.h 8648034aa702469afb553231677306cc6492a1ae
- F src/sqliteInt.h 525c061ae9aafc8d4720a018d82f0936d9eee5ab
 -F src/sqliteInt.h dc587b0727c2bc888d78d200d891620080567691
++F src/sqliteInt.h 341ce9e5b0397771fa6bd9dadb8ef4cbbd6224d0
  F src/sqliteLimit.h c0373387c287c8d0932510b5547ecde31b5da247
  F src/status.c a9e66593dfb28a9e746cba7153f84d49c1ddc4b1
  F src/table.c b46ad567748f24a326d9de40e5b9659f96ffff34
@@@ -457,11 -457,11 +457,11 @@@ F src/update.c b356b29d04c71f33c779f2cb
  F src/utf.c 699001c79f28e48e9bcdf8a463da029ea660540c
  F src/util.c a88b0466fddf445ce752226d4698ca3faada620a
  F src/vacuum.c 33c174b28886b2faf26e503b5a49a1c01a9b1c16
- F src/vdbe.c c7add5978cb84ae3a7bcb16f8b56cb3bbdf04b7e
- F src/vdbe.h b0866e4191f096f1c987a84b042c3599bdf5423b
 -F src/vdbe.c b1f2448184fa58c66fc94591004b1258964ef9da
++F src/vdbe.c 1fa3e8f3ee1cdfc56d9559bca9ca2c84e4a398be
+ F src/vdbe.h 59998ffd71d7caa8886bc78dafaf8caeccd4c13c
  F src/vdbeInt.h 281cb70332dc8b593b8c7afe776f3a2ba7d4255e
- F src/vdbeapi.c d6ebaa465f070eb1af8ba4e7b34583ece87bdd24
- F src/vdbeaux.c 35c9a9908174e5a26c96d15e1f98214814a39147
+ F src/vdbeapi.c 7a65f10684982daecfce50f557f2632b7f20b198
+ F src/vdbeaux.c 7c19b78999faae833e1be66dfa4e3deaf334d739
  F src/vdbeblob.c 2b3d1ad915dbe5dc92c48759dc18fa8c697e78e5
  F src/vdbemem.c 3b5a9a5b375458d3e12a50ae1aaa41eeec2175fd
  F src/vdbesort.c eda25cb2d1727efca6f7862fea32b8aa33c0face
@@@ -1547,8 -1547,7 +1547,8 @@@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a9
  F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
  F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
  F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
- P 0803390c152141c9ab4e7a28406b2a5d72a5c2fa 57d8dad35c2a9ab635e954dce7f3986ae1ca8ed2
- R d15a5cee6a51c7118a4d78b7d0cbd2de
- T +closed 57d8dad35c2a9ab635e954dce7f3986ae1ca8ed2
 -P f66614dc78e32d2d369518200b3322cd97990ffe
 -R b9395615953abce115528c9bb805cca4
 -U dan
 -Z c5b3bc3bd2550d6ddb6d6d5566bf3773
++P 8cd1a4451cce1fe28f462800e2be1dee1735c0d0 c7651d21bfdfd9b8cf04b26e0264bc58c03d247f
++R 97e00d1e041d69da0e0a6af8a75ee1a0
++T +closed c7651d21bfdfd9b8cf04b26e0264bc58c03d247f
 +U drh
- Z f9af43b146da8d8246d0b97014ae0d3a
++Z 857c1b54405ac0784389a22078eb728f

diff --cc manifest.uuid
index d15e64c7de36d8ec4f3eb7811e29e3feee30556a,5de3845661ac309654ddd31bef958dd4b35c844a..854e8f8a4749dd217935c027918ba77d59a006a6
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- 8cd1a4451cce1fe28f462800e2be1dee1735c0d0
 -c7651d21bfdfd9b8cf04b26e0264bc58c03d247f
++4801bd59a01dcc11a3eb9e776e7599b36f162d2a

diff --cc src/insert.c
index 93c22ae3f50c4545e313fd420fb822f42a5da75e,5bb8ba2ff9ed6793713972ea913f3287f5ce7a58..5370ef77edb02dc9176ece6a3bf5a0cb2459326d
--- 1/src/insert.c
--- 2/src/insert.c
+++ b/src/insert.c
@@@ -1668,6 -1668,23 +1668,25 @@@ void sqlite3GenerateConstraintChecks
    VdbeModuleComment((v, "END: GenCnstCks(%d)", seenReplace));
  }
  
++#ifdef SQLITE_ENABLE_NULL_TRIM
+ /*
+ ** Change the P5 operand on the last opcode (which should be an OP_MakeRecord)
+ ** to be the number of columns in table pTab that must not be NULL-trimmed.
+ **
+ ** Or if no columns of pTab may be NULL-trimmed, leave P5 at zero.
+ */
+ void sqlite3SetMakeRecordP5(Vdbe *v, Table *pTab){
+   u16 i;
+ 
+   /* Records with omitted columns are only allowed for schema format
+   ** version 2 and later (SQLite version 3.1.4, 2005-02-20). */
+   if( pTab->pSchema->file_format<2 ) return;
+ 
+   for(i=pTab->nCol; i>1 && pTab->aCol[i-1].pDflt==0; i--){}
+   sqlite3VdbeChangeP5(v, i);
+ }
++#endif
+ 
  /*
  ** This routine generates code to finish the INSERT or UPDATE operation
  ** that was started by a prior call to sqlite3GenerateConstraintChecks.

diff --cc src/sqliteInt.h
index 6344cac5f1a78f11c7044dd490d2862c8f5ba0fa,ceae4dcb1f8d4568c795effea42ca911ca48a57c..7ea8748b736eae808355899ddd27ae8f49551338
--- 1/src/sqliteInt.h
--- 2/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@@ -3790,6 -3790,7 +3790,11 @@@ int sqlite3GenerateIndexKey(Parse*, Ind
  void sqlite3ResolvePartIdxLabel(Parse*,int);
  void sqlite3GenerateConstraintChecks(Parse*,Table*,int*,int,int,int,int,
                                       u8,u8,int,int*,int*);
 -void sqlite3SetMakeRecordP5(Vdbe*,Table*);
++#ifdef SQLITE_ENABLE_NULL_TRIM
++  void sqlite3SetMakeRecordP5(Vdbe*,Table*);
++#else
++# define sqlite3SetMakeRecordP5(A,B)
++#endif
  void sqlite3CompleteInsertion(Parse*,Table*,int,int,int,int*,int,int,int);
  int sqlite3OpenTableAndIndices(Parse*, Table*, int, u8, int, u8*, int*, int*);
  void sqlite3BeginWriteOperation(Parse*, int, int);

diff --cc src/vdbe.c
index cbb7867512f2091b0da1391b7e83aa640419f257,88010a9a6fdc2af24215ce05076c91b6e62317bd..6838acccd5c9bf47bf47d6119059af9e35c0ce60
--- 1/src/vdbe.c
--- 2/src/vdbe.c
+++ b/src/vdbe.c
@@@ -2777,6 -2777,18 +2777,20 @@@ case OP_MakeRecord: 
      }while( zAffinity[0] );
    }
  
++#ifdef SQLITE_ENABLE_NULL_TRIM
+   /* NULLs can be safely trimmed from the end of the record, as long as
+   ** as the schema format is 2 or more and none of the omitted columns
+   ** have a non-NULL default value.  Also, the record must be left with
+   ** at least one field.  If P5>0 then it will be one more than the
+   ** index of the right-most column with a non-NULL default value */
+   if( pOp->p5 ){
+     while( (pLast->flags & MEM_Null)!=0 && nField>pOp->p5 ){
+       pLast--;
+       nField--;
+     }
+   }
++#endif
+ 
    /* Loop through the elements that will make up the record to figure
    ** out how much space is required for the new record.
    */