Reorder the elements of the Mem object for a small size reduction and

performance improvement.

FossilOrigin-Name: 0be3019ed794c10de67dfd645ceea7d45815bc4b

5 files changed, 26 insertions, 11 deletions

diff --git a/src/func.c b/src/func.c
index 0a8a9dda3..e1961118f 100644
--- a/src/func.c
+++ b/src/func.c
@@ -1492,6 +1492,7 @@ static void minmaxStep(
       sqlite3SkipAccumulatorLoad(context);
     }
   }else{
+    pBest->db = sqlite3_context_db_handle(context);
     sqlite3VdbeMemCopy(pBest, pArg);
   }
 }
diff --git a/src/vdbeInt.h b/src/vdbeInt.h
index 27b266986..5379d6b66 100644
--- a/src/vdbeInt.h
+++ b/src/vdbeInt.h
@@ -161,9 +161,6 @@ struct VdbeFrame {
 ** integer etc.) of the same value.
 */
 struct Mem {
-  sqlite3 *db;        /* The associated database connection */
-  char *z;            /* String or BLOB value */
-  double r;           /* Real value */
   union {
     i64 i;              /* Integer value used when MEM_Int is set in flags */
     int nZero;          /* Used when bit MEM_Zero is set in flags */
@@ -171,15 +168,19 @@ struct Mem {
     RowSet *pRowSet;    /* Used only when flags==MEM_RowSet */
     VdbeFrame *pFrame;  /* Used when flags==MEM_Frame */
   } u;
-  int n;              /* Number of characters in string value, excluding '\0' */
   u16 flags;          /* Some combination of MEM_Null, MEM_Str, MEM_Dyn, etc. */
   u8  enc;            /* SQLITE_UTF8, SQLITE_UTF16BE, SQLITE_UTF16LE */
+  int n;              /* Number of characters in string value, excluding '\0' */
+  double r;           /* Real value */
+  char *z;            /* String or BLOB value */
+  char *zMalloc;      /* Dynamic buffer allocated by sqlite3_malloc() */
+  /* ShallowCopy only needs to copy the information above */
+  sqlite3 *db;        /* The associated database connection */
+  void (*xDel)(void*);/* If not null, call this function to delete Mem.z */
 #ifdef SQLITE_DEBUG
   Mem *pScopyFrom;    /* This Mem is a shallow copy of pScopyFrom */
   void *pFiller;      /* So that sizeof(Mem) is a multiple of 8 */
 #endif
-  void (*xDel)(void *);  /* If not null, call this function to delete Mem.z */
-  char *zMalloc;      /* Dynamic buffer allocated by sqlite3_malloc() */
 };
 
 /* One or more of the following flags are set to indicate the validOK
diff --git a/src/vdbeapi.c b/src/vdbeapi.c
index b64f33c8c..14d6b8412 100644
--- a/src/vdbeapi.c
+++ b/src/vdbeapi.c
@@ -803,11 +803,21 @@ static const Mem *columnNullValue(void){
 #if defined(SQLITE_DEBUG) && defined(__GNUC__)
     __attribute__((aligned(8))) 
 #endif
-    = {0, "", (double)0, {0}, 0, MEM_Null, 0,
+    = {
+         .flags      = MEM_Null,
+         .enc        = 0,
+         .n          = 0,
+         .r          = (double)0,
+         .u          = {0},
+         .z          = 0,
+         .zMalloc    = 0,
+         .db         = 0,
+         .xDel       = 0,
 #ifdef SQLITE_DEBUG
-       0, 0,  /* pScopyFrom, pFiller */
+         .pScopyFrom = 0,
+         .pFiller    = 0,
 #endif
-       0, 0 };
+      };
   return &nullMem;
 }
 
diff --git a/src/vdbeaux.c b/src/vdbeaux.c
index 3360d919b..65792b485 100644
--- a/src/vdbeaux.c
+++ b/src/vdbeaux.c
@@ -3303,8 +3303,9 @@ static int vdbeCompareMemString(
     int n1, n2;
     Mem c1;
     Mem c2;
-    memset(&c1, 0, sizeof(c1));
-    memset(&c2, 0, sizeof(c2));
+    c1.db = c2.db = pMem1->db;
+    c1.flags = c2.flags = 0;
+    c1.zMalloc = c2.zMalloc = 0;
     sqlite3VdbeMemShallowCopy(&c1, pMem1, MEM_Ephem);
     sqlite3VdbeMemShallowCopy(&c2, pMem2, MEM_Ephem);
     v1 = sqlite3ValueText((sqlite3_value*)&c1, pColl->enc);
diff --git a/src/vdbemem.c b/src/vdbemem.c
index ea4def3f8..7785bc0de 100644
--- a/src/vdbemem.c
+++ b/src/vdbemem.c
@@ -730,6 +730,7 @@ void sqlite3VdbeMemAboutToChange(Vdbe *pVdbe, Mem *pMem){
 */
 void sqlite3VdbeMemShallowCopy(Mem *pTo, const Mem *pFrom, int srcType){
   assert( (pFrom->flags & MEM_RowSet)==0 );
+  assert( pTo->db==pFrom->db );
   VdbeMemReleaseExtern(pTo);
   memcpy(pTo, pFrom, MEMCELLSIZE);
   pTo->xDel = 0;
@@ -747,6 +748,7 @@ void sqlite3VdbeMemShallowCopy(Mem *pTo, const Mem *pFrom, int srcType){
 int sqlite3VdbeMemCopy(Mem *pTo, const Mem *pFrom){
   int rc = SQLITE_OK;
 
+  assert( pTo->db==pFrom->db );
   assert( (pFrom->flags & MEM_RowSet)==0 );
   VdbeMemReleaseExtern(pTo);
   memcpy(pTo, pFrom, MEMCELLSIZE);