1 files changed, 50 insertions, 13 deletions

diff --git a/src/update.c b/src/update.c
index c23601592..c927059aa 100644
--- a/src/update.c
+++ b/src/update.c
@@ -111,14 +111,15 @@ void sqlite3Update(
   AuthContext sContext;  /* The authorization context */
   NameContext sNC;       /* The name-context to resolve expressions in */
   int iDb;               /* Database containing the table being updated */
-  int j1;                /* Addresses of jump instructions */
   int okOnePass;         /* True for one-pass algorithm without the FIFO */
   int hasFK;             /* True if foreign key processing is required */
 
 #ifndef SQLITE_OMIT_TRIGGER
-  int isView;                  /* Trying to update a view */
-  Trigger *pTrigger;           /* List of triggers on pTab, if required */
+  int isView;            /* True when updating a view (INSTEAD OF trigger) */
+  Trigger *pTrigger;     /* List of triggers on pTab, if required */
+  int tmask;             /* Mask of TRIGGER_BEFORE|TRIGGER_AFTER */
 #endif
+  int newmask;
 
   /* Register Allocations */
   int regRowCount = 0;   /* A count of rows changed */
@@ -146,11 +147,13 @@ void sqlite3Update(
   ** updated is a view.
   */
 #ifndef SQLITE_OMIT_TRIGGER
-  pTrigger = sqlite3TriggersExist(pParse, pTab, TK_UPDATE, pChanges, 0);
+  pTrigger = sqlite3TriggersExist(pParse, pTab, TK_UPDATE, pChanges, &tmask);
   isView = pTab->pSelect!=0;
+  assert( pTrigger || tmask==0 );
 #else
 # define pTrigger 0
 # define isView 0
+# define tmask 0
 #endif
 #ifdef SQLITE_OMIT_VIEW
 # undef isView
@@ -160,7 +163,7 @@ void sqlite3Update(
   if( sqlite3ViewGetColumnNames(pParse, pTab) ){
     goto update_cleanup;
   }
-  if( sqlite3IsReadOnly(pParse, pTab, (pTrigger?1:0)) ){
+  if( sqlite3IsReadOnly(pParse, pTab, tmask) ){
     goto update_cleanup;
   }
   aXRef = sqlite3DbMallocRaw(db, sizeof(int) * pTab->nCol );
@@ -388,7 +391,9 @@ void sqlite3Update(
   ** with the required old.* column data.  */
   if( hasFK || pTrigger ){
     u32 oldmask = (hasFK ? sqlite3FkOldmask(pParse, pTab) : 0);
-    oldmask |= sqlite3TriggerOldmask(pParse, pTrigger, pChanges, pTab, onError);
+    oldmask |= sqlite3TriggerColmask(pParse, 
+        pTrigger, pChanges, 0, TRIGGER_BEFORE|TRIGGER_AFTER, pTab, onError
+    );
     for(i=0; i<pTab->nCol; i++){
       if( aXRef[i]<0 || oldmask==0xffffffff || (oldmask & (1<<i)) ){
         sqlite3VdbeAddOp3(v, OP_Column, iCur, i, regOld+i);
@@ -405,24 +410,42 @@ void sqlite3Update(
   /* Populate the array of registers beginning at regNew with the new
   ** row data. This array is used to check constaints, create the new
   ** table and index records, and as the values for any new.* references
-  ** made by triggers.  */
+  ** made by triggers.
+  **
+  ** If there are one or more BEFORE triggers, then do not populate the
+  ** registers associated with columns that are (a) not modified by
+  ** this UPDATE statement and (b) not accessed by new.* references. The
+  ** values for registers not modified by the UPDATE must be reloaded from 
+  ** the database after the BEFORE triggers are fired anyway (as the trigger 
+  ** may have modified them). So not loading those that are not going to
+  ** be used eliminates some redundant opcodes.
+  */
+  newmask = sqlite3TriggerColmask(
+      pParse, pTrigger, pChanges, 1, TRIGGER_BEFORE, pTab, onError
+  );
   for(i=0; i<pTab->nCol; i++){
     if( i==pTab->iPKey ){
       sqlite3VdbeAddOp2(v, OP_Null, 0, regNew+i);
     }else{
       j = aXRef[i];
-      if( j<0 ){
+      if( j>=0 ){
+        sqlite3ExprCode(pParse, pChanges->a[j].pExpr, regNew+i);
+      }else if( 0==(tmask&TRIGGER_BEFORE) || i>31 || (newmask&(1<<i)) ){
+        /* This branch loads the value of a column that will not be changed 
+        ** into a register. This is done if there are no BEFORE triggers, or
+        ** if there are one or more BEFORE triggers that use this value via
+        ** a new.* reference in a trigger program.
+        */
         sqlite3VdbeAddOp3(v, OP_Column, iCur, i, regNew+i);
         sqlite3ColumnDefault(v, pTab, i, regNew+i);
-      }else{
-        sqlite3ExprCode(pParse, pChanges->a[j].pExpr, regNew+i);
       }
     }
   }
 
   /* Fire any BEFORE UPDATE triggers. This happens before constraints are
-  ** verified. One could argue that this is wrong.  */
-  if( pTrigger ){
+  ** verified. One could argue that this is wrong.
+  */
+  if( tmask&TRIGGER_BEFORE ){
     sqlite3VdbeAddOp2(v, OP_Affinity, regNew, pTab->nCol);
     sqlite3TableAffinityStr(v, pTab);
     sqlite3CodeRowTrigger(pParse, pTrigger, TK_UPDATE, pChanges, 
@@ -432,11 +455,25 @@ void sqlite3Update(
     ** case, jump to the next row. No updates or AFTER triggers are 
     ** required. This behaviour - what happens when the row being updated
     ** is deleted or renamed by a BEFORE trigger - is left undefined in the
-    ** documentation.  */
+    ** documentation.
+    */
     sqlite3VdbeAddOp3(v, OP_NotExists, iCur, addr, regOldRowid);
+
+    /* If it did not delete it, the row-trigger may still have modified 
+    ** some of the columns of the row being updated. Load the values for 
+    ** all columns not modified by the update statement into their 
+    ** registers in case this has happened.
+    */
+    for(i=0; i<pTab->nCol; i++){
+      if( aXRef[i]<0 && i!=pTab->iPKey ){
+        sqlite3VdbeAddOp3(v, OP_Column, iCur, i, regNew+i);
+        sqlite3ColumnDefault(v, pTab, i, regNew+i);
+      }
+    }
   }
 
   if( !isView ){
+    int j1;                       /* Address of jump instruction */
 
     /* Do constraint checks. */
     sqlite3GenerateConstraintChecks(pParse, pTab, iCur, regNewRowid,