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Add the new OP_Once opcode. Use it to clean up and simplify various

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one-time initialization sections in the code, including the fix for
ticket [002caede898ae].

FossilOrigin-Name: 7f00552b739fad79517b042a6ed61abe743a917b
This commit is contained in:
drh
2011-09-16 01:34:43 +00:00
parent 5b6a9ed495
commit 48f2d3b10a
9 changed files with 51 additions and 41 deletions
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17
src/vdbe.c
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@@ -2021,6 +2021,16 @@ case OP_BitNot: { /* same as TK_BITNOT, in1, out2 */
break;
}
/* Opcode: Once P1 P2 * * *
**
** Jump to P2 if the value in register P1 is a not null or zero. If
** the value is NULL or zero, fall through and change the P1 register
** to an integer 1.
**
** When P1 is not used otherwise in a program, this opcode falls through
** once and jumps on all subsequent invocations. It is the equivalent
** of "OP_If P1 P2", followed by "OP_Integer 1 P1".
*/
/* Opcode: If P1 P2 P3 * *
**
** Jump to P2 if the value in register P1 is true. The value
@@ -2033,6 +2043,7 @@ case OP_BitNot: { /* same as TK_BITNOT, in1, out2 */
** is considered true if it has a numeric value of zero. If the value
** in P1 is NULL then take the jump if P3 is true.
*/
case OP_Once: /* jump, in1 */
case OP_If: /* jump, in1 */
case OP_IfNot: { /* jump, in1 */
int c;
@@ -2049,6 +2060,12 @@ case OP_IfNot: { /* jump, in1 */
}
if( c ){
pc = pOp->p2-1;
}else if( pOp->opcode==OP_Once ){
assert( (pIn1->flags & (MEM_Agg|MEM_Dyn|MEM_RowSet|MEM_Frame))==0 );
memAboutToChange(p, pIn1);
pIn1->flags = MEM_Int;
pIn1->u.i = 1;
REGISTER_TRACE(pOp->p1, pIn1);
}
break;
}