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Reduce parsing time for very large scripts by limiting the simplification backtrace depth. 

git-svn-id: http://voip.null.ro/svn/yate@5972 acf43c95-373e-0410-b603-e72c3f656dc1
This commit is contained in:
paulc 2015-05-15 15:17:54 +00:00
parent 0f8890f66f
commit 22dfd8e65a
1 changed files with 27 additions and 19 deletions
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46
libs/yscript/evaluator.cpp
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@ -27,6 +27,8 @@
using namespace TelEngine;
#define MAX_SIMPLIFY 16
#define MAKEOP(s,o) { s, ExpEvaluator::Opc ## o }
#define ASSIGN(s,o) { s "=", ExpEvaluator::Opc ## o | ExpEvaluator::OpcAssign }
static const TokenDict s_operators_c[] =
@ -696,10 +698,16 @@ bool ExpEvaluator::trySimplify()
{
DDebug(this,DebugInfo,"trySimplify");
bool done = false;
ObjList* opcodes = &m_opcodes;
for (unsigned int i = 0; ; i++) {
ExpOperation* o = static_cast<ExpOperation*>(m_opcodes[i]);
while ((i > MAX_SIMPLIFY) && opcodes->next()) {
// limit backtrace depth
opcodes = opcodes->next();
i--;
}
ExpOperation* o = static_cast<ExpOperation*>(opcodes->at(i));
if (!o) {
if (i >= m_opcodes.length())
if (i >= opcodes->length())
break;
else
continue;
@ -728,8 +736,8 @@ bool ExpEvaluator::trySimplify()
case OpcLe:
case OpcGe:
if (i >= 2) {
ExpOperation* op2 = static_cast<ExpOperation*>(m_opcodes[i-1]);
ExpOperation* op1 = static_cast<ExpOperation*>(m_opcodes[i-2]);
ExpOperation* op2 = static_cast<ExpOperation*>(opcodes->at(i-1));
ExpOperation* op1 = static_cast<ExpOperation*>(opcodes->at(i-2));
if (!op1 || !op2)
continue;
if (o->opcode() == OpcLAnd || o->opcode() == OpcAnd || o->opcode() == OpcMul) {
@ -737,9 +745,9 @@ bool ExpEvaluator::trySimplify()
(op2->opcode() == OpcPush && !op2->number() && op1->opcode() == OpcField)) {
ExpOperation* newOp = (o->opcode() == OpcLAnd) ? new ExpOperation(false) : new ExpOperation((int64_t)0);
newOp->lineNumber(o->lineNumber());
(m_opcodes+i)->set(newOp);
m_opcodes.remove(op1);
m_opcodes.remove(op2);
((*opcodes)+i)->set(newOp);
opcodes->remove(op1);
opcodes->remove(op2);
i -= 2;
done = true;
continue;
@ -750,9 +758,9 @@ bool ExpEvaluator::trySimplify()
(op2->opcode() == OpcPush && op2->number() && op1->opcode() == OpcField)) {
ExpOperation* newOp = new ExpOperation(true);
newOp->lineNumber(o->lineNumber());
(m_opcodes+i)->set(newOp);
m_opcodes.remove(op1);
m_opcodes.remove(op2);
((*opcodes)+i)->set(newOp);
opcodes->remove(op1);
opcodes->remove(op2);
i -= 2;
done = true;
continue;
@ -766,9 +774,9 @@ bool ExpEvaluator::trySimplify()
// replace operators and operation with computed constant
ExpOperation* newOp = popOne(stack);
newOp->lineNumber(o->lineNumber());
(m_opcodes+i)->set(newOp);
m_opcodes.remove(op1);
m_opcodes.remove(op2);
((*opcodes)+i)->set(newOp);
opcodes->remove(op1);
opcodes->remove(op2);
i -= 2;
done = true;
}
@ -779,7 +787,7 @@ bool ExpEvaluator::trySimplify()
case OpcNot:
case OpcLNot:
if (i >= 1) {
ExpOperation* op = static_cast<ExpOperation*>(m_opcodes[i-1]);
ExpOperation* op = static_cast<ExpOperation*>(opcodes->at(i-1));
if (!op)
continue;
if (op->opcode() == OpcPush) {
@ -789,16 +797,16 @@ bool ExpEvaluator::trySimplify()
// replace unary operator and operation with computed constant
ExpOperation* newOp = popOne(stack);
newOp->lineNumber(o->lineNumber());
(m_opcodes+i)->set(newOp);
m_opcodes.remove(op);
((*opcodes)+i)->set(newOp);
opcodes->remove(op);
i--;
done = true;
}
}
else if (op->opcode() == o->opcode() && op->opcode() != OpcLNot) {
// minus or bit negation applied twice - remove both operators
m_opcodes.remove(o);
m_opcodes.remove(op);
opcodes->remove(o);
opcodes->remove(op);
i--;
done = true;
}
@ -808,7 +816,7 @@ bool ExpEvaluator::trySimplify()
break;
}
}
m_lastOpcode = m_opcodes.last();
m_lastOpcode = opcodes->last();
return done;
}