int ForLoopUnroll::getLoopIncrement(TIntermLoop* node)
{
TIntermNode* expr = node->getExpression();
ASSERT(expr != NULL);
// for expression has one of the following forms:
// loop_index++
// loop_index--
// loop_index += constant_expression
// loop_index -= constant_expression
// ++loop_index
// --loop_index
// The last two forms are not specified in the spec, but I am assuming
// its an oversight.
TIntermUnary* unOp = expr->getAsUnaryNode();
TIntermBinary* binOp = unOp ? NULL : expr->getAsBinaryNode();
TOperator op = EOpNull;
TIntermConstantUnion* incrementNode = NULL;
if (unOp != NULL) {
op = unOp->getOp();
} else if (binOp != NULL) {
op = binOp->getOp();
ASSERT(binOp->getRight() != NULL);
incrementNode = binOp->getRight()->getAsConstantUnion();
ASSERT(incrementNode != NULL);
}
int increment = 0;
// The operator is one of: ++ -- += -=.
switch (op) {
case EOpPostIncrement:
case EOpPreIncrement:
ASSERT((unOp != NULL) && (binOp == NULL));
increment = 1;
break;
case EOpPostDecrement:
case EOpPreDecrement:
ASSERT((unOp != NULL) && (binOp == NULL));
increment = -1;
break;
case EOpAddAssign:
ASSERT((unOp == NULL) && (binOp != NULL));
increment = evaluateIntConstant(incrementNode);
break;
case EOpSubAssign:
ASSERT((unOp == NULL) && (binOp != NULL));
increment = - evaluateIntConstant(incrementNode);
break;
default:
ASSERT(false);
}
return increment;
}
bool ValidateLimitations::validateForLoopExpr(TIntermLoop *node,
int indexSymbolId)
{
TIntermNode *expr = node->getExpression();
if (expr == NULL)
{
error(node->getLine(), "Missing expression", "for");
return false;
}
// for expression has one of the following forms:
// loop_index++
// loop_index--
// loop_index += constant_expression
// loop_index -= constant_expression
// ++loop_index
// --loop_index
// The last two forms are not specified in the spec, but I am assuming
// its an oversight.
TIntermUnary *unOp = expr->getAsUnaryNode();
TIntermBinary *binOp = unOp ? NULL : expr->getAsBinaryNode();
TOperator op = EOpNull;
TIntermSymbol *symbol = NULL;
if (unOp != NULL)
{
op = unOp->getOp();
symbol = unOp->getOperand()->getAsSymbolNode();
}
else if (binOp != NULL)
{
op = binOp->getOp();
symbol = binOp->getLeft()->getAsSymbolNode();
}
// The operand must be loop index.
if (symbol == NULL)
{
error(expr->getLine(), "Invalid expression", "for");
return false;
}
if (symbol->getId() != indexSymbolId)
{
error(symbol->getLine(),
"Expected loop index", symbol->getSymbol().c_str());
return false;
}
// The operator is one of: ++ -- += -=.
switch (op)
{
case EOpPostIncrement:
case EOpPostDecrement:
case EOpPreIncrement:
case EOpPreDecrement:
ASSERT((unOp != NULL) && (binOp == NULL));
break;
case EOpAddAssign:
case EOpSubAssign:
ASSERT((unOp == NULL) && (binOp != NULL));
break;
default:
error(expr->getLine(), "Invalid operator", GetOperatorString(op));
return false;
}
// Loop index must be incremented/decremented with a constant.
if (binOp != NULL)
{
if (!isConstExpr(binOp->getRight()))
{
error(binOp->getLine(),
"Loop index cannot be modified by non-constant expression",
symbol->getSymbol().c_str());
return false;
}
}
return true;
}
