virtual bool isNullValue() const = 0;
virtual void print(std::ostream &O) const;
+
+ /// canTrap - Return true if evaluation of this constant could trap. This is
+ /// true for things like constant expressions that could divide by zero.
+ bool canTrap() const;
// Specialize get/setOperand for Constant's as their operands are always
// constants as well.
delete this;
}
+/// canTrap - Return true if evaluation of this constant could trap. This is
+/// true for things like constant expressions that could divide by zero.
+bool Constant::canTrap() const {
+ assert(getType()->isFirstClassType() && "Cannot evaluate aggregate vals!");
+ // The only thing that could possibly trap are constant exprs.
+ const ConstantExpr *CE = dyn_cast<ConstantExpr>(this);
+ if (!CE) return false;
+
+ // ConstantExpr traps if any operands can trap.
+ for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
+ if (getOperand(i)->canTrap())
+ return true;
+
+ // Otherwise, only specific operations can trap.
+ switch (CE->getOpcode()) {
+ default:
+ return false;
+ case Instruction::Div:
+ case Instruction::Rem:
+ // Div and rem can trap if the RHS is not known to be non-zero.
+ if (!isa<ConstantInt>(getOperand(1)) || getOperand(1)->isNullValue())
+ return true;
+ return false;
+ }
+}
+
+
// Static constructor to create a '0' constant of arbitrary type...
Constant *Constant::getNullValue(const Type *Ty) {
switch (Ty->getTypeID()) {