Implement first D-specific optimization pass: -simplify-drtcalls. It uses the machinery of the standard -simplify-libcalls pass, but optimizes calls to the D runtime instead of calls to C libraries. At the moment, these optimizations are implemented by this pass: - Avoid the runtime call for `arr.length = newlen` if it can determine that the new length isn't longer than the old one. - Ditto for `cast(T[]) arr` if it will clearly always succeed. (e.g. if the length of the original array is zero, or if the old element size is a multiple of the new element size)

// this head contains stuff used by all the IR

#ifndef LDC_IR_IR_H
#define LDC_IR_IR_H

#include <deque>

#include "ir/irforw.h"
#include "root.h"

struct IRState;
struct IrFunction;

struct IrBase : Object
{
    virtual ~IrBase() {}
};

struct Ir
{
    Ir();

    void setState(IRState* p)   { irs = p; }
    IRState* getState()         { return irs; }

    void addFunctionBody(IrFunction* f);
    void emitFunctionBodies();

private:
    IRState* irs;

    std::deque<IrFunction*> functionbodies;
};

#endif