设置llvm :: ConstantInt的值

本文介绍了设置llvm :: ConstantInt的值的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述 我在玩LLVM。我想到了在中间代码中改变常量的值。但是，对于类 llvm :: ConstantInt ，我看不到setvalue函数。任何想法如何修改IR代码中的常数值？I'm playing around with LLVM. I thought about changing value of a constant in the intermediate code. However, for the class llvm::ConstantInt, I don't see a setvalue function. Any idea how can I modify value of a constant in the IR code?推荐答案 ConstantInt是一个工厂，不是吗？类具有 get方法来构造新常量：ConstantInt is a factory, isn't it? Class has the get method to construct new constant: /* ... return a ConstantInt for the given value. */00069 static Constant *get(Type *Ty, uint64_t V, bool isSigned = false);所以，我想，你不能修改现有的ConstantInt。如果你想修改IR，你应该尝试改变指针到参数（改变IR本身，而不是常量对象）。So, I think, you can't modify existing ConstantInt. If you want to modify IR, you should try to change pointer to argument (change the IR itself, but not the constant object).可能你想要这样（请记住，我对LLVM没有经验;我几乎可以肯定示例不正确。）May be you want something like this (please remember, I have zero experience with LLVM; and I'm almost sure example is incorrect).Instruction *I = /* your argument */;/* check that instruction is of needed format, e.g: */if (I->getOpcode() == Instruction::Add) { /* read the first operand of instruction */ Value *oldvalue = I->getOperand(0); /* construct new constant; here 0x1234 is used as value */ Value *newvalue = ConstantInt::get(oldValue->getType(), 0x1234); /* replace operand with new value */ I->setOperand(0, newvalue);} 单独修改常数有一个解决方案（递增和递减图示）： /// AddOne - Add one to a ConstantInt. static Constant *AddOne(Constant *C) { return ConstantExpr::getAdd(C, ConstantInt::get(C->getType(), 1)); } /// SubOne - Subtract one from a ConstantInt. static Constant *SubOne(ConstantInt *C) { return ConstantInt::get(C->getContext(), C->getValue()-1); } PS，Constant.h在关于创建和删除常量 http://llvm.org/docs/doxygen/html/Constant_8h_source.html 00035 /// Note that Constants are immutable (once created they never change) 00036 /// and are fully shared by structural equivalence. This means that two 00037 /// structurally equivalent constants will always have the same address. 00038 /// Constants are created on demand as needed and never deleted: thus clients 00039 /// don't have to worry about the lifetime of the objects.00040 /// @brief LLVM Constant Representation 这篇关于设置llvm :: ConstantInt的值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！