从语义分析阶段重用符号表以生成代码 [英] Reusing symbol table from semantic analysis phase for code generation

问题描述

我目前正在为具有全局变量和嵌套子例程功能的语言构建编译器.以前，我只为语言创建过一个编译器，该语言只具有局部变量而没有嵌套的子例程.

I'm currently building a compiler for a language which has global variable and nested subroutine feature. Previously, I've only ever built a compiler for languages which only has local variable without nested subroutine.

在代码生成阶段，如何重用在语义分析阶段填充的符号表，我遇到了一个问题.我将符号表做成一堆链表，其中每个链表代表在特定作用域中声明的标识符.每次进入作用域时，都会创建一个新列表并将其推入堆栈，并成为当前作用域.同样，每次离开示波器时，都会弹出堆栈顶部的列表.最后，在语义分析完成之后，实际上我有一个空的符号表，就像它开始时一样.但是，代码生成器需要一个完全填充的符号表才能正确生成代码.如何在不重新进行语义分析期间(即在符号表中输入标识符)的情况下完成此操作?

I have a problem on how to reuse symbol table filled during semantic analysis phase in code generation phase. I make the symbol table as a stack of linked list, where each linked list represents identifiers declared in a particular scope. Every time it enters a scope, a new list is created and pushed to the stack and it becomes current scope. Likewise, every time it leaves a scope, the list on top of stack is popped. In the end, after the semantic analysis finishes, I practically have empty symbol table, just like when it starts. However, the code generator needs a completely filled symbol table to correctly generate code. How can this be done without re-doing what has been done during semantic analysis (i.e. entering identifiers to the symbol table)?

推荐答案

由于您的问题，这将有点抽象-因为我对编译器的内部数据结构一无所知.

This is going to be a bit abstract - as your question - since I don't know anything concrete about your compiler's internal data structures.

当您弹出范围时，而不是像现在假设的那样删除范围，请将指向范围数据的指针分配给该范围代码生成所基于的数据成员，以便代码生成器可以到达它.

When you pop your scope, instead of deleting it, as I assume you do now, assign the pointer to the scope data to a member of the data that you base code generation on for that scope, so that the code generator can get to it.

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