Paddle compiler

[tongxin]

PR types

New Features

PR changes

Describe

Included are files for declaring and building Piano optimization passes. Auxiliary utility classes are also given for future adoption.

The base pass class is defined in pass.h, along with macros for exhausting all registered pass classes. By registration we loosely refer to a pass class 1) whose pass name is included PASSDEF_ALL macro and 2) whose forward declaration is included in pass.h

The instantiate a pass object, be advised to use the make_pass macro with pass name and the compiler context pointer as parameters.

We intentionally decide not to rely on a registration table for sake of simplicity and performance.

[thisjiang]

不大明白为什么要把name设计为一个纯虚函数？作为构造函数参数不更好么？

class Pass {
 public:
  Pass(const std::string& name) : name_(name) {}
  virtual ~Pass() =default;
  const std::string& name() { return name_;}
 private:
  std::string name_;
};

class SubPass : public  Pass {
 public:
  SubPass() : Pass("SubPass") {}
};

[tongxin]

Hello，构造参数就要为每个对象分配 name 空间，虚函数的用意是一个类只需要一个常量 string，constexpr 也可以？

[thisjiang]

不管有没有name，虚函数意味着总是得给对象分配空间的，多个name感觉没啥负担

[thisjiang]

另外，constexpr应该不行，但const std::string& name应该可以，只要保证name只会在构造函数中被赋值且不会被修改。引用的负担也不大

[tongxin]

这块我想过，比较下来还是虚函数最好，name严格说都不算pass的本质属性，另外name()不频繁调用，对象只包含一个虚函数表指针。

[thisjiang]

这个应该是\而不是+1吧？另外这个name好像没有用到唉？

[tongxin]

这个 是 +1，展开之后相当于 +1 +1 +1 ... = number of pass classes

[thisjiang]

受教了，还没这么用过

[thisjiang]

感觉是不是弄复杂了。。。这儿用宏感觉没啥必要唉？

[tongxin]

只需要维护 PASSDEF_ALL 那个宏即可。。

[thisjiang]

这宏太多，有点头晕😂

[thisjiang]

为个逗号加个宏感觉冗余了吧？这样感觉反而容易用混淆

[tongxin]

不然在 enum PassId 里面展开缺逗号。。

[tongxin]

这我再改下

[tongxin]

如果已经包含了 pass class 的头文件，这是不是把已经定义的类屏蔽掉？

[thisjiang]

对的，会覆盖掉

[tongxin]

是的，这块需要改掉。