[PATCH] D35471: [Polly] [RFC] Calculate AST expression type

[Siddharth via Phabricator via llvm-commits]

bollu added inline comments.


================
Comment at: lib/CodeGen/PPCGCodeGeneration.cpp:1029
 
+    ExprBuilder.setFixedSizeMode(true);
     Value *NumElements = ExprBuilder.create(Res);
----------------
philip.pfaffe wrote:
> bollu wrote:
> > Can we create a wrapper that does this? Example,
> > 
> > ```lang=cpp
> > template<typename FTy>
> > auto scopeFixedSizeMode(FTy F, IslExprBuilder &ExprBuilder) -> decltype(FTy()) typename std::enable_if<!std::is_same<decltype(std::declval<FTy>()()), void>::value,
> >                  decltype(std::declval<FTy>()())>::type
> > scopedFixedSizeMode(FTy F) {
> >     ExprBuilder.setBuildMode(true);
> >     auto Ret = F();
> >     ExprBuilder.setBuildMode(false);
> >     return Ret;
> > }
> > 
> > template <typename FTy>
> > typename std::enable_if<std::is_same<decltype(std::declval<FTy>()()), void>::value, void>::type
> > scopedFixedSizeMode(FTy F) {
> >     ExprBuilder.setBuildMode(true);
> >     F();
> >     ExprBuilder.setBuildMode(false);
> > }
> > ```
> > 
> > The wrapper right now is crazy, but there has to be a way for this to be more "canonical".
> Here's a way to express the same thing more nicely:
> 
> ```lang=c++
> template<typename T> T Foo(std::function<T()> F) {                              
>   auto R = F();                                                                 
>   return R;                                                                     
> }                                                                               
>                                                                                 
> void Foo(std::function<void()> F) {                                             
>   F();                                                                          
> }
> ```
This should let us write


```lang=c++
ExprBuilder.setFixedSizeMode(true);
Value *NumElements = ExprBuilder.create(Res);
ExprBuilder.setFixedSizeMode(false);
```

as:

```lang=c++
Value *NumElements = scopedFixedSizeMode([&] () { ExprBuilder.create(Res); });
```

I primarily want this because it's much less error prone.


https://reviews.llvm.org/D35471