[PATCH] D122822: [Clang][CodeGen]Add constant array support for __builtin_dump_sturct

[Wang Yihan via Phabricator via cfe-commits]

yihanaa added inline comments.


================
Comment at: clang/lib/CodeGen/CGBuiltin.cpp:2048
+                                              QualType Type) {
+  static llvm::DenseMap<QualType, StringRef> Types;
   if (Types.empty()) {
----------------
yihanaa wrote:
> erichkeane wrote:
> > yihanaa wrote:
> > > erichkeane wrote:
> > > > yihanaa wrote:
> > > > > erichkeane wrote:
> > > > > > Instead of this initialization, can we make this a constexpr constructor/collection of some sort and instantiate it inline?  
> > > > > > Instead of this initialization, can we make this a constexpr constructor/collection of some sort and instantiate it inline?  
> > > > > 
> > > > > I don't have a good idea because it relies on Context to get some types like const char *
> > > > We could at minimum do a in inline-initializer instead of the branch below.
> > > I still haven't come up with a good idea to do it😔
> > Hrmph, `DenseMap` doesn't seem to have an init list ctor?!
> > 
> > Since this is a finite, known at compile time list of low 'N', I'd suggest just making it `static std::array<pair<QualType, StringRef>> Types = {{Context.CharTy, "%c"},...`.
> > 
> > Then just doing a llvm::find_if.  The list is small enough I suspect the DenseMap overhead is more than the use of `llvm::find_if`.
> Haha,DenseMap also has no constexpr ctor. I think the time complexity of these two is the same. 
The Context.CharTy... etc. are not static, So we might need a static value instead of it, and compare it with QualType


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  https://reviews.llvm.org/D122822/new/

https://reviews.llvm.org/D122822