[llvm-commits] [PATCH] Make Inits FoldingSetNodes

[David A. Greene]

Chris Lattner <clattner at apple.com> writes:

> On Jul 13, 2011, at 3:33 PM, David Greene wrote:
>     @@ -530,6 +629,23 @@ const Init *OpInit::resolveListElementReference(Record &R, const 
>     +const UnOpInit *UnOpInit::get(UnaryOp opc, const Init *lhs, RecTy *Type) {
>     +  FoldingSetNodeID ID;
>     +  ID.AddInteger(initUnOp);
>     +  ID.AddInteger(opc);
>     +  ID.AddString(Type->getAsString());
>     +  ID.AddPointer(lhs);
>
> DenseMap makes sense here.
>
>     +const BinOpInit *BinOpInit::get(BinaryOp opc, const Init *lhs,
>     +                                   const Init *rhs, RecTy *Type) {
>
> and here.
>
>     +const TernOpInit *TernOpInit::get(TernaryOp opc, const Init *lhs,
>     +                                  const Init *mhs, const Init *rhs,
>     +                                  RecTy *Type) {
>
> and here.

I am going through and uniquing Inits in their own unique ways.

Question on these three.  DenseMap of what?  There's an opcode, multiple
operands and a type.  What's the Key, a struct of these items?  Is a
DenseMap much more efficient than a FoldingSetNode when string
comparison/hash is involved?  Wouldn't hashing a struct of these and
putting them in a DenseMap basically be equivalent to a FoldingSet?

                                 -Dave