[lld] r244934 - Template OutputSection only over Is64Bit.

[Rafael Espíndola via llvm-commits]

On 9 September 2015 at 17:58, Rui Ueyama <ruiu at google.com> wrote:
> Sorry to resurrect this old thread, but as I take a look again at the ELF
> Writer's code, I found that this patch made the code a bit messy. Some
> functions or classes are specialized only for `Is64Bits` and others are for
> `ELFT`, although `ELFT` works for both cases. I really prefer code
> simplicity over marginal efficiency at this stage of development, so I agree
> with Sean. Can I roll it back?

The main value I see with the current setup is that the members we
have are plain structs. This means that they print cleanly on a
debugger.

The structs in ELFTypes.h are "unreadable". One has to fetch
individual fields and cast them to the proper type to read the value,
something like:

p (uint32_t) Value->st_name.

The logic of what is templated over ELFT or Is64Bits is actually
pretty simple: Stuff that reads inputs is ELFT. Stuff that we
construct is Is64Bit.

And last, it does reduce code duplication and increases the alignment
of the stuff we construct.

So my preference would be to keep it as is for now.

Cheers,
Rafael

P.S.: Once we can link something big but simple (static clang with
musl for example), I intend to benchmark and revisit the file output
strategy, so I will be taking a thorough look at this fairly soon.