crazy idea: Make all temporary symbols unnamed

[Duncan P. N. Exon Smith]

+grosbach,kledzik

> On 2015 Jun 17, at 10:09, Rafael Espíndola <rafael.espindola at gmail.com> wrote:
> 
> The attached patch is a work in progress.
> 
> What it does is make all symbols that would otherwise start with a .L
> (or L on MachO) unnamed.
> 
> There are two issues to be aware of:
> 
> * Some of these symbols can show up in the symbol table.
> * We still want to produce binary identical files when going through
> assembly files.
> 
> If the first one is handled, the second one goes away by making sure
> we ignore the name of *all* .L symbols: we pick one when writing
> assembly, but it never shows up in the final .o.

How do the 'l' symbols fit into this?  Unaffected, right?

> In this patch I have handled the first issue only in the ELF writer by
> supporting unnamed symbols.
> 
> Can symbols be unnamed on COFF and MachO?

Nick?

> If not, I think we could
> still do this and let those object writers invent a deterministic name
> at the very end, no?

Sounds plausible.

> I tested this locally by doing a bootstrap.
> 
> I tested the memory savings for llvm-mc are quite noticeable. When
> assembly a LTO llvm-as, the memory usage goes from 45,952,208 to
> 39,137,568 bytes.

Any memory stats for LTO codegen (bitcode => object)?

> 
> Cheers,
> Rafael
> <t.patch>