[LLVMdev] datalayout optimization question

[Duncan Sands]

Hi Sebastien,

> We are developing our own compiler front-end and use LLVM as back-end. We
> generate .ll files and use opt/llc to generate target specific code. When I
> generate datalayout information in my .ll file it seems that it enables more
> optimization from LLVM opt. How can I determine which optimization are driven by
> datalayout information generation ?
>
> In other words, when I don’t generate target specific datalayout information,
> what are the optimizations that are turned off ?

this will give you an idea:

   grep -l -r TargetData llvm/lib/Transforms

Several of these work in a degraded mode if they don't have target data, i.e.
they still do some optimizations, just not all of them.  Finally, there are a
few optimizations that could in theory be performed without target data but
aren't because either no-one implemented it, or it is tricky and didn't seem
worth it.

Ciao, Duncan.