Re: Removing ARCNET stuffs

[Andrew Cagney <andrew.cagney%gmail.com@localhost>]

I'm clearly out-of-date regarding SSA, its nice to be corrected.

On 8 June 2015 at 09:06, Anders Magnusson <ragge%ludd.ltu.se@localhost> wrote:
> Andrew Cagney skrev den 2015-06-01 20:41:
>>
> I do not understand why either of those choices need to be taken.
> Pcc has a reasonable intermediate representation, which in the optimizer
> is converted to SSA form, hammered on, and converted back.  This is
> done while retaining the intermediate representation, which is no problem.
>>
>> I'm being fast and loose.  My reading of the code was that debug info
>> was being generated by the back of the front end (very roughly
>> "gimplify" in this diagram of GCC
>> https://gcc.gnu.org/projects/tree-ssa/#ssa).   It was pretty much hard
>> wired printfs, and explained to me why "-g -O" wasn't supported.
>
> printf's are only used for data (which is spit out directly), not code.
> All code is dealt with function-wise, otherwise things like the register
> allocator would not work.
>
>>> Unless, I guess, what you're talking about is throwing away the
>>> existing backend entirely and writing a new SSA-based one, in which
>>> case I'd gently suggest that this is a large project :-)
>>
>> Exactly :-(
>>
> What is wrong with the existing backend?

As you state, the representation gets taken into and then out of SSA.
Why bother; at least for the converting to-ssa side?

Andrew