[PATCH 4/4] Initial version of RTL frontend

[Jeff Law]

On 05/10/2016 08:17 AM, Richard Biener wrote:
> On Tue, May 10, 2016 at 4:13 PM, David Malcolm <dmalcolm@redhat.com> wrote:
>> On Wed, 2016-05-04 at 16:49 -0400, David Malcolm wrote:
>> [...snip...]
>>>
>>> I wrote this by compiling a test.c with -fdump-rtl-all on
>>> x86_64-pc-linux-gnu, and then attempting to load the state at each
>>> pass, and then trying to run just one pass, and fixing bugs until the
>>> dump output from each pass was the same as when running the pass from
>>> cc1.  I've only done this with a small subset of passes, and with a
>>> very
>>> simple test case, so I'm sure there are plenty of bugs and "x86_64
>>> -isms"
>>> remaining.
>>
>> [...snip...]
>>
>> On the subject of "x86_64-isms", a couple of issues I ran into when
>> testing with --target=aarch64-linux-gnu:
>>
>> * roundtrip.exp fails due to different register names so e.g. this from
>> x86_64:
>>
>>      (reg:SI 5 di [ i ]))
>>
>>   becomes this after roundtripping on aarch64:
>>
>>      (reg:SI 5 x5 [ i ]))
>>
>>   (i.e. "di" vs "x5" for register 5).
>>
>> * unknown modes e.g. this from x86_64:
>>
>>     (reg:CCGC 17 flags)
>>
>>   fails on aarch64 due to the lack of a "CCGC" mode.
>
> I expect most (if not all) RTL testcases will be target specific.
Well, not if we take Bernd's idea and create a new backend for testing 
purposes.  If we want to know/test what reload's doing, we cons up the 
appropriate RTL for that testing backend, set the right flags and call 
reload() then look at the result.

Jeff