[PATCH 4/4] Initial version of RTL frontend

[Richard Biener]

On May 10, 2016 7:02:33 PM GMT+02:00, Jeff Law <law@redhat.com> wrote:
>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.

Hmm, I guess that some test cases rely on specific patterns being (not) present so we'd have one backend per testcase ... (Or .md file snippets per testcase).

Richard.

>Jeff