[PATCH 4/4] Initial version of RTL frontend

[David Malcolm]

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.