Re: [PATCH] sim: testsuite: push $arch out to targets

[Mike Frysinger via Gdb-patches <gdb-patches@sourceware.org>]

On 20 Jan 2021 12:53, Tom Tromey wrote:
> Mike> as we do multibuilds, we'll have multiple ports active, so a single
> Mike> variable won't cut it.  moving it here and out of autotols enables
> Mike> that.  as we do multitarget, this will help smooth the transition as
> Mike> we won't have to juggle each arch as it migrates.
> 
> I'm curious to hear about the plan here, specifically if you plan to
> tackle the "gdb can only include one sim" problem.

i've been slowly reworking the sim core to flip it from "the port owns the
central data structure" to "the core owns everything, and ports are just
given a pointer to their data structure".  that would allow for the core to
pick the backend instead of the backend picking the core.

there's other settings that make this difficult in the sim as it binds a
lot of configure-time settings into the build (like register & addresss
sizes & endianness).  so i'd expect at first we'd be able to do compatible
ports in a single build (e.g. all 32bit little endian).  where to go from
there will require experimentation.  i'm thinking the core compiles all
variants (32/64 le/be) and then the ports use defines to pick the right
ones for their subdir.

part of this work has been removing the ability for ports to deviate at
all: just make a single decision in the core, and everyone uses that.
we've given ports way too much leeway for too long.

at the very least, i have it working now where each subdir can be built
and installed in a single build.  this is helpful for doing quick tests
that changes at least compile.  obviously can't link a single gdb from
this, but gotta start somewhere.  i'm trying to do this incrementally
rather than flip a switch and have everyone migrate in a single commit.
especially because not all ports support even the common/ code atm.

sim $ ls
aarch64  config.cache   d10v   h8300   m32r        mips     ppc   testsuite
arm      config.log     erc32  igen    m68hc11     mn10300  pru   v850
avr      config.status  foo    iq2000  Makefile    moxie    rl78
bfin     cr16           frv    lm32    mcore       msp430   rx
bpf      cris           ft32   m32c    microblaze  or1k     sh
sim $ ls */run */libsim.a
aarch64/libsim.a  d10v/run         m32r/libsim.a        msp430/run
aarch64/run       erc32/libsim.a   m32r/run             or1k/libsim.a
arm/libsim.a      erc32/run        m68hc11/libsim.a     or1k/run
arm/run           frv/libsim.a     m68hc11/run          ppc/libsim.a
avr/libsim.a      frv/run          mcore/libsim.a       ppc/run
avr/run           ft32/libsim.a    mcore/run            pru/libsim.a
bfin/libsim.a     ft32/run         microblaze/libsim.a  pru/run
bfin/run          h8300/libsim.a   microblaze/run       rl78/libsim.a
bpf/libsim.a      h8300/run        mips/libsim.a        rl78/run
bpf/run           iq2000/libsim.a  mips/run             rx/libsim.a
cr16/libsim.a     iq2000/run       mn10300/libsim.a     rx/run
cr16/run          lm32/libsim.a    mn10300/run          sh/libsim.a
cris/libsim.a     lm32/run         moxie/libsim.a       sh/run
cris/run          m32c/libsim.a    moxie/run            v850/libsim.a
d10v/libsim.a     m32c/run         msp430/libsim.a      v850/run
-mike