Hello Wilco, Would you have further thoughts on the patches proposed in
https://gcc.gnu.org/ml/gcc-patches/2018-10/msg01453.html ? There was: 1) * config/aarch64/aarch64.c (PROBE_STACK_FIRST_REG) : Redefine as R9_REGNUM instead of 9. (PROBE_STACK_SECOND_REG): Redefine as R10_REGNUM instead of 10. 2) * config/aarch64/aarch64.h (FIXED_R18): New internal configuration macro, defaulted to 0. (FIXED_REGISTERS): Use it. (STATIC_CHAIN_REGNUM): Use r11 instead of r18. and 3) * config/aarch64/aarch64.c (aarch64_override_options): Once arch, cpu and tune were validated, insert SUBTARGET_OVERRIDE_OPTIONS if defined. Thanks a lot in advance! With Kind Regards, Olivier > On 23 Oct 2018, at 19:13, Olivier Hainque <hain...@adacore.com> wrote: > > Hi Wilco, > >> On 18 Oct 2018, at 19:08, Wilco Dijkstra <wilco.dijks...@arm.com> wrote: > >>> I wondered if we could set it to R11 unconditionally and picked >>> the way ensuring no change for !vxworks ports, especially since I >>> don't have means to test more than what I described above. >> >> Yes it should always be the same register, there is no gain in switching >> it dynamically. I'd suggest to use X9 since X8 is the last register used for >> arguments (STATIC_CHAIN_REGNUM is passed when calling a nested >> function) and some of the higher registers may be used as temporaries in >> prolog/epilog. > > Thanks for your feedback! I ported the patches > to gcc-8 and was able to get a functional toolchain > for aarch64-wrs-vxworks7 and aarch64-elf, passing > full Acats for a couple of runtime variants on VxWorks > (compiled for RTP or kernel mode) as well as a small > internal testsuite we have, dedicated to cross configurations. > > All the patches apply directly on mainline. > > As for the original patch, I also sanity checked that > "make all-gcc" passes (self tests included) there for > --target=aarch64-elf --enable-languages=c > > > There are three changes to the common aarch64 port files. > > It turns out that X9 doesn't work for STATIC_CHECK_REGNUM > because this conflicts with the registers used for -fstack-check: > > /* The pair of scratch registers used for stack probing. */ > #define PROBE_STACK_FIRST_REG 9 > #define PROBE_STACK_SECOND_REG 10 > > I didn't find that immediately (read, I first experienced a few > badly crashing test runs) because I searched for R9_REGNUM to check > for other uses, so the first patchlet attached simply adjusts > the two #defines above to use R9/R10_REGNUM. > > > 2018-10-23 Olivier Hainque <hain...@adacore.com> > > * config/aarch64/aarch64.c (PROBE_STACK_FIRST_REG) : Redefine as > R9_REGNUM instead of 9. > (PROBE_STACK_SECOND_REG): Redefine as R10_REGNUM instead of 10. > > > The second patch is the one which I proposed a few days ago > to allow a subtarget (in my case, the VxWorks port) to state that > R18 is to be considered fixed. Two changes compared to the original > patch: a comment attached to the default definition of FIXED_R18, > and the unconditional use of R11_REGNUM as an alternate STATIC_CHAIN_REGNUM. > > I suppose the latter could require extra testing than what I was > able to put in (since this is also changing for !vxworks configurations), > which Sam very kindly did on the first instance. > > I didn't touch CALL_SAVED_REGISTERS since this is 1 for r18 already. > I also didn't see a strong reason to move to a more dynamic scheme, > through conditional_register_usage. > > 2018-03-18 Olivier Hainque <hain...@adacore.com> > > * config/aarch64/aarch64.h (FIXED_R18): New internal > configuration macro, defaulted to 0. > (FIXED_REGISTERS): Use it. > (STATIC_CHAIN_REGNUM): Use r11 instead of r18. > > > The third patch proposes the introduction of support for a > conditional SUBTARGET_OVERRIDE_OPTIONS macro, as many other > architectures have, and which is needed by all VxWorks ports. > > In the current state, this one could possibly impact only > VxWorks, as no other config file would define the macro. > > I'm not 100% clear on the possible existence of rules regarding > the placement of this within the override_options functions. We used > something similar to what other ports do, and it worked just fine > for VxWorks. > > 2018-10-23 Olivier Hainque <hain...@adacore.com> > > * config/aarch64/aarch64.c (aarch64_override_options): Once > arch, cpu and tune were validated, insert SUBTARGET_OVERRIDE_OPTIONS > if defined. > > I'm happy to adjust any of all this if needed of course. > > Thanks in advance for your feedback! > > With Kind Regards, > > Olivier > > > <0001-Use-R9-R10_REGNUM-to-designate-stack-checking-regist.patch.txt><0002-Introduce-FIXED_R18-in-aarch64.h.patch.txt><0003-Support-for-SUBTARGET_OVERRIDE_OPTIONS-in-aarch64.c.patch.txt>
