Hello, This is a followup on a discussion we had a while ago, starting with
http://gcc.gnu.org/ml/gcc-patches/2010-08/msg01543.html The original issue was the vxworks port unduly clobbering explicit SPE related options on powerpc, which it still does. The proposed patch at the time was to prevent the clobbering locally, adding guards in the vxworks.h code as there are in a few other targets already. Joseph and David suggested to address this in a more general fashion, along lines proposed in http://gcc.gnu.org/ml/gcc-patches/2010-08/msg01667.html The attached patch is a first shot in this direction. Only lightly tested at this point, posted to get a first round of comments to validate that this corresponds to what was suggested. This indeed allows significant simplifications - cleaner configuration model, defaults control factorized, no need for e500-double.h any more. I'll be happy to do what I can to help in getting this in eventually. One piece that for sure needs updating is The TARGET_NO_LWSYNC change suggests that maybe keeping a TARGET_E500 macro would make sense after all, to convey "cpu features an E500 core" which happens to imply SPE support and no LWSYNC. We could have a TARGET_E500MC as well to make it clear that the latter family differs from the former. That's actually a detail in the set of changes at hand. In addition to what I understood of the suggestions made in the aforementioned thread, this patch includes a change on the choice of rs6000_cpu in options_override, so that it treats a --with-cpu passed at configure time as an implicit -mcpu in absence of an explicit one. This sounds reasonable and is useful for the more general change we're discussing. This patch allowed me to build a few configurations with as-expected results on gcc 4.7 base. The patch applies as-is on mainline. My first attempt at building there failed, with --target=powerpc-eabispe --with-cpu=8548 --enable-languages=c --disable-libada (internal compiler error on unwind-dw2.c) This failure reproduces with an unpatched tree as well, so there's something already broken in this area. I suppose I can can look into this one first. I'd appreciate feedback on the more general patch nevetheless :) (whether that's the right direction, things that you think should be done differently, indications as to how you'd like to proceed further (testing etc), ...) Thanks much in advance, Olivier 2012-05-07 Olivier Hainque <hain...@adacore.com> config/rs6000: * rs6000-opts.h (enum processor_type): Add PROCESSOR_PPC8548. * rs6000-cpus.def: Reference it for cpu="8548". * rs6000.md (cpu attribute definition): Add ppc8548. * 8540.md: indicate that the units/patterns apply to ppc8548 as well. * rs6000.c (rs6000_option_override_internal): Rename default_cpu into implicit_cpu, conveying what --with-cpu was passed at configure time. Treat implicit_cpu as have_cpu. Pick defaults for SPE related flags, check that what is queried is supported by the selected configuration. Rework the single/double_float and MASK_STRING resets to hit for all the E500 cores (854x + E500MC variants). Select the ppc8540 costs for PROCESSOR_PPC8548 as well. (rs6000_issue_rate): case CPU_PPC8548 together with CPU_PPC8540. (rs6000_use_sched_lookahead): Likewise, rewriting function as a case statement instead of a sequence of ifs. * rs6000.h (TARGET_E500): Remove. (TARGET_NO_LWSYNC): Adjust accordingly. * e500.h (TARGET_E500): Remove. (CHECK_E500_OPTIONS): Adjust accordingly. * eabispe.h (SUBSUBTARGET_OVERRIDE_OPTIONS): Remove. (TARGET_DEFAULT): Reformat definition to match the one in linuxspe.h. * linuxspe.h: Likewise. * vxworks.h: Remove bogus TARGET_E500 overrides and superfluous comments. * e500-double.h: Remove. gcc: * config.gcc (pick a default with_cpu): For powerpc*-*-*spe*, default to with_cpu=8548 if --enable-e500-double, and to 8540 otherwise. (set misc flags section): For powerpc*|rs6000*, remove inclusion of e500-double.h for --enable-e500-double.
e500.dif
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