Hi Segher! Thanks for the comments again!
on 2022/10/4 05:15, Segher Boessenkool wrote: > On Fri, Sep 30, 2022 at 08:15:37PM +0800, Kewen.Lin wrote: >> on 2022/9/30 01:11, Segher Boessenkool wrote: >>>> +#ifdef OS_MISSING_POWERPC64 >>>> + else if (OS_MISSING_POWERPC64) >>>> + /* It's unexpected to have OPTION_MASK_POWERPC64 on for OSes which >>>> + miss powerpc64 support, so disable it. */ >>>> + rs6000_isa_flags &= ~OPTION_MASK_POWERPC64; >>>> +#endif >>> >>> All silent stuff is always bad. >> >> OK, with more testings for replacing warning instead of silently disablement >> I noticed that some disablement is needed, one typical case is -m32 >> compilation >> on ppc64, we have OPTION_MASK_POWERPC64 on from TARGET_DEFAULT which is used >> for initialization (It makes sense to have it on in TARGET_DEFAULT because >> of it's 64 bit cpu). And -m32 compilation matches OS_MISSING_POWERPC64 >> (!TARGET_64BIT), so it's the case that we have an implicit >> OPTION_MASK_POWERPC64 >> on and OS_MISSING_POWERPC64 holds, but it's unexpected not to disable it but >> warn it. > > Right. If If mpowerpc64 is enabled while OS_MISSING_POWERPC64, warn for > that; > Currently if option powerpc64 is enabled explicitly while OS_MISSING_POWERPC64, there is no warning. One typical case is -m32 compilation on ppc64. I made a patch to warn for this case as you suggested (btw, this change can be taken separately from this rework), it caused some test cases to fail as below: gcc.dg/vect/vect-82_64.c gcc.dg/vect/vect-83_64.c gcc.target/powerpc/bswap64-4.c gcc.target/powerpc/ppc64-double-1.c gcc.target/powerpc/pr106680-4.c gcc.target/powerpc/rs6000-fpint-2.c It's fine to fix them with one additional option "-w" to disable the warning. But IIUC one concern is that if we want to test with "--target_board=unix'{-m32, -m32/-mpowerpc64}'", the latter combination will always have this warning, with one extra "-w" (that is -m32/-mpowerpc64/-w) can make some cases which aim to check warning msg ineffective. So maybe we want to re-consider it (like just leaving it as before)? > and if mpowerpc64 was only implicit, disable it as well (and say > we did!) But on ppc64 linux, for -m32 compilation mpowerpc64 is implicitly enabled since it's with bi-arch supported, I made a patch to disable it as well as warn it, it can't be bootstrapped since it warned for -m32 build (-Werror) and failed. So I refined it to something like: + /* With RS6000_BI_ARCH defined (bi-architecture (32/64) supported), + TARGET_DEFAULT has bit MASK_POWERPC64 on by default, to keep the + behavior consistent (like: no warnings for -m32 on ppc64), we + just sliently disable it. Otherwise, disable it and warn. */ + rs6000_isa_flags &= ~OPTION_MASK_POWERPC64; +#ifndef RS6000_BI_ARCH + warning (0, "powerpc64 is unexpected to be enabled on the " + "current OS"); +#endif BR, Kewen