Hi Koakuma, thanks for doing the research work! On Tue, 2024-06-25 at 02:06 +0000, Koakuma wrote: > John Paul Adrian Glaubitz <glaubitz@xxxxxxxxxxxxxxxxxxx> wrote: > > V8plus does not use VIS instructions and also has a different ELF machine > > type, namely EM_SPARC32PLUS instead of EM_SPARCV9 if I understand correctly. > > > > So, we should make sure that the above change will not affect the ELF machine > > type. > > When assembling with GNU as, there seem to be no control as to what > machine type we want to emit, as it simply tries to autodetect it based > on the instruction mix in the assembly code: > - If there's a V9 instruction inside, then use EM_SPARC32PLUS; and > - Emit EM_SPARC otherwise. Interesting. I actually expected some flags being passed to the linker to enable the EM_SPARC32PLUS machine type. > This is also the case with GCC - it simply happens that GCC will try > to emit V9 instructions whenever possible with `-m32 -mv8plus` > or `-m32 -mcpu=v9` so there's a high chance that the resulting object > file will be of a EM_SPARC32PLUS type, but this does not seem to be > a guaranteed behavior. Would be interesting to find out what Sun's own C/C++ compiler (Sun Studio) does in this case. I can try to run some tests on Solaris or you can check out the Solaris machines in the GCC compile farm [1]. > With LLVM's as, we can have finer control of emitted machine type, but > so far it never sets the type to EM_SPARC32PLUS - for this I have made > a patch over at https://github.com/llvm/llvm-project/pull/96583. I just had a brief look - will do the proper review later - and I think it's the right approach for the time being. However, I am wondering whether we should add "-mv8plus" to clang as well. I wondering though whether "-mcpu=v9 -m32" is truly identical to "-mv8plus" or not. > As for VIS, GCC (and clang when it eventually supports vectorization) > should not emit it unless explicitly asked, so I think we are > in the clear here? > > > With `-mvis`, GCC generates code that takes advantage of > > the UltraSPARC Visual Instruction Set extensions. > > The default is `-mno-vis`. > > From https://gcc.gnu.org/onlinedocs/gcc/SPARC-Options.html#index-mvis OK, very good to know. Yes, I think we should be safe here. Again, thanks a lot for getting this sorted out so quickly! Adrian > [1] https://gcc.gnu.org/wiki/CompileFarm -- .''`. John Paul Adrian Glaubitz : :' : Debian Developer `. `' Physicist `- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913
