Linux arm64 binaries

[tueda]

GitHub now provides Linux arm64 hosted runners. We can build arm64-linux binaries using CI.

[tueda]

The test cases moebius_1, moebius_2 and moebius_3 fail on ubuntu-22.04-arm. For example:

===============================================================================
moebius_1 (features.frm:113) FAILED
===============================================================================
FORM 5.0.0-beta.1 (Jan 24 2025, v5.0.0-beta.1-116-g3fa59b8)  Run: Sat Feb  8 03:42:25 2025
    S i,x;
    L F = sum_(i,1,200,moebius_(i)*x^i);
    P;
    .end:result;

Time =       0.00 sec    Generated terms =        122
               F         Terms in output =        122
                  result Bytes used      =       2940

   F =
      x + x^2 + x^3 + x^5 + x^6 + x^7 + x^10 + x^11 + x^13 + x^14 + x^15 + 
      x^17 + x^19 + x^21 + x^22 + x^23 + x^26 + x^29 + x^30 + x^31 + x^33 + 
      x^34 + x^35 + x^37 + x^38 + x^39 + x^41 + x^42 + x^43 + x^46 + x^47 + 
      x^51 + x^53 + x^55 + x^57 + x^58 + x^59 + x^61 + x^62 + x^65 + x^66 + 
      x^67 + x^69 + x^70 + x^71 + x^73 + x^74 + x^77 + x^78 + x^79 + x^82 + 
      x^83 + x^85 + x^86 + x^87 + x^89 + x^91 + x^93 + x^94 + x^95 + x^97 + 
      x^101 + x^102 + x^103 + x^105 + x^106 + x^107 + x^109 + x^110 + x^111 + 
      x^113 + x^114 + x^115 + x^118 + x^119 + x^122 + x^123 + x^127 + x^129 + 
      x^130 + x^131 + x^133 + x^134 + x^137 + x^138 + x^139 + x^141 + x^142 + 
      x^143 + x^145 + x^146 + x^149 + x^151 + x^154 + x^155 + x^157 + x^158 + 
      x^159 + x^161 + x^163 + x^165 + x^166 + x^167 + x^170 + x^173 + x^174 + 
      x^177 + x^178 + x^179 + x^181 + x^182 + x^183 + x^185 + x^186 + x^187 + 
      x^190 + x^191 + x^193 + x^194 + x^195 + x^197 + x^199;

  0.00 sec out of 0.00 sec
===============================================================================

This is because the current implementation of the Moebius() function assumes char is signed. If this is not the case, the function does not work properly and always returns non-negative numbers.

[jodavies]

When I once tested form on a Power machine I needed to compile with -fsigned-char if I remember correctly. Maybe this is the easiest fix, probably moebius is not the only potentially problematic code?

[tueda]

Well, I think using signed char instead of char when a signed char is required is the most portable and elegant approach.

[jodavies]

You are right, of course, but there are very many uses of char in the source files. When I had problems with this in the past, it was not with moebius, that function didn't exist at the time. The information about that was, I think, on the old forums.

[tueda]

Hmm, it seems that problems with this occur only for moebius_ on arm64 for now. We may encounter more issues when we expand the test coverage.