Currently, we add -mvsx when building the float128 support in libgcc. This allows us to build the float128 support on a big endian system where the default cpu is power4. While the libgcc support can be built, given there is no glibc support for float128 available.
However, adding -mvsx and building the libgcc float128 support causes problems if you set the default cpu to something like a 7540, which does not have VSX support. The assembler complains that when the code does a ".machine 7450", you cannot use VSX instructions. There are two patches in this set: In the first patch, the float128 libgcc support is only built if the default compiler has VSX support. If somebody wants to enable the glibc support for big endian, they would need to set the base cpu to power8 to enable building the libgcc float128 libraries. In the second patch, I adjusted the compiler tests so that they would only run the float128 tests when the compiler enables float128. I removed setting options for enabling the VSX instruction set (-mvsx), enabling float128 support in the compiler (-mfloat128), and enabling float128 hardware support (-mfloat128-hardware), even if -mcpu=power9 was used. I built little endian compilers and there were no regressions. I built big endian compilers with the --with-cpu=power5 configure option, and I verified that none of the float128 support functions are built. I also built big endian compilers on a power9 with the --with-cpu=native configure option, and I verified that the float128 support functions were built, since the default compiler used the VSX instruction set. I verified that on both sets of big endian builds, that all of the float128 tests were skipped, since there is no support for float128 in glibc and the GCC compiler does not enable float128 on those systems. Can I check these patches into the trunk assuming the original bugzilla author says they fix the problem? -- Michael Meissner, IBM PO Box 98, Ayer, Massachusetts, USA, 01432 email: meiss...@linux.ibm.com
