On Fri, 2020-05-15 at 08:11 +0200, Uros Bizjak via Gcc-patches wrote: > On Fri, May 15, 2020 at 1:13 AM H.J. Lu <hjl.to...@gmail.com> wrote: > > The -mgeneral-regs-only option generates code that uses only the > > general-purpose registers. It prevents the compiler from using vector > > registers. But GCC may still generate calls to memcpy, memmove, memset > > and memcmp library functions. In the GNU C library, these library > > functions are implementated with vector registers, which makes the > > -mgeneral-regs-only option less effective. The new -mavoid-libcall > > option expands memcpy, memmove and memset into REP MOVSB and REP STOSB > > sequence. This option can be further enhanced with a cmpmem pattern > > to expand memcmp into REP CMPSB sequence in the future. > > > > Tested on Linux/x86 and Linux/x86-64. OK for master? > > No. Library should provide functions that are appropriate for your > target. There are probably other places in the library that use XMM > registers, so there is no point working around only some specific > functions. Couldn't one make the argument that we should be using -ffreestanding and that -ffreestanding should be emitting the necessary inline code rather than calling out to memcpy or whatever it's doing.
jeff >
