https://sourceware.org/bugzilla/show_bug.cgi?id=25550
--- Comment #4 from H.J. Lu <hjl.tools at gmail dot com> --- (In reply to Jan Beulich from comment #3) > (In reply to H.J. Lu from comment #2) > > (In reply to Jan Beulich from comment #1) > > > However, as pointed out in the mail discussion already, consistent > > > behavior > > > should result (which currently isn't the case): > > > > > > 1. Since .arch generally enables prereqs for the specified ISA extension > > > (like AVX for AVX512F), disabling an extension also should disable > > > everything that it is considered a prereq for. > > > > Is SSE2 a prerequisite for AVX? > > This can be viewed either way, I guess. The history of the ISA extensions > suggests it is. But functionally nothing except the XMM registers have any > overlap, I think. Why is AVX a prerequisite for AVX512? > > > 2. Any ISA extension enabled should be enabled completely. The main > > > anomaly > > > looks to be SSE/SSE2 insns accessing MMX registers, where strictly > > > speaking > > > the MMX ISA extension isn't a prereq to the SSE* ones (it's only the > > > registers that are used), which gas also handles this way. > > > > For view point of assembly codes, enable MMX register without MMX ISA > > makes no sense. For example, emms is needed for proper MMX usage. > > Not necessarily, one can certainly get away without (using 4 FFREEP in a > row). What purpose does it serve? -- You are receiving this mail because: You are on the CC list for the bug.
