i386: Omit clobbers from vzeroupper until final [PR92190]

i386: Omit clobbers from vzeroupper until final [PR92190]

As mentioned in the PR, the CLOBBERs in vzeroupper are added there even for
registers that aren't ever live in the function before and break the
prologue/epilogue expansion with ms ABI (normal ABIs are fine, as they
consider all [xyz]mm registers call clobbered, but the ms ABI considers
xmm0-15 call used but the bits above low 128 ones call clobbered).
The following patch fixes it by not adding the clobbers during vzeroupper
pass (before pro_and_epilogue), but adding them for -fipa-ra purposes only
during the final output.  Perhaps we could add some CLOBBERs early (say for
df_regs_ever_live_p regs that aren't live in the live_regs bitmap, or
depending on the ABI either add all of them immediately, or for ms ABI add
CLOBBERs for xmm0-xmm5 if they don't have a SET) and add the rest later.
And the addition could be perhaps done at other spots, e.g. in an
epilogue_completed guarded splitter.

2020-02-05  Jakub Jelinek  <jakub@redhat.com>

	PR target/92190
	* config/i386/i386-features.c (ix86_add_reg_usage_to_vzeroupper): Only
	include sets and not clobbers in the vzeroupper pattern.
	* config/i386/sse.md (*avx_vzeroupper): Require in insn condition that
	the parallel has 17 (64-bit) or 9 (32-bit) elts.
	(*avx_vzeroupper_1): New define_insn_and_split.

	* gcc.target/i386/pr92190.c: New test.