[Bug target/117926] [14/15 Regression] emits 3dnow (MMX) instruction from autovectorized GIMPLE without emms at -O2 since r14-2786-gade30fad6669e5

[ubizjak at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117926

--- Comment #7 from Uroš Bizjak <ubizjak at gmail dot com> ---
Even better (and more reliable) solution: tag 3dNOW insns with an unspec:

 (define_insn "mmx_floatv2siv2sf2"
   [(set (match_operand:V2SF 0 "register_operand" "=y")
-       (float:V2SF (match_operand:V2SI 1 "nonimmediate_operand" "ym")))]
+       (float:V2SF (match_operand:V2SI 1 "nonimmediate_operand" "ym")))
+   (unspec [(const_int 0)] UNSPEC_3DNOW)]
   "TARGET_3DNOW"
   "pi2fd\t{%1, %0|%0, %1}"
   [(set_attr "type" "mmxcvt")