https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70873
--- Comment #26 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to Uroš Bizjak from comment #25)
> (In reply to H.J. Lu from comment #23)
>
> > We need to move those special SSE SF->DF splitters before
>
> No, this splitter will fail if the transformation doesn't result in a
> constant. So, we actually want this splitter first, to try to transform a
> memory load to a constant load, and moving others before this one would be
> harmful.
>
> > (define_split
> > [(set (match_operand 0 "any_fp_register_operand")
> > (float_extend (match_operand 1 "memory_operand")))]
> > "reload_completed
> > && (GET_MODE (operands[0]) == TFmode
> > || GET_MODE (operands[0]) == XFmode
> > || GET_MODE (operands[0]) == DFmode)"
> > [(set (match_dup 0) (match_dup 2))]
> > {
> > operands[2] = find_constant_src (curr_insn);
> >
> > if (operands[2] == NULL_RTX
> > || (SSE_REGNO_P (REGNO (operands[0]))
> > && standard_sse_constant_p (operands[2],
> > GET_MODE (operands[0])) != 1)
> > || (STACK_REGNO_P (REGNO (operands[0]))
> > && standard_80387_constant_p (operands[2]) < 1))
> > FAIL;
> > })
But when this splitter fails, no other splitters will be tried.
