https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70873
--- Comment #25 from Uroš Bizjak <ubizjak at gmail dot com> ---
(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;
> })
