On Mon, Jun 12, 2017 at 11:40:17AM -0700, Carl E. Love wrote:
> Michael:
>
> OK, so sounds like I should stick to the general wa register constraint.
> The third field of the define_expand I have what I believe is called the
> "condition string" as "TARGET_VSX". Is that the appropriate condition
> string? I see conditions string "VECTOR_UNIT_VSX_P (V4SFmode)" also
> used. Segher is thinking that this string would have the same effect as
> "TARGET_VSX"?? How does one select the correct condition string based
> on the register constraint?
In general, the idea was to allow you to turn off VSX support for one type, so
we used VECTOR_UNIT_VSX_P (mode) or VECTOR_MEM_VSX_P (mode) to say where there
were VSX arithmetic operations or memory operations on the particular type.
Note, it becomes an issue for V2DImode, as VECTOR_UNIT_VSX_P (V2DImode) is not
enabled until ISA 2.07 (power8), since we didn't have vector arithmetic
operations on V2DImode until then.
>
> Here is what I currently have for my define_expand. Is it correct?
>
> ;; Generate
> float2
> ;; convert two long long signed ints to float
>
> (define_expand "float2_v2di"
>
> [(match_operand:V4SF 0 "register_operand" "=wa")
>
> (unspec:V4SI [(match_operand:V2DI 1 "register_operand" "wa")
>
> (match_operand:V2DI 2 "register_operand" "wa")]
>
> UNSPEC_VSX_FLOAT2)]
>
>
>
> "TARGET_VSX"
>
> {
>
> rtx rtx_src1, rtx_src2, rtx_dst;
>
>
>
> rtx_dst = operands[0];
>
> rtx_src1 = operands[1];
>
> rtx_src2 = operands[2];
>
>
>
> rs6000_generate_float2_code (true, rtx_dst, rtx_src1, rtx_src2);
>
> DONE;
>
> })
>
> Thanks for your help on this.
>
You can simplify this to:
(define_expand "float2_v2di"
[(use (match_operand:V4SF 0 "register_operand"))
(use (match_operand:V2DI 1 "register_operand"))
(use (match_operand:V2DI 2 "register_operand"))]
"TARGET_VSX"
{
rtx rtx_src1, rtx_src2, rtx_dst;
rtx_dst = operands[0];
rtx_src1 = operands[1];
rtx_src2 = operands[2];
rs6000_generate_float2_code (true, rtx_dst, rtx_src1, rtx_src2);
DONE;
})
Since the gen* pattern never generates the code due to the DONE (the call to
rs6000_generate_float2_code does that). And since it is a define_expand,
the constraints are not used.
Now, if it had been a define_insn_and_split, then you would have needed the
unspec and the constraints.
--
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meiss...@linux.vnet.ibm.com, phone: +1 (978) 899-4797
