Hi!
On Fri, Feb 07, 2020 at 03:41:25PM +0100, m wrote:
> ...so I tried to write a corresponding matching pattern, like so:
>
> (define_insn "smulhshi3"
> [(set (match_operand:HI 0 "register_operand" "=r")
> (truncate:HI
> (ashiftrt:SI
> (mult:SI
> (sign_extend:SI (match_operand:HI 1
> "register_operand" "r"))
> (sign_extend:SI (match_operand:HI 2
> "register_operand" "r")))
> (const_int 15))))]
> "TARGET_PACKED_OPS"
> "mulq.h\\t%0, %1, %2")
>
> However, I am unable to trigger this code path. I have tried with the
> following C code:
>
> short mulq(short op1, short op2) {
> return (short) (((int) op1 * (int) op2) >> (32 / 2 - 1));
> }
>
> But I just get the regular 4-instruction result (2x sign extend, 1x mul,
> 1x shift).
What does -fdump-rtl-combine-all show it tried? *Did* it try anything?
Segher
