why shift is slower than integer multiply shift ,integer multiply

[azaonline]

You’re right, I totally forgot about mad24.

here’s the benchmark:

[codebox]mov.b32 $r62, %clock

mad24.lo.u32.u16.u16.u32 $r1, $r0.hi, $r0.lo, $r0

add.b32 $r3,$r0,$r0 //kill forwarding

add.b32 $r2,$r1,$1 //cause RAW stall

mov.b32 $r63, %clock[/codebox]

It executes 40 cycles, which reveals true mad24 latency of 40-8-8=24 cycles, believe it or not.

Also true with floating mul.

“mad24” is multiply-add instruction for integer on CUDA?

there are lots of “a*b+c”(int a,b,c) in my code. but why I can’t find “mad24” on its ptx?

my Gpu is G260.

How can I employ multiply-add operation of integer on CUDA to speedup my app?