On 21 September 2012 12:56, Eric Botcazou <ebotca...@adacore.com> wrote:
>> Here is a new patch, modifying tree-ssa-math-opts.c as you suggested.
>> It's indeed simpler :-)
>>
>> Validated with qemu-arm on target arm-none-linux-gnueabi.
>
> I cannot formally approve, but this looks good to me.
>
> However, could you check that this is also an improvement for PowerPC, which
> is the only other mainstream architecture with a bswaphi pattern AFAIK?
>
> --
> Eric Botcazou
I have not yet been able to build an environment to run the testsuite
with qemu-ppc (not sure about the best target & dejagnu board
selection).
However, when compiling a sample test
short myswaps16(short x) {
return (x << 8) | (x >> 8);
}
unsigned short myswapu16(unsigned short x) {
return (x << 8) | (x >> 8);
}
The generated code is now:
myswaps16:
rlwinm 10,3,8,16,23
rlwinm 9,3,24,24,31
or 9,9,10
extsh 3,9
blr
myswapu16:
rlwinm 10,3,8,16,23
rlwinm 9,3,24,24,31
or 9,9,10
rlwinm 3,9,0,0xffff
blr
While it was (without my patch):
myswaps16:
slwi 9,3,8
srawi 3,3,8
or 3,9,3
extsh 3,3
blr
myswapu16:
srwi 9,3,8
rlwinm 3,3,8,16,23
or 3,3,9
blr
I don't know PowerPC, but I am not sure it's an improvement. Is it?
Christophe.
