On Wed, 2020-03-11 at 13:04 +0000, Nidal Faour via Gcc-patches wrote:
> This patch is a code density oriented and attempt to remove redundant
> sign/zero
> extension from assignment statement.
> The approach taken is to use VRP data while expanding the assignment to RTL to
> determine whether a sign/zero extension is necessary.
> Thought the motivation of the patch is code density but it also good for
> speed.
>
> for example:
> extern unsigned int func ();
>
> unsigned char
> foo (unsigned int arg)
> {
> if (arg == 2)
> return 0;
>
> return (func() == arg || arg == 7);
> }
>
> the result of the comparison in the return will yield a False or True, which
> will be converted to integer and then casting to unsigned char.
> this casting from integer to unsigned char is redundant because the value is
> either 0 or 1.
>
> this patch is targeting the RISCV-32bit only.
> This patch has been tested on a real embedded project and saved about 0.2% of
> code size.
>
> P.S. I have an FSF license under Western Digital incorporation.
> P.S. I've attached the patch as a file in case my email client corrupted the
> patch itself
Just an FYI. We're at stage4 in our development cycle, as a result most
developers are focused on regression bugfixing until the gcc-10 release is
made.
I've put your patch into the queue of things to evaluate for gcc-11.
Thanks,
jeff
>
