On Mon, Feb 10, 2025 at 04:49:14PM +0100, Alexander Lobakin wrote: > From: Simon Horman <horms@xxxxxxxxxx> > Date: Sun, 9 Feb 2025 11:07:25 +0000 > > > On Thu, Feb 06, 2025 at 07:26:26PM +0100, Alexander Lobakin wrote: > >> There are cases when we need to explicitly unroll loops. For example, > >> cache operations, filling DMA descriptors on very high speeds etc. > >> Add compiler-specific attribute macros to give the compiler a hint > >> that we'd like to unroll a loop. > >> Example usage: > >> > >> #define UNROLL_BATCH 8 > >> > >> unrolled_count(UNROLL_BATCH) > >> for (u32 i = 0; i < UNROLL_BATCH; i++) > >> op(priv, i); > >> > >> Note that sometimes the compilers won't unroll loops if they think this > >> would have worse optimization and perf than without unrolling, and that > >> unroll attributes are available only starting GCC 8. For older compiler > >> versions, no hints/attributes will be applied. > >> For better unrolling/parallelization, don't have any variables that > >> interfere between iterations except for the iterator itself. > >> > >> Co-developed-by: Jose E. Marchesi <jose.marchesi@xxxxxxxxxx> # pragmas > >> Signed-off-by: Jose E. Marchesi <jose.marchesi@xxxxxxxxxx> > >> Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@xxxxxxxxx> > >> Signed-off-by: Alexander Lobakin <aleksander.lobakin@xxxxxxxxx> > > > > Hi Alexander, > > > > This patch adds four variants of the unrolled helper. But as far as I can > > tell the patch-set only makes use of one of them, unrolled_count(). > > > > I think it would be best if this patch only added helpers that are used. > > I thought they might help people in future. > I can remove them if you insist. BTW the original patch from Jose also > added several variants. I do slightly prefer only adding what is used.
