Re: [PATCH v5 21/23] powerpc: Simplify test in __dma_sync()
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From: Denis Kirjanov <hidden>
Date: 2016-02-04 11:56:04
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On 2/4/16, Christophe Leroy [off-list ref] wrote:
quoted hunk ↗ jump to hunk
This simplification helps the compiler. We now have only one test instead of two, so it reduces the number of branches. Signed-off-by: Christophe Leroy <redacted> --- v2: new v3: no change v4: no change v5: no change arch/powerpc/mm/dma-noncoherent.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/arch/powerpc/mm/dma-noncoherent.cb/arch/powerpc/mm/dma-noncoherent.c index 169aba4..2dc74e5 100644--- a/arch/powerpc/mm/dma-noncoherent.c +++ b/arch/powerpc/mm/dma-noncoherent.c@@ -327,7 +327,7 @@ void __dma_sync(void *vaddr, size_t size, int direction) * invalidate only when cache-line aligned otherwise there is * the potential for discarding uncommitted data from the cache */ - if ((start & (L1_CACHE_BYTES - 1)) || (size & (L1_CACHE_BYTES - 1))) + if ((start | end) & (L1_CACHE_BYTES - 1)) flush_dcache_range(start, end); else invalidate_dcache_range(start, end);
The previous version of address cache-line aligned check reads perfectly fine. What's the benefit of this micro optimization?
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