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Re: [PING] [PATCH] faster string operations for bulldozer (take 2)
- From: Roland McGrath <roland at hack dot frob dot com>
- To: OndÅej BÃlka <neleai at seznam dot cz>
- Cc: Carlos O'Donell <carlos at systemhalted dot org>, libc-alpha at sourceware dot org
- Date: Fri, 26 Apr 2013 12:23:21 -0700 (PDT)
- Subject: Re: [PING] [PATCH] faster string operations for bulldozer (take 2)
- References: <20120926171541 dot GA12300 at domone dot kolej dot mff dot cuni dot cz> <20120926172758 dot 56BEC2C097 at topped-with-meat dot com> <20120926184013 dot GA13454 at domone dot kolej dot mff dot cuni dot cz> <20120926194423 dot 15F9B2C061 at topped-with-meat dot com> <20120926211433 dot GA17771 at domone dot kolej dot mff dot cuni dot cz> <CAE2sS1i2nfrn58PNwtOXYx9qt=bWX_C4_fJN=CnGuefBTvN-Bw at mail dot gmail dot com> <20120930103730 dot GA5682 at domone dot kolej dot mff dot cuni dot cz> <20130426165614 dot GA16694 at domone dot kolej dot mff dot cuni dot cz>
> > + /* Assume unaligned loads are fast when avx is available. */
AVX in caps.
> > + if ((ecx & bit_AVX) != 0)
> > + __cpu_features.feature[index_Fast_Rep_String]
> > + |= ( bit_Fast_Unaligned_Load);
Drop the excess parens (and the excess space).
I didn't follow whatever previous discussion there was about the substance
of this. What is the rationale/evidence that AVX is (and always will be)
correlated with efficiency of unaligned loads?