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Richard, Thanks for your comments. Here a new version with the changes you suggested. Christophe On 11 February 2013 11:57, Richard Earnshaw <rearnsha@arm.com> wrote: > On 05/02/13 18:18, Christophe Lyon wrote: >> >> Hi, >> >> Following the discussion about "disable peeling" [1] a few weeks ago, >> it turned out that the vectorizer cost model needed some >> implementation for ARM. >> >> The attached patch implements arm_builtin_vectorization_cost and >> arm_add_stmt_cost, providing default costs when aligned and unaligned >> loads/stores have the same cost (=1). init_cost and finish_cost still >> use the default implementation (I noticed that x86 has chosen to >> duplicate the default implementation without changing it, why?) >> >> Benchmarking shows very little variation, expect a noticeable +1.6% on >> coremark. >> >> If this is OK, we can then discuss how to disable peeling completely >> when aligned and unaligned accesses have the same cost (and thus where >> peeling is a loss of performance). I think adding a new hook is >> necessary, since target descriptions may use different models for >> these costs (eg x86 makes no difference between unaligned loads and >> unaligned stores). >> >> Thanks, >> >> Christophe. >> >> [1] http://gcc.gnu.org/ml/gcc/2012-12/msg00036.html >> >> 2013-02-05 Christophe Lyon <christophe.lyon@linaro.org> >> >> * config/arm/arm.c (arm_builtin_vectorization_cost) >> (arm_add_stmt_cost): New functions. >> (TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST) >> (TARGET_VECTORIZE_ADD_STMT_COST): Define. >> (struct processor_costs): New struct type. >> (default_arm_cost): New struct of type processor_costs.= >> > > Christophe, > > Thanks for the patch. This is mostly OK, but please can you make the > following changes. > > +struct processor_costs { > > Please name this something like cpu_vec_costs. It's not the only cost table > in the back-end. > > +struct processor_costs default_arm_cost = { /* arm generic costs. */ > > Similarly, use something like default_arm_vec_cost. > > +const struct processor_costs *arm_cost = &default_arm_cost; > > And here. But better still, link this through the current_tune table rather > than introducing a new global. > > Finally, > > @@ -27256,4 +27272,130 @@ arm_validize_comparison (rtx *comparison, rtx * > op1, rtx * op2) > > } > > +/* Vectorizer cost model implementation. */ > > > Please put the patch in a more suitable location rather than just dumping it > at the end of the file. There are already numerous functions related to > costs that are mostly grouped together. I suggest this goes near the > rtx_costs code. > > R. > >
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vect-cost-model2.txt
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vect-cost-model2.patch
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