[gnu-linaro-tools] LP:602190 & LP:602285

[Yao Qi]

Send it again to linaro-toolchain at lists.linaro.org

On Wed, Aug 04, 2010 at 10:53:46PM +0800, Yao Qi wrote:
> LP:602190(https://bugs.launchpad.net/gcc-linaro/+bug/602190) and
> LP:602285(https://bugs.launchpad.net/gcc-linaro/+bug/602285) are
> related to this patch below.  You can get more details from comments
> of these bugs, since I've added my understand of the cause in
> comments.
> 
> This patch is to improve the performance of generated code, however,
> these two bugs are related to this patch(, correct me if I am wrong).
> Now, we have two options, 1) revert this patch, and make these test
> case pass; 2) keep this patch and fix test cases, 3) fix bugs and keep
> this patch,
> 
> What do you think?
> 
> 
> 2009-08-26  Daniel Jacobowitz  <dan at codesourcery.com>
> 
> 	Issue #6131 - Enable additional optimizations by default in Lite
> 	Issue #6103 - Reduce default unrolling parameters at -O3
> 
> 	* release-notes-csl.xml (Improved optimization for ARM): New note.
> 
> 	gcc/
> 	* config/arm/arm.c (arm_override_options): If flag_unroll_loops has
> 	the default value, adjust unrolling parameters.
> 	(arm_optimization_options): Set flag_unroll_loops to a default value.
> 	Enable flag_promote_loop_indices.
> 
> Modified: gcc/config/arm/arm.c
> ==============================================================================
> --- gcc/config/arm/arm.c (original)
> +++ gcc/config/arm/arm.c Fri Aug 28
> 14:41:19 2009
> @@ -55,6 +55,7 @@
>  #include "langhooks.h"
>  #include "df.h"
>  #include "intl.h"
> +#include "params.h"
>  
>  /* Forward definitions of types.  */
>  typedef struct minipool_node    Mnode;
> @@ -1857,6 +1858,29 @@
>        warning (0, 
>  	       "-low-irq-latency has no effect when compiling for the
> Thumb");
>        low_irq_latency = 0;
> +    }
> +
> +  /* CSL LOCAL */
> +  /* Loop unrolling can be a substantial win.  At -O2, limit to 2x
> +     unrolling by default to prevent excessive code growth; at -O3,
> +     limit to 4x unrolling by default.  We know we are not optimizing
> +     for size if this is set (see arm_optimization_options).  */
> +  if (flag_unroll_loops == 2)
> +    {
> +      if (optimize == 2)
> +	{
> +	  flag_unroll_loops = 1;
> +	  if (!PARAM_SET_P (PARAM_MAX_UNROLL_TIMES))
> +	    set_param_value ("max-unroll-times", 2);
> +	}
> +      else if (optimize > 2)
> +	{
> +	  flag_unroll_loops = 1;
> +	  if (!PARAM_SET_P (PARAM_MAX_UNROLL_TIMES))
> +	    set_param_value ("max-unroll-times", 4);
> +	}
> +      else
> +	flag_unroll_loops = 0;
>      }
>  }
>  
> @@ -21175,6 +21199,17 @@
>        set_param_value ("max-inline-insns-single", 1);
>        set_param_value ("max-inline-insns-auto", 1);
>      }
> +  else
> +    {
> +      /* CSL LOCAL */
> +      /* Set flag_unroll_loops to a default value, so that we can tell
> +	 if it was specified on the command line; see
> +	 arm_override_options.  */
> +      flag_unroll_loops = 2;
> +      /* Promote loop indices to int where possible.  Consider moving this
> +	 to -Os, also.  */
> +      flag_promote_loop_indices = 1;
> +    }
>  }
> 
> 
> -- 
> Yao Qi
> CodeSourcery
> yao at codesourcery.com
> (650) 331-3385 x739

-- 
Yao Qi
CodeSourcery
yao at codesourcery.com
(650) 331-3385 x739