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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@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@codesourcery.com (650) 331-3385 x739