re PR rtl-optimization/48455 (Huge code size regression for all ARM configurations)

2011-11-23  Vladimir Makarov  <vmakarov@redhat.com>

	PR rtl-optimization/48455
	* doc/invoke.texi (-fira-region): Document default values.

	* flags-types.h (enum ira_region): Add new value
	IRA_REGION_AUTODETECT.

	* common.opt (fira-region): Set up initial value to
	IRA_REGION_AUTODETECT.

	* toplev.c (process_options): Set up flag_ira_region depending on
	-O options.

	* ira.c (ira.c): Remove optimize guard for ira_build.

From-SVN: r181675

gcc/ChangeLog

@@ -1,3 +1,19 @@
+2011-11-23  Vladimir Makarov  <vmakarov@redhat.com>
+
+	PR rtl-optimization/48455
+	* doc/invoke.texi (-fira-region): Document default values.
+
+	* flags-types.h (enum ira_region): Add new value
+	IRA_REGION_AUTODETECT.
+
+	* common.opt (fira-region): Set up initial value to
+	IRA_REGION_AUTODETECT.
+
+	* toplev.c (process_options): Set up flag_ira_region depending on
+	-O options.
+
+	* ira.c (ira.c): Remove optimize guard for ira_build.
+
 2011-11-23  Chung-Lin Tang  <cltang@codesourcery.com>
 
 	PR rtl-optimization/50496

gcc/common.opt

@@ -1337,7 +1337,7 @@ EnumValue
 Enum(ira_algorithm) String(priority) Value(IRA_ALGORITHM_PRIORITY)
 
 fira-region=
-Common Joined RejectNegative Enum(ira_region) Var(flag_ira_region) Init(IRA_REGION_MIXED)
+Common Joined RejectNegative Enum(ira_region) Var(flag_ira_region) Init(IRA_REGION_AUTODETECT)
 -fira-region=[one|all|mixed] Set regions for IRA
 
 Enum

gcc/doc/invoke.texi

@@ -6731,13 +6731,16 @@ rule generates a better code.
 Use specified regions for the integrated register allocator.  The
 @var{region} argument should be one of @code{all}, @code{mixed}, or
 @code{one}.  The first value means using all loops as register
-allocation regions, the second value which is the default means using
-all loops except for loops with small register pressure as the
-regions, and third one means using all function as a single region.
-The first value can give best result for machines with small size and
-irregular register set, the third one results in faster and generates
-decent code and the smallest size code, and the default value usually
-give the best results in most cases and for most architectures.
+allocation regions, the second value which is enabled by default when
+compiling with optimization for speed (@option{-O}, @option{-O2},
+@dots{}) means using all loops except for loops with small register
+pressure as the regions, and third one which is enabled by default for
+@option{-Os} or @option{-O0} means using all function as a single
+region.  The first value can give best result for machines with small
+size and irregular register set, the third one results in faster and
+generates decent code and the smallest size code, and the second value
+usually give the best results in most cases and for most
+architectures.
 
 @item -fira-loop-pressure
 @opindex fira-loop-pressure

gcc/flag-types.h

@@ -118,7 +118,11 @@ enum ira_region
 {
   IRA_REGION_ONE,
   IRA_REGION_ALL,
-  IRA_REGION_MIXED
+  IRA_REGION_MIXED,
+  /* This value means that there were no options -fira-region on the
+     command line and that we should choose a value depending on the
+     used -O option.  */
+  IRA_REGION_AUTODETECT
 };
 
 /* The options for excess precision.  */

gcc/ira.c

@@ -3621,9 +3621,8 @@ ira (FILE *f)
 
   if (internal_flag_ira_verbose > 0 && ira_dump_file != NULL)
     fprintf (ira_dump_file, "Building IRA IR\n");
-  loops_p = ira_build (optimize
-		       && (flag_ira_region == IRA_REGION_ALL
-			   || flag_ira_region == IRA_REGION_MIXED));
+  loops_p = ira_build (flag_ira_region == IRA_REGION_ALL
+		       || flag_ira_region == IRA_REGION_MIXED);
 
   ira_assert (ira_conflicts_p || !loops_p);
 

gcc/toplev.c

@@ -1333,6 +1333,11 @@ process_options (void)
 	   "and -ftree-loop-linear)");
 #endif
 
+  /* One region RA really helps to decrease the code size.  */
+  if (flag_ira_region == IRA_REGION_AUTODETECT)
+    flag_ira_region
+      = optimize_size || !optimize ? IRA_REGION_ONE : IRA_REGION_MIXED;
+
   /* Unrolling all loops implies that standard loop unrolling must also
      be done.  */
   if (flag_unroll_all_loops)