tiny i386 prefetching code cleanup

[Jan Hubicka <hubicka at ucw dot cz>]

Hi,
prefetching is enabled based on software_prefetching_beneficial_p predicate.
Other target specific bits are listed in initial_ix86_tune_features tables,
and this one should be too.

Unless I will be told it is OK, I will hold the patch for stage1.
Bootstrapped/regtested x86_64-linux.

Honza

	* i386.h (ix86_tune_indices): Add X86_TUNE_SOFTWARE_PREFETCHING_BENEFICIAL.
	(TARGET_SOFTWARE_PREFETCHING_BENEFICIAL): New macro.
	* i386.c (initial_ix86_tune_features): Add X86_SOFTARE_PREFETCHING_BENEFICIAL:.
	(software_prefetching_beneficial_p): Remove.
	(ix86_option_override_internal): Use TARGET_SOFTWARE_PREFETCHING_BENEFICIAL
	instead of software_prefetching_beneficial_p.
Index: config/i386/i386.h
===================================================================
--- config/i386/i386.h	(revision 168831)
+++ config/i386/i386.h	(working copy)
@@ -322,6 +322,7 @@ enum ix86_tune_indices {
   X86_TUNE_FUSE_CMP_AND_BRANCH,
   X86_TUNE_OPT_AGU,
   X86_TUNE_VECTORIZE_DOUBLE,
+  X86_TUNE_SOFTWARE_PREFETCHING_BENEFICIAL,
 
   X86_TUNE_LAST
 };
@@ -418,6 +419,8 @@ extern unsigned char ix86_tune_features[
 #define TARGET_OPT_AGU ix86_tune_features[X86_TUNE_OPT_AGU]
 #define TARGET_VECTORIZE_DOUBLE \
 	ix86_tune_features[X86_TUNE_VECTORIZE_DOUBLE]
+#define TARGET_SOFTWARE_PREFETCHING_BENEFICIAL \
+	ix86_tune_features[X86_TUNE_SOFTWARE_PREFETCHING_BENEFICIAL]
 
 /* Feature tests against the various architecture variations.  */
 enum ix86_arch_indices {
Index: config/i386/i386.c
===================================================================
--- config/i386/i386.c	(revision 168831)
+++ config/i386/i386.c	(working copy)
@@ -1977,6 +1977,11 @@ static unsigned int initial_ix86_tune_fe
   /* X86_TUNE_VECTORIZE_DOUBLE: Enable double precision vector
      instructions.  */
   ~m_ATOM,
+
+  /* X86_SOFTARE_PREFETCHING_BENEFICIAL: Enable software prefetching
+     at -O3.  For the moment, the prefetching seems badly tuned for Intel
+     chips.  */
+  m_K6_GEODE | m_AMD_MULTIPLE
 };
 
 /* Feature tests against the various architecture variations.  */
@@ -3147,27 +3152,6 @@ ix86_target_string (int isa, int flags,
   return ret;
 }
 
-/* Return TRUE if software prefetching is beneficial for the
-   given CPU. */
-
-static bool
-software_prefetching_beneficial_p (void)
-{
-  switch (ix86_tune)
-    {
-    case PROCESSOR_GEODE:
-    case PROCESSOR_K6:
-    case PROCESSOR_ATHLON:
-    case PROCESSOR_K8:
-    case PROCESSOR_AMDFAM10:
-    case PROCESSOR_BTVER1:
-      return true;
-
-    default:
-      return false;
-    }
-}
-
 /* Return true, if profiling code should be emitted before
    prologue. Otherwise it returns false.
    Note: For x86 with "hotfix" it is sorried.  */
@@ -4095,7 +4079,7 @@ ix86_option_override_internal (bool main
   if (flag_prefetch_loop_arrays < 0
       && HAVE_prefetch
       && optimize >= 3
-      && software_prefetching_beneficial_p ())
+      && TARGET_SOFTWARE_PREFETCHING_BENEFICIAL)
     flag_prefetch_loop_arrays = 1;
 
   /* If using typedef char *va_list, signal that __builtin_va_start (&ap, 0)