Turnoff prefetching for -march=znver1

[Stepanyan, Victoria]

Hi Maintainers,

This patch disables prefetching for -march=znver1 which is turned on by default.

gcc/ChangeLog:

2016-02-02 Victoria Stepanyan <victoria.stepan...@amd.com>

        * gcc/config/i386/x86-tune.def: Disable default prefetching for 
-march=znver1

Ok for trunk?

Victoria


--- a/gcc/config/i386/x86-tune.def
+++ b/gcc/config/i386/x86-tune.def
@@ -218,7 +218,7 @@ DEF_TUNE (X86_TUNE_FOUR_JUMP_LIMIT, "four_jump_limit",
    at -O3.  For the moment, the prefetching seems badly tuned for Intel
    chips.  */
DEF_TUNE (X86_TUNE_SOFTWARE_PREFETCHING_BENEFICIAL, 
"software_prefetching_beneficial",
-          m_K6_GEODE | m_AMD_MULTIPLE)
+          m_K6_GEODE | m_ATHLON_K8 | m_AMDFAM10 | m_BDVER | m_BTVER)

/* X86_TUNE_LCP_STALL: Avoid an expensive length-changing prefix stall
    on 16-bit immediate moves into memory on Core2 and Corei7.  */