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src/hotspot/cpu/x86/vm_version_x86.cpp

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1763     FLAG_SET_DEFAULT(UseFastStosb, false);
1764   }
1765 
1766   // For AMD Processors use XMM/YMM MOVDQU instructions
1767   // for Object Initialization as default
1768   if (is_amd() && cpu_family() >= 0x19) {
1769     if (FLAG_IS_DEFAULT(UseFastStosb)) {
1770       UseFastStosb = false;
1771     }
1772   }
1773 
1774 #ifdef COMPILER2
1775   if (is_intel() && MaxVectorSize > 16) {
1776     if (FLAG_IS_DEFAULT(UseFastStosb)) {
1777       UseFastStosb = false;
1778     }
1779   }
1780 #endif
1781 
1782   // Use XMM/YMM MOVDQU instruction for Object Initialization
1783   if (!UseFastStosb && UseSSE >= 2 && UseUnalignedLoadStores) {
1784     if (FLAG_IS_DEFAULT(UseXMMForObjInit)) {
1785       UseXMMForObjInit = true;
1786     }
1787   } else if (UseXMMForObjInit) {
1788     warning("UseXMMForObjInit requires SSE2 and unaligned load/stores. Feature is switched off.");
1789     FLAG_SET_DEFAULT(UseXMMForObjInit, false);
1790   }
1791 
1792 #ifdef COMPILER2
1793   if (FLAG_IS_DEFAULT(AlignVector)) {
1794     // Modern processors allow misaligned memory operations for vectors.
1795     AlignVector = !UseUnalignedLoadStores;
1796   }
1797 #endif // COMPILER2
1798 
1799   if (FLAG_IS_DEFAULT(AllocatePrefetchInstr)) {
1800     if (AllocatePrefetchInstr == 3 && !supports_3dnow_prefetch()) {
1801       FLAG_SET_DEFAULT(AllocatePrefetchInstr, 0);
1802     } else if (!supports_sse() && supports_3dnow_prefetch()) {
1803       FLAG_SET_DEFAULT(AllocatePrefetchInstr, 3);

1763     FLAG_SET_DEFAULT(UseFastStosb, false);
1764   }
1765 
1766   // For AMD Processors use XMM/YMM MOVDQU instructions
1767   // for Object Initialization as default
1768   if (is_amd() && cpu_family() >= 0x19) {
1769     if (FLAG_IS_DEFAULT(UseFastStosb)) {
1770       UseFastStosb = false;
1771     }
1772   }
1773 
1774 #ifdef COMPILER2
1775   if (is_intel() && MaxVectorSize > 16) {
1776     if (FLAG_IS_DEFAULT(UseFastStosb)) {
1777       UseFastStosb = false;
1778     }
1779   }
1780 #endif
1781 
1782   // Use XMM/YMM MOVDQU instruction for Object Initialization
1783   if (UseSSE >= 2 && UseUnalignedLoadStores) {
1784     if (FLAG_IS_DEFAULT(UseXMMForObjInit)) {
1785       UseXMMForObjInit = true;
1786     }
1787   } else if (UseXMMForObjInit) {
1788     warning("UseXMMForObjInit requires SSE2 and unaligned load/stores. Feature is switched off.");
1789     FLAG_SET_DEFAULT(UseXMMForObjInit, false);
1790   }
1791 
1792 #ifdef COMPILER2
1793   if (FLAG_IS_DEFAULT(AlignVector)) {
1794     // Modern processors allow misaligned memory operations for vectors.
1795     AlignVector = !UseUnalignedLoadStores;
1796   }
1797 #endif // COMPILER2
1798 
1799   if (FLAG_IS_DEFAULT(AllocatePrefetchInstr)) {
1800     if (AllocatePrefetchInstr == 3 && !supports_3dnow_prefetch()) {
1801       FLAG_SET_DEFAULT(AllocatePrefetchInstr, 0);
1802     } else if (!supports_sse() && supports_3dnow_prefetch()) {
1803       FLAG_SET_DEFAULT(AllocatePrefetchInstr, 3);
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