--- a/src/hotspot/cpu/x86/vm_version_x86.cpp	Fri Oct 04 12:00:16 2019 -0400
+++ b/src/hotspot/cpu/x86/vm_version_x86.cpp	Fri Oct 04 11:45:16 2019 -0700
@@ -381,6 +381,10 @@
     __ cmpl(rax, 0xE0);
     __ jccb(Assembler::notEqual, legacy_setup); // jump if EVEX is not supported
 
+    __ lea(rsi, Address(rbp, in_bytes(VM_Version::std_cpuid1_offset())));
+    __ movl(rax, Address(rsi, 0));
+    __ cmpl(rax, 0x50654);              // If it is Skylake
+    __ jcc(Assembler::equal, legacy_setup);
     // If UseAVX is unitialized or is set by the user to include EVEX
     if (use_evex) {
       // EVEX setup: run in lowest evex mode
@@ -465,6 +469,11 @@
     __ cmpl(rax, 0xE0);
     __ jcc(Assembler::notEqual, legacy_save_restore);
 
+    __ lea(rsi, Address(rbp, in_bytes(VM_Version::std_cpuid1_offset())));
+    __ movl(rax, Address(rsi, 0));
+    __ cmpl(rax, 0x50654);              // If it is Skylake
+    __ jcc(Assembler::equal, legacy_save_restore);
+
     // If UseAVX is unitialized or is set by the user to include EVEX
     if (use_evex) {
       // EVEX check: run in lowest evex mode
@@ -660,6 +669,9 @@
   }
   if (FLAG_IS_DEFAULT(UseAVX)) {
     FLAG_SET_DEFAULT(UseAVX, use_avx_limit);
+    if (is_intel_family_core() && _model == CPU_MODEL_SKYLAKE && _stepping < 5) {
+      FLAG_SET_DEFAULT(UseAVX, 2);  //Set UseAVX=2 for Skylake
+    }
   } else if (UseAVX > use_avx_limit) {
     warning("UseAVX=%d is not supported on this CPU, setting it to UseAVX=%d", (int) UseAVX, use_avx_limit);
     FLAG_SET_DEFAULT(UseAVX, use_avx_limit);
@@ -1059,6 +1071,13 @@
   }
 #endif // COMPILER2 && ASSERT
 
+  if (!FLAG_IS_DEFAULT(AVX3Threshold)) {
+    if (!is_power_of_2(AVX3Threshold)) {
+      warning("AVX3Threshold must be a power of 2");
+      FLAG_SET_DEFAULT(AVX3Threshold, 4096);
+    }
+  }
+
 #ifdef _LP64
   if (FLAG_IS_DEFAULT(UseMultiplyToLenIntrinsic)) {
     UseMultiplyToLenIntrinsic = true;