Improve UseAVX setting and add cpu descriptions for zhaoxin processors.

[Vic Wang(BJ-RD)]

Hi All

Here is the patch that improving the UseAVX setting and add cpu descriptions for zhaoxin processors.
Can you help to review the patch and assign a number for a pull request?
Thank you!


Patch in my fork repository:
https://github.com/Double-Minds-JV/jdk/commit/06498b42ed54021b3ed14a9ccc9adf52e9360c9c

>diff --git a/src/hotspot/cpu/x86/vm_version_x86.cpp b/src/hotspot/cpu/x86/vm_version_x86.cpp
>index 094ab370190..4043b29f18c 100644
>--- a/src/hotspot/cpu/x86/vm_version_x86.cpp
>+++ b/src/hotspot/cpu/x86/vm_version_x86.cpp
>@@ -931,9 +931,17 @@ void VM_Version::get_processor_features() {
>   if (UseSSE < 1)
>     _features.clear_feature(CPU_SSE);
>
>-  //since AVX instructions is slower than SSE in some ZX cpus, force USEAVX=0.
>-  if (is_zx() && ((cpu_family() == 6) || (cpu_family() == 7))) {
>-    UseAVX = 0;
>+  // ZX cpus specific settings
>+  if (is_zx() && FLAG_IS_DEFAULT(UseAVX)) {
>+    if (cpu_family() == 7) {
>+      if (extended_cpu_model() == 0x5B || extended_cpu_model() == 0x6B) {
>+        UseAVX = 1;
>+      } else if (extended_cpu_model() == 0x1B || extended_cpu_model() == 0x3B) {
>+        UseAVX = 0;
>+      }
>+    } else if (cpu_family() == 6) {
>+      UseAVX = 0;
>+    }
>   }
>
>   // UseSSE is set to the smaller of what hardware supports and what
>@@ -2592,6 +2600,7 @@ void VM_Version::resolve_cpu_information_details(void) {
>
> const char* VM_Version::cpu_family_description(void) {
>   int cpu_family_id = extended_cpu_family();
>+  int cpu_model_id = extended_cpu_model();
>   if (is_amd()) {
>     if (cpu_family_id < ExtendedFamilyIdLength_AMD) {
>       return _family_id_amd[cpu_family_id];
>@@ -2605,6 +2614,22 @@ const char* VM_Version::cpu_family_description(void) {
>       return _family_id_intel[cpu_family_id];
>     }
>   }
>+  if (is_zx()) {
>+    if (cpu_family_id == 7) {
>+      switch (cpu_model_id) {
>+        case 0x1B:
>+          return "wudaokou";
>+        case 0x3B:
>+          return "lujiazui";
>+        case 0x5B:
>+          return "yongfeng";
>+        case 0x6B:
>+          return "shijidadao";
>+      }
>+    } else if (cpu_family_id == 6) {
>+      return "zhangjiang";
>+    }
>+  }
>   if (is_hygon()) {
>     return "Dhyana";
>   }
>@@ -2624,6 +2649,9 @@ int VM_Version::cpu_type_description(char* const buf, size_t buf_len) {
>   } else if (is_amd()) {
>     cpu_type = "AMD";
>     x64 = cpu_is_em64t() ? " AMD64" : "";
>+  } else if (is_zx()) {
>+    cpu_type = "Zhaoxin";
>+    x64 = cpu_is_em64t() ? " x86_64" : "";
>   } else if (is_hygon()) {
>     cpu_type = "Hygon";
>     x64 = cpu_is_em64t() ? " AMD64" : "";
>@@ -3236,6 +3264,12 @@ int VM_Version::allocate_prefetch_distance(bool use_watermark_prefetch) {
>     } else {
>       return 128; // Athlon
>     }
>+  } else if (is_zx()) {
>+    if (supports_sse2()) {
>+      return 256;
>+    } else {
>+      return 128;
>+    }
>   } else { // Intel
>     if (supports_sse3() && is_intel_server_family()) {
>       if (supports_sse4_2() && supports_ht()) { // Nehalem based cpus

I have run the jtreg tests after applying the patch, the test-summary shows follows:
>==============================
>Test summary
>==============================
>   TEST                                              TOTAL  PASS  FAIL ERROR  SKIP
>   jtreg:test/hotspot/jtreg:tier1                     3107  2797     0     0   310
>   jtreg:test/jdk:tier1                               2513  2472     0     0    41
>   jtreg:test/langtools:tier1                         4668  4656     0     0    12
>   jtreg:test/jaxp:tier1                                 0     0     0     0     0
>   jtreg:test/lib-test:tier1                            38    38     0     0     0
>==============================
>TEST SUCCESS

Best Regards!
Vic Wang


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