[vector api] Max/Min re-implementation

[Vladimir Ivanov]

Hi Jatin,

> http://cr.openjdk.java.net/~kkharbas/MaxMinVector/webrev.00

src/hotspot/cpu/x86/assembler_x86.cpp:

+void Assembler::evpmovd2m(KRegister kdst, XMMRegister src, int 
vector_len) {
+  assert(UseAVX > 2  && VM_Version::supports_avx512bw(), "");

+void Assembler::evpmovq2m(KRegister kdst, XMMRegister src, int 
vector_len) {
+  assert(UseAVX > 2  && VM_Version::supports_avx512bw(), "");

Intel 64 Architecture Software Developer Manual [1] states that 
vpmovd2m/vpmovq2m requires either DQ or DQ+VL (depending on vector_len).

Does BW imply DQ is available as well? Also, how hard would it be to 
assert VL when needed?

=======================================================================

src/hotspot/cpu/x86/x86.ad:

+          if (UseAVX < 1 && (bt == T_FLOAT || bt == T_DOUBLE))

I'd prefer to see UseAVX == 0 check instead.

=======================================================================

-instruct min4F_reg_evex(vecX dst, vecX src1, vecX src2) %{
+instruct min4F_reg_evex(vecX dst, vecX a, vecX b, vecX atmp, vecX btmp) %{
    predicate(UseAVX > 2 && VM_Version::supports_avx512vl() && ...
...
    ins_encode %{
      int vector_len = 0;
-    __ vminps($dst$$XMMRegister, $src1$$XMMRegister, 
$src2$$XMMRegister, vector_len);
+    KRegister ktmp = k1;
+    KRegister mask = k0;
+    __ evpmovd2m(ktmp, $a$$XMMRegister, vector_len);

Does VL always imply BW/DQ?

=======================================================================

+instruct min16F_reg_evex(vecZ dst, vecZ a, vecZ b, vecZ atmp, vecZ btmp) %{
+  predicate(UseAVX > 2 && n->as_Vector()->length() == 16 && 
n->bottom_type()->is_vect()->element_basic_type() == T_FLOAT);
...
+    int vector_len = 2;
+    KRegister ktmp = k1;
+    KRegister mask = k0;
+    __ evpmovd2m(ktmp, $a$$XMMRegister, vector_len);

Don't you need a check for BW/DQ here?

(Same for min8D_reg_evex, max16F_reg_evex, max8D_reg_evex.)

Best regards,
Vladimir Ivanov

[1] https://software.intel.com/en-us/articles/intel-sdm