[PATCH 1/2] rs6000: Add support for _mm_minpos_epu16

["Paul A. Clarke" <pc@us.ibm.com>]

Add a naive implementation of the subject x86 intrinsic to
ease porting.

2021-06-02  Paul A. Clarke  <pc@us.ibm.com>

gcc/ChangeLog:
        * config/rs6000/smmintrin.h (_mm_minpos_epu16): New.
---
 gcc/config/rs6000/smmintrin.h | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/gcc/config/rs6000/smmintrin.h b/gcc/config/rs6000/smmintrin.h
index bdf6eb365d88..358a48958192 100644
--- a/gcc/config/rs6000/smmintrin.h
+++ b/gcc/config/rs6000/smmintrin.h
@@ -116,4 +116,31 @@ _mm_blendv_epi8 (__m128i __A, __m128i __B, __m128i __mask)
   return (__m128i) vec_sel ((__v16qu) __A, (__v16qu) __B, __lmask);
 }
 
+/* Return horizontal packed word minimum and its index in bits [15:0]
+   and bits [18:16] respectively.  */
+extern __inline __m128i __attribute__((__gnu_inline__, __always_inline__, __artificial__))
+_mm_minpos_epu16 (__m128i __A)
+{
+  union __u
+    {
+      __m128i __m;
+      __v8hu __uh;
+    };
+  union __u __u = { .__m = __A }, __r = { .__m = {0} };
+  unsigned short __ridx = 0;
+  unsigned short __rmin = __u.__uh[__ridx];
+  for (unsigned long __i = __ridx+1;
+       __i < sizeof (__u.__uh) / sizeof (__u.__uh[0]);
+       __i++)
+    {
+      if (__u.__uh[__i] < __rmin)
+        {
+          __rmin = __u.__uh[__i];
+          __ridx = __i;
+        }
+    }
+  __r.__uh[0] = __rmin;
+  __r.__uh[1] = __ridx;
+  return __r.__m;
+}
 #endif
-- 
2.27.0