[Bug target/99881] Regression compare -O2 -ftree-vectorize with -O2 on SKX/CLX

[hjl.tools at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99881

--- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> ---
Created attachment 50501
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50501&action=edit
A patch to add vec_contruct cost

ix86_builtin_vectorization_cost has

      case vec_construct:
        {
          /* N element inserts into SSE vectors.  */
          int cost = TYPE_VECTOR_SUBPARTS (vectype) * ix86_cost->sse_op;
          /* One vinserti128 for combining two SSE vectors for AVX256.  */
          if (GET_MODE_BITSIZE (mode) == 256)
            cost += ix86_vec_cost (mode, ix86_cost->addss);
          /* One vinserti64x4 and two vinserti128 for combining SSE
             and AVX256 vectors to AVX512.  */
          else if (GET_MODE_BITSIZE (mode) == 512)
            cost += 3 * ix86_vec_cost (mode, ix86_cost->addss);
          return cost; 
        }

Add vec_contruct cost for vec_construct operation.