text: /*
   * Double-precision vector log(x) function.
   *
   * Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   * See https://llvm.org/LICENSE.txt for license information.
   * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   */
  
  #include "mathlib.h"
  #include "v_math.h"
  #include "v_log.h"
  #if V_SUPPORTED
  
  /* Worst-case error: 1.17 + 0.5 ulp.  */
  
  static const f64_t Poly[] = {
    /* rel error: 0x1.6272e588p-56 in [ -0x1.fc1p-9 0x1.009p-8 ].  */
    -0x1.ffffffffffff7p-2,
     0x1.55555555170d4p-2,
    -0x1.0000000399c27p-2,
     0x1.999b2e90e94cap-3,
    -0x1.554e550bd501ep-3,
  };
  
  #define A0 v_f64 (Poly[0])
  #define A1 v_f64 (Poly[1])
  #define A2 v_f64 (Poly[2])
  #define A3 v_f64 (Poly[3])
  #define A4 v_f64 (Poly[4])
  #define Ln2 v_f64 (0x1.62e42fefa39efp-1)
  #define N (1 << V_LOG_TABLE_BITS)
  #define OFF v_u64 (0x3fe6900900000000)
  
  struct entry
  {
    v_f64_t invc;
    v_f64_t logc;
  };
  
  static inline struct entry
  lookup (v_u64_t i)
  {
    struct entry e;
  #ifdef SCALAR
    e.invc = __v_log_data[i].invc;
    e.logc = __v_log_data[i].logc;
  #else
    e.invc[0] = __v_log_data[i[0]].invc;
    e.logc[0] = __v_log_data[i[0]].logc;
    e.invc[1] = __v_log_data[i[1]].invc;
    e.logc[1] = __v_log_data[i[1]].logc;
  #endif
    return e;
  }
  
  VPCS_ATTR
  __attribute__ ((noinline)) static v_f64_t
  specialcase (v_f64_t x, v_f64_t y, v_u64_t cmp)
  {
    return v_call_f64 (log, x, y, cmp);
  }
  
  VPCS_ATTR
  v_f64_t
  V_NAME(log) (v_f64_t x)
  {
    v_f64_t z, r, r2, p, y, kd, hi;
    v_u64_t ix, iz, tmp, top, i, cmp;
    v_s64_t k;
    struct entry e;
  
    ix = v_as_u64_f64 (x);
    top = ix >> 48;
    cmp = v_cond_u64 (top - v_u64 (0x0010) >= v_u64 (0x7ff0 - 0x0010));
  
    /* x = 2^k z; where z is in range [OFF,2*OFF) and exact.
       The range is split into N subintervals.
       The ith subinterval contains z and c is near its center.  */
    tmp = ix - OFF;
    i = (tmp >> (52 - V_LOG_TABLE_BITS)) % N;
    k = v_as_s64_u64 (tmp) >> 52; /* arithmetic shift */
    iz = ix - (tmp & v_u64 (0xfffULL << 52));
    z = v_as_f64_u64 (iz);
    e = lookup (i);
  
    /* log(x) = log1p(z/c-1) + log(c) + k*Ln2.  */
    r = v_fma_f64 (z, e.invc, v_f64 (-1.0));
    kd = v_to_f64_s64 (k);
  
    /* hi = r + log(c) + k*Ln2.  */
    hi = v_fma_f64 (kd, Ln2, e.logc + r);
    /* y = r2*(A0 + r*A1 + r2*(A2 + r*A3 + r2*A4)) + hi.  */
    r2 = r * r;
    y = v_fma_f64 (A3, r, A2);
    p = v_fma_f64 (A1, r, A0);
    y = v_fma_f64 (A4, r2, y);
    y = v_fma_f64 (y, r2, p);
    y = v_fma_f64 (y, r2, hi);
  
    if (unlikely (v_any_u64 (cmp)))
      return specialcase (x, y, cmp);
    return y;
  }
  VPCS_ALIAS
  #endif
  