5261 libm should stop using synonyms.h
5298 fabs is 0-sized, confuses dis(1) and others
Reviewed by: Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
Approved by: Gordon Ross <gwr@nexenta.com>

          --- old/usr/src/lib/libm/i386/src/ilogbf.s
          +++ new/usr/src/lib/libm/i386/src/ilogbf.s

   1    1  /*
   2    2   * CDDL HEADER START
   3    3   *
   4    4   * The contents of this file are subject to the terms of the
   5    5   * Common Development and Distribution License (the "License").
   6    6   * You may not use this file except in compliance with the License.
   7    7   *
   8    8   * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9    9   * or http://www.opensolaris.org/os/licensing.
  10   10   * See the License for the specific language governing permissions
  11   11   * and limitations under the License.
  12   12   *
  13   13   * When distributing Covered Code, include this CDDL HEADER in each
  14   14   * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15   15   * If applicable, add the following below this CDDL HEADER, with the
  16   16   * fields enclosed by brackets "[]" replaced with your own identifying
  17   17   * information: Portions Copyright [yyyy] [name of copyright owner]
  18   18   *
  19   19   * CDDL HEADER END
  20   20   */
  21   21  /*
  22   22   * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.

  23   23   */
  24   24  /*
  25   25   * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  26   26   * Use is subject to license terms.
  27   27   */
  28   28  
  29   29          .file "ilogbf.s"
  30   30  
  31   31  #include "libm.h"
  32   32  LIBM_ANSI_PRAGMA_WEAK(ilogbf,function)
  33      -#include "libm_synonyms.h"
  34   33  #include "xpg6.h"
  35   34  
  36   35          .data
  37   36          .align  8
  38   37  two23:  .long   0x4b000000              / 2**23
  39   38  
  40   39          ENTRY(ilogbf)
  41   40          movl    4(%esp),%eax            / eax <-- x
  42   41          testl   $0x7f800000,%eax        / is bexp(x) 0?
  43   42          jz      .bexp_0                 / jump if x is 0 or subnormal

  44   43                                          / here, biased exponent is non-zero
  45   44          andl    $0x7fffffff,%eax        / eax <-- abs(x)
  46   45          cmpl    $0x7f800000,%eax        / is bexp(x) 0xff?
  47   46          jae     .bexp_all_1             / jump if x is NaN or Inf
  48   47          shrl    $23,%eax                / eax <-- zero_xtnd(bexp(x))
  49   48          subl    $127,%eax               / unbias exponent by 127
  50   49          ret
  51   50  
  52   51  .bexp_all_1:
  53   52          movl    $0x7fffffff,%eax        / x is NaN or inf, so return 0x7fffffff
  54   53          jmp     0f
  55   54  
  56   55  .bexp_0:
  57   56          andl    $0x7fffffff,%eax        / eax <-- abs(x), and
  58   57                                          / ZF = 1 iff x = 0.0
  59   58          jnz     .ilogb_subnorm
  60   59          movl    $0x80000001,%eax        / x is +/-0, so return 0x80000001
  61   60  0:
  62   61          PIC_SETUP(0)
  63   62          PIC_G_LOAD(movzwl,__xpg6,ecx)
  64   63          PIC_WRAPUP
  65   64          andl    $_C99SUSv3_ilogb_0InfNaN_raises_invalid,%ecx
  66   65          cmpl    $0,%ecx
  67   66          je      1f
  68   67          fldz
  69   68          fdivp   %st,%st(0)              / raise invalid as per SUSv3
  70   69  1:
  71   70          ret
  72   71  
  73   72  .ilogb_subnorm:                         / subnormal input
  74   73          flds    4(%esp)                 / push x
  75   74          PIC_SETUP(1)
  76   75          fmuls   PIC_L(two23)            / x*2**23; rebias x by 127+23,
  77   76                                          /          instead of 127
  78   77          PIC_WRAPUP
  79   78          subl    $4,%esp                 / set up storage area
  80   79          fstps   (%esp)                  / store x*2**23 in storage area
  81   80          fwait                           / (shouldn't raise exception, but
  82   81                                          / just in case)
  83   82          movl    $0x7f800000,%eax        / eax <-- single_bexp_mask
  84   83          andl    (%esp),%eax             / eax[23..30]  <-- bexp(x*2**23),
  85   84                                          / rest_of(eax) <-- 0
  86   85          shrl    $23,%eax                / eax <-- zero_xtnd(bexp(x*2**23))
  87   86          subl    $150,%eax               / unbias rebiased x by 150 (= 127 + 23)
  88   87          addl    $4,%esp                 / restore stack for caller
  89   88          ret
  90   89          .align  4
  91   90          SET_SIZE(ilogbf)

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