sysdeps/ia64/_mcount.S

   1 /* Machine-specific calling sequence for `mcount' profiling function.  ia64
   2    Copyright (C) 2000 Free Software Foundation, Inc.
   3      Contributed by David Mosberger <davidm@hpl.hp.com>
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 /* Assembly stub to invoke _mcount().  Compiler generated code calls
  22    this stub before executing a function's prologue and without saving
  23    any registers.  It is therefore necessary to preserve the input
  24    registers as they may contain function arguments.  To work
  25    correctly with frame-less functions, it is also necessary to
  26    preserve the return pointer (b0 aka rp).
  27
  28    State upon entering _mcount:
  29
  30     r8  address of return value structure (used only when called
  31         function returns a large structure)
  32     r15 static link (used only for nested functions)
  33     in0 ar.pfs to restore before returning to the function that
  34         called _mcount
  35     in1 gp value to restore before returning to the function that
  36         called _mcount
  37     in2 return address in the function that invoked the caller
  38         of _mcount (frompc)
  39     in3 address of the global-offset table entry that holds the
  40         profile count dword allocated by the compiler; to get
  41         the address of this dword, use "ld8 in2=[in2]; this
  42         dword can be used in any way by _mcount (including
  43         not at all, as is the case with the current implementation)
  44     b0  address to return to after _mcount is done
  45 */
  46
  47 #include <sysdep.h>
  48
  49 #undef ret
  50
  51 LEAF(_mcount)
  52         .prologue ASM_UNW_PRLG_RP|ASM_UNW_PRLG_PFS, ASM_UNW_PRLG_GRSAVE(4)
  53         alloc loc1 = ar.pfs, 4, 4, 3, 0
  54         mov loc0 = rp
  55         .body
  56         mov loc2 = r8   // gcc uses r8 to pass pointer to return structure
  57         ;;
  58         mov loc3 = r15  // gcc uses r15 to pass the static link to nested functions
  59         mov out0 = in2
  60         mov out1 = rp
  61         br.call.sptk.few rp = __mcount
  62         ;;
  63 .here:
  64 {
  65         .mii
  66         mov gp = in1
  67         mov r2 = ip
  68         mov ar.pfs = loc1
  69 }
  70         ;;
  71         adds r2 = _mcount_ret_helper - .here, r2
  72         mov b7 = loc0
  73         mov rp = in2
  74         ;;
  75         mov r8 = loc2
  76         mov r15 = loc3
  77         mov b6 = r2
  78         br.ret.sptk.few b6
  79 END(_mcount)
  80
  81 LOCAL_LEAF(_mcount_ret_helper)
  82         .prologue
  83         .altrp b7
  84         .save ar.pfs, r40
  85         .body
  86         alloc r2 = ar.pfs, 0, 0, 9, 0
  87         mov ar.pfs = r40
  88         br b7
  89 END(_mcount_ret_helper)
  90
  91 weak_alias (_mcount, mcount)