coregrind/pub_core_transtab_asm.h

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/*--- Asm-only TransTab stuff.             pub_core_transtab_asm.h ---*/
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/*
   This file is part of Valgrind, a dynamic binary instrumentation
   framework.

   Copyright (C) 2000-2009 Julian Seward
      jseward@acm.org

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   This program is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307, USA.

   The GNU General Public License is contained in the file COPYING.
*/

#ifndef __PUB_CORE_TRANSTAB_ASM_H
#define __PUB_CORE_TRANSTAB_ASM_H

/* Constants for the fast translation lookup cache.  It is a direct
   mapped cache, with 2^VG_TT_FAST_BITS entries.

   On x86/amd64, the cache index is computed as
   'address[VG_TT_FAST_BITS-1 : 0]'.

   On ppc32/ppc64, the bottom two bits of instruction addresses are
   zero, which means that function causes only 1/4 of the entries to
   ever be used.  So instead the function is '(address >>u
   2)[VG_TT_FAST_BITS-1 : 0]' on those targets.

   On ARM we do like ppc32/ppc64, although that will have to be
   revisited when we come to implement Thumb. */

#define VG_TT_FAST_BITS 15
#define VG_TT_FAST_SIZE (1 << VG_TT_FAST_BITS)
#define VG_TT_FAST_MASK ((VG_TT_FAST_SIZE) - 1)

/* This macro isn't usable in asm land; nevertheless this seems
   like a good place to put it. */
#if defined(VGA_x86) || defined(VGA_amd64)
#  define VG_TT_FAST_HASH(_addr)  ((((UWord)(_addr))     ) & VG_TT_FAST_MASK)
#elif defined(VGA_ppc32) || defined(VGA_ppc64) || defined(VGA_arm)
#  define VG_TT_FAST_HASH(_addr)  ((((UWord)(_addr)) >> 2) & VG_TT_FAST_MASK)
#else
#  error "VG_TT_FAST_HASH: unknown platform"
#endif

#endif   // __PUB_CORE_TRANSTAB_ASM_H

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/*--- end                                                          ---*/
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