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) 2000-2013 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/mips32/mips64/arm64, 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 shift by 1, since Thumb insns can be of size 2, hence to
   minimise collisions and maximise cache utilisation we need to take
   into account all but the least significant bit.

   On s390x the rightmost bit of an instruction address is zero.
   For best table utilization shift the address to the right by 1 bit. */

#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_s390x) || defined(VGA_arm)
#  define VG_TT_FAST_HASH(_addr)  ((((UWord)(_addr)) >> 1) & VG_TT_FAST_MASK)

#elif defined(VGA_ppc32) || defined(VGA_ppc64be) || defined(VGA_ppc64le) \
      || defined(VGA_mips32) || defined(VGA_mips64) || defined(VGA_arm64)
#  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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