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1 
2 /*--------------------------------------------------------------------*/
3 /*--- Asm-only TransTab stuff.             pub_core_transtab_asm.h ---*/
4 /*--------------------------------------------------------------------*/
5 
6 /*
7    This file is part of Valgrind, a dynamic binary instrumentation
8    framework.
9 
10    Copyright (C) 2000-2015 Julian Seward
11       jseward@acm.org
12 
13    This program is free software; you can redistribute it and/or
14    modify it under the terms of the GNU General Public License as
15    published by the Free Software Foundation; either version 2 of the
16    License, or (at your option) any later version.
17 
18    This program is distributed in the hope that it will be useful, but
19    WITHOUT ANY WARRANTY; without even the implied warranty of
20    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
21    General Public License for more details.
22 
23    You should have received a copy of the GNU General Public License
24    along with this program; if not, write to the Free Software
25    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
26    02111-1307, USA.
27 
28    The GNU General Public License is contained in the file COPYING.
29 */
30 
31 #ifndef __PUB_CORE_TRANSTAB_ASM_H
32 #define __PUB_CORE_TRANSTAB_ASM_H
33 
34 /* Constants for the fast translation lookup cache.  It is a direct
35    mapped cache, with 2^VG_TT_FAST_BITS entries.
36 
37    On x86/amd64, the cache index is computed as
38    'address[VG_TT_FAST_BITS-1 : 0]'.
39 
40    On ppc32/ppc64/mips32/mips64/arm64, the bottom two bits of
41    instruction addresses are zero, which means that function causes
42    only 1/4 of the entries to ever be used.  So instead the function
43    is '(address >>u 2)[VG_TT_FAST_BITS-1 : 0]' on those targets.
44 
45    On ARM we shift by 1, since Thumb insns can be of size 2, hence to
46    minimise collisions and maximise cache utilisation we need to take
47    into account all but the least significant bit.
48 
49    On s390x the rightmost bit of an instruction address is zero.
50    For best table utilization shift the address to the right by 1 bit. */
51 
52 #define VG_TT_FAST_BITS 15
53 #define VG_TT_FAST_SIZE (1 << VG_TT_FAST_BITS)
54 #define VG_TT_FAST_MASK ((VG_TT_FAST_SIZE) - 1)
55 
56 /* This macro isn't usable in asm land; nevertheless this seems
57    like a good place to put it. */
58 
59 #if defined(VGA_x86) || defined(VGA_amd64)
60 #  define VG_TT_FAST_HASH(_addr)  ((((UWord)(_addr))     ) & VG_TT_FAST_MASK)
61 
62 #elif defined(VGA_s390x) || defined(VGA_arm)
63 #  define VG_TT_FAST_HASH(_addr)  ((((UWord)(_addr)) >> 1) & VG_TT_FAST_MASK)
64 
65 #elif defined(VGA_ppc32) || defined(VGA_ppc64be) || defined(VGA_ppc64le) \
66       || defined(VGA_mips32) || defined(VGA_mips64) || defined(VGA_arm64)
67 #  define VG_TT_FAST_HASH(_addr)  ((((UWord)(_addr)) >> 2) & VG_TT_FAST_MASK)
68 
69 #elif defined(VGA_tilegx)
70 #  define VG_TT_FAST_HASH(_addr)  ((((UWord)(_addr)) >> 3) & VG_TT_FAST_MASK)
71 
72 #else
73 #  error "VG_TT_FAST_HASH: unknown platform"
74 #endif
75 
76 #endif   // __PUB_CORE_TRANSTAB_ASM_H
77 
78 /*--------------------------------------------------------------------*/
79 /*--- end                                                          ---*/
80 /*--------------------------------------------------------------------*/
81