2 Copyright (C) 2012 Paul Davis
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 #include "libpbd-config.h"
22 #define _XOPEN_SOURCE 600
23 #include <cstring> // for memset
28 #ifdef PLATFORM_WINDOWS
33 #include "pbd/error.h"
40 /* This function is provided by MSVC are part of the compiler instrinsics. We
41 * don't care about this on OS X (though perhaps we should), but we need to
42 * test AVX support on Linux also. It doesn't hurt that this works on OS X
46 #if __GNUC__ > 4 || __GNUC__ == 4 && __GNUC_MINOR__ >= 4
47 static inline unsigned long long _xgetbv(unsigned int index){
48 unsigned int eax, edx;
49 __asm__ __volatile__("xgetbv" : "=a"(eax), "=d"(edx) : "c"(index));
50 return ((unsigned long long)edx << 32) | eax;
58 unsigned long cpuflags = 0;
62 #if !( (defined __x86_64__) || (defined __i386__) || (defined _M_X64) || (defined _M_IX86) ) // !ARCH_X86
66 #ifdef PLATFORM_WINDOWS
68 // Get CPU flags using Microsoft function
69 // It works for both 64 and 32 bit systems
70 // no need to use assembler for getting info from register, this function does this for us
73 cpuflags = cpuInfo[3];
77 #ifndef _LP64 /* *nix; 32 bit version. This odd macro constant is required because we need something that identifies this as a 32 bit
78 build on Linux and on OS X. Anything that serves this purpose will do, but this is the best thing we've identified
90 : "%eax", "%ecx", "%edx"
93 #else /* *nix; 64 bit version */
95 /* asm notes: although we explicitly save&restore rbx, we must tell
96 gcc that ebx,rbx is clobbered so that it doesn't try to use it as an intermediate
97 register when storing rbx. gcc 4.3 didn't make this "mistake", but gcc 4.4
98 does, at least on x86_64.
109 : "%rax", "%rbx", "%rcx", "%rdx"
113 #endif /* PLATFORM_WINDOWS */
115 if (cpuflags & ((1<<27) /* AVX */ |(1<<28) /* XGETBV */)) {
117 std::cerr << "Looks like AVX\n";
119 /* now check if YMM resters state is saved: which means OS does
120 * know about new YMM registers and saves them during context
121 * switches it's true for most cases, but we must be sure
123 * giving 0 as the argument to _xgetbv() fetches the
124 * XCR_XFEATURE_ENABLED_MASK, which we need to check for
125 * the 2nd and 3rd bits, indicating correct register save/restore.
128 uint64_t xcrFeatureMask = _xgetbv (0);
130 if (xcrFeatureMask & 0x6) {
131 std::cerr << "Definitely AVX\n";
132 _flags = Flags (_flags | (HasAVX) );
136 if (cpuflags & (1<<25)) {
137 _flags = Flags (_flags | (HasSSE|HasFlushToZero));
140 if (cpuflags & (1<<26)) {
141 _flags = Flags (_flags | HasSSE2);
144 if (cpuflags & (1 << 24)) {
148 /* DAZ wasn't available in the first version of SSE. Since
149 setting a reserved bit in MXCSR causes a general protection
150 fault, we need to be able to check the availability of this
151 feature without causing problems. To do this, one needs to
152 set up a 512-byte area of memory to save the SSE state to,
153 using fxsave, and then one needs to inspect bytes 28 through
154 31 for the MXCSR_MASK value. If bit 6 is set, DAZ is
155 supported, otherwise, it isn't.
158 #ifndef HAVE_POSIX_MEMALIGN
159 # ifdef PLATFORM_WINDOWS
160 fxbuf = (char **) _aligned_malloc (sizeof (char *), 16);
162 *fxbuf = (char *) _aligned_malloc (512, 16);
165 # warning using default malloc for aligned memory
166 fxbuf = (char **) malloc (sizeof (char *));
168 *fxbuf = (char *) malloc (512);
172 (void) posix_memalign ((void **) &fxbuf, 16, sizeof (char *));
174 (void) posix_memalign ((void **) fxbuf, 16, 512);
178 memset (*fxbuf, 0, 512);
195 uint32_t mxcsr_mask = *((uint32_t*) &((*fxbuf)[28]));
197 /* if the mask is zero, set its default value (from intel specs) */
199 if (mxcsr_mask == 0) {
203 if (mxcsr_mask & (1<<6)) {
204 _flags = Flags (_flags | HasDenormalsAreZero);
207 #if !defined HAVE_POSIX_MEMALIGN && defined PLATFORM_WINDOWS
208 _aligned_free (*fxbuf);
209 _aligned_free (fxbuf);