gen/platfunc.c

   1 /*
   2  * Copyright (c) 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 #if defined(__i386__) || defined(__x86_64__)
  25
  26 #include <stdlib.h>
  27 #include <machine/cpu_capabilities.h>
  28 #include "platfunc.h"
  29
  30 #define PLAT_CAP_MASK (kHasMMX | kHasSSE | kHasSSE2 | kHasSSE3 | kCache32 | kCache64 | kCache128 | kFastThreadLocalStorage | kHasSupplementalSSE3 | k64Bit | kHasSSE4_1 | kHasSSE4_2 | kHasAES | kInOrderPipeline | kSlow | kUP)
  31
  32 inline static int __get_cpu_capabilities() {
  33         return *((int32_t*)_COMM_PAGE_CPU_CAPABILITIES);
  34 }
  35
  36 inline static int num_cpus(int capabilities) {
  37         return (capabilities & kNumCPUs) >> kNumCPUsShift;
  38 }
  39
  40 /* TODO: If 8151810 is fixed (or full support for visibility("internal") is added), change this to visibility("internal") */
  41 void __attribute__((visibility("hidden"))) *find_platform_function(const platfunc_descriptor *descriptors[]) {
  42         int cap = __get_cpu_capabilities(),
  43             have_cpus = num_cpus(cap);
  44
  45         for (int i = 0; descriptors[i] != 0; i++) {
  46                 int musthave_cpus = num_cpus(descriptors[i]->musthave),
  47                     canthave_cpus = num_cpus(descriptors[i]->canthave);
  48                 uint32_t musthave = descriptors[i]->musthave & PLAT_CAP_MASK,
  49                                  canthave = descriptors[i]->canthave & PLAT_CAP_MASK;
  50                 /* First check that the CPU supports all the features that are in musthave */
  51                 if ((musthave & cap) != musthave)
  52                         continue;
  53                 /* Now check that the CPU doesn't have any of the features that are in canthave */
  54                 if ((canthave & cap) != 0)
  55                         continue;
  56                 /* Special case check for the number of CPUs. */
  57                 /* TODO: Should there be a way to specify < or > num cpus? */
  58                 if (musthave_cpus != 0 && have_cpus != musthave_cpus)
  59                         continue;
  60                 if (canthave_cpus != 0 && have_cpus == canthave_cpus)
  61                         continue;
  62                 /* otherwise, we have found our preferred implementation */
  63                 return descriptors[i]->address;
  64         }
  65
  66         /* We didn't find an acceptable implementation. (bug in data structures!) */
  67         return NULL;
  68 }
  69
  70 #endif