src/cpu.cpp

   1 /*
   2  * This file is part of OpenTTD.
   3  * OpenTTD 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, version 2.
   4  * OpenTTD 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.
   5  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
   6  */
   7
   8 /** @file cpu.cpp OS/CPU/compiler dependent CPU specific calls. */
   9
  10 #include "stdafx.h"
  11 #include "core/bitmath_func.hpp"
  12
  13 #include "safeguards.h"
  14
  15 #undef RDTSC_AVAILABLE
  16
  17 /* rdtsc for MSC_VER, uses simple inline assembly, or _rdtsc
  18  * from external win64.asm because VS2005 does not support inline assembly */
  19 #if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64)) && !defined(RDTSC_AVAILABLE)
  20 #include <intrin.h>
  21 uint64 ottd_rdtsc()
  22 {
  23         return __rdtsc();
  24 }
  25 #define RDTSC_AVAILABLE
  26 #endif
  27
  28 /* rdtsc for OS/2. Hopefully this works, who knows */
  29 #if defined (__WATCOMC__) && !defined(RDTSC_AVAILABLE)
  30 unsigned __int64 ottd_rdtsc();
  31 # pragma aux ottd_rdtsc = 0x0F 0x31 value [edx eax] parm nomemory modify exact [edx eax] nomemory;
  32 # define RDTSC_AVAILABLE
  33 #endif
  34
  35 /* rdtsc for all other *nix-en (hopefully). Use GCC syntax */
  36 #if (defined(__i386__) || defined(__x86_64__)) && !defined(RDTSC_AVAILABLE)
  37 uint64 ottd_rdtsc()
  38 {
  39         uint32 high, low;
  40         __asm__ __volatile__ ("rdtsc" : "=a" (low), "=d" (high));
  41         return ((uint64)high << 32) | low;
  42 }
  43 # define RDTSC_AVAILABLE
  44 #endif
  45
  46 /* rdtsc for PPC which has this not */
  47 #if (defined(__POWERPC__) || defined(__powerpc__)) && !defined(RDTSC_AVAILABLE)
  48 uint64 ottd_rdtsc()
  49 {
  50         uint32 high = 0, high2 = 0, low;
  51         /* PPC does not have rdtsc, so we cheat by reading the two 32-bit time-counters
  52          * it has, 'Move From Time Base (Upper)'. Since these are two reads, in the
  53          * very unlikely event that the lower part overflows to the upper part while we
  54          * read it; we double-check and reread the registers */
  55         asm volatile (
  56                                   "mftbu %0\n"
  57                                   "mftb %1\n"
  58                                   "mftbu %2\n"
  59                                   "cmpw %3,%4\n"
  60                                   "bne- $-16\n"
  61                                   : "=r" (high), "=r" (low), "=r" (high2)
  62                                   : "0" (high), "2" (high2)
  63                                   );
  64         return ((uint64)high << 32) | low;
  65 }
  66 # define RDTSC_AVAILABLE
  67 #endif
  68
  69 /* In all other cases we have no support for rdtsc. No major issue,
  70  * you just won't be able to profile your code with TIC()/TOC() */
  71 #if !defined(RDTSC_AVAILABLE)
  72 #warning "(non-fatal) No support for rdtsc(), you won't be able to profile with TIC/TOC"
  73 uint64 ottd_rdtsc() {return 0;}
  74 #endif
  75
  76
  77 /**
  78  * Definitions for CPU detection:
  79  *
  80  * MSVC offers cpu information while gcc only implements in gcc 4.8
  81  * __builtin_cpu_supports and friends
  82  * http://msdn.microsoft.com/library/vstudio/hskdteyh%28v=vs.100%29.aspx
  83  * http://gcc.gnu.org/onlinedocs/gcc/X86-Built-in-Functions.html
  84  *
  85  * Other platforms/architectures don't have CPUID, so zero the info and then
  86  * most (if not all) of the features are set as if they do not exist.
  87  */
  88 #if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64))
  89 void ottd_cpuid(int info[4], int type)
  90 {
  91         __cpuid(info, type);
  92 }
  93 #elif defined(__x86_64__) || defined(__i386)
  94 void ottd_cpuid(int info[4], int type)
  95 {
  96 #if defined(__i386) && defined(__PIC__)
  97         /* The easy variant would be just cpuid, however... ebx is being used by the GOT (Global Offset Table)
  98          * in case of PIC;
  99          * clobbering ebx is no alternative: some compiler versions don't like this
 100          * and will issue an error message like
 101          *   "can't find a register in class 'BREG' while reloading 'asm'"
 102          */
 103         __asm__ __volatile__ (
 104                         "xchgl %%ebx, %1 \n\t"
 105                         "cpuid           \n\t"
 106                         "xchgl %%ebx, %1 \n\t"
 107                         : "=a" (info[0]), "=r" (info[1]), "=c" (info[2]), "=d" (info[3])
 108                         /* It is safe to write "=r" for (info[1]) as in case that PIC is enabled for i386,
 109                          * the compiler will not choose EBX as target register (but something else).
 110                          */
 111                         : "a" (type)
 112         );
 113 #else
 114         __asm__ __volatile__ (
 115                         "cpuid           \n\t"
 116                         : "=a" (info[0]), "=b" (info[1]), "=c" (info[2]), "=d" (info[3])
 117                         : "a" (type)
 118         );
 119 #endif /* i386 PIC */
 120 }
 121 #else
 122 void ottd_cpuid(int info[4], int type)
 123 {
 124         info[0] = info[1] = info[2] = info[3] = 0;
 125 }
 126 #endif
 127
 128 bool HasCPUIDFlag(uint type, uint index, uint bit)
 129 {
 130         int cpu_info[4] = {-1};
 131         ottd_cpuid(cpu_info, 0);
 132         uint max_info_type = cpu_info[0];
 133         if (max_info_type < type) return false;
 134
 135         ottd_cpuid(cpu_info, type);
 136         return HasBit(cpu_info[index], bit);
 137 }