add thread-safe runtime SSE OS support detection for most operating systems; clean...
authorJosh Coalson <jcoalson@users.sourceforce.net>
Sat, 3 Mar 2007 01:52:19 +0000 (01:52 +0000)
committerJosh Coalson <jcoalson@users.sourceforce.net>
Sat, 3 Mar 2007 01:52:19 +0000 (01:52 +0000)
doc/html/changelog.html
src/libFLAC/cpu.c

index 668404f..b91843f 100644 (file)
                        <li>
                                libraries:
                                <ul>
-                                       <li>(none)</li>
+                                       <li>Added runtime detection of SSE OS support for most operating systems</li>
                                </ul>
                        </li>
                        <li>
index d78c7e1..50f7d26 100644 (file)
@@ -37,7 +37,9 @@
 #include <stdlib.h>
 #include <stdio.h>
 
-#if defined FLAC__CPU_PPC
+#if defined FLAC__CPU_IA32
+# include <signal.h>
+#elif defined FLAC__CPU_PPC
 # if !defined FLAC__NO_ASM
 #  if defined FLAC__SYS_DARWIN
 #   include <sys/sysctl.h>
 #   endif
 #  else /* FLAC__SYS_DARWIN */
 
-#   ifdef __FreeBSD__
-#    include <sys/types.h>
-#    include <sys/sysctl.h>
-#   endif
-
 #   include <signal.h>
 #   include <setjmp.h>
 
@@ -74,6 +71,21 @@ static void sigill_handler (int sig)
 # endif /* FLAC__NO_ASM */
 #endif /* FLAC__CPU_PPC */
 
+#if defined (__NetBSD__) || defined(__OpenBSD__)
+#include <sys/param.h>
+#include <sys/sysctl.h>
+#include <machine/cpu.h>
+#endif
+
+#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__DragonFly__)
+#include <sys/types.h>
+#include <sys/sysctl.h>
+#endif
+
+#if defined(__APPLE__)
+/* how to get sysctlbyname()? */
+#endif
+
 const unsigned FLAC__CPUINFO_IA32_CPUID_CMOV = 0x00008000;
 const unsigned FLAC__CPUINFO_IA32_CPUID_MMX = 0x00800000;
 const unsigned FLAC__CPUINFO_IA32_CPUID_FXSR = 0x01000000;
@@ -85,8 +97,62 @@ const unsigned FLAC__CPUINFO_IA32_CPUID_EXTENDED_AMD_EXT3DNOW = 0x40000000;
 const unsigned FLAC__CPUINFO_IA32_CPUID_EXTENDED_AMD_EXTMMX = 0x00400000;
 
 
+/*
+ * Extra stuff needed for detection of OS support for SSE on IA-32
+ */
+#if defined(FLAC__CPU_IA32) && !defined FLAC__NO_ASM && defined FLAC__HAS_NASM && !defined FLAC__NO_SSE_OS && !defined FLAC__SSE_OS
+# if defined(__linux__)
+/*
+ * If the OS doesn't support SSE, we will get here with a SIGILL.  We
+ * modify the return address to jump over the offending SSE instruction
+ * and also the operation following it that indicates the instruction
+ * executed successfully.  In this way we use no global variables and
+ * stay thread-safe.
+ *
+ * 3 + 3 + 6:
+ *   3 bytes for "xorps xmm0,xmm0"
+ *   3 bytes for estimate of how long the follwing "inc var" instruction is
+ *   6 bytes extra in case our estimate is wrong
+ * 12 bytes puts us in the NOP "landing zone"
+ */
+#  define USE_OBSOLETE_SIGCONTEXT_FLAVOR /*@@@@@@ #define this to use the older signal handler method */
+#  ifdef USE_OBSOLETE_SIGCONTEXT_FLAVOR
+       static void sigill_handler_sse_os(int signal, struct sigcontext sc)
+       {
+               (void)signal;
+               sc.eip += 3 + 3 + 6;
+       }
+#  else
+#   include <sys/ucontext.h>
+       static void sigill_handler_sse_os(int signal, siginfo_t *si, void *uc)
+       {
+               (void)signal, (void)si;
+               ((ucontext_t*)uc)->uc_mcontext.gregs[14/*REG_EIP*/] += 3 + 3 + 6;
+       }
+#  endif
+# elif defined(_MSC_VER)
+#  include <windows.h>
+#  define USE_TRY_CATCH_FLAVOR /*@@@@@@ #define this to use the try/catch method for catching illegal opcode exception */
+#  ifdef USE_TRY_CATCH_FLAVOR
+#  else
+       LONG CALLBACK sigill_handler_sse_os(EXCEPTION_POINTERS *ep)
+       {
+               if(ep->ExceptionRecord->ExceptionCode == EXCEPTION_ILLEGAL_INSTRUCTION) {
+                       ep->ContextRecord->Eip += 3 + 3 + 6;
+                       return EXCEPTION_CONTINUE_EXECUTION;
+               }
+               return EXCEPTION_CONTINUE_SEARCH;
+       }
+#  endif
+# endif
+#endif
+
+
 void FLAC__cpu_info(FLAC__CPUInfo *info)
 {
+/*
+ * IA32-specific
+ */
 #ifdef FLAC__CPU_IA32
        info->type = FLAC__CPUINFO_TYPE_IA32;
 #if !defined FLAC__NO_ASM && defined FLAC__HAS_NASM
@@ -94,23 +160,11 @@ void FLAC__cpu_info(FLAC__CPUInfo *info)
        {
                unsigned cpuid = FLAC__cpu_info_asm_ia32();
                info->data.ia32.cmov = (cpuid & FLAC__CPUINFO_IA32_CPUID_CMOV)? true : false;
-               info->data.ia32.mmx = (cpuid & FLAC__CPUINFO_IA32_CPUID_MMX)? true : false;
+               info->data.ia32.mmx  = (cpuid & FLAC__CPUINFO_IA32_CPUID_MMX )? true : false;
                info->data.ia32.fxsr = (cpuid & FLAC__CPUINFO_IA32_CPUID_FXSR)? true : false;
-               info->data.ia32.sse = (cpuid & FLAC__CPUINFO_IA32_CPUID_SSE)? true : false;
+               info->data.ia32.sse  = (cpuid & FLAC__CPUINFO_IA32_CPUID_SSE )? true : false;
                info->data.ia32.sse2 = (cpuid & FLAC__CPUINFO_IA32_CPUID_SSE2)? true : false;
 
-#ifndef FLAC__SSE_OS
-               info->data.ia32.fxsr = info->data.ia32.sse = info->data.ia32.sse2 = false;
-#elif defined(__FreeBSD__)
-               /* on FreeBSD we can double-check via sysctl whether the OS supports SSE */
-               {
-                       int sse;
-                       size_t len = sizeof(sse);
-                       if (sysctlbyname("hw.instruction_sse", &sse, &len, NULL, 0) || !sse)
-                               info->data.ia32.fxsr = info->data.ia32.sse = info->data.ia32.sse2 = false;
-               }
-#endif
-
 #ifdef FLAC__USE_3DNOW
                cpuid = FLAC__cpu_info_extended_amd_asm_ia32();
                info->data.ia32._3dnow = (cpuid & FLAC__CPUINFO_IA32_CPUID_EXTENDED_AMD_3DNOW)? true : false;
@@ -119,23 +173,135 @@ void FLAC__cpu_info(FLAC__CPUInfo *info)
 #else
                info->data.ia32._3dnow = info->data.ia32.ext3dnow = info->data.ia32.extmmx = false;
 #endif
+
+               /*
+                * now have to check for OS support of SSE/SSE2
+                */
+               if(info->data.ia32.fxsr || info->data.ia32.sse || info->data.ia32.sse2) {
+#if defined FLAC__NO_SSE_OS
+                       /* assume user knows better than us; turn it off */
+                       info->data.ia32.fxsr = info->data.ia32.sse = info->data.ia32.sse2 = false;
+#elif defined FLAC__SSE_OS
+                       /* assume user knows better than us; leave as detected above */
+#elif defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__DragonFly__) || defined(__APPLE__)
+                       int sse = 0;
+                       size_t len;
+                       /* at least one of these must work: */
+                       len = sizeof(sse); sse = sse || (sysctlbyname("hw.instruction_sse", &sse, &len, NULL, 0) == 0 && sse);
+                       len = sizeof(sse); sse = sse || (sysctlbyname("hw.optional.sse"   , &sse, &len, NULL, 0) == 0 && sse); /* __APPLE__ ? */
+                       if(!sse)
+                               info->data.ia32.fxsr = info->data.ia32.sse = info->data.ia32.sse2 = false;
+#elif defined(__NetBSD__) || defined (__OpenBSD__)
+# if __NetBSD_Version__ >= 105250000 || (defined __OpenBSD__)
+                       int val = 0, mib[2] = { CTL_MACHDEP, CPU_SSE };
+                       size_t len = sizeof(val);
+                       if(sysctl(mib, 2, &val, &len, NULL, 0) < 0 || !val)
+                               info->data.ia32.fxsr = info->data.ia32.sse = info->data.ia32.sse2 = false;
+                       else { /* double-check SSE2 */
+                               mib[1] = CPU_SSE2;
+                               len = sizeof(val);
+                               if(sysctl(mib, 2, &val, &len, NULL, 0) < 0 || !val)
+                                       info->data.ia32.sse2 = false;
+                       }
+# else
+                       info->data.ia32.fxsr = info->data.ia32.sse = info->data.ia32.sse2 = false;
+# endif
+#elif defined(__linux__)
+                       int sse = 0;
+                       struct sigaction sigill_save;
+#ifdef USE_OBSOLETE_SIGCONTEXT_FLAVOR
+                       if(0 == sigaction(SIGILL, NULL, &sigill_save) && signal(SIGILL, (void (*)(int))sigill_handler_sse_os) != SIG_ERR)
+#else
+                       struct sigaction sigill_sse;
+                       sigill_sse.sa_sigaction = sigill_handler_sse_os;
+                       __sigemptyset(&sigill_sse.sa_mask);
+                       sigill_sse.sa_flags = SA_SIGINFO | SA_RESETHAND; /* SA_RESETHAND just in case our SIGILL return jump breaks, so we don't get stuck in a loop */
+                       if(0 == sigaction(SIGILL, &sigill_sse, &sigill_save))
+#endif
+                       {
+                               /* http://www.ibiblio.org/gferg/ldp/GCC-Inline-Assembly-HOWTO.html */
+                               /* see sigill_handler_sse_os() for an explanation of the following: */
+                               asm volatile (
+                                       "xorl %0,%0\n\t"          /* for some reason, still need to do this to clear 'sse' var */
+                                       "xorps %%xmm0,%%xmm0\n\t" /* will cause SIGILL if unsupported by OS */
+                                       "incl %0\n\t"             /* SIGILL handler will jump over this */
+                                       /* landing zone */
+                                       "nop\n\t" /* SIGILL jump lands here if "inc" is 9 bytes */
+                                       "nop\n\t"
+                                       "nop\n\t"
+                                       "nop\n\t"
+                                       "nop\n\t"
+                                       "nop\n\t"
+                                       "nop\n\t" /* SIGILL jump lands here if "inc" is 3 bytes (expected) */
+                                       "nop\n\t"
+                                       "nop"     /* SIGILL jump lands here if "inc" is 1 byte */
+                                       : "=r"(sse)
+                                       : "r"(sse)
+                               );
+
+                               sigaction(SIGILL, &sigill_save, NULL);
+                       }
+
+                       if(!sse)
+                               info->data.ia32.fxsr = info->data.ia32.sse = info->data.ia32.sse2 = false;
+#elif defined(_MSC_VER)
+# ifdef USE_TRY_CATCH_FLAVOR
+                       _try {
+                               __asm xorps xmm0,xmm0
+                       }
+                       _except(EXCEPTION_EXECUTE_HANDLER) {
+                               if (_exception_code() == STATUS_ILLEGAL_INSTRUCTION)
+                                       info->data.ia32.fxsr = info->data.ia32.sse = info->data.ia32.sse2 = false;
+                       }
+# else
+                       int sse = 0;
+                       LPTOP_LEVEL_EXCEPTION_FILTER save = SetUnhandledExceptionFilter(sigill_handler_sse_os);
+                       /* see GCC version above for explanation */
+                       //@@@@@@ http://msdn2.microsoft.com/en-us/library/4ks26t93.aspx
+                       //@@@@@@ http://www.daniweb.com/techtalkforums/thread8072.html
+                       //@@@@@@ http://www.codeproject.com/cpp/gccasm.asp
+                       //@@@@@@ http://www.hick.org/~mmiller/msvc_inline_asm.html
+                       __asm {
+                               xorps xmm0,xmm0
+                               inc sse
+                               nop
+                               nop
+                               nop
+                               nop
+                               nop
+                               nop
+                               nop
+                               nop
+                               nop
+                       }
+                       SetUnhandledExceptionFilter(save);
+                       if(!sse)
+                               info->data.ia32.fxsr = info->data.ia32.sse = info->data.ia32.sse2 = false;
+fprintf(stderr,"\n@@@@@@ SSE OS=%d %d\n",sse?1:0,sse);
+# endif
+#else
+                       /* no way to test, disable to be safe */
+                       info->data.ia32.fxsr = info->data.ia32.sse = info->data.ia32.sse2 = false;
+#endif
+               }
        }
 #else
        info->use_asm = false;
 #endif
+
+/*
+ * PPC-specific
+ */
 #elif defined FLAC__CPU_PPC
        info->type = FLAC__CPUINFO_TYPE_PPC;
-#if !defined FLAC__NO_ASM
+# if !defined FLAC__NO_ASM
        info->use_asm = true;
-#ifdef FLAC__USE_ALTIVEC
-#if defined FLAC__SYS_DARWIN
+#  ifdef FLAC__USE_ALTIVEC
+#   if defined FLAC__SYS_DARWIN
        {
-               int selectors[2] = { CTL_HW, HW_VECTORUNIT };
-               int result = 0;
-               size_t length = sizeof(result);
-               int error = sysctl(selectors, 2, &result, &length, 0, 0);
-
-               info->data.ppc.altivec = error==0 ? result!=0 : 0;
+               int val = 0, mib[2] = { CTL_HW, HW_VECTORUNIT };
+               size_t len = sizeof(val);
+               info->data.ppc.altivec = !(sysctl(mib, 2, &val, &len, NULL, 0) || !val);
        }
        {
                host_basic_info_data_t hostInfo;
@@ -146,14 +312,15 @@ void FLAC__cpu_info(FLAC__CPUInfo *info)
 
                info->data.ppc.ppc64 = (hostInfo.cpu_type == CPU_TYPE_POWERPC) && (hostInfo.cpu_subtype == CPU_SUBTYPE_POWERPC_970);
        }
-#else /* FLAC__SYS_DARWIN */
+#   else /* FLAC__USE_ALTIVEC && !FLAC__SYS_DARWIN */
        {
                /* no Darwin, do it the brute-force way */
-               /* this is borrowed from MPlayer from the libmpeg2 library */
+               /* @@@@@@ this is not thread-safe; replace with SSE OS method above or remove */
                info->data.ppc.altivec = 0;
                info->data.ppc.ppc64 = 0;
 
                signal (SIGILL, sigill_handler);
+               canjump = 0;
                if (!sigsetjmp (jmpbuf, 1)) {
                        canjump = 1;
 
@@ -176,16 +343,20 @@ void FLAC__cpu_info(FLAC__CPUInfo *info)
 
                        info->data.ppc.ppc64 = 1;
                }
-               signal (SIGILL, SIG_DFL);
+               signal (SIGILL, SIG_DFL); /*@@@@@@ should save and restore old signal */
        }
-#endif /* FLAC__SYS_DARWIN */
-#else /* FLAC__USE_ALTIVEC */
+#   endif
+#  else /* !FLAC__USE_ALTIVEC */
        info->data.ppc.altivec = 0;
        info->data.ppc.ppc64 = 0;
-#endif /* FLAC__USE_ALTIVEC */
-#else /* FLAC__NO_ASM */
+#  endif
+# else
        info->use_asm = false;
-#endif /* FLAC__NO_ASM */
+# endif
+
+/*
+ * unknown CPI
+ */
 #else
        info->type = FLAC__CPUINFO_TYPE_UNKNOWN;
        info->use_asm = false;