From 1b9fce56c4f28a092dd1cd6a1dbe8921c442824e Mon Sep 17 00:00:00 2001 From: Daniel Kolesa Date: Tue, 27 Aug 2019 21:47:48 +0200 Subject: [PATCH] util: add auxv based PowerPC AltiVec/VSX detection At least on Linux, we can use the ELF auxiliary vector to detect the presence of AltiVec, VSX and other CPU features without having to go through handling SIGILL, which has various problems of its own. A similar thing is already being done for ARM to detect NEON. Reviewed-by: Matt Turner Signed-off-by: Daniel Kolesa --- src/util/u_cpu_detect.c | 29 +++++++++++++++++++++++++---- 1 file changed, 25 insertions(+), 4 deletions(-) diff --git a/src/util/u_cpu_detect.c b/src/util/u_cpu_detect.c index 4df10c62ef5..abfea65b24d 100644 --- a/src/util/u_cpu_detect.c +++ b/src/util/u_cpu_detect.c @@ -92,7 +92,7 @@ static int has_cpuid(void); #endif -#if defined(PIPE_ARCH_PPC) && !defined(PIPE_OS_APPLE) +#if defined(PIPE_ARCH_PPC) && !defined(PIPE_OS_APPLE) && !defined(PIPE_OS_LINUX) static jmp_buf __lv_powerpc_jmpbuf; static volatile sig_atomic_t __lv_powerpc_canjump = 0; @@ -126,8 +126,29 @@ check_os_altivec_support(void) util_cpu_caps.has_altivec = 1; } } -#else /* !PIPE_OS_APPLE */ - /* not on Apple/Darwin, do it the brute-force way */ +#elif defined(PIPE_OS_LINUX) /* !PIPE_OS_APPLE */ +#if defined(PIPE_ARCH_PPC_64) + Elf64_auxv_t aux; +#else + Elf32_auxv_t aux; +#endif + int fd = open("/proc/self/auxv", O_RDONLY | O_CLOEXEC); + if (fd >= 0) { + while (read(fd, &aux, sizeof(aux)) == sizeof(aux)) { + if (aux.a_type == AT_HWCAP) { + char *env_vsx = getenv("GALLIVM_VSX"); + uint64_t hwcap = aux.a_un.a_val; + util_cpu_caps.has_altivec = (hwcap >> 28) & 1; + if (!env_vsx || env_vsx[0] != '0') { + util_cpu_caps.has_vsx = (hwcap >> 7) & 1; + } + break; + } + } + close(fd); + } +#else /* !PIPE_OS_APPLE && !PIPE_OS_LINUX */ + /* not on Apple/Darwin or Linux, do it the brute-force way */ /* this is borrowed from the libmpeg2 library */ signal(SIGILL, sigill_handler); if (setjmp(__lv_powerpc_jmpbuf)) { @@ -171,7 +192,7 @@ check_os_altivec_support(void) util_cpu_caps.has_altivec = 0; } } -#endif /* !PIPE_OS_APPLE */ +#endif /* !PIPE_OS_APPLE && !PIPE_OS_LINUX */ } #endif /* PIPE_ARCH_PPC */ -- 2.30.2