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https://github.com/cuberite/libdeflate.git
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f2c3a5b4e9
* Bring in common headers and program code from xpack project * Move program code to programs/ * Move library code to lib/ * GNU89 and MSVC2010 compatibility * Other changes
150 lines
3.8 KiB
C
150 lines
3.8 KiB
C
/*
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* x86_cpu_features.c - feature detection for x86 processors
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*
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* Written in 2015 by Eric Biggers <ebiggers3@gmail.com>
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*
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* To the extent possible under law, the author(s) have dedicated all copyright
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* and related and neighboring rights to this software to the public domain
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* worldwide. This software is distributed without any warranty.
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*
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* You should have received a copy of the CC0 Public Domain Dedication along
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* with this software. If not, see
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* <http://creativecommons.org/publicdomain/zero/1.0/>.
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*/
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#include "x86_cpu_features.h"
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#if X86_CPU_FEATURES_ENABLED
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#define DEBUG 0
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#if DEBUG
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# include <stdio.h>
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#endif
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u32 _x86_cpu_features = 0;
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/* With old GCC versions we have to manually save and restore the x86_32 PIC
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* register (ebx). See: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47602 */
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#if defined(__i386__) && defined(__PIC__)
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# define EBX_CONSTRAINT "=r"
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#else
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# define EBX_CONSTRAINT "=b"
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#endif
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/* Execute the CPUID instruction. */
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static inline void
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cpuid(u32 leaf, u32 subleaf, u32 *a, u32 *b, u32 *c, u32 *d)
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{
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__asm__(".ifnc %%ebx, %1; mov %%ebx, %1; .endif\n"
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"cpuid \n"
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".ifnc %%ebx, %1; xchg %%ebx, %1; .endif\n"
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: "=a" (*a), EBX_CONSTRAINT (*b), "=c" (*c), "=d" (*d)
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: "a" (leaf), "c" (subleaf));
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}
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/* Read an extended control register. */
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static inline u64
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read_xcr(u32 index)
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{
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u32 edx, eax;
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/* Execute the "xgetbv" instruction. Old versions of binutils do not
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* recognize this instruction, so list the raw bytes instead. */
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__asm__ (".byte 0x0f, 0x01, 0xd0" : "=d" (edx), "=a" (eax) : "c" (index));
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return ((u64)edx << 32) | eax;
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}
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#define IS_SET(reg, bit) ((reg) & ((u32)1 << (bit)))
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/* Initialize _x86_cpu_features with bits for interesting processor features. */
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void
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x86_setup_cpu_features(void)
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{
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u32 features = 0;
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u32 dummy1, dummy2, dummy3, dummy4;
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u32 max_function;
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u32 features_1, features_2, features_3, features_4;
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bool os_saves_ymm_regs = false;
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/* Get maximum supported function */
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cpuid(0, 0, &max_function, &dummy2, &dummy3, &dummy4);
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if (max_function < 1)
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goto out;
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/* Standard feature flags */
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cpuid(1, 0, &dummy1, &dummy2, &features_2, &features_1);
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if (IS_SET(features_1, 25))
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features |= X86_CPU_FEATURE_SSE;
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if (IS_SET(features_1, 26))
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features |= X86_CPU_FEATURE_SSE2;
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if (IS_SET(features_2, 0))
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features |= X86_CPU_FEATURE_SSE3;
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if (IS_SET(features_2, 9))
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features |= X86_CPU_FEATURE_SSSE3;
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if (IS_SET(features_2, 19))
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features |= X86_CPU_FEATURE_SSE4_1;
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if (IS_SET(features_2, 20))
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features |= X86_CPU_FEATURE_SSE4_2;
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if (IS_SET(features_2, 27)) /* OSXSAVE set? */
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if ((read_xcr(0) & 0x6) == 0x6)
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os_saves_ymm_regs = true;
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if (os_saves_ymm_regs && IS_SET(features_2, 28))
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features |= X86_CPU_FEATURE_AVX;
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if (max_function < 7)
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goto out;
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/* Extended feature flags */
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cpuid(7, 0, &dummy1, &features_3, &features_4, &dummy4);
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if (IS_SET(features_3, 3))
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features |= X86_CPU_FEATURE_BMI;
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if (os_saves_ymm_regs && IS_SET(features_3, 5))
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features |= X86_CPU_FEATURE_AVX2;
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if (IS_SET(features_3, 8))
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features |= X86_CPU_FEATURE_BMI2;
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out:
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#if DEBUG
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printf("Detected x86 CPU features: ");
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if (features & X86_CPU_FEATURE_SSE)
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printf("SSE ");
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if (features & X86_CPU_FEATURE_SSE2)
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printf("SSE2 ");
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if (features & X86_CPU_FEATURE_SSE3)
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printf("SSE3 ");
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if (features & X86_CPU_FEATURE_SSSE3)
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printf("SSSE3 ");
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if (features & X86_CPU_FEATURE_SSE4_1)
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printf("SSE4.1 ");
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if (features & X86_CPU_FEATURE_SSE4_2)
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printf("SSE4.2 ");
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if (features & X86_CPU_FEATURE_BMI)
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printf("BMI ");
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if (features & X86_CPU_FEATURE_AVX)
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printf("AVX ");
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if (features & X86_CPU_FEATURE_BMI2)
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printf("BMI2 ");
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if (features & X86_CPU_FEATURE_AVX2)
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printf("AVX2 ");
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printf("\n");
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#endif /* DEBUG */
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_x86_cpu_features = features | X86_CPU_FEATURES_KNOWN;
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}
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#endif /* X86_CPU_FEATURES_ENABLED */
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