Text file src/pkg/vendor/golang.org/x/sys/cpu/cpu_gccgo.c

     1	// Copyright 2018 The Go Authors. All rights reserved.
     2	// Use of this source code is governed by a BSD-style
     3	// license that can be found in the LICENSE file.
     4	
     5	// +build 386 amd64 amd64p32
     6	// +build gccgo
     7	
     8	#include <cpuid.h>
     9	#include <stdint.h>
    10	
    11	// Need to wrap __get_cpuid_count because it's declared as static.
    12	int
    13	gccgoGetCpuidCount(uint32_t leaf, uint32_t subleaf,
    14	                   uint32_t *eax, uint32_t *ebx,
    15	                   uint32_t *ecx, uint32_t *edx)
    16	{
    17		return __get_cpuid_count(leaf, subleaf, eax, ebx, ecx, edx);
    18	}
    19	
    20	// xgetbv reads the contents of an XCR (Extended Control Register)
    21	// specified in the ECX register into registers EDX:EAX.
    22	// Currently, the only supported value for XCR is 0.
    23	//
    24	// TODO: Replace with a better alternative:
    25	//
    26	//     #include <xsaveintrin.h>
    27	//
    28	//     #pragma GCC target("xsave")
    29	//
    30	//     void gccgoXgetbv(uint32_t *eax, uint32_t *edx) {
    31	//       unsigned long long x = _xgetbv(0);
    32	//       *eax = x & 0xffffffff;
    33	//       *edx = (x >> 32) & 0xffffffff;
    34	//     }
    35	//
    36	// Note that _xgetbv is defined starting with GCC 8.
    37	void
    38	gccgoXgetbv(uint32_t *eax, uint32_t *edx)
    39	{
    40		__asm("  xorl %%ecx, %%ecx\n"
    41		      "  xgetbv"
    42		    : "=a"(*eax), "=d"(*edx));
    43	}

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