1//go:build gc
2
3package platform
4
5// CpuFeatures exposes the capabilities for this CPU, queried via the Has, HasExtra methods.
6var CpuFeatures = loadCpuFeatureFlags()
7
8// cpuFeatureFlags implements CpuFeatureFlags interface.
9type cpuFeatureFlags struct {
10 flags uint64
11 extraFlags uint64
12}
13
14// cpuid exposes the CPUID instruction to the Go layer (https://www.amd.com/system/files/TechDocs/25481.pdf)
15// implemented in cpuid_amd64.s
16func cpuid(arg1, arg2 uint32) (eax, ebx, ecx, edx uint32)
17
18// cpuidAsBitmap combines the result of invoking cpuid to uint64 bitmap.
19func cpuidAsBitmap(arg1, arg2 uint32) uint64 {
20 _ /* eax */, _ /* ebx */, ecx, edx := cpuid(arg1, arg2)
21 return (uint64(edx) << 32) | uint64(ecx)
22}
23
24// loadStandardRange load flags from the standard range, panics otherwise.
25func loadStandardRange(id uint32) uint64 {
26 // ensure that the id is in the valid range, returned by cpuid(0,0)
27 maxRange, _, _, _ := cpuid(0, 0)
28 if id > maxRange {
29 panic("cannot query standard CPU flags")
30 }
31 return cpuidAsBitmap(id, 0)
32}
33
34// loadStandardRange load flags from the extended range, panics otherwise.
35func loadExtendedRange(id uint32) uint64 {
36 // ensure that the id is in the valid range, returned by cpuid(0x80000000,0)
37 maxRange, _, _, _ := cpuid(0x80000000, 0)
38 if id > maxRange {
39 panic("cannot query extended CPU flags")
40 }
41 return cpuidAsBitmap(id, 0)
42}
43
44func loadCpuFeatureFlags() CpuFeatureFlags {
45 return &cpuFeatureFlags{
46 flags: loadStandardRange(1),
47 extraFlags: loadExtendedRange(0x80000001),
48 }
49}
50
51// Has implements the same method on the CpuFeatureFlags interface.
52func (f *cpuFeatureFlags) Has(cpuFeature CpuFeature) bool {
53 return (f.flags & uint64(cpuFeature)) != 0
54}
55
56// HasExtra implements the same method on the CpuFeatureFlags interface.
57func (f *cpuFeatureFlags) HasExtra(cpuFeature CpuFeature) bool {
58 return (f.extraFlags & uint64(cpuFeature)) != 0
59}
60
61// Raw implements the same method on the CpuFeatureFlags interface.
62func (f *cpuFeatureFlags) Raw() uint64 {
63 // Below, we only set bits for the features we care about,
64 // instead of setting all the unnecessary bits obtained from the
65 // CPUID instruction.
66 var ret uint64
67 if f.Has(CpuFeatureAmd64SSE3) {
68 ret = 1 << 0
69 }
70 if f.Has(CpuFeatureAmd64SSE4_1) {
71 ret |= 1 << 1
72 }
73 if f.Has(CpuFeatureAmd64SSE4_2) {
74 ret |= 1 << 2
75 }
76 if f.HasExtra(CpuExtraFeatureAmd64ABM) {
77 ret |= 1 << 3
78 }
79 return ret
80}