D Programming Language 2.0

Last update Tue Jan 1 10:14:39 2013


Identify the characteristics of the host CPU, providing information about cache sizes and assembly optimisation hints. This module is provided primarily for assembly language programmers.

Some of this information was extremely difficult to track down. Some of the documents below were found only in cached versions stored by search engines! This code relies on information found in:

Currently only works on x86 and Itanium CPUs. Many processors have bugs in their microcode for the CPUID instruction, so sometimes the cache information may be incorrect.

Boost License 1.0

Don Clugston, Tomas Lindquist Olsen <tomas@famolsen.dk>


struct CacheInfo;
Cache size and behaviour

size_t size;
Size of the cache, in kilobytes, per CPU. For L1 unified (data + code) caches, this size is half the physical size. (we don't halve it for larger sizes, since normally data size is much greater than code size for critical loops).

ubyte associativity;
Number of ways of associativity, eg: 1 = direct mapped 2 = 2-way set associative 3 = 3-way set associative ubyte.max = fully associative

uint lineSize;
Number of bytes read into the cache when a cache miss occurs.

CacheInfo[5] datacache;
Scheduled for deprecation. Please use dataCaches instead.

nothrow @property @trusted const(CacheInfo)[5u] dataCaches();
The data caches. If there are fewer than 5 physical caches levels, the remaining levels are set to size_t.max (== entire memory space)

nothrow @property @trusted string vendor();
Returns vendor string, for display purposes only. Do NOT use this to determine features! Note that some CPUs have programmable vendorIDs.

nothrow @property @trusted string processor();
Returns processor string, for display purposes only

nothrow @property @trusted bool x87onChip();
Does it have an x87 FPU on-chip?

nothrow @property @trusted bool mmx();
Is MMX supported?

nothrow @property @trusted bool sse();
Is SSE supported?

nothrow @property @trusted bool sse2();
Is SSE2 supported?

nothrow @property @trusted bool sse3();
Is SSE3 supported?

nothrow @property @trusted bool ssse3();
Is SSSE3 supported?

nothrow @property @trusted bool sse41();
Is SSE4.1 supported?

nothrow @property @trusted bool sse42();
Is SSE4.2 supported?

nothrow @property @trusted bool sse4a();
Is SSE4a supported?

nothrow @property @trusted bool aes();
Is AES supported

nothrow @property @trusted bool hasPclmulqdq();
Is pclmulqdq supported

nothrow @property @trusted bool hasRdrand();
Is rdrand supported

nothrow @property @trusted bool avx();
Is AVX supported

nothrow @property @trusted bool vaes();
Is VEX-Encoded AES supported

nothrow @property @trusted bool hasVpclmulqdq();
Is vpclmulqdq supported

nothrow @property @trusted bool fma();
Is FMA supported

nothrow @property @trusted bool fp16c();
Is FP16C supported

nothrow @property @trusted bool avx2();
Is AVX2 supported

nothrow @property @trusted bool hle();
Is HLE (hardware lock elision) supported

nothrow @property @trusted bool rtm();
Is RTM (restricted transactional memory) supported

nothrow @property @trusted bool amd3dnow();
Is AMD 3DNOW supported?

nothrow @property @trusted bool amd3dnowExt();
Is AMD 3DNOW Ext supported?

nothrow @property @trusted bool amdMmx();
Are AMD extensions to MMX supported?

nothrow @property @trusted bool hasFxsr();
Is fxsave/fxrstor supported?

nothrow @property @trusted bool hasCmov();
Is cmov supported?

nothrow @property @trusted bool hasRdtsc();
Is rdtsc supported?

nothrow @property @trusted bool hasCmpxchg8b();
Is cmpxchg8b supported?

nothrow @property @trusted bool hasCmpxchg16b();
Is cmpxchg8b supported?

nothrow @property @trusted bool hasSysEnterSysExit();

nothrow @property @trusted bool has3dnowPrefetch();
Is 3DNow prefetch supported?

nothrow @property @trusted bool hasLahfSahf();
Are LAHF and SAHF supported in 64-bit mode?

nothrow @property @trusted bool hasPopcnt();
Is POPCNT supported?

nothrow @property @trusted bool hasLzcnt();
Is LZCNT supported?

nothrow @property @trusted bool isX86_64();
Is this an Intel64 or AMD 64?

nothrow @property @trusted bool isItanium();
Is this an IA64 (Itanium) processor?

nothrow @property @trusted bool hyperThreading();
Is hyperthreading supported?

nothrow @property @trusted uint threadsPerCPU();
Returns number of threads per CPU

nothrow @property @trusted uint coresPerCPU();
Returns number of cores in CPU

nothrow @property @trusted bool preferAthlon();
Optimisation hints for assembly code.

For forward compatibility, the CPU is compared against different microarchitectures. For 32-bit x86, comparisons are made against the Intel PPro/PII/PIII/PM family.

The major 32-bit x86 microarchitecture 'dynasties' have been:

* Intel P6 (PentiumPro, PII, PIII, PM, Core, Core2). * AMD Athlon (K7, K8, K10). * Intel NetBurst (Pentium 4, Pentium D). * In-order Pentium (Pentium1, PMMX, Atom)

Other early CPUs (Nx586, AMD K5, K6, Centaur C3, Transmeta, Cyrix, Rise) were mostly in-order.

Some new processors do not fit into the existing categories:

* Intel Atom 230/330 (family 6, model 0x1C) is an in-order core. * Centaur Isiah = VIA Nano (family 6, model F) is an out-of-order core.

Within each dynasty, the optimisation techniques are largely identical (eg, use instruction pairing for group 4). Major instruction set improvements occur within each dynasty. Does this CPU perform better on AMD K7 code than PentiumPro..Core2 code?

nothrow @property @trusted bool preferPentium4();
Does this CPU perform better on Pentium4 code than PentiumPro..Core2 code?

nothrow @property @trusted bool preferPentium1();
Does this CPU perform better on Pentium I code than Pentium Pro code?

uint stepping;
Warning: This field will be turned into a property in a future release.

Processor type (vendor-dependent). This should be visible ONLY for display purposes.

uint model;
Warning: This field will be turned into a property in a future release.

Processor type (vendor-dependent). This should be visible ONLY for display purposes.

uint family;
Warning: This field will be turned into a property in a future release.

Processor type (vendor-dependent). This should be visible ONLY for display purposes.

uint numCacheLevels;
This field has been deprecated. Please use cacheLevels instead.

nothrow @property @trusted uint cacheLevels();
The number of cache levels in the CPU.