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In the x86 architecture, the CPUID instruction (identified by a CPUID opcode) is a processor supplementary instruction (its name derived from CPU Identification) allowing software to discover details of the processor.
The instructions below are those enabled by the BMI bit in CPUID. Intel officially considers LZCNT as part of BMI, but advertises LZCNT support using the ABM CPUID feature flag. [3] BMI1 is available in AMD's Jaguar, [5] Piledriver [6] and newer processors, and in Intel's Haswell [7] and newer processors.
The update contains information about which processors it is designed for, so that this can be checked against the result of the CPUID instruction. [1] The structure is a 48-byte header, followed by 2,000 bytes intended to be read directly by the processor to be updated: [ 1 ]
Special purpose instructions also often lack explicit operands; for example, CPUID in the x86 architecture writes values into four implicit destination registers. This distinction between explicit and implicit operands is important in code generators, especially in the register allocation and live range tracking parts.
Takes as input a CPUID leaf index in EAX and, depending on leaf, a sub-index in ECX. Result is returned in EAX,EBX,ECX,EDX. [e] Instruction is serializing, and causes a mandatory #VMEXIT under virtualization. Support for CPUID can be checked by toggling bit 21 of EFLAGS (EFLAGS.ID) – if this bit can be toggled, CPUID is present. Usually 3 [f]
The types of operations may include arithmetic, data copying, logical operations, and program control, as well as special instructions (e.g., CPUID). [10] In addition to the opcode, many instructions also specify the data (known as operands) the operation will act upon, although some instructions may have implicit operands or none at all. [10]
Separate from the stack definition of a MISC architecture, is the MISC architecture being defined by the number of instructions supported. Typically a minimal instruction set computer is viewed as having 32 or fewer instructions, [1] [2] [3] where NOP, RESET, and CPUID type instructions are usually not counted by consensus due to their fundamental nature.
GCC supports FMA4 with -mfma4 since version 4.5.0 [25] and FMA3 with -mfma since version 4.7.0. Microsoft Visual C++ 2010 SP1 supports FMA4 instructions. [26] Microsoft Visual C++ 2012 supports FMA3 instructions (if the processor also supports AVX2 instruction set extension). Microsoft Visual C++ since VC 2013; PathScale supports FMA4 with ...