- •Chapter 1 Intel® Advanced Vector Extensions
- •1.1 About This Document
- •1.2 Overview
- •1.3.2 Instruction Syntax Enhancements
- •1.3.3 VEX Prefix Instruction Encoding Support
- •1.4 Overview AVX2
- •1.5 Functional Overview
- •1.6 General Purpose Instruction Set Enhancements
- •2.1 Detection of PCLMULQDQ and AES Instructions
- •2.2 Detection of AVX and FMA Instructions
- •2.2.1 Detection of FMA
- •2.2.3 Detection of AVX2
- •2.3.1 FMA Instruction Operand Order and Arithmetic Behavior
- •2.4 Accessing YMM Registers
- •2.5 Memory alignment
- •2.7 Instruction Exception Specification
- •2.7.1 Exceptions Type 1 (Aligned memory reference)
- •2.7.2 Exceptions Type 2 (>=16 Byte Memory Reference, Unaligned)
- •2.7.3 Exceptions Type 3 (<16 Byte memory argument)
- •2.7.5 Exceptions Type 5 (<16 Byte mem arg and no FP exceptions)
- •2.7.7 Exceptions Type 7 (No FP exceptions, no memory arg)
- •2.7.8 Exceptions Type 8 (AVX and no memory argument)
- •2.8.1 Clearing Upper YMM State Between AVX and Legacy SSE Instructions
- •2.8.3 Unaligned Memory Access and Buffer Size Management
- •2.9 CPUID Instruction
- •3.1 YMM State, VEX Prefix and Supported Operating Modes
- •3.2 YMM State Management
- •3.2.1 Detection of YMM State Support
- •3.2.2 Enabling of YMM State
- •3.2.4 The Layout of XSAVE Area
- •3.2.5 XSAVE/XRSTOR Interaction with YMM State and MXCSR
- •3.2.6 Processor Extended State Save Optimization and XSAVEOPT
- •3.2.6.1 XSAVEOPT Usage Guidelines
- •3.3 Reset Behavior
- •3.4 Emulation
- •4.1 Instruction Formats
- •4.1.1 VEX and the LOCK prefix
- •4.1.2 VEX and the 66H, F2H, and F3H prefixes
- •4.1.3 VEX and the REX prefix
- •4.1.4 The VEX Prefix
- •4.1.4.1 VEX Byte 0, bits[7:0]
- •4.1.4.2 VEX Byte 1, bit [7] - ‘R’
- •4.1.5 Instruction Operand Encoding and VEX.vvvv, ModR/M
- •4.1.6 The Opcode Byte
- •4.1.7 The MODRM, SIB, and Displacement Bytes
- •4.1.8 The Third Source Operand (Immediate Byte)
- •4.1.9.1 Vector Length Transition and Programming Considerations
- •4.1.10 AVX Instruction Length
- •4.2 Vector SIB (VSIB) Memory Addressing
- •4.3 VEX Encoding Support for GPR Instructions
- •5.1 Interpreting InstructIon Reference Pages
- •5.1.1 Instruction Format
- •5.1.2 Opcode Column in the Instruction Summary Table
- •5.1.3 Instruction Column in the Instruction Summary Table
- •5.1.4 Operand Encoding column in the Instruction Summary Table
- •5.1.5 64/32 bit Mode Support column in the Instruction Summary Table
- •5.1.6 CPUID Support column in the Instruction Summary Table
- •5.2 Summary of Terms
- •5.3 Instruction SET Reference
- •MPSADBW - Multiple Sum of Absolute Differences
- •PALIGNR - Byte Align
- •PBLENDW - Blend Packed Words
- •PHADDW/PHADDD - Packed Horizontal Add
- •PHADDSW - Packed Horizontal Add with Saturation
- •PHSUBW/PHSUBD - Packed Horizontal Subtract
- •PHSUBSW - Packed Horizontal Subtract with Saturation
- •PMOVSX - Packed Move with Sign Extend
- •PMOVZX - Packed Move with Zero Extend
- •PMULDQ - Multiply Packed Doubleword Integers
- •PMULHRSW - Multiply Packed Unsigned Integers with Round and Scale
- •PMULHUW - Multiply Packed Unsigned Integers and Store High Result
- •PMULHW - Multiply Packed Integers and Store High Result
- •PMULLW/PMULLD - Multiply Packed Integers and Store Low Result
- •PMULUDQ - Multiply Packed Unsigned Doubleword Integers
- •POR - Bitwise Logical Or
- •PSADBW - Compute Sum of Absolute Differences
- •PSHUFB - Packed Shuffle Bytes
- •PSHUFD - Shuffle Packed Doublewords
- •PSHUFLW - Shuffle Packed Low Words
- •PSIGNB/PSIGNW/PSIGND - Packed SIGN
- •PSLLDQ - Byte Shift Left
- •PSLLW/PSLLD/PSLLQ - Bit Shift Left
- •PSRAW/PSRAD - Bit Shift Arithmetic Right
- •PSRLDQ - Byte Shift Right
- •PSRLW/PSRLD/PSRLQ - Shift Packed Data Right Logical
- •PSUBB/PSUBW/PSUBD/PSUBQ -Packed Integer Subtract
- •PSUBSB/PSUBSW -Subtract Packed Signed Integers with Signed Saturation
- •PSUBUSB/PSUBUSW -Subtract Packed Unsigned Integers with Unsigned Saturation
- •PXOR - Exclusive Or
- •VPBLENDD - Blend Packed Dwords
- •VPERMD - Full Doublewords Element Permutation
- •VPERMPD - Permute Double-Precision Floating-Point Elements
- •VPERMPS - Permute Single-Precision Floating-Point Elements
- •VPERMQ - Qwords Element Permutation
- •VPSLLVD/VPSLLVQ - Variable Bit Shift Left Logical
- •VPSRAVD - Variable Bit Shift Right Arithmetic
- •VPSRLVD/VPSRLVQ - Variable Bit Shift Right Logical
- •VGATHERDPD/VGATHERQPD - Gather Packed DP FP values Using Signed Dword/Qword Indices
- •VGATHERDPS/VGATHERQPS - Gather Packed SP FP values Using Signed Dword/Qword Indices
- •VPGATHERDD/VPGATHERQD - Gather Packed Dword values Using Signed Dword/Qword Indices
- •VPGATHERDQ/VPGATHERQQ - Gather Packed Qword values Using Signed Dword/Qword Indices
- •6.1 FMA InstructIon SET Reference
- •Chapter 7 Instruction Set Reference - VEX-Encoded GPR Instructions
- •7.1 Instruction Format
- •7.2 INSTRUCTION SET REFERENCE
- •BZHI - Zero High Bits Starting with Specified Bit Position
- •INVPCID - Invalidate Processor Context ID
- •Chapter 8 Post-32nm Processor Instructions
- •8.1 Overview
- •8.2 CPUID Detection of New Instructions
- •8.4 Vector Instruction Exception Specification
- •8.6 Using RDRAND Instruction and Intrinsic
- •8.7 Instruction Reference
- •A.1 AVX Instructions
- •A.2 Promoted Vector Integer Instructions in AVX2
- •B.1 Using Opcode Tables
- •B.2 Key to Abbreviations
- •B.2.1 Codes for Addressing Method
- •B.2.2 Codes for Operand Type
- •B.2.3 Register Codes
- •B.2.4 Opcode Look-up Examples for One, Two, and Three-Byte Opcodes
- •B.2.4.1 One-Byte Opcode Instructions
- •B.2.4.2 Two-Byte Opcode Instructions
- •B.2.4.3 Three-Byte Opcode Instructions
- •B.2.4.4 VEX Prefix Instructions
- •B.2.5 Superscripts Utilized in Opcode Tables
- •B.3 One, Two, and THREE-Byte Opcode Maps
- •B.4.1 Opcode Look-up Examples Using Opcode Extensions
- •B.4.2 Opcode Extension Tables
- •B.5 Escape Opcode Instructions
- •B.5.1 Opcode Look-up Examples for Escape Instruction Opcodes
- •B.5.2 Escape Opcode Instruction Tables
- •B.5.2.1 Escape Opcodes with D8 as First Byte
- •B.5.2.2 Escape Opcodes with D9 as First Byte
- •B.5.2.3 Escape Opcodes with DA as First Byte
- •B.5.2.4 Escape Opcodes with DB as First Byte
- •B.5.2.5 Escape Opcodes with DC as First Byte
- •B.5.2.6 Escape Opcodes with DD as First Byte
- •B.5.2.7 Escape Opcodes with DE as First Byte
- •B.5.2.8 Escape Opcodes with DF As First Byte
INSTRUCTION FORMAT
CHAPTER 4
INSTRUCTION FORMAT
AVX F16C, AVX2 and FMA instructions are encoded using a more efficient format than previous instruction extensions in the Intel 64 and IA-32 architecture. The improved encoding format uses a new prefix referred to as “VEX“. The VEX prefix may be two or three bytes long, depending on the instruction semantics. Despite the length of the VEX prefix, the instruction encoding format using VEX addresses two important issues: (a) there exists inefficiency in instruction encoding due to SIMD prefixes and some fields of the REX prefix, (b) Both SIMD prefixes and REX prefix increase in instruction byte-length. This chapter describes the instruction encoding format using VEX.
VEX-prefix encoding enables a subset of AVX2 instructions to support “vector SIM“ form of memory addressing. This is described in Section 4.2.
VEX-prefix encoding also enables some general purpose instructions to support three-operand syntax. This is described in Section 4.3.
4.1INSTRUCTION FORMATS
Legacy instruction set extensions in IA-32 architecture employs one or more “singlepurpose“ byte as an “escape opcode“, or required SIMD prefix (66H, F2H, F3H) to expand the processing capability of the instruction set. Intel 64 architecture uses the REX prefix to expand the encoding of register access in instruction operands. Both SIMD prefixes and REX prefix carry the side effect that they can cause the length of an instruction to increase significantly. Legacy Intel 64 and IA-32 instruction set are limited to supporting instruction syntax of only two operands that can be encoded to access registers (and only one can access a memory address).
Instruction encoding using VEX prefix provides several advantages:
•Instruction syntax support for three operands and up-to four operands when necessary. For example, the third source register used by VBLENDVPD is encoded using bits 7:4 of the immediate byte.
•Encoding support for vector length of 128 bits (using XMM registers) and 256 bits (using YMM registers)
•Encoding support for instruction syntax of non-destructive source operands.
•Elimination of escape opcode byte (0FH), SIMD prefix byte (66H, F2H, F3H) via a compact bit field representation within the VEX prefix.
•Elimination of the need to use REX prefix to encode the extended half of generalpurpose register sets (R8-R15) for direct register access, memory addressing, or accessing XMM8-XMM15 (including YMM8-YMM15).
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