x86 prefixes and escape opcodes flowchart

Summary

x86 prefixes and escape opcodes flowchart Published on 2023-07-29. Last updated on 2025-04-27 start here | v ╔══════════════════════════════════════════════════╗ ╔═══════════════════════════════════════════════╤══╗ ║ 2-byte instructions (legacy map 1) ║ ║ 1-byte instructions (legacy map 0) │0F------------->║ ║ ║ └──╢ ║ operand type specified ┌──┐ ┌──┐ ║ ╟──────────────────────────────────────────────────╢ .------->║ via mandatory prefixes │38│ │3A--------------. ║ 40-4F ║ | ║ - none (packed single) └─|┘ └──┘ ║ | ╟───────────────────────────|──────────────────────╢ | .---->║ - 66 (packed double) | ║ | ║ ┌──┐ ┌──┬──┐ | ║ | | ║ - F2 (scalar single) | ║ | ║ .--62│ │66│67│ | ║ | | +->║ - F3 (scalar double) | ║ | ║ | └──┘ └─|┴─|┘ | ║ | | | ╚═══════════════════════════════|══════════════════╝ | ║ | | | | ┌──┬──┐ ║ | | | v | ║ | | | | │C4│C5-----. ║ | | | ╔══════════════════════════════════════════════════╗ | ║ | | | | └|─┼──┤ | ║ | | | ║ 3-byte instructions (legacy map 2) ║ | ╟──┐ | ┌──┬──┐ | | | | │D5│ | ║ | +---->║ ║ | ║F0│ | │F2│F3│ | | | | └─|┘ | ║ | | | ║ operand type specified ║ | ╚══╧═|═╧═|╧═|╧══════|══|════|══════|═══|═════|═════╝ | | +->║ via mandatory prefixes ║ | | | | ^ ^ | | | ^ ^ | | ^ | | | | ║ - none (packed single) ║ | | | | | | | | | | | | | +---|----------+ | | ║ - 66 (packed double) ║ | v '--+--+ +--+--' v | | v v | v m bit | | | ║ - F2 (scalar single) ║ | ┏━━━━┓ | ┏━━━|┓┏|━━━┓┏━━|━┓┏━━━━┓ | | | ║ - F3 (scalar double) ║ | ┃EVEX┃ | ┃REX1┃┃VEX3┃┃REX2┃┃VEX2┃------' | | ╚══════════════════════════════════════════════════╝ | ┗━━|━┛ | ┗━━━━┛┗━━|━┛┗━━━━┛┗━━━━┛ | | | | ^ | | | ╔══════════════════════════════════════════════════╗ | | | +-------->--------------+---->║ 3-byte instructions (legacy map 3) ║<-+ | | m bits | ║ ║ '---------+---->-----------------------------------------+->║ operand type specified ║ | ║ via mandatory prefixes ║ | ║ - none (packed single) ║ | ║ - 66 (packed double) ║ | ║ - F2 (scalar single) ║ | ║ - F3 (scalar double) ║ | ╚══════════════...