FRIDAY, SEPTEMBER 25, 2026
x86/apx
Limit REX2 payload printing in x86 disassembly
Disassembler output for x86 APX instructions now more accurately reflects REX2 encoding.
The x86 disassembler has been updated to limit the printing of the REX2 payload when its bits are properly consumed. This change ensures the output more closely matches the original instruction encoding, and simplifies existing conditional logic.
In Details
This commit refines the disassembly output for x86 instructions utilizing the REX2 prefix. When the REX2 bits are fully processed and only indicate the presence of REX2 encoding, the disassembler now prints a simplified {rex2} representation instead of a more verbose payload. This improves output clarity and matches the behavior of similar existing code.
For Context
- x86
- A family of instruction set architectures developed by Intel, widely used in desktop and server computers.
- APX
- A set of extensions to the x86 instruction set, likely referring to features like AVX-512 or other advanced vector/instruction set extensions.
- REX2 payload
- In x86 assembly, REX prefixes are used to extend instruction functionality. REX2 specifically might refer to a particular combination or usage of these prefixes, and its 'payload' would be the data or specific encoding bits associated with it.
- Disassembler
- A tool that translates machine code (binary instructions) back into assembly language.