Maxwell CUDA ISA


This currently is not a complete reference of known functionality, but where behaviour not obvious from envydis/gm107.c can be documented.

Some notes for reading this documentation:

  • An instruction’s docs is split into three sections, the forms text, the description and the behaviour text.
  • The first operand is usually the destination.
  • The behaviour text uses the notation SRC<n>/DST, while the forms text does not.
  • REG<n> is a reference to a register.
  • CB<n> is a reference to the contents of a constant buffer.
  • U<b>_<n> is a b-bit unsigned immediate value.
  • S<b>_<n> is a b-bit signed immediate value.
  • Some subtleties may lie in an instruction’s description if putting it in the behaviour text would be too verbose.
  • add_with_carry(a, b) returns the sum of a and b using the carry flag, and writes the carry flag.
    • It does not use and/or set the carry flag if the appropriate instruction flags are not specified.
  • Instruction flags in between [ and ] are optional.
  • The order of the flags (even in between [ and ]) is what is expected by envyas.
  • The “carry flag” or “condition code” is not a instruction flag, but a register.
  • The terms “condition code” and “carry flag” are used interchangeably, depending on which is clearest.


The instructions are roughly divided into the following groups: