MIPS/GCC Procedure Calling Conventions (cont.)

Called Routine

• Step-1: Establish stack frame.

  • Subtract the frame size from the stack pointer. subiu $sp, $sp, <frame-size>
  • Typically, minimum frame size is 32 bytes (8 words).

• Step-2: Save callee saved registers in the frame.

  • Register $fp is always saved.
  • Register $ra is saved if routine makes a call.
  • Registers $s0-$s7 are saved if they are used.

• Step-3: Establish Frame pointer

  • Add the stack <frame size> - 4 to the address in $sp addiu $fp, $sp, <frame-size> - 4

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