16.151 SUBS (shifted register)

Subtract (shifted register), setting flags.

This instruction is used by the aliases:

  • CMP (shifted register).
  • NEGS.

Syntax

SUBS Wd, Wn, Wm{, shift #amount} ; 32-bit

SUBS Xd, Xn, Xm{, shift #amount} ; 64-bit

Where:

Wd
Is the 32-bit name of the general-purpose destination register.
Wn
Is the 32-bit name of the first general-purpose source register.
Wm
Is the 32-bit name of the second general-purpose source register.
amount

Depends on the instruction variant:

32-bit general registers
Is the shift amount, in the range 0 to 31, defaulting to 0.
64-bit general registers
Is the shift amount, in the range 0 to 63, defaulting to 0.
Xd
Is the 64-bit name of the general-purpose destination register.
Xn
Is the 64-bit name of the first general-purpose source register.
Xm
Is the 64-bit name of the second general-purpose source register.
shift
Is the optional shift type to be applied to the second source operand, defaulting to LSL, and can be one of LSL, LSR, or ASR.

Operation

Subtract (shifted register), setting flags, subtracts an optionally-shifted register value from a register value, and writes the result to the destination register. It updates the condition flags based on the result.

Rd = Rn - shift(Rm, amount), where R is either W or X.

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