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SUBPS

Subtract Pointer, setting Flags subtracts the 56-bit address held in the second source register from the 56-bit address held in the first source register, sign-extends the result to 64-bits, and writes the result to the destination register. It updates the condition flags based on the result of the subtraction.

This instruction is used by the alias CMPP.

Integer
(Armv8.5)

313029282726252423222120191817161514131211109876543210
10111010110Xm000000XnXd

Integer

SUBPS <Xd>, <Xn|SP>, <Xm|SP>

integer d = UInt(Xd);
integer n = UInt(Xn);
integer m = UInt(Xm);

Assembler Symbols

<Xd>

Is the 64-bit name of the general-purpose destination register, encoded in the "Xd" field.

<Xn|SP>

Is the 64-bit name of the first source general-purpose register or stack pointer, encoded in the "Xn" field.

<Xm|SP>

Is the 64-bit name of the second general-purpose source register or stack pointer, encoded in the "Xm" field.

Alias Conditions

AliasIs preferred when
CMPPS == '1' && Xd == '11111'

Operation

bits(64) operand1 = if n == 31 then SP[] else X[n];
bits(64) operand2 = if m == 31 then SP[] else X[m];
operand1 = SignExtend(operand1<55:0>, 64);
operand2 = SignExtend(operand2<55:0>, 64);

bits(64) result;
bits(4) nzcv;

operand2 = NOT(operand2);
(result, nzcv) = AddWithCarry(operand1, operand2, '1');

PSTATE.<N,Z,C,V> = nzcv;
X[d] = result;
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