Itanium® Architecture for Programmers: Understanding 64-Bit Processors and EPIC Principles

4.2. Integer Arithmetic Instructions

We elect to describe integer arithmetic instructions, which are among the type A instructions for ALU operations, as the first systematic discussion of the Itanium instruction set. We will refer back to the SQUARES program where some of these were used.

4.2.1. Addition and Subtraction

Computer architectures universally provide for basic arithmetic operations where two source operands are combined appropriately into a destination value.

Addition

We have already mentioned the addition instruction in previous chapters. This Itanium instruction is implemented in several forms:

add      r1=r2,r3             // r1 <— r2 + r3
add      r1=r2,r3,1           // r1 <— r2 + r3 + 1
adds     r1=imm14,r3          // r1 <— sext(imm14) + r3
addl     r1=imm22,r3          // r1 <— ...