Chapter 3.5, Problem 3.6PP

Program Plan Intro

Load Effective Address:

• The load effective address instruction “leaq” is a variant of “movq” instruction.
• The instruction form reads memory to a register, but memory is not been referenced at all.
• The first operand of instruction is a memory reference; it copies effective address to destination.
• The pointers could be generated for later references of memory.
• The common arithmetic operations could be described compactly using this instruction.
• The operand in destination should be a register.

Example:

The example for a “leaq” instruction is shown below:

leaq 6(%rdx, %rdx,3)

Here, “%rdx” contains value of x. In given code, “%rdx” sets register “%rax” to “4x+6”.