Execution Unit Resources; Terminology - AMD Athlon Processor x86 Optimization Manual

AMD Athlon™ Processor x86 Code Optimization

Execution Unit Resources

Terminology

Operands
Results
Examples
148
The execution units operate with two types of register values—
operands and results. There are three operand types and two
result types, which are described in this section.
The three types of operands are as follows:
Address register operands—Used for address calculations of
load and store instructions
Data register operands—Used for register instructions
Store data register operands—Used for memory stores
The two types of results are as follows:
Data register
instructions
Address register results—Produced by LEA or PUSH
instructions
The following examples illustrate the operand and result
definitions:
ADD EAX, EBX
The ADD instruction has two data register operands (EAX
and EBX) and one data register result (EAX).
MOV EBX, [ESP+4*ECX+8]
The Load instruction has two address register operands
(ESP and ECX as base and index registers, respectively)
and a data register result (EBX).
MOV [ESP+4*ECX+8], EAX
The Store instruction has a data register operand (EAX)
and two address register operands (ESP and ECX as base
and index registers, respectively).
LEA ESI, [ESP+4*ECX+8]
The LEA instruction has address register operands (ESP
and ECX as base and index registers, respectively), and an
address register result (ESI).
results—Produced
;Load
;Store
22007E/0—November 1999
by load or register
Execution Unit Resources