Intel ARCHITECTURE IA-32 User Manual download pdf (Page 93)

100

101

General Optimization Guidelines 2

2-21

Examples 2-6, Example 2-7 provide basic rules for a static prediction

algorithm.

In Example 2-6, the backward branch (

JC Begin) is not in the BTB the

first time through, therefore, the BTB does not issue a prediction. The

static predictor, however, will predict the branch to be taken, so a

misprediction will not occur.

The first branch instruction (

JC Begin) in Example 2-7 segment is a

conditional forward branch. It is not in the BTB the first time through,

but the static predictor will predict the branch to fall through

The static prediction algorithm correctly predicts that the Call

Convert

instruction will be taken, even before the branch has any

branch history in the BTB.

Example 2-6 Static Taken Prediction Example

Begin: mov eax, mem32

and eax, ebx

imul eax, edx

shld eax, 7

jc Begin

Example 2-7 Static Not-Taken Prediction Example

mov eax, mem32

and eax, ebx

imul eax, edx

shld eax, 7

jc Begin

mov eax, 0

Begin: call Convert

1 2 ... 88 89 90 91 92 93 94 95 96 97 98 ... 567 568

Comments to this Manuals

No comments

Intel ARCHITECTURE IA-32 User Manual Page 93

Comments to this Manuals

Related products and manuals for Computer Accessories Intel ARCHITECTURE IA-32