Intel ARCHITECTURE IA-32 - Example 2-6 Static Taken Prediction Example; Example 2-7 Static Not-Taken Prediction Example

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