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Next: Run-time branch prediction Up: Control Hazards, Branch Prediction Previous: Branch delays in a deeper pipeline

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Two cycle load delay:

LD R1,100(R2)

$\fbox{DS}$

ADD R4,R1,R3

$\fbox{EX}$

Three cycle branch delay:

BEQZ R1,Label

$\fbox{EX}$

$\fbox{IF}$

Delayed branches are of little value here

l|@ @*13p0.9em BEQZ R1,Label

$\fbox{EX}$

$\fbox{IF}$

Delayed branches are of little value here

l|@ @*13p0.9em LD R1,100(R2) & IF & IS & RF & EX & DF & $\fbox{DS}$ & TC & WB
& & IF & IS & RF & EX & DF & DS & TC
& & & IF & IS & RF & EX & DF & DS
ADD R4,R1,R3 & & & & IF & IS & RF & $\fbox{EX}$ & DF

Three cycle branch delay:

BEQZ R1,Label

$\fbox{EX}$

$\fbox{IF}$

Delayed branches are of little value here

l|@ @*13p0.9em BEQZ R1,Label & IF & IS & RF & $\fbox{EX}$ & DF & DS & TC & WB
& & IF & IS & RF & EX & DF & DS & TC
& & & IF & IS & RF & EX & DF & DS
& & & & IF & IS & RF & EX & DF
& & & & & $\fbox{IF}$ & IS & RF & EX
Delayed branches are of little value here

6in

BEQZ R1,Label

$\fbox{EX}$

$\fbox{IF}$

Delayed branches are of little value here

6in

LD R1,100(R2)

$\fbox{DS}$

ADD R4,R1,R3

$\fbox{EX}$

Three cycle branch delay:

BEQZ R1,Label

$\fbox{EX}$

$\fbox{IF}$

Delayed branches are of little value here

l|@ @*13p0.9em BEQZ R1,Label

$\fbox{EX}$

$\fbox{IF}$

Delayed branches are of little value here

l|@ @*13p0.9em LD R1,100(R2) & IF & IS & RF & EX & DF & $\fbox{DS}$ & TC & WB
& & IF & IS & RF & EX & DF & DS & TC
& & & IF & IS & RF & EX & DF & DS
ADD R4,R1,R3 & & & & IF & IS & RF & $\fbox{EX}$ & DF

Three cycle branch delay:

BEQZ R1,Label

$\fbox{EX}$

$\fbox{IF}$

Delayed branches are of little value here

6in

BEQZ R1,Label

$\fbox{EX}$

$\fbox{IF}$

Delayed branches are of little value here

Next: Run-time branch prediction Up: Control Hazards, Branch Prediction Previous: Branch delays in a deeper pipeline