What is branch hazard?

What is branch hazard?

Control Dependency (Branch Hazards) This type of dependency occurs during the transfer of control instructions such as BRANCH, CALL, JMP, etc. On many instruction architectures, the processor will not know the target address of these instructions when it needs to insert the new instruction into the pipeline.

What are hazards in computer architecture?

In the domain of central processing unit (CPU) design, hazards are problems with the instruction pipeline in CPU microarchitectures when the next instruction cannot execute in the following clock cycle, and can potentially lead to incorrect computation results.

What are the hazards in pipelining?

There are three types of hazards: Structural hazards: Hardware cannot support certain combinations of instructions (two instructions in the pipeline require the same resource). Data hazards: Instruction depends on result of prior instruction still in the pipeline.

What are the hazards of conditional branches in pipeline?

Control Hazards occur when conditional branches interfere with instruction fetches in a pipeline. The problem is that it is not known whether or not a conditional branch will be taken until some time after the cycle for fetching the next instruction.

What are the five stages of pipeline?

The classic five stage RISC pipeline

• Instruction fetch.
• Instruction decode.
• Execute.
• Memory access.
• Writeback.
• Structural hazards.
• Data hazards.
• Control hazards.

What is Pipelining hazard explain with example?

Pipeline hazards are situations that prevent the next instruction in the instruction stream from executing during its designated clock cycles. Any condition that causes a stall in the pipeline operations can be called a hazard.

What are the branch hazards alternatives?

Four Branch Hazard Alternatives

• Execute successor instructions in sequence.
• Squash instructions in pipeline if branch actually taken.
• Advantage of late pipeline state update.
• 47% MIPS branches not taken on average.
• PC+4 already calculated, so use it to get next instruction.

What are the 5 pipeline stages in computer architecture?

Basic five-stage pipeline in a RISC machine (IF = Instruction Fetch, ID = Instruction Decode, EX = Execute, MEM = Memory access, WB = Register write back).