Given the following sequence of assembly language instructions: I1: lw $3, 100($

Question

Given the following sequence of assembly language instructions:
I1: lw $3, 100($5)
I2: add $6, $3, $2
I3: sub $9, $3, $8
I4: lw $1, 2000($9)
I5: add $5, $4, $3
I6: addi $7, $1, #8
(a) Assume there is a data forwarding circuit in this pipelined processor and data is written in the first half-cycle and read in the second half-cycle, insert nop instructions to eliminate the data hazard in the above program. Show a pipeline execution diagram for the program, where all data forwards are marked with arrows. Moreover, on the data path circuit, identify the data value, inputs and outputs of the data forwarding unit in cycles when data is forwarded.
(b) Assume there is a data forwarding circuit and hazard detection unit in this pipelined processor and data is written in the first half-cycle and read in the second half-cycle. Show a pipeline execution diagram for the program, where all stalls are marked with “**” and identify the inputs and outputs of the data hazard detection unit in cycles when stalls are inserted.

Explanation / Answer

For the CDA 5155 programming assignments, you will utilize the LC2

(Little Computer 2014). The LC2 is exceptionally basic, yet it is general

enough to take care of complex issues. For this venture, you will just need to know

the direction set and guideline configuration of the LC2.

The LC2 is a 8-enroll, 32-bit PC. All locations are

word-addresses. The LC2 has 65536 expressions of memory. By low level computing construct

tradition, enroll 0 will dependably contain the esteem 0.

There are 4 direction positions (bit 0 is the slightest critical piece). Bits

31-25 are unused for all guidelines, and ought to dependably be 0.

R-sort guidelines (include, nand, mult):

bits 24-22: opcode

bits 21-19: reg A

bits 18-16: reg B

bits 15-3: unused (ought to all be 0)

bits 2-0: destReg

I-write directions (lw, sw, beq):

bits 24-22: opcode

bits 21-19: reg A

bits 18-16: reg B

bits 15-0: offsetField (a 16-bit, 2's supplement number with a scope of

- 32768 to 32767)

O-sort directions (end, noop):

bits 24-22: opcode

bits 21-0: unused (ought to all be 0)

- - - - -

Table 1: Description of Machine Instructions

- - - - -

Low level computing construct    Opcode in binary       Action

name for instruction   (bits 24, 23, 22)

- - - - -

include (R-sort format)   000            add substance of regA with

substance of regB, store

brings about destReg.

nand (R-sort format)   001           nand substance of regA with

substance of regB, store

brings about destReg.

lw (I-write format)   010           load regB from memory. Memory

address is framed by including

offsetField with the substance of

regA.

sw (I-write format)   011           store regB into memory. Memory

address is framed by including

offsetField with the substance of

regA.

beq (I-write format)   100           if the substance of regA and

regB are the same, then branch

to the address PC+1+offsetField,

where PC is the address of the

beq direction.

mult (R-sort format)   101            multiplies substance of regA with

substance of regB, store

brings about destReg.

end (O-sort format)   110           increment the PC (as with all

guidelines), then end the

machine (let the test system

see that the machine

ended).

noop (O-sort format)   111           do nothing.

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