APPENDICES
APPENDICES-12 M32R-FPU Software Manual (Rev.1.01)

(2) Pipeline Flow with Stalls

A pipeline stage may stall due to execution of a process or branch instruction.

The following diagrams show typical stall cases.

<Case 1> An instruction which requires several cycles is executed in E
IF D E WB
DIV R1,R2 E E
IF D stall WB
ADD R3,R4 Estall
IF D WBEstallstall
IF Dstall WBEstall

ADD R5,R6

ADD R7,R8

<Case 2> An instruction which requires more than 1 cycle for its operand access is executed
IF D E WB
LD R1,@R2 MEM1
IF D WBE stall
IF D stall WBE
IF D WBEstall

ADD R5,R6

ADD R7,R8

MEM1
MEM2MEM1

LD R3,@R4

MEM2MEM1
••••
stall
••••
stall
••••
stall
••••
Other than no-wait
memory access
••••
••••
••••
••••
stall: a pipeline stall

Appendix Figure 3.2.3 Pipeline Flow with Stalls (1)

APPENDIX 3
Appendix 3 Pipeline Processing