SH7706 Datasheet, PDF (132/749 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH™ RISC engine Family/SH7700 Series

Section 4 Exception Processing
All general exception events occur in a relative order in the execution sequence of an instruction
(i.e. execution order), but are handled at priority level 2 in instruction-stream order (i.e. program
order), where an exception detected in a preceding instruction is accepted prior to an exception
detected in a subsequent instruction.
Three general exception events (reserved instruction code exception, unconditional trap, and
illegal slot instruction exception) are detected in the decode stage (ID stage) of different
instructions and are mutually exclusive events in the instruction pipeline. They have the same
execution priority. Figure 4.2 shows the order of general exception acceptance.
Pipeline Sequence:
Instruction n
IF ID EX MA WB
TLB miss (data access)
Instruction n + 1
IF ID EX MA WB
TLB miss (instruction access)
Instruction n + 2
Detection Order:
IF ID EX MA WB
RIE (reserved instruction exception)
TLB miss (instruction n+1)
TLB miss (instruction n) and RIE (instruction n + 2) = simultaneous detection
Handling Order:
Program Order:
TLB miss (instruction n)
1
Re-execution of instruction n
TLB miss (instruction n + 1)
2
Re-execution of instruction n + 1
RIE (instruction n + 2)
3
Legend:
IF = Instruction fetch
ID = Instruction decode
EX = Instruction execution
MA = Memory access
WB = Write back
Figure 4.2 Example of Acceptance Order of General Exceptions
Rev. 5.00 May 29, 2006 page 84 of 698
REJ09B0146-0500