RISCV 32 decoder encountered a segmentation fault

[zhaorui233]

I wrote a C program base RISCV 32 imc instruction set, and then I debug the program using gem5 simulator.
Something went wrong while the program was running, the gem5 got crushed while decoding the instruction '0x0791'.
Here is the log:

1752000: system.cpu.decoder: Requesting bytes 0x43980791 from address 0x7b8 <br> 1752000: system.cpu.decoder: emi is 0x10000000791 <br /> 1752000: system.cpu.decoder: emi is compressed <br /> <bad format>1752000: system.cpu.decoder: emi is 0x10000000791 <br /> 1752000: system.cpu.decoder: Decoding instruction 0x00000791 at address 0x7b8 <br /> gem5 has encountered a segmentation fault!

The '0x0791' is a compress instruction, which means addi a5,a5,4

After I debuged the gem5, I found the function src/riscv/decoder.cc/StaticInstPtr Decoder::decode(ExtMachInst mach_inst, Addr addr) didn't perform as expected.
I guess StaticInstPtr &si = instMap[mach_inst]; cause the segmentation fault, but I don't know how to solve the program.
Please help.

[zhaorui233]

I tried not to use the compressed instruction set, but instruction '0x00478793' (addi a5,a5,4) also meets the same problem.

[powerjg]

I'm glad you were able to solve this! What was the solution to this problem?