QEMU crashes with failed assertion when executing compressed instructions with C extension support disabled

Host environment

• QEMU flavor: qemu-system-riscv64
• QEMU version: master
• QEMU command line:

  ./qemu-system-riscv64 -m 128M -smp 1 -machine virt -cpu rv64,c=off -bios none -kernel <image>

Emulated/Virtualized environment

• Architecture: riscv64

Description of problem

When executing compressed instructions with compressed instruction support disabled (c=off), the tcg riscv translations fails an assertion.

qemu-system-riscv64: qemu/accel/tcg/translate-all.c:1449: tb_gen_code: Assertion `tb->size != 0' failed.

I believe that the issue is caused due to the fact that the compressed instruction without RVC support branch of the decode_opc function does not update ctx->pc_succ_insn, which causes ctx->base.pc_next to not be updated in riscv_tr_translate_insn, which then finally triggers the assertion once the tcg generation returns to tb_gen_code.

Side note, it also seems like the gen_exception_illegal call in the same if case is not needed, since we also call it again at the end of the function.