riscv64: Fix encoding for c.addi4spn
#7208
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afonso360
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Oct 10, 2023
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👋 Hey,
I was running fuzzgen on riscv when it crashed with an illegal instruction. When generating large stack offsets, we can use the compressed instruction
c.addi4spn, It has a range of{4,1020}bytes. However we were accidentally not encoding the MSB on the immediate field.This meant that the instruction would be encoded with an offset of 0, which is illegal for this instruction. The fix here is to ensure that the MSB bit is encoded correctly.