The set of instructions that require decode_save_opc for
unwinding is really fairly small -- only insns that can
raise ILLEGAL_INSN at runtime. This includes CSR, anything
that uses a *new* fp rounding mode, and many privileged insns.
Since unwind info is stored as the difference from the
previous insn, storing a 0 for most insns minimizes the
size of the unwind info.
Booting a debian kernel image to the missing rootfs panic yields
- gen code size 22226819/1026886656
+ gen code size 21601907/1026886656
on 41k TranslationBlocks, a savings of 610kB or a bit less than 3%.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20220604231004.49990-4-richard.henderson@linaro.org>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
a9814e3e08