This hack was introduced in issue#287 which later becomes endless maintainance pain.
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Our previous check_exit_request use `brcond` in the middle of a TranslationBlock which
breaks the assumptions and thus a hack to liveness_pass_1 is used for _all_ brcond instructions
which causes issues for MIPS and many other scenarios.
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This patch also resolves PC not sync-ed when no memory hooks are installed, finally. Now
Unicorn will always have correct PC no matter what happens.
tcg: Fix do_nonatomic_op_* vs signed operations
The smin/smax/umin/umax operations require the operands to be
properly sign extended. Do not drop the MO_SIGN bit from the
load, and additionally extend the val input.
