O3: Squash the violator and younger instructions instead not all insts.
O3: Squash the violator and younger instructions instead not all insts.

Change the way instructions are squashed on memory ordering violations
to squash the violator and younger instructions, not all instructions
that are younger than the instruction they violated (no reason to throw
away valid work).

haowu4682/gem5,LingxiaoJIA/gem5,haowu4682/gem5,haowu4682/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5,haowu4682/gem5,LingxiaoJIA/gem5,haowu4682/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5,haowu4682/gem5,haowu4682/gem5,haowu4682/gem5,LingxiaoJIA/gem5,haowu4682/gem5