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896617b776
heuristic: the value is already live at the new memory operation if it is used by some other instruction in the memop's block. This is cheap and simple to compute (moreso than full liveness). This improves the new heuristic even more. For example, it cuts two out of three new instructions out of 255.vortex:DbmFileInGrpHdr, which is one of the functions that the heuristic regressed. This overall eliminates another 40 instructions from 403.gcc and visibly reduces register pressure in 255.vortex (though this only actually ends up saving the 2 instructions from the whole program). git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60084 91177308-0d34-0410-b5e6-96231b3b80d8