On 10/05/2011 07:22 PM, William J. Schmidt wrote:
I don't know off the top of my head -- I'll have to gather that information. The issue is that the profitability is really context-sensitive, so just the isolated costs of insns aren't enough. The forward propagation of the add into (mem (reg REG)) looks like a slam dunk in the absence of other information, but if there are other nearby references using nonzero offsets from REG, this just extends the lifetimes of X and Y without eliminating the need for REG.
True, however there are other passes that do this kind of un-CSE and lifetime reduction.
Paolo
