[llvm-dev] RFC: New aggressive dead code elimination pass

[David Callahan via llvm-dev]

Hi,

I have a new variant of Aggressive Dead Code Elimination that also removes dead branching. It is designed to minimize the cost of control-dependence analysis in the common case where almost the entire program is live. It also can optionally remove dead but may-be-infinite loops.

When enabled for –O3 (replacing current ADCE pass) and removing loops, impact on SPEC2006 is in the noise but it impacts internal benchmarks suites 1-2% with a comparable increase in compile time.   My expectation would be to enable –O3 only until we have some experience with cost but I suspect it should be fine –O2.

What information would the community like to see about such a change before I put up a diff and (including tweaks to unit tests).

Thanks
david
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