[PATCH] D128796: [SCCP] Simplify CFG in SCCP as well

[Nikita Popov via Phabricator via llvm-commits]

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Currently, we only remove dead blocks and non-feasible edges in IPSCCP, but not in SCCP. I'm not aware of any strong reason for that difference, so this patch updates SCCP to perform the CFG cleanup as well.

Compile-time impact seems to be pretty minimal: http://llvm-compile-time-tracker.com/compare.php?from=f65c88c42fdd0e46d16fe31737e6627c56de77c3&to=d9d221a4687368b26083ca34a230e69f9f0fb59b&stat=instructions

For the test case from https://reviews.llvm.org/D126962#3611579 the result after `-sccp` now looks like this: https://gist.github.com/nikic/d50c03ec140bf9de217c9960d4f60a08 `-jump-threading` does nothing on this, but `-simplifycfg` will produce the optimal result.


https://reviews.llvm.org/D128796

Files:
  llvm/lib/Transforms/Scalar/SCCP.cpp
  llvm/test/Transforms/GVN/gvn-loop-load-pre-order.ll
  llvm/test/Transforms/SCCP/2004-12-10-UndefBranchBug.ll
  llvm/test/Transforms/SCCP/2008-01-27-UndefCorrelate.ll
  llvm/test/Transforms/SCCP/preserve-analysis.ll
  llvm/test/Transforms/SCCP/sccptest.ll
  llvm/test/Transforms/SCCP/strictfp-phis-fcmp.ll
  llvm/test/Transforms/SCCP/strictfp-phis-fcmps.ll
  llvm/test/Transforms/SCCP/widening.ll

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