[all-commits] [llvm/llvm-project] c99269: Revert "[nfc][mlgo] Incrementally update Dominator...

[Hans via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: c992690179eb5de6efe47d5c8f3a23f2302723f2
      https://github.com/llvm/llvm-project/commit/c992690179eb5de6efe47d5c8f3a23f2302723f2
  Author: Hans Wennborg <hans at chromium.org>
  Date:   2024-08-27 (Tue, 27 Aug 2024)

  Changed paths:
    M llvm/include/llvm/Analysis/FunctionPropertiesAnalysis.h
    M llvm/lib/Analysis/FunctionPropertiesAnalysis.cpp
    M llvm/lib/Analysis/MLInlineAdvisor.cpp

  Log Message:
  -----------
  Revert "[nfc][mlgo] Incrementally update DominatorTreeAnalysis in FunctionPropertiesAnalysis (#104867)"

This seems to cause asserts in our builds:

  llvm/include/llvm/Support/GenericDomTreeConstruction.h:927:
  static void llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<BasicBlock, false>>::DeleteEdge(DomTreeT &, const BatchUpdatePtr, const NodePtr, const NodePtr) [DomTreeT = llvm::DominatorTreeBase<BasicBlock, false>]:
  Assertion `!IsSuccessor(To, From) && "Deleted edge still exists in the CFG!"' failed.

and

  llvm/lib/Analysis/FunctionPropertiesAnalysis.cpp:390:
  DominatorTree &llvm::FunctionPropertiesUpdater::getUpdatedDominatorTree(FunctionAnalysisManager &) const:
  Assertion `DT.getNode(BB)' failed.

See comment on the PR.

> We need the dominator tree analysis for loop info analysis, which we need to get features like most nested loop and number of top level loops. Invalidating and recomputing these from scratch after each successful inlining can sometimes lead to lengthy compile times. We don't need to recompute from scratch, though, since we have some boundary information about where the changes to the CFG happen; moreover, for dom tree, the API supports incrementally updating the analysis result.
>
> This change addresses the dom tree part. The loop info is still recomputed from scratch. This does reduce the compile time quite significantly already, though (~5x in a specific case)
>
> The loop info change might be more involved and would follow in a subsequent PR.

This reverts commit a2a5508bdae7d115b6c3ace461beb7a987a44407 and the
follow-up commit cdd11d694a406a98a16d6265168ee2fbe1b6a87c.



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