[PATCH] D124490: [InstrProf] Minimal Block Coverage

[Ellis Hoag via Phabricator via llvm-commits]

ellis added inline comments.


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Comment at: llvm/lib/Transforms/Instrumentation/BlockCoverageInference.cpp:137
+    BlockSet ReachableFromEntry, ReachableFromExit;
+    getReachableAvoiding(&EntryBlock, &BB, /*IsForward=*/true,
+                         ReachableFromEntry);
----------------
MaskRay wrote:
> ellis wrote:
> > MaskRay wrote:
> > > The time complexity is O(|BB|^2) and can be problematic.
> > I've added a comment discussing the runtime. We do know of a linear time algorithm that would compute the Dependencies maps, but it is significantly more complicated. We thought it would be best to first add this simpler implementation and in the future we can use the linear algorithm if we find that it gives a significant speedup in practice.
> We have quadratic time algorithms like `O((V+E)(c+1))` used in gcov.
I haven't forgotten about this, I just wanted to resolve the other comments first.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D124490/new/

https://reviews.llvm.org/D124490