llvm /
llvm /
796e6423ba13e3a03e52b47d6e1239d88b8d9304 [Dominators] Simplify and optimize path compression used in link-eval forest.
Summary:
* NodeToInfo[*] have been allocated so the addresses are stable. We can store them instead of NodePtr to save NumToNode lookups.
* Nodes are traversed twice. Using `Visited` to check the traversal number is expensive and obscure. Just split the two traversals into two loops explicitly.
* The check `VInInfo.DFSNum < LastLinked` is redundant as it is implied by `VInInfo->Parent < LastLinked`
* VLabelInfo PLabelInfo are used to save a NodeToInfo lookup in the second traversal.
Also add some comments explaining eval().
This shows a ~4.5% improvement (9.8444s -> 9.3996s) on
perf stat -r 10 taskset -c 0 opt -passes=$(printf '%.0srequire<domtree>,invalidate<domtree>,' {1..1000})'require<domtree>' -disable-output sqlite-autoconf-3270100/sqlite3.bc
Reviewers: kuhar, sanjoy, asbirlea
Reviewed By: kuhar
Subscribers: brzycki, NutshellySima, kristina, jdoerfert, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D58327
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@354433 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed
