From 22e324d7a47ba631d5a46e897ef47a86f792b379 Mon Sep 17 00:00:00 2001 From: Tobias Grosser Date: Tue, 8 Jul 2014 22:51:03 +0000 Subject: [PATCH] DominanceInfo is strongly preferred over RegionInfo This is and always was strong community consensus. Make this clear in the header in case newcomers may not be aware. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212570 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/Analysis/RegionInfo.h | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/include/llvm/Analysis/RegionInfo.h b/include/llvm/Analysis/RegionInfo.h index 82a788d1bb8..93a1a48720f 100644 --- a/include/llvm/Analysis/RegionInfo.h +++ b/include/llvm/Analysis/RegionInfo.h @@ -22,6 +22,16 @@ // itself is not, but in practice runtime seems to be in the order of magnitude // of dominance tree calculation. // +// WARNING: LLVM is generally very concerned about compile time such that +// the use of additional analysis passes in the default +// optimization sequence is avoided as much as possible. +// Specifically, if you do not need the RegionInfo, but dominance +// information could be sufficient please base your work only on +// the dominator tree. Most passes maintain it, such that using +// it has often near zero cost. In contrast RegionInfo is by +// default not available, is not maintained by existing +// transformations and there is no intention to do so. +// //===----------------------------------------------------------------------===// #ifndef LLVM_ANALYSIS_REGIONINFO_H