[llvm] r306778 - [Dominators] Don't compute DFS InOut numbers eagerly.

[Jakub Kuderski via llvm-commits]

Author: kuhar
Date: Thu Jun 29 18:28:21 2017
New Revision: 306778

URL: http://llvm.org/viewvc/llvm-project?rev=306778&view=rev
Log:
[Dominators] Don't compute DFS InOut numbers eagerly.

Summary:
DFS InOut numbers currently get eagerly computer upon DomTree construction. They are only needed to answer dome dominance queries and they get invalidated by updates and recalculations. Because of that, it is faster in practice to compute them lazily when they are actually needed.

Clang built without this patch takes 6m 45s to boostrap on my machine, and with the patch applied 6m 38s.

Reviewers: sanjoy, dberlin, chandlerc

Reviewed By: dberlin

Subscribers: davide, llvm-commits

Differential Revision: https://reviews.llvm.org/D34296

Modified:
    llvm/trunk/include/llvm/Support/GenericDomTreeConstruction.h
    llvm/trunk/test/Analysis/Dominators/2006-10-02-BreakCritEdges.ll
    llvm/trunk/unittests/IR/DominatorTreeTest.cpp

Modified: llvm/trunk/include/llvm/Support/GenericDomTreeConstruction.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/GenericDomTreeConstruction.h?rev=306778&r1=306777&r2=306778&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Support/GenericDomTreeConstruction.h (original)
+++ llvm/trunk/include/llvm/Support/GenericDomTreeConstruction.h Thu Jun 29 18:28:21 2017
@@ -277,8 +277,6 @@ struct SemiNCAInfo {
       DT.DomTreeNodes[W] = IDomNode->addChild(
           llvm::make_unique<DomTreeNodeBase<NodeT>>(W, IDomNode));
     }
-
-    DT.updateDFSNumbers();
   }
 
   void doFullDFSWalk(const DomTreeT &DT) {

Modified: llvm/trunk/test/Analysis/Dominators/2006-10-02-BreakCritEdges.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/Dominators/2006-10-02-BreakCritEdges.ll?rev=306778&r1=306777&r2=306778&view=diff
==============================================================================
--- llvm/trunk/test/Analysis/Dominators/2006-10-02-BreakCritEdges.ll (original)
+++ llvm/trunk/test/Analysis/Dominators/2006-10-02-BreakCritEdges.ll Thu Jun 29 18:28:21 2017
@@ -2,7 +2,7 @@
 ; RUN: opt < %s -passes='require<domtree>,break-crit-edges,print<domtree>' -disable-output 2>&1| FileCheck %s
 ; PR932
 
-; CHECK: [3] %brtrue {1,2}
+; CHECK: [3] %brtrue {{{[0-9]+}},{{[0-9]+}}}
 
 declare void @use1(i32)
 

Modified: llvm/trunk/unittests/IR/DominatorTreeTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/IR/DominatorTreeTest.cpp?rev=306778&r1=306777&r2=306778&view=diff
==============================================================================
--- llvm/trunk/unittests/IR/DominatorTreeTest.cpp (original)
+++ llvm/trunk/unittests/IR/DominatorTreeTest.cpp Thu Jun 29 18:28:21 2017
@@ -220,6 +220,7 @@ TEST(DominatorTree, Unreachable) {
         EXPECT_EQ(PostDominatedBBs.size(), 0UL);
 
         // Check DFS Numbers before
+        DT->updateDFSNumbers();
         EXPECT_EQ(DT->getNode(BB0)->getDFSNumIn(), 0UL);
         EXPECT_EQ(DT->getNode(BB0)->getDFSNumOut(), 7UL);
         EXPECT_EQ(DT->getNode(BB1)->getDFSNumIn(), 1UL);
@@ -235,6 +236,7 @@ TEST(DominatorTree, Unreachable) {
         DT->recalculate(F);
 
         // Check DFS Numbers after
+        DT->updateDFSNumbers();
         EXPECT_EQ(DT->getNode(BB0)->getDFSNumIn(), 0UL);
         EXPECT_EQ(DT->getNode(BB0)->getDFSNumOut(), 9UL);
         EXPECT_EQ(DT->getNode(BB1)->getDFSNumIn(), 1UL);