Add a new helper RecomputeDominatorTree

It clears loop and dominance information, and builds the dominator
tree. It also dchecks that we are not calling this methods with
irreducible loops, as it is not supported.

When adding this helper we found a partial LSE bug as it was
recomputing dominator tree for irreducible loops.

Test: art/test/testrunner/testrunner.py --host --64 -b --optimizing
Bug: 304749506
Change-Id: Ia4cc72cd19779ad881fa686e52b43679fe5a64d3

1 files changed, 9 insertions, 6 deletions

diff --git a/compiler/optimizing/nodes.cc b/compiler/optimizing/nodes.cc
index 5795ea7ca9..53ed49a307 100644
--- a/compiler/optimizing/nodes.cc
+++ b/compiler/optimizing/nodes.cc
@@ -255,6 +255,14 @@ GraphAnalysisResult HGraph::BuildDominatorTree() {
   return kAnalysisSuccess;
 }
 
+GraphAnalysisResult HGraph::RecomputeDominatorTree() {
+  DCHECK(!HasIrreducibleLoops()) << "Recomputing loop information in graphs with irreducible loops "
+                                 << "is unsupported, as it could lead to loop header changes";
+  ClearLoopInformation();
+  ClearDominanceInformation();
+  return BuildDominatorTree();
+}
+
 void HGraph::ClearDominanceInformation() {
   for (HBasicBlock* block : GetActiveBlocks()) {
     block->ClearDominanceInformation();
@@ -3001,12 +3009,7 @@ HInstruction* HGraph::InlineInto(HGraph* outer_graph, HInvoke* invoke) {
       }
     }
     if (rerun_loop_analysis) {
-      DCHECK(!outer_graph->HasIrreducibleLoops())
-          << "Recomputing loop information in graphs with irreducible loops "
-          << "is unsupported, as it could lead to loop header changes";
-      outer_graph->ClearLoopInformation();
-      outer_graph->ClearDominanceInformation();
-      outer_graph->BuildDominatorTree();
+      outer_graph->RecomputeDominatorTree();
     } else if (rerun_dominance) {
       outer_graph->ClearDominanceInformation();
       outer_graph->ComputeDominanceInformation();