Recompute dominator tree after DCE.
bug:22031382
(cherry picked from commit 1f82ecc6a0c9f88d03d6d1a6d95eeb8707bd06c1)
Change-Id: I9a74edb185cb806045903dfe9695d9cc1a02e86b
diff --git a/compiler/optimizing/dead_code_elimination.cc b/compiler/optimizing/dead_code_elimination.cc
index 6fbe75e..2362cc1 100644
--- a/compiler/optimizing/dead_code_elimination.cc
+++ b/compiler/optimizing/dead_code_elimination.cc
@@ -67,6 +67,7 @@
ArenaBitVector affected_loops(allocator, graph_->GetBlocks().Size(), false);
MarkReachableBlocks(graph_->GetEntryBlock(), &live_blocks);
+ bool removed_one_or_more_blocks = false;
// Remove all dead blocks. Iterate in post order because removal needs the
// block's chain of dominators and nested loops need to be updated from the
@@ -83,9 +84,17 @@
MaybeRecordDeadBlock(block);
MarkLoopHeadersContaining(*block, &affected_loops);
block->DisconnectAndDelete();
+ removed_one_or_more_blocks = true;
}
}
+ // If we removed at least one block, we need to recompute the full
+ // dominator tree.
+ if (removed_one_or_more_blocks) {
+ graph_->ClearDominanceInformation();
+ graph_->ComputeDominanceInformation();
+ }
+
// Connect successive blocks created by dead branches. Order does not matter.
for (HReversePostOrderIterator it(*graph_); !it.Done();) {
HBasicBlock* block = it.Current();