[PATCH] D60357: Improve visited block tracking in isPotentiallyReachable.

[Nick Lewycky via Phabricator via llvm-commits]

nicholas updated this revision to Diff 194004.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D60357/new/

https://reviews.llvm.org/D60357

Files:
  llvm/lib/Analysis/CFG.cpp


Index: llvm/lib/Analysis/CFG.cpp
===================================================================
--- llvm/lib/Analysis/CFG.cpp
+++ llvm/lib/Analysis/CFG.cpp
@@ -189,14 +189,23 @@
       // All blocks in a single loop are reachable from all other blocks. From
       // any of these blocks, we can skip directly to the exits of the loop,
       // ignoring any other blocks inside the loop body.
+      Visited.insert(Outer->block_begin(), Outer->block_end());
       Outer->getExitBlocks(Worklist);
     } else if (DTN) {
-      // The dominance check effectively visited all blocks dominated by BB.
-      // Skip over the descendants of the DomTreeNode to visit their successors.
-      for (auto I = df_begin(DTN), E = df_end(DTN); I != E; ++I) {
-        for (auto Succ : successors(I->getBlock()))
+      // The dominance check effectively visits all blocks dominated by BB. Skip
+      // over the domtree-descendants of the block to visit their successors.
+      for (auto I = df_begin(DTN), E = df_end(DTN); I != E;) {
+        for (auto Succ : successors(I->getBlock())) {
           if (!DT->dominates(DTN, DT->getNode(Succ)))
             Worklist.push_back(Succ);
+        }
+        ++I;
+        while (I != E && !Visited.insert(I->getBlock()).second) {
+          // Don't enqueue any domtree-descendants of a visited block. We've
+          // already either visited its descendants or enqueued them.
+          // I.skipChildren() implicitly performs ++I.
+          I.skipChildren();
+        }
       }
     } else {
       Worklist.append(succ_begin(BB), succ_end(BB));


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D60357.194004.patch
Type: text/x-patch
Size: 1595 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20190406/a75904b0/attachment.bin>