[llvm] r373522 - Recommit "[GlobalOpt] Pass DTU to removeUnreachableBlocks instead of recomputing."

[Florian Hahn via llvm-commits]

Author: fhahn
Date: Wed Oct  2 13:40:13 2019
New Revision: 373522

URL: http://llvm.org/viewvc/llvm-project?rev=373522&view=rev
Log:
Recommit "[GlobalOpt] Pass DTU to removeUnreachableBlocks instead of recomputing."

The cause for the revert should be fixed by r373513 /
a80b6c15425f82521c624ff24c5c0a34cd534d54

This reverts commit 47dbcbd8ec6bf6c0b9cbe5811e81a37cc55e73ef.

Modified:
    llvm/trunk/lib/Transforms/IPO/GlobalOpt.cpp

Modified: llvm/trunk/lib/Transforms/IPO/GlobalOpt.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/GlobalOpt.cpp?rev=373522&r1=373521&r2=373522&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/IPO/GlobalOpt.cpp (original)
+++ llvm/trunk/lib/Transforms/IPO/GlobalOpt.cpp Wed Oct  2 13:40:13 2019
@@ -2285,14 +2285,10 @@ OptimizeFunctions(Module &M,
     // So, remove unreachable blocks from the function, because a) there's
     // no point in analyzing them and b) GlobalOpt should otherwise grow
     // some more complicated logic to break these cycles.
-    // Removing unreachable blocks might invalidate the dominator so we
-    // recalculate it.
     if (!F->isDeclaration()) {
-      if (removeUnreachableBlocks(*F)) {
-        auto &DT = LookupDomTree(*F);
-        DT.recalculate(*F);
-        Changed = true;
-      }
+      auto &DT = LookupDomTree(*F);
+      DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Lazy);
+      Changed |= removeUnreachableBlocks(*F, &DTU);
     }
 
     Changed |= processGlobal(*F, GetTLI, LookupDomTree);