[llvm] r316612 - Revert r316582 [Local] Fix a bug in the domtree update logic for MergeBasicBlockIntoOnlyPred.

[Balaram Makam via llvm-commits]

Author: bmakam
Date: Wed Oct 25 14:32:54 2017
New Revision: 316612

URL: http://llvm.org/viewvc/llvm-project?rev=316612&view=rev
Log:
Revert r316582 [Local] Fix a bug in the domtree update logic for MergeBasicBlockIntoOnlyPred.

Summary: This reverts commit r316582. It looks like this commit broke tests on one buildbot:
http://lab.llvm.org:8011/builders/llvm-clang-x86_64-expensive-checks-win/builds/5719

. . .
Failing Tests (1):
    LLVM :: Transforms/CalledValuePropagation/simple-arguments.ll

Reviewers:

Subscribers:

Modified:
    llvm/trunk/lib/Transforms/Utils/Local.cpp
    llvm/trunk/unittests/Transforms/Utils/Local.cpp

Modified: llvm/trunk/lib/Transforms/Utils/Local.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/Local.cpp?rev=316612&r1=316611&r2=316612&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/Local.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/Local.cpp Wed Oct 25 14:32:54 2017
@@ -649,13 +649,9 @@ void llvm::MergeBasicBlockIntoOnlyPred(B
     DestBB->moveAfter(PredBB);
 
   if (DT) {
-    // For some irreducible CFG we end up having forward-unreachable blocks
-    // so check if getNode returns a valid node before updating the domtree.
-    if (DomTreeNode *DTN = DT->getNode(PredBB)) {
-      BasicBlock *PredBBIDom = DTN->getIDom()->getBlock();
-      DT->changeImmediateDominator(DestBB, PredBBIDom);
-      DT->eraseNode(PredBB);
-    }
+    BasicBlock *PredBBIDom = DT->getNode(PredBB)->getIDom()->getBlock();
+    DT->changeImmediateDominator(DestBB, PredBBIDom);
+    DT->eraseNode(PredBB);
   }
   // Nuke BB.
   PredBB->eraseFromParent();

Modified: llvm/trunk/unittests/Transforms/Utils/Local.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Transforms/Utils/Local.cpp?rev=316612&r1=316611&r2=316612&view=diff
==============================================================================
--- llvm/trunk/unittests/Transforms/Utils/Local.cpp (original)
+++ llvm/trunk/unittests/Transforms/Utils/Local.cpp Wed Oct 25 14:32:54 2017
@@ -166,48 +166,3 @@ TEST(Local, ReplaceDbgDeclare) {
       Declares++;
   EXPECT_EQ(2, Declares);
 }
-
-/// Build the dominator tree for the function and run the Test.
-static void runWithDomTree(
-    Module &M, StringRef FuncName,
-    function_ref<void(Function &F, DominatorTree *DT)> Test) {
-  auto *F = M.getFunction(FuncName);
-  ASSERT_NE(F, nullptr) << "Could not find " << FuncName;
-  // Compute the dominator tree for the function.
-  DominatorTree DT(*F);
-  Test(*F, &DT);
-}
-
-TEST(Local, MergeBasicBlockIntoOnlyPred) {
-  LLVMContext C;
-
-  std::unique_ptr<Module> M = parseIR(
-      C,
-      "define i32 @f(i8* %str) {\n"
-      "entry:\n"
-      "  br label %bb2.i\n"
-      "bb2.i:                                            ; preds = %bb4.i, %entry\n"
-      "  br i1 false, label %bb4.i, label %base2flt.exit204\n"
-      "bb4.i:                                            ; preds = %bb2.i\n"
-      "  br i1 false, label %base2flt.exit204, label %bb2.i\n"
-      "bb10.i196.bb7.i197_crit_edge:                     ; No predecessors!\n"
-      "  br label %bb7.i197\n"
-      "bb7.i197:                                         ; preds = %bb10.i196.bb7.i197_crit_edge\n"
-      "  %.reg2mem.0 = phi i32 [ %.reg2mem.0, %bb10.i196.bb7.i197_crit_edge ]\n"
-      "  br i1 undef, label %base2flt.exit204, label %base2flt.exit204\n"
-      "base2flt.exit204:                                 ; preds = %bb7.i197, %bb7.i197, %bb2.i, %bb4.i\n"
-      "  ret i32 0\n"
-      "}\n");
-  runWithDomTree(
-      *M, "f", [&](Function &F, DominatorTree *DT) {
-        for (Function::iterator I = F.begin(), E = F.end(); I != E;) {
-          BasicBlock *BB = &*I++;
-          BasicBlock *SinglePred = BB->getSinglePredecessor();
-          if (!SinglePred || SinglePred == BB || BB->hasAddressTaken()) continue;
-          BranchInst *Term = dyn_cast<BranchInst>(SinglePred->getTerminator());
-          if (Term && !Term->isConditional())
-            MergeBasicBlockIntoOnlyPred(BB, DT);
-        }
-        EXPECT_TRUE(DT->verify());
-      });
-}