[llvm] r329650 - Revert "[PR16756] Use SSAUpdaterBulk in JumpThreading."

[Michael Zolotukhin via llvm-commits]

Author: mzolotukhin
Date: Mon Apr  9 17:42:43 2018
New Revision: 329650

URL: http://llvm.org/viewvc/llvm-project?rev=329650&view=rev
Log:
Revert "[PR16756] Use SSAUpdaterBulk in JumpThreading."

This reverts commit r329644.

Modified:
    llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp?rev=329650&r1=329649&r2=329650&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp Mon Apr  9 17:42:43 2018
@@ -66,7 +66,6 @@
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 #include "llvm/Transforms/Utils/Cloning.h"
 #include "llvm/Transforms/Utils/SSAUpdater.h"
-#include "llvm/Transforms/Utils/SSAUpdaterBulk.h"
 #include "llvm/Transforms/Utils/ValueMapper.h"
 #include <algorithm>
 #include <cassert>
@@ -1990,13 +1989,9 @@ bool JumpThreadingPass::ThreadEdge(Basic
   // now have to update all uses of the value to use either the original value,
   // the cloned value, or some PHI derived value.  This can require arbitrary
   // PHI insertion, of which we are prepared to do, clean these up now.
-  SSAUpdaterBulk SSAUpdate;
+  SSAUpdater SSAUpdate;
   SmallVector<Use*, 16> UsesToRename;
-
-  unsigned VarNum = 0;
   for (Instruction &I : *BB) {
-    UsesToRename.clear();
-
     // Scan all uses of this instruction to see if it is used outside of its
     // block, and if so, record them in UsesToRename.
     for (Use &U : I.uses()) {
@@ -2013,15 +2008,19 @@ bool JumpThreadingPass::ThreadEdge(Basic
     // If there are no uses outside the block, we're done with this instruction.
     if (UsesToRename.empty())
       continue;
-    SSAUpdate.AddVariable(VarNum, I.getName(), I.getType());
 
-    // We found a use of I outside of BB - we need to rename all uses of I that
-    // are outside its block to be uses of the appropriate PHI node etc.
-    SSAUpdate.AddAvailableValue(VarNum, BB, &I);
-    SSAUpdate.AddAvailableValue(VarNum, NewBB, ValueMapping[&I]);
-    for (auto U : UsesToRename)
-      SSAUpdate.AddUse(VarNum, U);
-    VarNum++;
+    DEBUG(dbgs() << "JT: Renaming non-local uses of: " << I << "\n");
+
+    // We found a use of I outside of BB.  Rename all uses of I that are outside
+    // its block to be uses of the appropriate PHI node etc.  See ValuesInBlocks
+    // with the two values we know.
+    SSAUpdate.Initialize(I.getType(), I.getName());
+    SSAUpdate.AddAvailableValue(BB, &I);
+    SSAUpdate.AddAvailableValue(NewBB, ValueMapping[&I]);
+
+    while (!UsesToRename.empty())
+      SSAUpdate.RewriteUse(*UsesToRename.pop_back_val());
+    DEBUG(dbgs() << "\n");
   }
 
   // Ok, NewBB is good to go.  Update the terminator of PredBB to jump to
@@ -2038,10 +2037,6 @@ bool JumpThreadingPass::ThreadEdge(Basic
                      {DominatorTree::Insert, PredBB, NewBB},
                      {DominatorTree::Delete, PredBB, BB}});
 
-  // Apply all updates we queued with DDT and get the updated Dominator Tree.
-  DominatorTree *DT = &DDT->flush();
-  SSAUpdate.RewriteAllUses(DT);
-
   // At this point, the IR is fully up to date and consistent.  Do a quick scan
   // over the new instructions and zap any that are constants or dead.  This
   // frequently happens because of phi translation.