Reapply "[PR16756] Use SSAUpdaterBulk in JumpThreading." one more time.

Hopefully, changing set to vector removes nondeterminism detected by
some bots, or the new assert will catch something.

This reverts commit r330180.

llvm-svn: 330403

1 files changed, 22 insertions, 16 deletions

diff --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
index 29c707799bd..59e653b338d 100644
--- a/llvm/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
@@ -66,6 +66,7 @@
 #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>
@@ -1989,15 +1990,20 @@ bool JumpThreadingPass::ThreadEdge(BasicBlock *BB,
   // 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.
-  SSAUpdater SSAUpdate;
-  SmallVector<Use*, 16> UsesToRename;
+  SSAUpdaterBulk SSAUpdate;
+
+  unsigned VarNum = 0;
   for (Instruction &I : *BB) {
+    SmallVector<Use*, 16> UsesToRename;
+
     // Scan all uses of this instruction to see if it is used outside of its
-    // block, and if so, record them in UsesToRename.
+    // block, and if so, record them in UsesToRename. Also, skip phi operands
+    // from PredBB - we'll remove them anyway.
     for (Use &U : I.uses()) {
       Instruction *User = cast<Instruction>(U.getUser());
       if (PHINode *UserPN = dyn_cast<PHINode>(User)) {
-        if (UserPN->getIncomingBlock(U) == BB)
+        if (UserPN->getIncomingBlock(U) == BB ||
+            UserPN->getIncomingBlock(U) == PredBB)
           continue;
       } else if (User->getParent() == BB)
         continue;
@@ -2008,19 +2014,15 @@ bool JumpThreadingPass::ThreadEdge(BasicBlock *BB,
     // 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());
 
-    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");
+    // 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++;
   }
 
   // Ok, NewBB is good to go.  Update the terminator of PredBB to jump to
@@ -2037,6 +2039,10 @@ bool JumpThreadingPass::ThreadEdge(BasicBlock *BB,
                      {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.