Revert r332168: "Reapply "[PR16756] Use SSAUpdaterBulk in JumpThreading.""
There were a couple of issues reported (PR38047, PR37929) - I'll reland the patch when I figure out and fix the rootcause. llvm-svn: 336393
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@ -66,7 +66,6 @@
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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#include "llvm/Transforms/Utils/Cloning.h"
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#include "llvm/Transforms/Utils/SSAUpdater.h"
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#include "llvm/Transforms/Utils/SSAUpdaterBulk.h"
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#include "llvm/Transforms/Utils/ValueMapper.h"
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#include <algorithm>
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#include <cassert>
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@ -2014,28 +2013,23 @@ bool JumpThreadingPass::ThreadEdge(BasicBlock *BB,
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{DominatorTree::Insert, PredBB, NewBB},
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{DominatorTree::Delete, PredBB, BB}});
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// Apply all updates we queued with DDT and get the updated Dominator Tree.
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DominatorTree *DT = &DDT->flush();
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// If there were values defined in BB that are used outside the block, then we
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// now have to update all uses of the value to use either the original value,
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// the cloned value, or some PHI derived value. This can require arbitrary
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// PHI insertion, of which we are prepared to do, clean these up now.
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SSAUpdaterBulk SSAUpdate;
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SSAUpdater SSAUpdate;
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SmallVector<Use*, 16> UsesToRename;
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for (Instruction &I : *BB) {
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SmallVector<Use*, 16> UsesToRename;
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// Scan all uses of this instruction to see if their uses are no longer
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// dominated by the previous def and if so, record them in UsesToRename.
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// Also, skip phi operands from PredBB - we'll remove them anyway.
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for (Use &U : I.uses()) {
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Instruction *User = cast<Instruction>(U.getUser());
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if (PHINode *UserPN = dyn_cast<PHINode>(User)) {
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if (UserPN->getIncomingBlock(U) == BB ||
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UserPN->getIncomingBlock(U) == PredBB)
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if (UserPN->getIncomingBlock(U) == BB)
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continue;
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} else if (DT->dominates(&I, U))
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} else if (User->getParent() == BB)
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continue;
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UsesToRename.push_back(&U);
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@ -2044,18 +2038,20 @@ bool JumpThreadingPass::ThreadEdge(BasicBlock *BB,
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// If there are no uses outside the block, we're done with this instruction.
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if (UsesToRename.empty())
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continue;
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unsigned VarNum = SSAUpdate.AddVariable(I.getName(), I.getType());
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LLVM_DEBUG(dbgs() << "JT: Renaming non-local uses of: " << I << "\n");
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// We found a use of I outside of BB - we need to rename all uses of I that
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// are outside its block to be uses of the appropriate PHI node etc.
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SSAUpdate.AddAvailableValue(VarNum, BB, &I);
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SSAUpdate.AddAvailableValue(VarNum, NewBB, ValueMapping[&I]);
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for (auto *U : UsesToRename)
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SSAUpdate.AddUse(VarNum, U);
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// We found a use of I outside of BB. Rename all uses of I that are outside
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// its block to be uses of the appropriate PHI node etc. See ValuesInBlocks
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// with the two values we know.
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SSAUpdate.Initialize(I.getType(), I.getName());
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SSAUpdate.AddAvailableValue(BB, &I);
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SSAUpdate.AddAvailableValue(NewBB, ValueMapping[&I]);
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while (!UsesToRename.empty())
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SSAUpdate.RewriteUse(*UsesToRename.pop_back_val());
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LLVM_DEBUG(dbgs() << "\n");
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}
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SSAUpdate.RewriteAllUses(DT);
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// At this point, the IR is fully up to date and consistent. Do a quick scan
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// over the new instructions and zap any that are constants or dead. This
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// frequently happens because of phi translation.
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