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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
This commit is contained in:
Michael Zolotukhin 2018-07-05 22:10:31 +00:00
parent 80d9f1708f
commit a5f2c52a1e
1 changed files with 15 additions and 19 deletions
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34
llvm/lib/Transforms/Scalar/JumpThreading.cpp
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@ -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>
@ -2014,28 +2013,23 @@ 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();
// If there were values defined in BB that are used outside the block, then we
// 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;
for (Instruction &I : *BB) {
SSAUpdater SSAUpdate;
SmallVector<Use*, 16> UsesToRename;
for (Instruction &I : *BB) {
// Scan all uses of this instruction to see if their uses are no longer
// dominated by the previous def 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 ||
UserPN->getIncomingBlock(U) == PredBB)
if (UserPN->getIncomingBlock(U) == BB)
continue;
} else if (DT->dominates(&I, U))
} else if (User->getParent() == BB)
continue;
UsesToRename.push_back(&U);
@ -2044,18 +2038,20 @@ bool JumpThreadingPass::ThreadEdge(BasicBlock *BB,
// If there are no uses outside the block, we're done with this instruction.
if (UsesToRename.empty())
continue;
unsigned VarNum = SSAUpdate.AddVariable(I.getName(), I.getType());
LLVM_DEBUG(dbgs() << "JT: Renaming non-local uses of: " << I << "\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);
// 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());
LLVM_DEBUG(dbgs() << "\n");
}
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.