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-rw-r--r--llvm/lib/Transforms/Scalar/JumpThreading.cpp56
-rw-r--r--llvm/lib/Transforms/Utils/SSAUpdaterBulk.cpp25
2 files changed, 42 insertions, 39 deletions
diff --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
index 29c707799bd..796b6abcbfd 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>
@@ -1985,19 +1986,33 @@ bool JumpThreadingPass::ThreadEdge(BasicBlock *BB,
// PHI nodes for NewBB now.
AddPHINodeEntriesForMappedBlock(SuccBB, BB, NewBB, ValueMapping);
+ // Update the terminator of PredBB to jump to NewBB instead of BB. This
+ // eliminates predecessors from BB, which requires us to simplify any PHI
+ // nodes in BB.
+ TerminatorInst *PredTerm = PredBB->getTerminator();
+ for (unsigned i = 0, e = PredTerm->getNumSuccessors(); i != e; ++i)
+ if (PredTerm->getSuccessor(i) == BB) {
+ BB->removePredecessor(PredBB, true);
+ PredTerm->setSuccessor(i, NewBB);
+ }
+
// 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.
- SSAUpdater SSAUpdate;
- SmallVector<Use*, 16> UsesToRename;
+ SSAUpdaterBulk SSAUpdate;
+
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;
@@ -2008,35 +2023,24 @@ 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());
- 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);
}
- // Ok, NewBB is good to go. Update the terminator of PredBB to jump to
- // NewBB instead of BB. This eliminates predecessors from BB, which requires
- // us to simplify any PHI nodes in BB.
- TerminatorInst *PredTerm = PredBB->getTerminator();
- for (unsigned i = 0, e = PredTerm->getNumSuccessors(); i != e; ++i)
- if (PredTerm->getSuccessor(i) == BB) {
- BB->removePredecessor(PredBB, true);
- PredTerm->setSuccessor(i, NewBB);
- }
-
DDT->applyUpdates({{DominatorTree::Insert, NewBB, SuccBB},
{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.
diff --git a/llvm/lib/Transforms/Utils/SSAUpdaterBulk.cpp b/llvm/lib/Transforms/Utils/SSAUpdaterBulk.cpp
index dbc671cc16f..61ceb9c9277 100644
--- a/llvm/lib/Transforms/Utils/SSAUpdaterBulk.cpp
+++ b/llvm/lib/Transforms/Utils/SSAUpdaterBulk.cpp
@@ -38,18 +38,19 @@ static BasicBlock *getUserBB(Use *U) {
/// Add a new variable to the SSA rewriter. This needs to be called before
/// AddAvailableValue or AddUse calls.
-void SSAUpdaterBulk::AddVariable(unsigned Var, StringRef Name, Type *Ty) {
- assert(Rewrites.find(Var) == Rewrites.end() && "Variable added twice!");
+unsigned SSAUpdaterBulk::AddVariable(StringRef Name, Type *Ty) {
+ unsigned Var = Rewrites.size();
DEBUG(dbgs() << "SSAUpdater: Var=" << Var << ": initialized with Ty = " << *Ty
<< ", Name = " << Name << "\n");
RewriteInfo RI(Name, Ty);
- Rewrites[Var] = RI;
+ Rewrites.push_back(RI);
+ return Var;
}
/// Indicate that a rewritten value is available in the specified block with the
/// specified value.
void SSAUpdaterBulk::AddAvailableValue(unsigned Var, BasicBlock *BB, Value *V) {
- assert(Rewrites.find(Var) != Rewrites.end() && "Should add variable first!");
+ assert(Var < Rewrites.size() && "Variable not found!");
DEBUG(dbgs() << "SSAUpdater: Var=" << Var << ": added new available value"
<< *V << " in " << BB->getName() << "\n");
Rewrites[Var].Defines[BB] = V;
@@ -58,7 +59,7 @@ void SSAUpdaterBulk::AddAvailableValue(unsigned Var, BasicBlock *BB, Value *V) {
/// Record a use of the symbolic value. This use will be updated with a
/// rewritten value when RewriteAllUses is called.
void SSAUpdaterBulk::AddUse(unsigned Var, Use *U) {
- assert(Rewrites.find(Var) != Rewrites.end() && "Should add variable first!");
+ assert(Var < Rewrites.size() && "Variable not found!");
DEBUG(dbgs() << "SSAUpdater: Var=" << Var << ": added a use" << *U->get()
<< " in " << getUserBB(U)->getName() << "\n");
Rewrites[Var].Uses.push_back(U);
@@ -67,7 +68,7 @@ void SSAUpdaterBulk::AddUse(unsigned Var, Use *U) {
/// Return true if the SSAUpdater already has a value for the specified variable
/// in the specified block.
bool SSAUpdaterBulk::HasValueForBlock(unsigned Var, BasicBlock *BB) {
- return Rewrites.count(Var) ? Rewrites[Var].Defines.count(BB) : false;
+ return (Var < Rewrites.size()) ? Rewrites[Var].Defines.count(BB) : false;
}
// Compute value at the given block BB. We either should already know it, or we
@@ -126,16 +127,14 @@ ComputeLiveInBlocks(const SmallPtrSetImpl<BasicBlock *> &UsingBlocks,
/// requested uses update.
void SSAUpdaterBulk::RewriteAllUses(DominatorTree *DT,
SmallVectorImpl<PHINode *> *InsertedPHIs) {
- for (auto &P : Rewrites) {
+ for (auto &R : Rewrites) {
// Compute locations for new phi-nodes.
// For that we need to initialize DefBlocks from definitions in R.Defines,
// UsingBlocks from uses in R.Uses, then compute LiveInBlocks, and then use
// this set for computing iterated dominance frontier (IDF).
// The IDF blocks are the blocks where we need to insert new phi-nodes.
ForwardIDFCalculator IDF(*DT);
- RewriteInfo &R = P.second;
- DEBUG(dbgs() << "SSAUpdater: Var=" << P.first << ": rewriting "
- << R.Uses.size() << " use(s)\n");
+ DEBUG(dbgs() << "SSAUpdater: rewriting " << R.Uses.size() << " use(s)\n");
SmallPtrSet<BasicBlock *, 2> DefBlocks;
for (auto &Def : R.Defines)
@@ -165,7 +164,7 @@ void SSAUpdaterBulk::RewriteAllUses(DominatorTree *DT,
}
// Fill in arguments of the inserted PHIs.
- for (auto PN : InsertedPHIsForVar) {
+ for (auto *PN : InsertedPHIsForVar) {
BasicBlock *PBB = PN->getParent();
for (BasicBlock *Pred : PredCache.get(PBB))
PN->addIncoming(computeValueAt(Pred, R, DT), Pred);
@@ -182,8 +181,8 @@ void SSAUpdaterBulk::RewriteAllUses(DominatorTree *DT,
// Notify that users of the existing value that it is being replaced.
if (OldVal != V && OldVal->hasValueHandle())
ValueHandleBase::ValueIsRAUWd(OldVal, V);
- DEBUG(dbgs() << "SSAUpdater: Var=" << P.first << ": replacing" << *OldVal
- << " with " << *V << "\n");
+ DEBUG(dbgs() << "SSAUpdater: replacing " << *OldVal << " with " << *V
+ << "\n");
U->set(V);
}
}
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