X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FAnalysis%2FPHITransAddr.cpp;h=bfe86425119be24c0a87d9414c16e8ebe019dabe;hb=93710f07f02b3961556d2344e1baab1f53e4b45e;hp=ce7eca5d27c155823f9e161a36b1a99011ea7f4f;hpb=210e45af3a579beeefb001c8f13c94e80407aad5;p=oota-llvm.git

diff --git a/lib/Analysis/PHITransAddr.cpp b/lib/Analysis/PHITransAddr.cpp
index ce7eca5d27c..bfe86425119 100644
--- a/lib/Analysis/PHITransAddr.cpp
+++ b/lib/Analysis/PHITransAddr.cpp
@@ -12,60 +12,429 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Analysis/PHITransAddr.h"
-#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 
-/// IsPHITranslatable - If this needs PHI translation, return true if we have
-/// some hope of doing it.  This should be used as a filter to avoid calling
-/// GetPHITranslatedValue in hopeless situations.
-bool PHITransAddr::IsPHITranslatable() const {
-  return true; // not a good filter.
+static bool CanPHITrans(Instruction *Inst) {
+  if (isa<PHINode>(Inst) ||
+      isa<GetElementPtrInst>(Inst))
+    return true;
+
+  if (isa<CastInst>(Inst) &&
+      isSafeToSpeculativelyExecute(Inst))
+    return true;
+
+  if (Inst->getOpcode() == Instruction::Add &&
+      isa<ConstantInt>(Inst->getOperand(1)))
+    return true;
+
+  //   cerr << "MEMDEP: Could not PHI translate: " << *Pointer;
+  //   if (isa<BitCastInst>(PtrInst) || isa<GetElementPtrInst>(PtrInst))
+  //     cerr << "OP:\t\t\t\t" << *PtrInst->getOperand(0);
+  return false;
+}
+
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+void PHITransAddr::dump() const {
+  if (!Addr) {
+    dbgs() << "PHITransAddr: null\n";
+    return;
+  }
+  dbgs() << "PHITransAddr: " << *Addr << "\n";
+  for (unsigned i = 0, e = InstInputs.size(); i != e; ++i)
+    dbgs() << "  Input #" << i << " is " << *InstInputs[i] << "\n";
 }
+#endif
+
+
+static bool VerifySubExpr(Value *Expr,
+                          SmallVectorImpl<Instruction*> &InstInputs) {
+  // If this is a non-instruction value, there is nothing to do.
+  Instruction *I = dyn_cast<Instruction>(Expr);
+  if (!I) return true;
+
+  // If it's an instruction, it is either in Tmp or its operands recursively
+  // are.
+  SmallVectorImpl<Instruction*>::iterator Entry =
+    std::find(InstInputs.begin(), InstInputs.end(), I);
+  if (Entry != InstInputs.end()) {
+    InstInputs.erase(Entry);
+    return true;
+  }
+
+  // If it isn't in the InstInputs list it is a subexpr incorporated into the
+  // address.  Sanity check that it is phi translatable.
+  if (!CanPHITrans(I)) {
+    errs() << "Instruction in PHITransAddr is not phi-translatable:\n";
+    errs() << *I << '\n';
+    llvm_unreachable("Either something is missing from InstInputs or "
+                     "CanPHITrans is wrong.");
+  }
+
+  // Validate the operands of the instruction.
+  for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
+    if (!VerifySubExpr(I->getOperand(i), InstInputs))
+      return false;
+
+  return true;
+}
+
+/// Verify - Check internal consistency of this data structure.  If the
+/// structure is valid, it returns true.  If invalid, it prints errors and
+/// returns false.
+bool PHITransAddr::Verify() const {
+  if (!Addr) return true;
+
+  SmallVector<Instruction*, 8> Tmp(InstInputs.begin(), InstInputs.end());
+
+  if (!VerifySubExpr(Addr, Tmp))
+    return false;
+
+  if (!Tmp.empty()) {
+    errs() << "PHITransAddr contains extra instructions:\n";
+    for (unsigned i = 0, e = InstInputs.size(); i != e; ++i)
+      errs() << "  InstInput #" << i << " is " << *InstInputs[i] << "\n";
+    llvm_unreachable("This is unexpected.");
+  }
+
+  // a-ok.
+  return true;
+}
+
 
-/// GetPHITranslatedValue - Given a computation that satisfied the
-/// isPHITranslatable predicate, see if we can translate the computation into
-/// the specified predecessor block.  If so, return that value, otherwise
-/// return null.
-Value *PHITransAddr::GetPHITranslatedValue(Value *InVal, BasicBlock *CurBB,
-                                           BasicBlock *Pred,
-                                           const TargetData *TD) const {
-  // Not a great implementation.
-  return 0;
+/// IsPotentiallyPHITranslatable - If this needs PHI translation, return true
+/// if we have some hope of doing it.  This should be used as a filter to
+/// avoid calling PHITranslateValue in hopeless situations.
+bool PHITransAddr::IsPotentiallyPHITranslatable() const {
+  // If the input value is not an instruction, or if it is not defined in CurBB,
+  // then we don't need to phi translate it.
+  Instruction *Inst = dyn_cast<Instruction>(Addr);
+  return !Inst || CanPHITrans(Inst);
 }
 
-/// GetAvailablePHITranslatePointer - Return the value computed by
-/// PHITranslatePointer if it dominates PredBB, otherwise return null.
+
+static void RemoveInstInputs(Value *V,
+                             SmallVectorImpl<Instruction*> &InstInputs) {
+  Instruction *I = dyn_cast<Instruction>(V);
+  if (!I) return;
+
+  // If the instruction is in the InstInputs list, remove it.
+  SmallVectorImpl<Instruction*>::iterator Entry =
+    std::find(InstInputs.begin(), InstInputs.end(), I);
+  if (Entry != InstInputs.end()) {
+    InstInputs.erase(Entry);
+    return;
+  }
+
+  assert(!isa<PHINode>(I) && "Error, removing something that isn't an input");
+
+  // Otherwise, it must have instruction inputs itself.  Zap them recursively.
+  for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
+    if (Instruction *Op = dyn_cast<Instruction>(I->getOperand(i)))
+      RemoveInstInputs(Op, InstInputs);
+  }
+}
+
+Value *PHITransAddr::PHITranslateSubExpr(Value *V, BasicBlock *CurBB,
+                                         BasicBlock *PredBB,
+                                         const DominatorTree *DT) {
+  // If this is a non-instruction value, it can't require PHI translation.
+  Instruction *Inst = dyn_cast<Instruction>(V);
+  if (!Inst) return V;
+
+  // Determine whether 'Inst' is an input to our PHI translatable expression.
+  bool isInput = std::count(InstInputs.begin(), InstInputs.end(), Inst);
+
+  // Handle inputs instructions if needed.
+  if (isInput) {
+    if (Inst->getParent() != CurBB) {
+      // If it is an input defined in a different block, then it remains an
+      // input.
+      return Inst;
+    }
+
+    // If 'Inst' is defined in this block and is an input that needs to be phi
+    // translated, we need to incorporate the value into the expression or fail.
+
+    // In either case, the instruction itself isn't an input any longer.
+    InstInputs.erase(std::find(InstInputs.begin(), InstInputs.end(), Inst));
+
+    // If this is a PHI, go ahead and translate it.
+    if (PHINode *PN = dyn_cast<PHINode>(Inst))
+      return AddAsInput(PN->getIncomingValueForBlock(PredBB));
+
+    // If this is a non-phi value, and it is analyzable, we can incorporate it
+    // into the expression by making all instruction operands be inputs.
+    if (!CanPHITrans(Inst))
+      return nullptr;
+
+    // All instruction operands are now inputs (and of course, they may also be
+    // defined in this block, so they may need to be phi translated themselves.
+    for (unsigned i = 0, e = Inst->getNumOperands(); i != e; ++i)
+      if (Instruction *Op = dyn_cast<Instruction>(Inst->getOperand(i)))
+        InstInputs.push_back(Op);
+  }
+
+  // Ok, it must be an intermediate result (either because it started that way
+  // or because we just incorporated it into the expression).  See if its
+  // operands need to be phi translated, and if so, reconstruct it.
+
+  if (CastInst *Cast = dyn_cast<CastInst>(Inst)) {
+    if (!isSafeToSpeculativelyExecute(Cast)) return nullptr;
+    Value *PHIIn = PHITranslateSubExpr(Cast->getOperand(0), CurBB, PredBB, DT);
+    if (!PHIIn) return nullptr;
+    if (PHIIn == Cast->getOperand(0))
+      return Cast;
+
+    // Find an available version of this cast.
+
+    // Constants are trivial to find.
+    if (Constant *C = dyn_cast<Constant>(PHIIn))
+      return AddAsInput(ConstantExpr::getCast(Cast->getOpcode(),
+                                              C, Cast->getType()));
+
+    // Otherwise we have to see if a casted version of the incoming pointer
+    // is available.  If so, we can use it, otherwise we have to fail.
+    for (User *U : PHIIn->users()) {
+      if (CastInst *CastI = dyn_cast<CastInst>(U))
+        if (CastI->getOpcode() == Cast->getOpcode() &&
+            CastI->getType() == Cast->getType() &&
+            (!DT || DT->dominates(CastI->getParent(), PredBB)))
+          return CastI;
+    }
+    return nullptr;
+  }
+
+  // Handle getelementptr with at least one PHI translatable operand.
+  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) {
+    SmallVector<Value*, 8> GEPOps;
+    bool AnyChanged = false;
+    for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i) {
+      Value *GEPOp = PHITranslateSubExpr(GEP->getOperand(i), CurBB, PredBB, DT);
+      if (!GEPOp) return nullptr;
+
+      AnyChanged |= GEPOp != GEP->getOperand(i);
+      GEPOps.push_back(GEPOp);
+    }
+
+    if (!AnyChanged)
+      return GEP;
+
+    // Simplify the GEP to handle 'gep x, 0' -> x etc.
+    if (Value *V = SimplifyGEPInst(GEPOps, DL, TLI, DT)) {
+      for (unsigned i = 0, e = GEPOps.size(); i != e; ++i)
+        RemoveInstInputs(GEPOps[i], InstInputs);
+
+      return AddAsInput(V);
+    }
+
+    // Scan to see if we have this GEP available.
+    Value *APHIOp = GEPOps[0];
+    for (User *U : APHIOp->users()) {
+      if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(U))
+        if (GEPI->getType() == GEP->getType() &&
+            GEPI->getNumOperands() == GEPOps.size() &&
+            GEPI->getParent()->getParent() == CurBB->getParent() &&
+            (!DT || DT->dominates(GEPI->getParent(), PredBB))) {
+          bool Mismatch = false;
+          for (unsigned i = 0, e = GEPOps.size(); i != e; ++i)
+            if (GEPI->getOperand(i) != GEPOps[i]) {
+              Mismatch = true;
+              break;
+            }
+          if (!Mismatch)
+            return GEPI;
+        }
+    }
+    return nullptr;
+  }
+
+  // Handle add with a constant RHS.
+  if (Inst->getOpcode() == Instruction::Add &&
+      isa<ConstantInt>(Inst->getOperand(1))) {
+    // PHI translate the LHS.
+    Constant *RHS = cast<ConstantInt>(Inst->getOperand(1));
+    bool isNSW = cast<BinaryOperator>(Inst)->hasNoSignedWrap();
+    bool isNUW = cast<BinaryOperator>(Inst)->hasNoUnsignedWrap();
+
+    Value *LHS = PHITranslateSubExpr(Inst->getOperand(0), CurBB, PredBB, DT);
+    if (!LHS) return nullptr;
+
+    // If the PHI translated LHS is an add of a constant, fold the immediates.
+    if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(LHS))
+      if (BOp->getOpcode() == Instruction::Add)
+        if (ConstantInt *CI = dyn_cast<ConstantInt>(BOp->getOperand(1))) {
+          LHS = BOp->getOperand(0);
+          RHS = ConstantExpr::getAdd(RHS, CI);
+          isNSW = isNUW = false;
+
+          // If the old 'LHS' was an input, add the new 'LHS' as an input.
+          if (std::count(InstInputs.begin(), InstInputs.end(), BOp)) {
+            RemoveInstInputs(BOp, InstInputs);
+            AddAsInput(LHS);
+          }
+        }
+
+    // See if the add simplifies away.
+    if (Value *Res = SimplifyAddInst(LHS, RHS, isNSW, isNUW, DL, TLI, DT)) {
+      // If we simplified the operands, the LHS is no longer an input, but Res
+      // is.
+      RemoveInstInputs(LHS, InstInputs);
+      return AddAsInput(Res);
+    }
+
+    // If we didn't modify the add, just return it.
+    if (LHS == Inst->getOperand(0) && RHS == Inst->getOperand(1))
+      return Inst;
+
+    // Otherwise, see if we have this add available somewhere.
+    for (User *U : LHS->users()) {
+      if (BinaryOperator *BO = dyn_cast<BinaryOperator>(U))
+        if (BO->getOpcode() == Instruction::Add &&
+            BO->getOperand(0) == LHS && BO->getOperand(1) == RHS &&
+            BO->getParent()->getParent() == CurBB->getParent() &&
+            (!DT || DT->dominates(BO->getParent(), PredBB)))
+          return BO;
+    }
+
+    return nullptr;
+  }
+
+  // Otherwise, we failed.
+  return nullptr;
+}
+
+
+/// PHITranslateValue - PHI translate the current address up the CFG from
+/// CurBB to Pred, updating our state to reflect any needed changes.  If the
+/// dominator tree DT is non-null, the translated value must dominate
+/// PredBB.  This returns true on failure and sets Addr to null.
+bool PHITransAddr::PHITranslateValue(BasicBlock *CurBB, BasicBlock *PredBB,
+                                     const DominatorTree *DT) {
+  assert(Verify() && "Invalid PHITransAddr!");
+  Addr = PHITranslateSubExpr(Addr, CurBB, PredBB, DT);
+  assert(Verify() && "Invalid PHITransAddr!");
+
+  if (DT) {
+    // Make sure the value is live in the predecessor.
+    if (Instruction *Inst = dyn_cast_or_null<Instruction>(Addr))
+      if (!DT->dominates(Inst->getParent(), PredBB))
+        Addr = nullptr;
+  }
+
+  return Addr == nullptr;
+}
+
+/// PHITranslateWithInsertion - PHI translate this value into the specified
+/// predecessor block, inserting a computation of the value if it is
+/// unavailable.
+///
+/// All newly created instructions are added to the NewInsts list.  This
+/// returns null on failure.
+///
 Value *PHITransAddr::
-GetAvailablePHITranslatedValue(Value *V,
-                               BasicBlock *CurBB, BasicBlock *PredBB,
-                               const TargetData *TD,
-                               const DominatorTree &DT) const {
-  // See if PHI translation succeeds.
-  V = GetPHITranslatedValue(V, CurBB, PredBB, TD);
-  if (V == 0) return 0;
-  
-  // Make sure the value is live in the predecessor.
-  if (Instruction *Inst = dyn_cast_or_null<Instruction>(V))
-    if (!DT.dominates(Inst->getParent(), PredBB))
-      return 0;
-  return V;
+PHITranslateWithInsertion(BasicBlock *CurBB, BasicBlock *PredBB,
+                          const DominatorTree &DT,
+                          SmallVectorImpl<Instruction*> &NewInsts) {
+  unsigned NISize = NewInsts.size();
+
+  // Attempt to PHI translate with insertion.
+  Addr = InsertPHITranslatedSubExpr(Addr, CurBB, PredBB, DT, NewInsts);
+
+  // If successful, return the new value.
+  if (Addr) return Addr;
+
+  // If not, destroy any intermediate instructions inserted.
+  while (NewInsts.size() != NISize)
+    NewInsts.pop_back_val()->eraseFromParent();
+  return nullptr;
 }
 
+
 /// InsertPHITranslatedPointer - Insert a computation of the PHI translated
 /// version of 'V' for the edge PredBB->CurBB into the end of the PredBB
 /// block.  All newly created instructions are added to the NewInsts list.
 /// This returns null on failure.
 ///
 Value *PHITransAddr::
-InsertPHITranslatedPointer(Value *InVal, BasicBlock *CurBB,
-                           BasicBlock *PredBB, const TargetData *TD,
-                           const DominatorTree &DT,
-                           SmallVectorImpl<Instruction*> &NewInsts) const {
+InsertPHITranslatedSubExpr(Value *InVal, BasicBlock *CurBB,
+                           BasicBlock *PredBB, const DominatorTree &DT,
+                           SmallVectorImpl<Instruction*> &NewInsts) {
   // See if we have a version of this value already available and dominating
-  // PredBB.  If so, there is no need to insert a new copy.
-  if (Value *Res = GetAvailablePHITranslatedValue(InVal, CurBB, PredBB, TD, DT))
+  // PredBB.  If so, there is no need to insert a new instance of it.
+  PHITransAddr Tmp(InVal, DL);
+  if (!Tmp.PHITranslateValue(CurBB, PredBB, &DT))
+    return Tmp.getAddr();
+
+  // If we don't have an available version of this value, it must be an
+  // instruction.
+  Instruction *Inst = cast<Instruction>(InVal);
+
+  // Handle cast of PHI translatable value.
+  if (CastInst *Cast = dyn_cast<CastInst>(Inst)) {
+    if (!isSafeToSpeculativelyExecute(Cast)) return nullptr;
+    Value *OpVal = InsertPHITranslatedSubExpr(Cast->getOperand(0),
+                                              CurBB, PredBB, DT, NewInsts);
+    if (!OpVal) return nullptr;
+
+    // Otherwise insert a cast at the end of PredBB.
+    CastInst *New = CastInst::Create(Cast->getOpcode(),
+                                     OpVal, InVal->getType(),
+                                     InVal->getName()+".phi.trans.insert",
+                                     PredBB->getTerminator());
+    NewInsts.push_back(New);
+    return New;
+  }
+
+  // Handle getelementptr with at least one PHI operand.
+  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) {
+    SmallVector<Value*, 8> GEPOps;
+    BasicBlock *CurBB = GEP->getParent();
+    for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i) {
+      Value *OpVal = InsertPHITranslatedSubExpr(GEP->getOperand(i),
+                                                CurBB, PredBB, DT, NewInsts);
+      if (!OpVal) return nullptr;
+      GEPOps.push_back(OpVal);
+    }
+
+    GetElementPtrInst *Result =
+      GetElementPtrInst::Create(GEPOps[0], makeArrayRef(GEPOps).slice(1),
+                                InVal->getName()+".phi.trans.insert",
+                                PredBB->getTerminator());
+    Result->setIsInBounds(GEP->isInBounds());
+    NewInsts.push_back(Result);
+    return Result;
+  }
+
+#if 0
+  // FIXME: This code works, but it is unclear that we actually want to insert
+  // a big chain of computation in order to make a value available in a block.
+  // This needs to be evaluated carefully to consider its cost trade offs.
+
+  // Handle add with a constant RHS.
+  if (Inst->getOpcode() == Instruction::Add &&
+      isa<ConstantInt>(Inst->getOperand(1))) {
+    // PHI translate the LHS.
+    Value *OpVal = InsertPHITranslatedSubExpr(Inst->getOperand(0),
+                                              CurBB, PredBB, DT, NewInsts);
+    if (OpVal == 0) return 0;
+
+    BinaryOperator *Res = BinaryOperator::CreateAdd(OpVal, Inst->getOperand(1),
+                                           InVal->getName()+".phi.trans.insert",
+                                                    PredBB->getTerminator());
+    Res->setHasNoSignedWrap(cast<BinaryOperator>(Inst)->hasNoSignedWrap());
+    Res->setHasNoUnsignedWrap(cast<BinaryOperator>(Inst)->hasNoUnsignedWrap());
+    NewInsts.push_back(Res);
     return Res;
+  }
+#endif
 
-  // Not a great implementation.
-  return 0;
+  return nullptr;
 }