//===----------------------------------------------------------------------===//
#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, AC)) {
+ 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, AC)) {
+ // 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, AC);
+ 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(
+ GEP->getSourceElementType(), 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;
}
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