Example #1
0
/// \brief Simplify arithmetic intrinsics with overflow and known identity
/// constants such as 0 and 1.
/// If this returns a value other than SILValue() then the instruction was
/// simplified to a value which doesn't overflow.  The overflow case is handled
/// in SILCombine.
static SILValue simplifyBinaryWithOverflow(BuiltinInst *BI,
                                           llvm::Intrinsic::ID ID) {
  OperandValueArrayRef Args = BI->getArguments();
  assert(Args.size() >= 2);

  const SILValue &Op1 = Args[0];
  const SILValue &Op2 = Args[1];

  auto *IntOp1 = dyn_cast<IntegerLiteralInst>(Op1);
  auto *IntOp2 = dyn_cast<IntegerLiteralInst>(Op2);

  // If both ops are not constants, we cannot do anything.
  // FIXME: Add cases where we can do something, eg, (x - x) -> 0
  if (!IntOp1 && !IntOp2)
    return SILValue();

  // Calculate the result.

  switch (ID) {
  default: llvm_unreachable("Invalid case");
  case llvm::Intrinsic::sadd_with_overflow:
  case llvm::Intrinsic::uadd_with_overflow:
    // 0 + X -> X
    if (match(Op1, m_Zero()))
      return Op2;
    // X + 0 -> X
    if (match(Op2, m_Zero()))
      return Op1;
    return SILValue();
  case llvm::Intrinsic::ssub_with_overflow:
  case llvm::Intrinsic::usub_with_overflow:
    // X - 0 -> X
    if (match(Op2, m_Zero()))
      return Op1;
    return SILValue();
  case llvm::Intrinsic::smul_with_overflow:
  case llvm::Intrinsic::umul_with_overflow:
    // 0 * X -> 0
    if (match(Op1, m_Zero()))
      return Op1;
    // X * 0 -> 0
    if (match(Op2, m_Zero()))
      return Op2;
    // 1 * X -> X
    if (match(Op1, m_One()))
      return Op2;
    // X * 1 -> X
    if (match(Op2, m_One()))
      return Op1;
    return SILValue();
  }
  return SILValue();
}
Example #2
0
  /// Like ValueIsPHI but also check if the PHI has no source
  /// operands, i.e., it was just added.
  static SILPhiArgument *ValueIsNewPHI(SILValue Val, SILSSAUpdater *Updater) {
    SILPhiArgument *PHI = ValueIsPHI(Val, Updater);
    if (PHI) {
      auto *PhiBB = PHI->getParent();
      size_t PhiIdx = PHI->getIndex();

      // If all predecessor edges are 'not set' this is a new phi.
      for (auto *PredBB : PhiBB->getPredecessorBlocks()) {
        OperandValueArrayRef Edges =
            getEdgeValuesForTerminator(PredBB->getTerminator(), PhiBB);

        assert(PhiIdx < Edges.size() && "Not enough edges!");

        SILValue V = Edges[PhiIdx];
        // Check for the 'not set' sentinel.
        if (V != Updater->PHISentinel.get())
          return nullptr;
      }
      return PHI;
    }
    return nullptr;
  }
Example #3
0
/// We rotated a loop if it has the following properties.
///
/// * It has an exiting header with a conditional branch.
/// * It has a preheader (the function will try to create one for critical edges
///   from cond_br).
///
/// We will rotate at most up to the basic block passed as an argument.
/// We will not rotate a loop where the header is equal to the latch except is
/// RotateSingleBlockLoops is true.
///
/// Note: The code relies on the 'UpTo' basic block to stay within the rotate
/// loop for termination.
bool swift::rotateLoop(SILLoop *L, DominanceInfo *DT, SILLoopInfo *LI,
                       bool RotateSingleBlockLoops, SILBasicBlock *UpTo,
                       bool ShouldVerify) {
  assert(L != nullptr && DT != nullptr && LI != nullptr &&
         "Missing loop information");

  auto *Header = L->getHeader();
  if (!Header)
    return false;

  // We need a preheader - this is also a canonicalization for follow-up
  // passes.
  auto *Preheader = L->getLoopPreheader();
  if (!Preheader) {
    LLVM_DEBUG(llvm::dbgs() << *L << " no preheader\n");
    LLVM_DEBUG(L->getHeader()->getParent()->dump());
    return false;
  }

  if (!RotateSingleBlockLoops && (Header == UpTo || isSingleBlockLoop(L)))
    return false;

  assert(RotateSingleBlockLoops || L->getBlocks().size() != 1);

  // Need a conditional branch that guards the entry into the loop.
  auto *LoopEntryBranch = dyn_cast<CondBranchInst>(Header->getTerminator());
  if (!LoopEntryBranch)
    return false;

  // The header needs to exit the loop.
  if (!L->isLoopExiting(Header)) {
    LLVM_DEBUG(llvm::dbgs() << *L << " not an exiting header\n");
    LLVM_DEBUG(L->getHeader()->getParent()->dump());
    return false;
  }

  // We need a single backedge and the latch must not exit the loop if it is
  // also the header.
  auto *Latch = L->getLoopLatch();
  if (!Latch) {
    LLVM_DEBUG(llvm::dbgs() << *L << " no single latch\n");
    return false;
  }

  // Make sure we can duplicate the header.
  SmallVector<SILInstruction *, 8> MoveToPreheader;
  if (!canDuplicateOrMoveToPreheader(L, Preheader, Header, MoveToPreheader)) {
    LLVM_DEBUG(llvm::dbgs() << *L
                            << " instructions in header preventing rotating\n");
    return false;
  }

  auto *NewHeader = LoopEntryBranch->getTrueBB();
  auto *Exit = LoopEntryBranch->getFalseBB();
  if (L->contains(Exit))
    std::swap(NewHeader, Exit);
  assert(L->contains(NewHeader) && !L->contains(Exit) &&
         "Could not find loop header and exit block");

  // We don't want to rotate such that we merge two headers of separate loops
  // into one. This can be turned into an assert again once we have guaranteed
  // preheader insertions.
  if (!NewHeader->getSinglePredecessorBlock() && Header != Latch)
    return false;

  // Now that we know we can perform the rotation - move the instructions that
  // need moving.
  for (auto *Inst : MoveToPreheader)
    Inst->moveBefore(Preheader->getTerminator());

  LLVM_DEBUG(llvm::dbgs() << " Rotating " << *L);

  // Map the values for the duplicated header block. We are duplicating the
  // header instructions into the end of the preheader.
  llvm::DenseMap<ValueBase *, SILValue> ValueMap;

  // The original 'phi' argument values are just the values coming from the
  // preheader edge.
  ArrayRef<SILArgument *> PHIs = Header->getArguments();
  OperandValueArrayRef PreheaderArgs =
      cast<BranchInst>(Preheader->getTerminator())->getArgs();
  assert(PHIs.size() == PreheaderArgs.size() &&
         "Basic block arguments and incoming edge mismatch");

  // Here we also store the value index to use into the value map (versus
  // non-argument values where the operand use decides which value index to
  // use).
  for (unsigned Idx = 0, E = PHIs.size(); Idx != E; ++Idx)
    ValueMap[PHIs[Idx]] = PreheaderArgs[Idx];

  // The other instructions are just cloned to the preheader.
  TermInst *PreheaderBranch = Preheader->getTerminator();
  for (auto &Inst : *Header) {
    if (SILInstruction *cloned = Inst.clone(PreheaderBranch)) {
      mapOperands(cloned, ValueMap);

      // The actual operand will sort out which result idx to use.
      auto instResults = Inst.getResults();
      auto clonedResults = cloned->getResults();
      assert(instResults.size() == clonedResults.size());
      for (auto i : indices(instResults))
        ValueMap[instResults[i]] = clonedResults[i];
    }
  }

  PreheaderBranch->dropAllReferences();
  PreheaderBranch->eraseFromParent();

  // If there were any uses of instructions in the duplicated loop entry check
  // block rewrite them using the ssa updater.
  rewriteNewLoopEntryCheckBlock(Header, Preheader, ValueMap);

  L->moveToHeader(NewHeader);

  // Now the original preheader dominates all of headers children and the
  // original latch dominates the header.
  updateDomTree(DT, Preheader, Latch, Header);

  assert(DT->getNode(NewHeader)->getIDom() == DT->getNode(Preheader));
  assert(!DT->dominates(Header, Exit) ||
         DT->getNode(Exit)->getIDom() == DT->getNode(Preheader));
  assert(DT->getNode(Header)->getIDom() == DT->getNode(Latch) ||
         ((Header == Latch) &&
          DT->getNode(Header)->getIDom() == DT->getNode(Preheader)));

  // Beautify the IR. Move the old header to after the old latch as it is now
  // the latch.
  Header->moveAfter(Latch);

  // Merge the old latch with the old header if possible.
  mergeBasicBlockWithSuccessor(Latch, DT, LI);

  // Create a new preheader.
  splitIfCriticalEdge(Preheader, NewHeader, DT, LI);

  if (ShouldVerify) {
    DT->verify();
    LI->verify();
    Latch->getParent()->verify();
  }

  LLVM_DEBUG(llvm::dbgs() << "  to " << *L);
  LLVM_DEBUG(L->getHeader()->getParent()->dump());
  return true;
}
Example #4
0
File: CFG.cpp Project: adrfer/swift
/// \brief Changes the edge value between a branch and destination basic block
/// at the specified index. Changes all edges from \p Branch to \p Dest to carry
/// the value.
///
/// \param Branch The branch to modify.
/// \param Dest The destination of the edge.
/// \param Idx The index of the argument to modify.
/// \param Val The new value to use.
/// \return The new branch. Deletes the old one.
/// Changes the edge value between a branch and destination basic block at the
/// specified index.
TermInst *swift::changeEdgeValue(TermInst *Branch, SILBasicBlock *Dest,
                                 size_t Idx, SILValue Val) {
  SILBuilderWithScope Builder(Branch);

  if (CondBranchInst *CBI = dyn_cast<CondBranchInst>(Branch)) {
    SmallVector<SILValue, 8> TrueArgs;
    SmallVector<SILValue, 8> FalseArgs;

    OperandValueArrayRef OldTrueArgs = CBI->getTrueArgs();
    bool BranchOnTrue = CBI->getTrueBB() == Dest;
    assert((!BranchOnTrue || Idx < OldTrueArgs.size()) && "Not enough edges");

    // Copy the edge values overwriting the edge at Idx.
    for (unsigned i = 0, e = OldTrueArgs.size(); i != e; ++i) {
      if (BranchOnTrue && Idx == i)
        TrueArgs.push_back(Val);
      else
        TrueArgs.push_back(OldTrueArgs[i]);
    }
    assert(TrueArgs.size() == CBI->getTrueBB()->getNumBBArg() &&
           "Destination block's number of arguments must match");

    OperandValueArrayRef OldFalseArgs = CBI->getFalseArgs();
    bool BranchOnFalse = CBI->getFalseBB() == Dest;
    assert((!BranchOnFalse || Idx < OldFalseArgs.size()) && "Not enough edges");

    // Copy the edge values overwriting the edge at Idx.
    for (unsigned i = 0, e = OldFalseArgs.size(); i != e; ++i) {
      if (BranchOnFalse && Idx == i)
        FalseArgs.push_back(Val);
      else
        FalseArgs.push_back(OldFalseArgs[i]);
    }
    assert(FalseArgs.size() == CBI->getFalseBB()->getNumBBArg() &&
           "Destination block's number of arguments must match");

    CBI = Builder.createCondBranch(CBI->getLoc(), CBI->getCondition(),
                                    CBI->getTrueBB(), TrueArgs,
                                    CBI->getFalseBB(), FalseArgs);
    Branch->dropAllReferences();
    Branch->eraseFromParent();
    return CBI;
  }

  if (BranchInst *BI = dyn_cast<BranchInst>(Branch)) {
    SmallVector<SILValue, 8> Args;

    assert(Idx < BI->getNumArgs() && "Not enough edges");
    OperandValueArrayRef OldArgs = BI->getArgs();

    // Copy the edge values overwriting the edge at Idx.
    for (unsigned i = 0, e = OldArgs.size(); i != e; ++i) {
      if (Idx == i)
        Args.push_back(Val);
      else
        Args.push_back(OldArgs[i]);
    }
    assert(Args.size() == Dest->getNumBBArg());

    BI = Builder.createBranch(BI->getLoc(), BI->getDestBB(), Args);
    Branch->dropAllReferences();
    Branch->eraseFromParent();
    return BI;
  }

  llvm_unreachable("Unhandled terminator leading to merge block");
}
Example #5
0
 SILValue getValueForBlock(size_t Idx, SILBasicBlock *BB, TermInst *TI) {
   OperandValueArrayRef Args = getEdgeValuesForTerminator(TI, BB);
   assert(Idx < Args.size() && "Not enough values on incoming edge");
   return Args[Idx];
 }
SILInstruction *
SILCombiner::optimizeApplyOfConvertFunctionInst(FullApplySite AI,
        ConvertFunctionInst *CFI) {
    // We only handle simplification of static function references. If we don't
    // have one, bail.
    FunctionRefInst *FRI = dyn_cast<FunctionRefInst>(CFI->getOperand());
    if (!FRI)
        return nullptr;

    // Grab our relevant callee types...
    CanSILFunctionType SubstCalleeTy = AI.getSubstCalleeType();
    auto ConvertCalleeTy =
        CFI->getOperand()->getType().castTo<SILFunctionType>();

    // ... and make sure they have no unsubstituted generics. If they do, bail.
    if (SubstCalleeTy->hasArchetype() || ConvertCalleeTy->hasArchetype())
        return nullptr;

    // Ok, we can now perform our transformation. Grab AI's operands and the
    // relevant types from the ConvertFunction function type and AI.
    Builder.setCurrentDebugScope(AI.getDebugScope());
    OperandValueArrayRef Ops = AI.getArgumentsWithoutIndirectResults();
    auto OldOpTypes = SubstCalleeTy->getParameterSILTypes();
    auto NewOpTypes = ConvertCalleeTy->getParameterSILTypes();

    assert(Ops.size() == OldOpTypes.size() &&
           "Ops and op types must have same size.");
    assert(Ops.size() == NewOpTypes.size() &&
           "Ops and op types must have same size.");

    llvm::SmallVector<SILValue, 8> Args;
    for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
        SILValue Op = Ops[i];
        SILType OldOpType = OldOpTypes[i];
        SILType NewOpType = NewOpTypes[i];

        // Convert function takes refs to refs, address to addresses, and leaves
        // other types alone.
        if (OldOpType.isAddress()) {
            assert(NewOpType.isAddress() && "Addresses should map to addresses.");
            auto UAC = Builder.createUncheckedAddrCast(AI.getLoc(), Op, NewOpType);
            Args.push_back(UAC);
        } else if (OldOpType.isHeapObjectReferenceType()) {
            assert(NewOpType.isHeapObjectReferenceType() &&
                   "refs should map to refs.");
            auto URC = Builder.createUncheckedRefCast(AI.getLoc(), Op, NewOpType);
            Args.push_back(URC);
        } else {
            Args.push_back(Op);
        }
    }

    SILType CCSILTy = SILType::getPrimitiveObjectType(ConvertCalleeTy);
    // Create the new apply inst.
    SILInstruction *NAI;
    if (auto *TAI = dyn_cast<TryApplyInst>(AI))
        NAI = Builder.createTryApply(AI.getLoc(), FRI, CCSILTy,
                                     ArrayRef<Substitution>(), Args,
                                     TAI->getNormalBB(), TAI->getErrorBB());
    else
        NAI = Builder.createApply(AI.getLoc(), FRI, CCSILTy,
                                  ConvertCalleeTy->getSILResult(),
                                  ArrayRef<Substitution>(), Args,
                                  cast<ApplyInst>(AI)->isNonThrowing());
    return NAI;
}
/// \brief Fold arithmetic intrinsics with overflow.
static SILInstruction *
constantFoldBinaryWithOverflow(BuiltinInst *BI, llvm::Intrinsic::ID ID,
                               bool ReportOverflow,
                               Optional<bool> &ResultsInError) {
  OperandValueArrayRef Args = BI->getArguments();
  assert(Args.size() >= 2);

  auto *Op1 = dyn_cast<IntegerLiteralInst>(Args[0]);
  auto *Op2 = dyn_cast<IntegerLiteralInst>(Args[1]);

  // If either Op1 or Op2 is not a literal, we cannot do anything.
  if (!Op1 || !Op2)
    return nullptr;

  // Calculate the result.
  APInt LHSInt = Op1->getValue();
  APInt RHSInt = Op2->getValue();
  bool Overflow;
  APInt Res = constantFoldBinaryWithOverflow(LHSInt, RHSInt, Overflow, ID);

  // If we can statically determine that the operation overflows,
  // warn about it if warnings are not disabled by ResultsInError being null.
  if (ResultsInError.hasValue() && Overflow && ReportOverflow) {
    // Try to infer the type of the constant expression that the user operates
    // on. If the intrinsic was lowered from a call to a function that takes
    // two arguments of the same type, use the type of the LHS argument.
    // This would detect '+'/'+=' and such.
    Type OpType;
    SILLocation Loc = BI->getLoc();
    const ApplyExpr *CE = Loc.getAsASTNode<ApplyExpr>();
    SourceRange LHSRange, RHSRange;
    if (CE) {
      const auto *Args = dyn_cast_or_null<TupleExpr>(CE->getArg());
      if (Args && Args->getNumElements() == 2) {
        // Look through inout types in order to handle += well.
        CanType LHSTy = Args->getElement(0)->getType()->getInOutObjectType()->
                         getCanonicalType();
        CanType RHSTy = Args->getElement(1)->getType()->getCanonicalType();
        if (LHSTy == RHSTy)
          OpType = Args->getElement(1)->getType();
        
        LHSRange = Args->getElement(0)->getSourceRange();
        RHSRange = Args->getElement(1)->getSourceRange();
      }
    }

    bool Signed = false;
    StringRef Operator = "+";
    
    switch (ID) {
      default: llvm_unreachable("Invalid case");
      case llvm::Intrinsic::sadd_with_overflow:
        Signed = true;
        break;
      case llvm::Intrinsic::uadd_with_overflow:
        break;
      case llvm::Intrinsic::ssub_with_overflow:
        Operator = "-";
        Signed = true;
        break;
      case llvm::Intrinsic::usub_with_overflow:
        Operator = "-";
        break;
      case llvm::Intrinsic::smul_with_overflow:
        Operator = "*";
        Signed = true;
        break;
      case llvm::Intrinsic::umul_with_overflow:
        Operator = "*";
        break;
    }

    if (!OpType.isNull()) {
      diagnose(BI->getModule().getASTContext(),
               Loc.getSourceLoc(),
               diag::arithmetic_operation_overflow,
               LHSInt.toString(/*Radix*/ 10, Signed),
               Operator,
               RHSInt.toString(/*Radix*/ 10, Signed),
               OpType).highlight(LHSRange).highlight(RHSRange);
    } else {
      // If we cannot get the type info in an expected way, describe the type.
      diagnose(BI->getModule().getASTContext(),
               Loc.getSourceLoc(),
               diag::arithmetic_operation_overflow_generic_type,
               LHSInt.toString(/*Radix*/ 10, Signed),
               Operator,
               RHSInt.toString(/*Radix*/ 10, Signed),
               Signed,
               LHSInt.getBitWidth()).highlight(LHSRange).highlight(RHSRange);
    }
    ResultsInError = Optional<bool>(true);
  }

  return constructResultWithOverflowTuple(BI, Res, Overflow);
}