C++ BinaryOperator::eraseFromParent方法代码示例

bool AMDGPUCodeGenPrepare::promoteUniformOpToI32(BinaryOperator &I) const {
  assert(needsPromotionToI32(I.getType()) &&
         "I does not need promotion to i32");

  if (I.getOpcode() == Instruction::SDiv ||
      I.getOpcode() == Instruction::UDiv)
    return false;

  IRBuilder<> Builder(&I);
  Builder.SetCurrentDebugLocation(I.getDebugLoc());

  Type *I32Ty = getI32Ty(Builder, I.getType());
  Value *ExtOp0 = nullptr;
  Value *ExtOp1 = nullptr;
  Value *ExtRes = nullptr;
  Value *TruncRes = nullptr;

  if (isSigned(I)) {
    ExtOp0 = Builder.CreateSExt(I.getOperand(0), I32Ty);
    ExtOp1 = Builder.CreateSExt(I.getOperand(1), I32Ty);
  } else {
    ExtOp0 = Builder.CreateZExt(I.getOperand(0), I32Ty);
    ExtOp1 = Builder.CreateZExt(I.getOperand(1), I32Ty);
  }
  ExtRes = copyFlags(I, Builder.CreateBinOp(I.getOpcode(), ExtOp0, ExtOp1));
  TruncRes = Builder.CreateTrunc(ExtRes, I.getType());

  I.replaceAllUsesWith(TruncRes);
  I.eraseFromParent();

  return true;
}

bool AMDGPUCodeGenPrepare::promoteUniformOpToI32(BinaryOperator &I) const {
  assert(needsPromotionToI32(I.getType()) &&
         "I does not need promotion to i32");

  if (I.getOpcode() == Instruction::SDiv ||
      I.getOpcode() == Instruction::UDiv ||
      I.getOpcode() == Instruction::SRem ||
      I.getOpcode() == Instruction::URem)
    return false;

  IRBuilder<> Builder(&I);
  Builder.SetCurrentDebugLocation(I.getDebugLoc());

  Type *I32Ty = getI32Ty(Builder, I.getType());
  Value *ExtOp0 = nullptr;
  Value *ExtOp1 = nullptr;
  Value *ExtRes = nullptr;
  Value *TruncRes = nullptr;

  if (isSigned(I)) {
    ExtOp0 = Builder.CreateSExt(I.getOperand(0), I32Ty);
    ExtOp1 = Builder.CreateSExt(I.getOperand(1), I32Ty);
  } else {
    ExtOp0 = Builder.CreateZExt(I.getOperand(0), I32Ty);
    ExtOp1 = Builder.CreateZExt(I.getOperand(1), I32Ty);
  }

  ExtRes = Builder.CreateBinOp(I.getOpcode(), ExtOp0, ExtOp1);
  if (Instruction *Inst = dyn_cast<Instruction>(ExtRes)) {
    if (promotedOpIsNSW(cast<Instruction>(I)))
      Inst->setHasNoSignedWrap();

    if (promotedOpIsNUW(cast<Instruction>(I)))
      Inst->setHasNoUnsignedWrap();

    if (const auto *ExactOp = dyn_cast<PossiblyExactOperator>(&I))
      Inst->setIsExact(ExactOp->isExact());
  }

  TruncRes = Builder.CreateTrunc(ExtRes, I.getType());

  I.replaceAllUsesWith(TruncRes);
  I.eraseFromParent();

  return true;
}

bool AMDGPUCodeGenPrepare::visitBinaryOperator(BinaryOperator &I) {
  if (ST->has16BitInsts() && needsPromotionToI32(I.getType()) &&
      DA->isUniform(&I) && promoteUniformOpToI32(I))
    return true;

  bool Changed = false;
  Instruction::BinaryOps Opc = I.getOpcode();
  Type *Ty = I.getType();
  Value *NewDiv = nullptr;
  if ((Opc == Instruction::URem || Opc == Instruction::UDiv ||
       Opc == Instruction::SRem || Opc == Instruction::SDiv) &&
      Ty->getScalarSizeInBits() <= 32) {
    Value *Num = I.getOperand(0);
    Value *Den = I.getOperand(1);
    IRBuilder<> Builder(&I);
    Builder.SetCurrentDebugLocation(I.getDebugLoc());

    if (VectorType *VT = dyn_cast<VectorType>(Ty)) {
      NewDiv = UndefValue::get(VT);

      for (unsigned N = 0, E = VT->getNumElements(); N != E; ++N) {
        Value *NumEltN = Builder.CreateExtractElement(Num, N);
        Value *DenEltN = Builder.CreateExtractElement(Den, N);
        Value *NewElt = expandDivRem32(Builder, I, NumEltN, DenEltN);
        if (!NewElt)
          NewElt = Builder.CreateBinOp(Opc, NumEltN, DenEltN);
        NewDiv = Builder.CreateInsertElement(NewDiv, NewElt, N);
      }
    } else {
      NewDiv = expandDivRem32(Builder, I, Num, Den);
    }

    if (NewDiv) {
      I.replaceAllUsesWith(NewDiv);
      I.eraseFromParent();
      Changed = true;
    }
  }

  return Changed;
}

/// updateLoopIterationSpace -- Update loop's iteration space if loop 
/// body is executed for certain IV range only. For example,
/// 
/// for (i = 0; i < N; ++i) {
///   if ( i > A && i < B) {
///     ...
///   }
/// }
/// is transformed to iterators from A to B, if A > 0 and B < N.
///
bool LoopIndexSplit::updateLoopIterationSpace() {
  SplitCondition = NULL;
  if (ExitCondition->getPredicate() == ICmpInst::ICMP_NE
      || ExitCondition->getPredicate() == ICmpInst::ICMP_EQ)
    return false;
  BasicBlock *Latch = L->getLoopLatch();
  BasicBlock *Header = L->getHeader();
  BranchInst *BR = dyn_cast<BranchInst>(Header->getTerminator());
  if (!BR) return false;
  if (!isa<BranchInst>(Latch->getTerminator())) return false;
  if (BR->isUnconditional()) return false;
  BinaryOperator *AND = dyn_cast<BinaryOperator>(BR->getCondition());
  if (!AND) return false;
  if (AND->getOpcode() != Instruction::And) return false;
  ICmpInst *Op0 = dyn_cast<ICmpInst>(AND->getOperand(0));
  ICmpInst *Op1 = dyn_cast<ICmpInst>(AND->getOperand(1));
  if (!Op0 || !Op1)
    return false;
  IVBasedValues.insert(AND);
  IVBasedValues.insert(Op0);
  IVBasedValues.insert(Op1);
  if (!cleanBlock(Header)) return false;
  BasicBlock *ExitingBlock = ExitCondition->getParent();
  if (!cleanBlock(ExitingBlock)) return false;

  // If the merge point for BR is not loop latch then skip this loop.
  if (BR->getSuccessor(0) != Latch) {
    DominanceFrontier::iterator DF0 = DF->find(BR->getSuccessor(0));
    assert (DF0 != DF->end() && "Unable to find dominance frontier");
    if (!DF0->second.count(Latch))
      return false;
  }
  
  if (BR->getSuccessor(1) != Latch) {
    DominanceFrontier::iterator DF1 = DF->find(BR->getSuccessor(1));
    assert (DF1 != DF->end() && "Unable to find dominance frontier");
    if (!DF1->second.count(Latch))
      return false;
  }
    
  // Verify that loop exiting block has only two predecessor, where one pred
  // is split condition block. The other predecessor will become exiting block's
  // dominator after CFG is updated. TODO : Handle CFG's where exiting block has
  // more then two predecessors. This requires extra work in updating dominator
  // information.
  BasicBlock *ExitingBBPred = NULL;
  for (pred_iterator PI = pred_begin(ExitingBlock), PE = pred_end(ExitingBlock);
       PI != PE; ++PI) {
    BasicBlock *BB = *PI;
    if (Header == BB)
      continue;
    if (ExitingBBPred)
      return false;
    else
      ExitingBBPred = BB;
  }

  if (!restrictLoopBound(*Op0))
    return false;

  if (!restrictLoopBound(*Op1))
    return false;

  // Update CFG.
  if (BR->getSuccessor(0) == ExitingBlock)
    BR->setUnconditionalDest(BR->getSuccessor(1));
  else
    BR->setUnconditionalDest(BR->getSuccessor(0));

  AND->eraseFromParent();
  if (Op0->use_empty())
    Op0->eraseFromParent();
  if (Op1->use_empty())
    Op1->eraseFromParent();

  // Update domiantor info. Now, ExitingBlock has only one predecessor, 
  // ExitingBBPred, and it is ExitingBlock's immediate domiantor.
  DT->changeImmediateDominator(ExitingBlock, ExitingBBPred);

  BasicBlock *ExitBlock = ExitingBlock->getTerminator()->getSuccessor(1);
  if (L->contains(ExitBlock))
    ExitBlock = ExitingBlock->getTerminator()->getSuccessor(0);

  // If ExitingBlock is a member of the loop basic blocks' DF list then
  // replace ExitingBlock with header and exit block in the DF list
  DominanceFrontier::iterator ExitingBlockDF = DF->find(ExitingBlock);
  for (Loop::block_iterator I = L->block_begin(), E = L->block_end();
       I != E; ++I) {
    BasicBlock *BB = *I;
    if (BB == Header || BB == ExitingBlock)
//.........这里部分代码省略.........

// Insert an intrinsic for fast fdiv for safe math situations where we can
// reduce precision. Leave fdiv for situations where the generic node is
// expected to be optimized.
bool AMDGPUCodeGenPrepare::visitFDiv(BinaryOperator &FDiv) {
  Type *Ty = FDiv.getType();

  // TODO: Handle half
  if (!Ty->getScalarType()->isFloatTy())
    return false;

  MDNode *FPMath = FDiv.getMetadata(LLVMContext::MD_fpmath);
  if (!FPMath)
    return false;

  const FPMathOperator *FPOp = cast<const FPMathOperator>(&FDiv);
  float ULP = FPOp->getFPAccuracy();
  if (ULP < 2.5f)
    return false;

  FastMathFlags FMF = FPOp->getFastMathFlags();
  bool UnsafeDiv = HasUnsafeFPMath || FMF.unsafeAlgebra() ||
                                      FMF.allowReciprocal();
  if (ST->hasFP32Denormals() && !UnsafeDiv)
    return false;

  IRBuilder<> Builder(FDiv.getParent(), std::next(FDiv.getIterator()), FPMath);
  Builder.setFastMathFlags(FMF);
  Builder.SetCurrentDebugLocation(FDiv.getDebugLoc());

  const AMDGPUIntrinsicInfo *II = TM->getIntrinsicInfo();
  Function *Decl
    = II->getDeclaration(Mod, AMDGPUIntrinsic::amdgcn_fdiv_fast, {});

  Value *Num = FDiv.getOperand(0);
  Value *Den = FDiv.getOperand(1);

  Value *NewFDiv = nullptr;

  if (VectorType *VT = dyn_cast<VectorType>(Ty)) {
    NewFDiv = UndefValue::get(VT);

    // FIXME: Doesn't do the right thing for cases where the vector is partially
    // constant. This works when the scalarizer pass is run first.
    for (unsigned I = 0, E = VT->getNumElements(); I != E; ++I) {
      Value *NumEltI = Builder.CreateExtractElement(Num, I);
      Value *DenEltI = Builder.CreateExtractElement(Den, I);
      Value *NewElt;

      if (shouldKeepFDivF32(NumEltI, UnsafeDiv)) {
        NewElt = Builder.CreateFDiv(NumEltI, DenEltI);
      } else {
        NewElt = Builder.CreateCall(Decl, { NumEltI, DenEltI });
      }

      NewFDiv = Builder.CreateInsertElement(NewFDiv, NewElt, I);
    }
  } else {
    if (!shouldKeepFDivF32(Num, UnsafeDiv))
      NewFDiv = Builder.CreateCall(Decl, { Num, Den });
  }

  if (NewFDiv) {
    FDiv.replaceAllUsesWith(NewFDiv);
    NewFDiv->takeName(&FDiv);
    FDiv.eraseFromParent();
  }

  return true;
}