third_party/subzero/src/IcePhiLoweringImpl.h

//===------ subzero/src/IcePhiLoweringImpl.h - Phi lowering -----*- C++ -*-===//
//
//                        The Subzero Code Generator
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
/// \brief Utilities for targets to lower Phis.
///
//===----------------------------------------------------------------------===//

#ifndef SUBZERO_SRC_ICEPHILOWERINGIMPL_H
#define SUBZERO_SRC_ICEPHILOWERINGIMPL_H

#include "IceCfg.h"
#include "IceCfgNode.h"
#include "IceDefs.h"
#include "IceInst.h"
#include "IceOperand.h"

namespace Ice {
namespace PhiLowering {

/// Turn an i64 Phi instruction into a pair of i32 Phi instructions, to preserve
/// integrity of liveness analysis. This is needed for 32-bit targets. This
/// assumes the 32-bit target has loOperand, hiOperand, and legalizeUndef
/// methods. Undef values are also legalized, since loOperand() and hiOperand()
/// don't expect Undef input.
template <class TargetT>
void prelowerPhis32Bit(TargetT *Target, CfgNode *Node, Cfg *Func) {
  for (Inst &I : Node->getPhis()) {
    auto *Phi = llvm::dyn_cast<InstPhi>(&I);
    if (Phi->isDeleted())
      continue;
    Variable *Dest = Phi->getDest();
    Type DestTy = Dest->getType();
    if (DestTy == IceType_i64) {
      auto *DestLo = llvm::cast<Variable>(Target->loOperand(Dest));
      auto *DestHi = llvm::cast<Variable>(Target->hiOperand(Dest));
      auto *PhiLo = InstPhi::create(Func, Phi->getSrcSize(), DestLo);
      auto *PhiHi = InstPhi::create(Func, Phi->getSrcSize(), DestHi);
      for (SizeT I = 0; I < Phi->getSrcSize(); ++I) {
        Operand *Src = Phi->getSrc(I);
        CfgNode *Label = Phi->getLabel(I);
        Src = Target->legalizeUndef(Src);
        PhiLo->addArgument(Target->loOperand(Src), Label);
        PhiHi->addArgument(Target->hiOperand(Src), Label);
      }
      Node->getPhis().push_back(PhiLo);
      Node->getPhis().push_back(PhiHi);
      Phi->setDeleted();
    } else if (isVectorType(DestTy) &&
               Target->shouldSplitToVariableVecOn32(DestTy)) {
      auto *DstVec = llvm::cast<VariableVecOn32>(Dest);
      SizeT Idx = 0;
      for (Variable *DestElem : DstVec->getContainers()) {
        auto *PhiElem = InstPhi::create(Func, Phi->getSrcSize(), DestElem);
        for (SizeT I = 0; I < Phi->getSrcSize(); ++I) {
          Operand *Src = Phi->getSrc(I);
          CfgNode *Label = Phi->getLabel(I);
          Src = Target->legalizeUndef(Src);
          auto *SrcVec = llvm::cast<VariableVecOn32>(Src);
          PhiElem->addArgument(SrcVec->getContainers()[Idx], Label);
        }
        ++Idx;
        Node->getPhis().push_back(PhiElem);
      }
      Phi->setDeleted();
    }
  }
}

} // end of namespace PhiLowering
} // end of namespace Ice

#endif // SUBZERO_SRC_ICEPHILOWERINGIMPL_H