path: root/lib/Transforms/InstCombine/InstCombineCalls.cpp

//===- InstCombineCalls.cpp -----------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the visitCall and visitInvoke functions.
//
//===----------------------------------------------------------------------===//

#include "InstCombine.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Transforms/Utils/BuildLibCalls.h"
#include "llvm/Transforms/Utils/Local.h"
using namespace llvm;

/// getPromotedType - Return the specified type promoted as it would be to pass
/// though a va_arg area.
static const Type *getPromotedType(const Type *Ty) {
  if (const IntegerType* ITy = dyn_cast<IntegerType>(Ty)) {
    if (ITy->getBitWidth() < 32)
      return Type::getInt32Ty(Ty->getContext());
  }
  return Ty;
}


Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
  unsigned DstAlign = getKnownAlignment(MI->getArgOperand(0), TD);
  unsigned SrcAlign = getKnownAlignment(MI->getArgOperand(1), TD);
  unsigned MinAlign = std::min(DstAlign, SrcAlign);
  unsigned CopyAlign = MI->getAlignment();

  if (CopyAlign < MinAlign) {
    MI->setAlignment(ConstantInt::get(MI->getAlignmentType(), 
                                             MinAlign, false));
    return MI;
  }
  
  // If MemCpyInst length is 1/2/4/8 bytes then replace memcpy with
  // load/store.
  ConstantInt *MemOpLength = dyn_cast<ConstantInt>(MI->getArgOperand(2));
  if (MemOpLength == 0) return 0;
  
  // Source and destination pointer types are always "i8*" for intrinsic.  See
  // if the size is something we can handle with a single primitive load/store.
  // A single load+store correctly handles overlapping memory in the memmove
  // case.
  unsigned Size = MemOpLength->getZExtValue();
  if (Size == 0) return MI;  // Delete this mem transfer.
  
  if (Size > 8 || (Size&(Size-1)))
    return 0;  // If not 1/2/4/8 bytes, exit.
  
  // Use an integer load+store unless we can find something better.
  unsigned SrcAddrSp =
    cast<PointerType>(MI->getArgOperand(1)->getType())->getAddressSpace();
  unsigned DstAddrSp =
    cast<PointerType>(MI->getArgOperand(0)->getType())->getAddressSpace();

  const IntegerType* IntType = IntegerType::get(MI->getContext(), Size<<3