llvm/lib/Analysis/MemoryLocation.cpp

//===- MemoryLocation.cpp - Memory location descriptions -------------------==//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include "llvm/Analysis/MemoryLocation.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/IntrinsicsARM.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
using namespace llvm;

void LocationSize::print(raw_ostream &OS) const {
  OS << "LocationSize::";
  if (*this == beforeOrAfterPointer())
    OS << "beforeOrAfterPointer";
  else if (*this == afterPointer())
    OS << "afterPointer";
  else if (*this == mapEmpty())
    OS << "mapEmpty";
  else if (*this == mapTombstone())
    OS << "mapTombstone";
  else if (isPrecise())
    OS << "precise(" << getValue() << ')';
  else
    OS << "upperBound(" << getValue() << ')';
}

MemoryLocation MemoryLocation::get(const LoadInst *LI) {
  const auto &DL = LI->getModule()->getDataLayout();

  return MemoryLocation(
      LI->getPointerOperand(),
      LocationSize::precise(DL.getTypeStoreSize(LI->getType())),
      LI->getAAMetadata());
}

MemoryLocation MemoryLocation::get(const StoreInst *SI) {
  const auto &DL = SI->getModule()->getDataLayout();

  return MemoryLocation(SI->getPointerOperand(),
                        LocationSize::precise(DL.getTypeStoreSize(
                            SI->getValueOperand()->getType())),
                        SI->getAAMetadata());
}

MemoryLocation MemoryLocation::get(const VAArgInst *VI) {
  return MemoryLocation(VI->getPointerOperand(),
                        LocationSize::afterPointer(), VI->getAAMetadata());
}

MemoryLocation MemoryLocation::get(const AtomicCmpXchgInst *CXI) {
  const auto &DL = CXI->getModule()->getDataLayout();

  return MemoryLocation(CXI->getPointerOperand(),
                        LocationSize::precise(DL.getTypeStoreSize(
                            CXI->getCompareOperand()->getType())),
                        CXI->getAAMetadata());
}

MemoryLocation MemoryLocation::get(const AtomicRMWInst *RMWI) {
  const auto &DL = RMWI->getModule()->getDataLayout();

  return MemoryLocation(RMWI->getPointerOperand(),
                        LocationSize::precise(DL.getTypeStoreSize(
                            RMWI->getValOperand()->getType())),
                        RMWI->getAAMetadata());
}

Optional<MemoryLocation> MemoryLocation::getOrNone(const Instruction *Inst) {
  switch (Inst->getOpcode()) {
  case Instruction::Load:
    return get(cast<LoadInst>(Inst));
  case Instruction::Store:
    return get(cast<StoreInst>(Inst));
  case Instruction::VAArg:
    return get(cast<VAArgInst>(Inst));
  case Instruction::AtomicCmpXchg:
    return get(cast<AtomicCmpXchgInst>(Inst));
  case Instruction::AtomicRMW:
    return get(cast<AtomicRMWInst>(Inst));
  default:
    return None;
  }
}

MemoryLocation MemoryLocation::getForSource(const MemTransferInst *MTI) {
  return getForSource(cast<AnyMemTransferInst>(MTI));
}

MemoryLocation MemoryLocation::getForSource(const AtomicMemTransferInst *MTI) {
  return getForSource(cast<AnyMemTransferInst>(MTI));
}

MemoryLocation MemoryLocation::getForSource(const AnyMemTransferInst *MTI) {
  auto Size = LocationSize::afterPointer();
  if (ConstantInt *C = dyn_cast<ConstantInt>(MTI->getLength()))
    Size = LocationSize::precise(C->getValue().getZExtValue());

  // memcpy/memmove can have AA tags. For memcpy, they apply
  // to both the source and the destination.
  return MemoryLocation(MTI->getRawSource(), Size, MTI->getAAMetadata());
}

MemoryLocation MemoryLocation::getForDest(const MemIntrinsic *MI) {
  return getForDest(cast<AnyMemIntrinsic>(MI));
}

MemoryLocation MemoryLocation::getForDest(const AtomicMemIntrinsic *MI) {
  return getForDest(cast<AnyMemIntrinsic>(MI));
}

MemoryLocation MemoryLocation::getForDest(const AnyMemIntrinsic *MI) {
  auto Size = LocationSize::afterPointer();
  if (ConstantInt *C = dyn_cast<ConstantInt>(MI->getLength()))
    Size = LocationSize::precise(C->getValue().getZExtValue());

  // memcpy/memmove can have AA tags. For memcpy, they apply
  // to both the source and the destination.
  return MemoryLocation(MI->getRawDest(), Size, MI->getAAMetadata());
}

MemoryLocation MemoryLocation::getForArgument(const CallBase *Call,
                                              unsigned ArgIdx,
                                              const TargetLibraryInfo *TLI) {
  AAMDNodes AATags = Call->getAAMetadata();
  const Value *Arg = Call->getArgOperand(ArgIdx);

  // We may be able to produce an exact size for known intrinsics.
  if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Call)) {
    const DataLayout &DL = II->getModule()->getDataLayout();

    switch (II->getIntrinsicID()) {
    default:
      break;
    case Intrinsic::memset:
    case Intrinsic::memcpy:
    case Intrinsic::memcpy_inline:
    case Intrinsic::memmove:
      assert((ArgIdx == 0 || ArgIdx == 1) &&
             "Invalid argument index for memory intrinsic");
      if (ConstantInt *LenCI = dyn_cast<ConstantInt>(II->getArgOperand(2)))
        return MemoryLocation(Arg, LocationSize::precise(LenCI->getZExtValue()),
                              AATags);
      return MemoryLocation::getAfter(Arg, AATags);

    case Intrinsic::lifetime_start:
    case Intrinsic::lifetime_end:
    case Intrinsic::invariant_start:
      assert(ArgIdx == 1 && "Invalid argument index");
      return MemoryLocation(
          Arg,
          LocationSize::precise(
              cast<ConstantInt>(II->getArgOperand(0))->getZExtValue()),
          AATags);

    case Intrinsic::masked_load:
      assert(ArgIdx == 0 && "Invalid argument index");
      return MemoryLocation(
          Arg,
          LocationSize::upperBound(DL.getTypeStoreSize(II->getType())),
          AATags);

    case Intrinsic::masked_store:
      assert(ArgIdx == 1 && "Invalid argument index");
      return MemoryLocation(
          Arg,
          LocationSize::upperBound(
              DL.getTypeStoreSize(II->getArgOperand(0)->getType())),
          AATags);

    case Intrinsic::invariant_end:
      // The first argument to an invariant.end is a "descriptor" type (e.g. a
      // pointer to a empty struct) which is never actually dereferenced.
      if (ArgIdx == 0)
        return MemoryLocation(Arg, LocationSize::precise(0), AATags);
      assert(ArgIdx == 2 && "Invalid argument index");
      return MemoryLocation(
          Arg,
          LocationSize::precise(
              cast<ConstantInt>(II->getArgOperand(1))->getZExtValue()),
          AATags);

    case Intrinsic::arm_neon_vld1:
      assert(ArgIdx == 0 && "Invalid argument index");
      // LLVM's vld1 and vst1 intrinsics currently only support a single
      // vector register.
      return MemoryLocation(
          Arg, LocationSize::precise(DL.getTypeStoreSize(II->getType())),
          AATags);

    case Intrinsic::arm_neon_vst1:
      assert(ArgIdx == 0 && "Invalid argument index");
      return MemoryLocation(Arg,
                            LocationSize::precise(DL.getTypeStoreSize(
                                II->getArgOperand(1)->getType())),
                            AATags);
    }
  }

  // We can bound the aliasing properties of memset_pattern16 just as we can
  // for memcpy/memset.  This is particularly important because the
  // LoopIdiomRecognizer likes to turn loops into calls to memset_pattern16
  // whenever possible.
  LibFunc F;
  if (TLI && TLI->getLibFunc(*Call, F) && TLI->has(F)) {
    switch (F) {
    case LibFunc_memset_pattern16:
      assert((ArgIdx == 0 || ArgIdx == 1) &&
             "Invalid argument index for memset_pattern16");
      if (ArgIdx == 1)
        return MemoryLocation(Arg, LocationSize::precise(16), AATags);
      if (const ConstantInt *LenCI =
              dyn_cast<ConstantInt>(Call->getArgOperand(2)))
        return MemoryLocation(Arg, LocationSize::precise(LenCI->getZExtValue()),
                              AATags);
      return MemoryLocation::getAfter(Arg, AATags);
    case LibFunc_bcmp:
    case LibFunc_memcmp:
      assert((ArgIdx == 0 || ArgIdx == 1) &&
             "Invalid argument index for memcmp/bcmp");
      if (const ConstantInt *LenCI =
              dyn_cast<ConstantInt>(Call->getArgOperand(2)))
        return MemoryLocation(Arg, LocationSize::precise(LenCI->getZExtValue()),
                              AATags);
      return MemoryLocation::getAfter(Arg, AATags);
    case LibFunc_memchr:
      assert((ArgIdx == 0) && "Invalid argument index for memchr");
      if (const ConstantInt *LenCI =
              dyn_cast<ConstantInt>(Call->getArgOperand(2)))
        return MemoryLocation(Arg, LocationSize::precise(LenCI->getZExtValue()),
                              AATags);
      return MemoryLocation::getAfter(Arg, AATags);
    case LibFunc_memccpy:
      assert((ArgIdx == 0 || ArgIdx == 1) &&
             "Invalid argument index for memccpy");
      // We only know an upper bound on the number of bytes read/written.
      if (const ConstantInt *LenCI =
              dyn_cast<ConstantInt>(Call->getArgOperand(3)))
        return MemoryLocation(
            Arg, LocationSize::upperBound(LenCI->getZExtValue()), AATags);
      return MemoryLocation::getAfter(Arg, AATags);
    default:
      break;
    };
  }
  // FIXME: Handle memset_pattern4 and memset_pattern8 also.

  return MemoryLocation::getBeforeOrAfter(Call->getArgOperand(ArgIdx), AATags);
}