//===- 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 "InstCombineInternal.h" #include "llvm/ADT/Statistic.h" #include "llvm/Analysis/MemoryBuiltins.h" #include "llvm/IR/CallSite.h" #include "llvm/IR/Dominators.h" #include "llvm/IR/PatternMatch.h" #include "llvm/IR/Statepoint.h" #include "llvm/Transforms/Utils/BuildLibCalls.h" #include "llvm/Transforms/Utils/Local.h" #include "llvm/Transforms/Utils/SimplifyLibCalls.h" using namespace llvm; using namespace PatternMatch; #define DEBUG_TYPE "instcombine" STATISTIC(NumSimplified, "Number of library calls simplified"); /// getPromotedType - Return the specified type promoted as it would be to pass /// though a va_arg area. static Type *getPromotedType(Type *Ty) { if (IntegerType* ITy = dyn_cast(Ty)) { if (ITy->getBitWidth() < 32) return Type::getInt32Ty(Ty->getContext()); } return Ty; } /// reduceToSingleValueType - Given an aggregate type which ultimately holds a /// single scalar element, like {{{type}}} or [1 x type], return type. static Type *reduceToSingleValueType(Type *T) { while (!T->isSingleValueType()) { if (StructType *STy = dyn_cast(T)) { if (STy->getNumElements() == 1) T = STy->getElementType(0); else break; } else if (ArrayType *ATy = dyn_cast(T)) { if (ATy->getNumElements() == 1) T = ATy->getElementType(); else break; } else break; } return T; } Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) { unsigned DstAlign = getKnownAlignment(MI->getArgOperand(0), DL, MI, AC, DT); unsigned SrcAlign = getKnownAlignment(MI->getArgOperand(1), DL, MI, AC, DT); 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(MI->getArgOperand(2)); if (!MemOpLength) return nullptr; // 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. uint64_t Size = MemOpLength->getLimitedValue(); assert(Size && "0-sized memory transferring should be removed already."); if (Size > 8 || (Size&(Size-1))) return nullptr; // If not 1/2/4/8 bytes, exit. // Use an integer load+store unless we can find something better. unsigned SrcAddrSp = cast(MI->getArgOperand(1)->getType())->getAddressSpace(); unsigned DstAddrSp = cast(MI->getArgOperand(0)->getType())->getAddressSpace(); IntegerType* IntType = IntegerType::get(MI->getContext(), Size<<3); Type *NewSrcPtrTy = PointerType::get(IntType, SrcAddrSp); Type *NewDstPtrTy = PointerType::get(IntType, DstAddrSp); // Memcpy forces the use of i8* for the source and destination. That means // that if you're using memcpy to move one double around, you'll get a cast // from double* to i8*. We'd much rather use a double load+store rather than // an i64 load+store, here because this improves the odds that the source or // dest address will be promotable. See if we can find a better type than the // integer datatype. Value *StrippedDest = MI->getArgOperand(0)->stripPointerCasts(); MDNode *CopyMD = nullptr; if (StrippedDest != MI->getArgOperand(0)) { Type *SrcETy = cast(StrippedDest->getType()) ->getElementType(); if (SrcETy->isSized() && DL.getTypeStoreSize(SrcETy) == Size) { // The SrcETy might be something like {{{double}}} or [1 x double]. Rip // down through these levels if so. SrcETy = reduceToSingleValueType(SrcETy); if (SrcETy->isSingleValueType()) { NewSrcPtrTy = PointerType::get(SrcETy, SrcAddrSp); NewDstPtrTy = PointerType::get(SrcETy, DstAddrSp); // If the memcpy has metadata describing the members, see if we can // get the TBAA tag describing our copy. if (MDNode *M = MI->getMetadata(LLVMContext::MD_tbaa_struct)) { if (M->getNumOperands() == 3 && M->getOperand(0) && mdconst::hasa(M->getOperand(0)) && mdconst::extract(M->getOperand(0))->isNullValue() && M->getOperand(1) && mdconst::hasa(M->getOperand(1)) && mdconst::extract(M->getOperand(1))->getValue() == Size && M->getOperand(2) && isa(M->getOperand(2))) CopyMD = cast(M->getOperand(2)); } } } } // If the memcpy/memmove provides better alignment info than we can // infer, use it. SrcAlign = std::max(SrcAlign, CopyAlign); DstAlign = std::max(DstAlign, CopyAlign); Value *Src = Builder->CreateBitCast(MI->getArgOperand(1), NewSrcPtrTy); Value *Dest = Builder->CreateBitCast(MI->getArgOperand(0), NewDstPtrTy); LoadInst *L = Builder->CreateLoad(Src, MI->isVolatile()); L->setAlignment(SrcAlign); if (CopyMD) L->setMetadata(LLVMContext::MD_tbaa, CopyMD); StoreInst *S = Builder->CreateStore(L, Dest, MI->isVolatile()); S->setAlignment(DstAlign); if (CopyMD) S->setMetadata(LLVMContext::MD_tbaa, CopyMD); // Set the size of the copy to 0, it will be deleted on the next iteration. MI->setArgOperand(2, Constant::getNullValue(MemOpLength->getType())); return MI; } Instruction *InstCombiner::SimplifyMemSet(MemSetInst *MI) { unsigned Alignment = getKnownAlignment(MI->getDest(), DL, MI, AC, DT); if (MI->getAlignment() < Alignment) { MI->setAlignment(ConstantInt::get(MI->getAlignmentType(), Alignment, false)); return MI; } // Extract the length and alignment and fill if they are constant. ConstantInt *LenC = dyn_cast(MI->getLength()); ConstantInt *FillC = dyn_cast(MI->getValue()); if (!LenC || !FillC || !FillC->getType()->isIntegerTy(8)) return nullptr; uint64_t Len = LenC->getLimitedValue(); Alignment = MI->getAlignment(); assert(Len && "0-sized memory setting should be removed already."); // memset(s,c,n) -> store s, c (for n=1,2,4,8) if (Len <= 8 && isPowerOf2_32((uint32_t)Len)) { Type *ITy = IntegerType::get(MI->getContext(), Len*8); // n=1 -> i8. Value *Dest = MI->getDest(); unsigned DstAddrSp = cast(Dest->getType())->getAddressSpace(); Type *NewDstPtrTy = PointerType::get(ITy, DstAddrSp); Dest = Builder->CreateBitCast(Dest, NewDstPtrTy); // Alignment 0 is identity for alignment 1 for memset, but not store. if (Alignment == 0) Alignment = 1; // Extract the fill value and store. uint64_t Fill = FillC->getZExtValue()*0x0101010101010101ULL; StoreInst *S = Builder->CreateStore(ConstantInt::get(ITy, Fill), Dest, MI->isVolatile()); S->setAlignment(Alignment); // Set the size of the copy to 0, it will be deleted on the next iteration. MI->setLength(Constant::getNullValue(LenC->getType())); return MI; } return nullptr; } /// The shuffle mask for a perm2*128 selects any two halves of two 256-bit /// source vectors, unless a zero bit is set. If a zero bit is set, /// then ignore that half of the mask and clear that half of the vector. static Value *SimplifyX86vperm2(const IntrinsicInst &II, InstCombiner::BuilderTy &Builder) { if (auto CInt = dyn_cast(II.getArgOperand(2))) { VectorType *VecTy = cast(II.getType()); ConstantAggregateZero *ZeroVector = ConstantAggregateZero::get(VecTy); // The immediate permute control byte looks like this: // [1:0] - select 128 bits from sources for low half of destination // [2] - ignore // [3] - zero low half of destination // [5:4] - select 128 bits from sources for high half of destination // [6] - ignore // [7] - zero high half of destination uint8_t Imm = CInt->getZExtValue(); bool LowHalfZero = Imm & 0x08; bool HighHalfZero = Imm & 0x80; // If both zero mask bits are set, this was just a weird way to // generate a zero vector. if (LowHalfZero && HighHalfZero) return ZeroVector; // If 0 or 1 zero mask bits are set, this is a simple shuffle. unsigned NumElts = VecTy->getNumElements(); unsigned HalfSize = NumElts / 2; SmallVector ShuffleMask(NumElts); // The high bit of the selection field chooses the 1st or 2nd operand. bool LowInputSelect = Imm & 0x02; bool HighInputSelect = Imm & 0x20; // The low bit of the selection field chooses the low or high half // of the selected operand. bool LowHalfSelect = Imm & 0x01; bool HighHalfSelect = Imm & 0x10; // Determine which operand(s) are actually in use for this instruction. Value *V0 = LowInputSelect ? II.getArgOperand(1) : II.getArgOperand(0); Value *V1 = HighInputSelect ? II.getArgOperand(1) : II.getArgOperand(0); // If needed, replace operands based on zero mask. V0 = LowHalfZero ? ZeroVector : V0; V1 = HighHalfZero ? ZeroVector : V1; // Permute low half of result. unsigned StartIndex = LowHalfSelect ? HalfSize : 0; for (unsigned i = 0; i < HalfSize; ++i) ShuffleMask[i] = StartIndex + i; // Permute high half of result. StartIndex = HighHalfSelect ? HalfSize : 0; StartIndex += NumElts; for (unsigned i = 0; i < HalfSize; ++i) ShuffleMask[i + HalfSize] = StartIndex + i; return Builder.CreateShuffleVector(V0, V1, ShuffleMask); } return nullptr; } /// visitCallInst - CallInst simplification. This mostly only handles folding /// of intrinsic instructions. For normal calls, it allows visitCallSite to do /// the heavy lifting. /// Instruction *InstCombiner::visitCallInst(CallInst &CI) { if (isFreeCall(&CI, TLI)) return visitFree(CI); // If the caller function is nounwind, mark the call as nounwind, even if the // callee isn't. if (CI.getParent()->getParent()->doesNotThrow() && !CI.doesNotThrow()) { CI.setDoesNotThrow(); return &CI; } IntrinsicInst *II = dyn_cast(&CI); if (!II) return visitCallSite(&CI); // Intrinsics cannot occur in an invoke, so handle them here instead of in // visitCallSite. if (MemIntrinsic *MI = dyn_cast(II)) { bool Changed = false; // memmove/cpy/set of zero bytes is a noop. if (Constant *NumBytes = dyn_cast(MI->getLength())) { if (NumBytes->isNullValue()) return EraseInstFromFunction(CI); if (ConstantInt *CI = dyn_cast(NumBytes)) if (CI->getZExtValue() == 1) { // Replace the instruction with just byte operations. We would // transform other cases to loads/stores, but we don't know if // alignment is sufficient. } } // No other transformations apply to volatile transfers. if (MI->isVolatile()) return nullptr; // If we have a memmove and the source operation is a constant global, // then the source and dest pointers can't alias, so we can change this // into a call to memcpy. if (MemMoveInst *MMI = dyn_cast(MI)) { if (GlobalVariable *GVSrc = dyn_cast(MMI->getSource())) if (GVSrc->isConstant()) { Module *M = CI.getParent()->getParent()->getParent(); Intrinsic::ID MemCpyID = Intrinsic::memcpy; Type *Tys[3] = { CI.getArgOperand(0)->getType(), CI.getArgOperand(1)->getType(), CI.getArgOperand(2)->getType() }; CI.setCalledFunction(Intrinsic::getDeclaration(M, MemCpyID, Tys)); Changed = true; } } if (MemTransferInst *MTI = dyn_cast(MI)) { // memmove(x,x,size) -> noop. if (MTI->getSource() == MTI->getDest()) return EraseInstFromFunction(CI); } // If we can determine a pointer alignment that is bigger than currently // set, update the alignment. if (isa(MI)) { if (Instruction *I = SimplifyMemTransfer(MI)) return I; } else if (MemSetInst *MSI = dyn_cast(MI)) { if (Instruction *I = SimplifyMemSet(MSI)) return I; } if (Changed) return II; } switch (II->getIntrinsicID()) { default: break; case Intrinsic::objectsize: { uint64_t Size; if (getObjectSize(II->getArgOperand(0), Size, DL, TLI)) return ReplaceInstUsesWith(CI, ConstantInt::get(CI.getType(), Size)); return nullptr; } case Intrinsic::bswap: { Value *IIOperand = II->getArgOperand(0); Value *X = nullptr; // bswap(bswap(x)) -> x if (match(IIOperand, m_BSwap(m_Value(X)))) return ReplaceInstUsesWith(CI, X); // bswap(trunc(bswap(x))) -> trunc(lshr(x, c)) if (match(IIOperand, m_Trunc(m_BSwap(m_Value(X))))) { unsigned C = X->getType()->getPrimitiveSizeInBits() - IIOperand->getType()->getPrimitiveSizeInBits(); Value *CV = ConstantInt::get(X->getType(), C); Value *V = Builder->CreateLShr(X, CV); return new TruncInst(V, IIOperand->getType()); } break; } case Intrinsic::powi: if (ConstantInt *Power = dyn_cast(II->getArgOperand(1))) { // powi(x, 0) -> 1.0 if (Power->isZero()) return ReplaceInstUsesWith(CI, ConstantFP::get(CI.getType(), 1.0)); // powi(x, 1) -> x if (Power->isOne()) return ReplaceInstUsesWith(CI, II->getArgOperand(0)); // powi(x, -1) -> 1/x if (Power->isAllOnesValue()) return BinaryOperator::CreateFDiv(ConstantFP::get(CI.getType(), 1.0), II->getArgOperand(0)); } break; case Intrinsic::cttz: { // If all bits below the first known one are known zero, // this value is constant. IntegerType *IT = dyn_cast(II->getArgOperand(0)->getType()); // FIXME: Try to simplify vectors of integers. if (!IT) break; uint32_t BitWidth = IT->getBitWidth(); APInt KnownZero(BitWidth, 0); APInt KnownOne(BitWidth, 0); computeKnownBits(II->getArgOperand(0), KnownZero, KnownOne, 0, II); unsigned TrailingZeros = KnownOne.countTrailingZeros(); APInt Mask(APInt::getLowBitsSet(BitWidth, TrailingZeros)); if ((Mask & KnownZero) == Mask) return ReplaceInstUsesWith(CI, ConstantInt::get(IT, APInt(BitWidth, TrailingZeros))); } break; case Intrinsic::ctlz: { // If all bits above the first known one are known zero, // this value is constant. IntegerType *IT = dyn_cast(II->getArgOperand(0)->getType()); // FIXME: Try to simplify vectors of integers. if (!IT) break; uint32_t BitWidth = IT->getBitWidth(); APInt KnownZero(BitWidth, 0); APInt KnownOne(BitWidth, 0); computeKnownBits(II->getArgOperand(0), KnownZero, KnownOne, 0, II); unsigned LeadingZeros = KnownOne.countLeadingZeros(); APInt Mask(APInt::getHighBitsSet(BitWidth, LeadingZeros)); if ((Mask & KnownZero) == Mask) return ReplaceInstUsesWith(CI, ConstantInt::get(IT, APInt(BitWidth, LeadingZeros))); } break; case Intrinsic::uadd_with_overflow: { Value *LHS = II->getArgOperand(0), *RHS = II->getArgOperand(1); OverflowResult OR = computeOverflowForUnsignedAdd(LHS, RHS, II); if (OR == OverflowResult::NeverOverflows) return CreateOverflowTuple(II, Builder->CreateNUWAdd(LHS, RHS), false); if (OR == OverflowResult::AlwaysOverflows) return CreateOverflowTuple(II, Builder->CreateAdd(LHS, RHS), true); } // FALL THROUGH uadd into sadd case Intrinsic::sadd_with_overflow: // Canonicalize constants into the RHS. if (isa(II->getArgOperand(0)) && !isa(II->getArgOperand(1))) { Value *LHS = II->getArgOperand(0); II->setArgOperand(0, II->getArgOperand(1)); II->setArgOperand(1, LHS); return II; } // X + undef -> undef if (isa(II->getArgOperand(1))) return ReplaceInstUsesWith(CI, UndefValue::get(II->getType())); if (ConstantInt *RHS = dyn_cast(II->getArgOperand(1))) { // X + 0 -> {X, false} if (RHS->isZero()) { return CreateOverflowTuple(II, II->getArgOperand(0), false, /*ReUseName*/false); } } // We can strength reduce reduce this signed add into a regular add if we // can prove that it will never overflow. if (II->getIntrinsicID() == Intrinsic::sadd_with_overflow) { Value *LHS = II->getArgOperand(0), *RHS = II->getArgOperand(1); if (WillNotOverflowSignedAdd(LHS, RHS, *II)) { return CreateOverflowTuple(II, Builder->CreateNSWAdd(LHS, RHS), false); } } break; case Intrinsic::usub_with_overflow: case Intrinsic::ssub_with_overflow: { Value *LHS = II->getArgOperand(0), *RHS = II->getArgOperand(1); // undef - X -> undef // X - undef -> undef if (isa(LHS) || isa(RHS)) return ReplaceInstUsesWith(CI, UndefValue::get(II->getType())); if (ConstantInt *ConstRHS = dyn_cast(RHS)) { // X - 0 -> {X, false} if (ConstRHS->isZero()) { return CreateOverflowTuple(II, LHS, false, /*ReUseName*/false); } } if (II->getIntrinsicID() == Intrinsic::ssub_with_overflow) { if (WillNotOverflowSignedSub(LHS, RHS, *II)) { return CreateOverflowTuple(II, Builder->CreateNSWSub(LHS, RHS), false); } } else { if (WillNotOverflowUnsignedSub(LHS, RHS, *II)) { return CreateOverflowTuple(II, Builder->CreateNUWSub(LHS, RHS), false); } } break; } case Intrinsic::umul_with_overflow: { Value *LHS = II->getArgOperand(0), *RHS = II->getArgOperand(1); OverflowResult OR = computeOverflowForUnsignedMul(LHS, RHS, II); if (OR == OverflowResult::NeverOverflows) return CreateOverflowTuple(II, Builder->CreateNUWMul(LHS, RHS), false); if (OR == OverflowResult::AlwaysOverflows) return CreateOverflowTuple(II, Builder->CreateMul(LHS, RHS), true); } // FALL THROUGH case Intrinsic::smul_with_overflow: // Canonicalize constants into the RHS. if (isa(II->getArgOperand(0)) && !isa(II->getArgOperand(1))) { Value *LHS = II->getArgOperand(0); II->setArgOperand(0, II->getArgOperand(1)); II->setArgOperand(1, LHS); return II; } // X * undef -> undef if (isa(II->getArgOperand(1))) return ReplaceInstUsesWith(CI, UndefValue::get(II->getType())); if (ConstantInt *RHSI = dyn_cast(II->getArgOperand(1))) { // X*0 -> {0, false} if (RHSI->isZero()) return ReplaceInstUsesWith(CI, Constant::getNullValue(II->getType())); // X * 1 -> {X, false} if (RHSI->equalsInt(1)) { return CreateOverflowTuple(II, II->getArgOperand(0), false, /*ReUseName*/false); } } if (II->getIntrinsicID() == Intrinsic::smul_with_overflow) { Value *LHS = II->getArgOperand(0), *RHS = II->getArgOperand(1); if (WillNotOverflowSignedMul(LHS, RHS, *II)) { return CreateOverflowTuple(II, Builder->CreateNSWMul(LHS, RHS), false); } } break; case Intrinsic::minnum: case Intrinsic::maxnum: { Value *Arg0 = II->getArgOperand(0); Value *Arg1 = II->getArgOperand(1); // fmin(x, x) -> x if (Arg0 == Arg1) return ReplaceInstUsesWith(CI, Arg0); const ConstantFP *C0 = dyn_cast(Arg0); const ConstantFP *C1 = dyn_cast(Arg1); // Canonicalize constants into the RHS. if (C0 && !C1) { II->setArgOperand(0, Arg1); II->setArgOperand(1, Arg0); return II; } // fmin(x, nan) -> x if (C1 && C1->isNaN()) return ReplaceInstUsesWith(CI, Arg0); // This is the value because if undef were NaN, we would return the other // value and cannot return a NaN unless both operands are. // // fmin(undef, x) -> x if (isa(Arg0)) return ReplaceInstUsesWith(CI, Arg1); // fmin(x, undef) -> x if (isa(Arg1)) return ReplaceInstUsesWith(CI, Arg0); Value *X = nullptr; Value *Y = nullptr; if (II->getIntrinsicID() == Intrinsic::minnum) { // fmin(x, fmin(x, y)) -> fmin(x, y) // fmin(y, fmin(x, y)) -> fmin(x, y) if (match(Arg1, m_FMin(m_Value(X), m_Value(Y)))) { if (Arg0 == X || Arg0 == Y) return ReplaceInstUsesWith(CI, Arg1); } // fmin(fmin(x, y), x) -> fmin(x, y) // fmin(fmin(x, y), y) -> fmin(x, y) if (match(Arg0, m_FMin(m_Value(X), m_Value(Y)))) { if (Arg1 == X || Arg1 == Y) return ReplaceInstUsesWith(CI, Arg0); } // TODO: fmin(nnan x, inf) -> x // TODO: fmin(nnan ninf x, flt_max) -> x if (C1 && C1->isInfinity()) { // fmin(x, -inf) -> -inf if (C1->isNegative()) return ReplaceInstUsesWith(CI, Arg1); } } else { assert(II->getIntrinsicID() == Intrinsic::maxnum); // fmax(x, fmax(x, y)) -> fmax(x, y) // fmax(y, fmax(x, y)) -> fmax(x, y) if (match(Arg1, m_FMax(m_Value(X), m_Value(Y)))) { if (Arg0 == X || Arg0 == Y) return ReplaceInstUsesWith(CI, Arg1); } // fmax(fmax(x, y), x) -> fmax(x, y) // fmax(fmax(x, y), y) -> fmax(x, y) if (match(Arg0, m_FMax(m_Value(X), m_Value(Y)))) { if (Arg1 == X || Arg1 == Y) return ReplaceInstUsesWith(CI, Arg0); } // TODO: fmax(nnan x, -inf) -> x // TODO: fmax(nnan ninf x, -flt_max) -> x if (C1 && C1->isInfinity()) { // fmax(x, inf) -> inf if (!C1->isNegative()) return ReplaceInstUsesWith(CI, Arg1); } } break; } case Intrinsic::ppc_altivec_lvx: case Intrinsic::ppc_altivec_lvxl: // Turn PPC lvx -> load if the pointer is known aligned. if (getOrEnforceKnownAlignment(II->getArgOperand(0), 16, DL, II, AC, DT) >= 16) { Value *Ptr = Builder->CreateBitCast(II->getArgOperand(0), PointerType::getUnqual(II->getType())); return new LoadInst(Ptr); } break; case Intrinsic::ppc_vsx_lxvw4x: case Intrinsic::ppc_vsx_lxvd2x: { // Turn PPC VSX loads into normal loads. Value *Ptr = Builder->CreateBitCast(II->getArgOperand(0), PointerType::getUnqual(II->getType())); return new LoadInst(Ptr, Twine(""), false, 1); } case Intrinsic::ppc_altivec_stvx: case Intrinsic::ppc_altivec_stvxl: // Turn stvx -> store if the pointer is known aligned. if (getOrEnforceKnownAlignment(II->getArgOperand(1), 16, DL, II, AC, DT) >= 16) { Type *OpPtrTy = PointerType::getUnqual(II->getArgOperand(0)->getType()); Value *Ptr = Builder->CreateBitCast(II->getArgOperand(1), OpPtrTy); return new StoreInst(II->getArgOperand(0), Ptr); } break; case Intrinsic::ppc_vsx_stxvw4x: case Intrinsic::ppc_vsx_stxvd2x: { // Turn PPC VSX stores into normal stores. Type *OpPtrTy = PointerType::getUnqual(II->getArgOperand(0)->getType()); Value *Ptr = Builder->CreateBitCast(II->getArgOperand(1), OpPtrTy); return new StoreInst(II->getArgOperand(0), Ptr, false, 1); } case Intrinsic::ppc_qpx_qvlfs: // Turn PPC QPX qvlfs -> load if the pointer is known aligned. if (getOrEnforceKnownAlignment(II->getArgOperand(0), 16, DL, II, AC, DT) >= 16) { Value *Ptr = Builder->CreateBitCast(II->getArgOperand(0), PointerType::getUnqual(II->getType())); return new LoadInst(Ptr); } break; case Intrinsic::ppc_qpx_qvlfd: // Turn PPC QPX qvlfd -> load if the pointer is known aligned. if (getOrEnforceKnownAlignment(II->getArgOperand(0), 32, DL, II, AC, DT) >= 32) { Value *Ptr = Builder->CreateBitCast(II->getArgOperand(0), PointerType::getUnqual(II->getType())); return new LoadInst(Ptr); } break; case Intrinsic::ppc_qpx_qvstfs: // Turn PPC QPX qvstfs -> store if the pointer is known aligned. if (getOrEnforceKnownAlignment(II->getArgOperand(1), 16, DL, II, AC, DT) >= 16) { Type *OpPtrTy = PointerType::getUnqual(II->getArgOperand(0)->getType()); Value *Ptr = Builder->CreateBitCast(II->getArgOperand(1), OpPtrTy); return new StoreInst(II->getArgOperand(0), Ptr); } break; case Intrinsic::ppc_qpx_qvstfd: // Turn PPC QPX qvstfd -> store if the pointer is known aligned. if (getOrEnforceKnownAlignment(II->getArgOperand(1), 32, DL, II, AC, DT) >= 32) { Type *OpPtrTy = PointerType::getUnqual(II->getArgOperand(0)->getType()); Value *Ptr = Builder->CreateBitCast(II->getArgOperand(1), OpPtrTy); return new StoreInst(II->getArgOperand(0), Ptr); } break; case Intrinsic::x86_sse_storeu_ps: case Intrinsic::x86_sse2_storeu_pd: case Intrinsic::x86_sse2_storeu_dq: // Turn X86 storeu -> store if the pointer is known aligned. if (getOrEnforceKnownAlignment(II->getArgOperand(0), 16, DL, II, AC, DT) >= 16) { Type *OpPtrTy = PointerType::getUnqual(II->getArgOperand(1)->getType()); Value *Ptr = Builder->CreateBitCast(II->getArgOperand(0), OpPtrTy); return new StoreInst(II->getArgOperand(1), Ptr); } break; case Intrinsic::x86_sse_cvtss2si: case Intrinsic::x86_sse_cvtss2si64: case Intrinsic::x86_sse_cvttss2si: case Intrinsic::x86_sse_cvttss2si64: case Intrinsic::x86_sse2_cvtsd2si: case Intrinsic::x86_sse2_cvtsd2si64: case Intrinsic::x86_sse2_cvttsd2si: case Intrinsic::x86_sse2_cvttsd2si64: { // These intrinsics only demand the 0th element of their input vectors. If // we can simplify the input based on that, do so now. unsigned VWidth = cast(II->getArgOperand(0)->getType())->getNumElements(); APInt DemandedElts(VWidth, 1); APInt UndefElts(VWidth, 0); if (Value *V = SimplifyDemandedVectorElts(II->getArgOperand(0), DemandedElts, UndefElts)) { II->setArgOperand(0, V); return II; } break; } // Constant fold << Ci. // FIXME: We don't handle _dq because it's a shift of an i128, but is // represented in the IR as <2 x i64>. A per element shift is wrong. case Intrinsic::x86_sse2_psll_d: case Intrinsic::x86_sse2_psll_q: case Intrinsic::x86_sse2_psll_w: case Intrinsic::x86_sse2_pslli_d: case Intrinsic::x86_sse2_pslli_q: case Intrinsic::x86_sse2_pslli_w: case Intrinsic::x86_avx2_psll_d: case Intrinsic::x86_avx2_psll_q: case Intrinsic::x86_avx2_psll_w: case Intrinsic::x86_avx2_pslli_d: case Intrinsic::x86_avx2_pslli_q: case Intrinsic::x86_avx2_pslli_w: case Intrinsic::x86_sse2_psrl_d: case Intrinsic::x86_sse2_psrl_q: case Intrinsic::x86_sse2_psrl_w: case Intrinsic::x86_sse2_psrli_d: case Intrinsic::x86_sse2_psrli_q: case Intrinsic::x86_sse2_psrli_w: case Intrinsic::x86_avx2_psrl_d: case Intrinsic::x86_avx2_psrl_q: case Intrinsic::x86_avx2_psrl_w: case Intrinsic::x86_avx2_psrli_d: case Intrinsic::x86_avx2_psrli_q: case Intrinsic::x86_avx2_psrli_w: { // Simplify if count is constant. To 0 if >= BitWidth, // otherwise to shl/lshr. auto CDV = dyn_cast(II->getArgOperand(1)); auto CInt = dyn_cast(II->getArgOperand(1)); if (!CDV && !CInt) break; ConstantInt *Count; if (CDV) Count = cast(CDV->getElementAsConstant(0)); else Count = CInt; auto Vec = II->getArgOperand(0); auto VT = cast(Vec->getType()); if (Count->getZExtValue() > VT->getElementType()->getPrimitiveSizeInBits() - 1) return ReplaceInstUsesWith( CI, ConstantAggregateZero::get(Vec->getType())); bool isPackedShiftLeft = true; switch (II->getIntrinsicID()) { default : break; case Intrinsic::x86_sse2_psrl_d: case Intrinsic::x86_sse2_psrl_q: case Intrinsic::x86_sse2_psrl_w: case Intrinsic::x86_sse2_psrli_d: case Intrinsic::x86_sse2_psrli_q: case Intrinsic::x86_sse2_psrli_w: case Intrinsic::x86_avx2_psrl_d: case Intrinsic::x86_avx2_psrl_q: case Intrinsic::x86_avx2_psrl_w: case Intrinsic::x86_avx2_psrli_d: case Intrinsic::x86_avx2_psrli_q: case Intrinsic::x86_avx2_psrli_w: isPackedShiftLeft = false; break; } unsigned VWidth = VT->getNumElements(); // Get a constant vector of the same type as the first operand. auto VTCI = ConstantInt::get(VT->getElementType(), Count->getZExtValue()); if (isPackedShiftLeft) return BinaryOperator::CreateShl(Vec, Builder->CreateVectorSplat(VWidth, VTCI)); return BinaryOperator::CreateLShr(Vec, Builder->CreateVectorSplat(VWidth, VTCI)); } case Intrinsic::x86_sse41_pmovsxbw: case Intrinsic::x86_sse41_pmovsxwd: case Intrinsic::x86_sse41_pmovsxdq: case Intrinsic::x86_sse41_pmovzxbw: case Intrinsic::x86_sse41_pmovzxwd: case Intrinsic::x86_sse41_pmovzxdq: { // pmov{s|z}x ignores the upper half of their input vectors. unsigned VWidth = cast(II->getArgOperand(0)->getType())->getNumElements(); unsigned LowHalfElts = VWidth / 2; APInt InputDemandedElts(APInt::getBitsSet(VWidth, 0, LowHalfElts)); APInt UndefElts(VWidth, 0); if (Value *TmpV = SimplifyDemandedVectorElts( II->getArgOperand(0), InputDemandedElts, UndefElts)) { II->setArgOperand(0, TmpV); return II; } break; } case Intrinsic::x86_sse4a_insertqi: { // insertqi x, y, 64, 0 can just copy y's lower bits and leave the top // ones undef // TODO: eventually we should lower this intrinsic to IR if (auto CIWidth = dyn_cast(II->getArgOperand(2))) { if (auto CIStart = dyn_cast(II->getArgOperand(3))) { unsigned Index = CIStart->getZExtValue(); // From AMD documentation: "a value of zero in the field length is // defined as length of 64". unsigned Length = CIWidth->equalsInt(0) ? 64 : CIWidth->getZExtValue(); // From AMD documentation: "If the sum of the bit index + length field // is greater than 64, the results are undefined". // Note that both field index and field length are 8-bit quantities. // Since variables 'Index' and 'Length' are unsigned values // obtained from zero-extending field index and field length // respectively, their sum should never wrap around. if ((Index + Length) > 64) return ReplaceInstUsesWith(CI, UndefValue::get(II->getType())); if (Length == 64 && Index == 0) { Value *Vec = II->getArgOperand(1); Value *Undef = UndefValue::get(Vec->getType()); const uint32_t Mask[] = { 0, 2 }; return ReplaceInstUsesWith( CI, Builder->CreateShuffleVector( Vec, Undef, ConstantDataVector::get( II->getContext(), makeArrayRef(Mask)))); } else if (auto Source = dyn_cast(II->getArgOperand(0))) { if (Source->hasOneUse() && Source->getArgOperand(1) == II->getArgOperand(1)) { // If the source of the insert has only one use and it's another // insert (and they're both inserting from the same vector), try to // bundle both together. auto CISourceWidth = dyn_cast(Source->getArgOperand(2)); auto CISourceStart = dyn_cast(Source->getArgOperand(3)); if (CISourceStart && CISourceWidth) { unsigned Start = CIStart->getZExtValue(); unsigned Width = CIWidth->getZExtValue(); unsigned End = Start + Width; unsigned SourceStart = CISourceStart->getZExtValue(); unsigned SourceWidth = CISourceWidth->getZExtValue(); unsigned SourceEnd = SourceStart + SourceWidth; unsigned NewStart, NewWidth; bool ShouldReplace = false; if (Start <= SourceStart && SourceStart <= End) { NewStart = Start; NewWidth = std::max(End, SourceEnd) - NewStart; ShouldReplace = true; } else if (SourceStart <= Start && Start <= SourceEnd) { NewStart = SourceStart; NewWidth = std::max(SourceEnd, End) - NewStart; ShouldReplace = true; } if (ShouldReplace) { Constant *ConstantWidth = ConstantInt::get( II->getArgOperand(2)->getType(), NewWidth, false); Constant *ConstantStart = ConstantInt::get( II->getArgOperand(3)->getType(), NewStart, false); Value *Args[4] = { Source->getArgOperand(0), II->getArgOperand(1), ConstantWidth, ConstantStart }; Module *M = CI.getParent()->getParent()->getParent(); Value *F = Intrinsic::getDeclaration(M, Intrinsic::x86_sse4a_insertqi); return ReplaceInstUsesWith(CI, Builder->CreateCall(F, Args)); } } } } } } break; } case Intrinsic::x86_sse41_pblendvb: case Intrinsic::x86_sse41_blendvps: case Intrinsic::x86_sse41_blendvpd: case Intrinsic::x86_avx_blendv_ps_256: case Intrinsic::x86_avx_blendv_pd_256: case Intrinsic::x86_avx2_pblendvb: { // Convert blendv* to vector selects if the mask is constant. // This optimization is convoluted because the intrinsic is defined as // getting a vector of floats or doubles for the ps and pd versions. // FIXME: That should be changed. Value *Mask = II->getArgOperand(2); if (auto C = dyn_cast(Mask)) { auto Tyi1 = Builder->getInt1Ty(); auto SelectorType = cast(Mask->getType()); auto EltTy = SelectorType->getElementType(); unsigned Size = SelectorType->getNumElements(); unsigned BitWidth = EltTy->isFloatTy() ? 32 : (EltTy->isDoubleTy() ? 64 : EltTy->getIntegerBitWidth()); assert((BitWidth == 64 || BitWidth == 32 || BitWidth == 8) && "Wrong arguments for variable blend intrinsic"); SmallVector Selectors; for (unsigned I = 0; I < Size; ++I) { // The intrinsics only read the top bit uint64_t Selector; if (BitWidth == 8) Selector = C->getElementAsInteger(I); else Selector = C->getElementAsAPFloat(I).bitcastToAPInt().getZExtValue(); Selectors.push_back(ConstantInt::get(Tyi1, Selector >> (BitWidth - 1))); } auto NewSelector = ConstantVector::get(Selectors); return SelectInst::Create(NewSelector, II->getArgOperand(1), II->getArgOperand(0), "blendv"); } else { break; } } case Intrinsic::x86_avx_vpermilvar_ps: case Intrinsic::x86_avx_vpermilvar_ps_256: case Intrinsic::x86_avx_vpermilvar_pd: case Intrinsic::x86_avx_vpermilvar_pd_256: { // Convert vpermil* to shufflevector if the mask is constant. Value *V = II->getArgOperand(1); unsigned Size = cast(V->getType())->getNumElements(); assert(Size == 8 || Size == 4 || Size == 2); uint32_t Indexes[8]; if (auto C = dyn_cast(V)) { // The intrinsics only read one or two bits, clear the rest. for (unsigned I = 0; I < Size; ++I) { uint32_t Index = C->getElementAsInteger(I) & 0x3; if (II->getIntrinsicID() == Intrinsic::x86_avx_vpermilvar_pd || II->getIntrinsicID() == Intrinsic::x86_avx_vpermilvar_pd_256) Index >>= 1; Indexes[I] = Index; } } else if (isa(V)) { for (unsigned I = 0; I < Size; ++I) Indexes[I] = 0; } else { break; } // The _256 variants are a bit trickier since the mask bits always index // into the corresponding 128 half. In order to convert to a generic // shuffle, we have to make that explicit. if (II->getIntrinsicID() == Intrinsic::x86_avx_vpermilvar_ps_256 || II->getIntrinsicID() == Intrinsic::x86_avx_vpermilvar_pd_256) { for (unsigned I = Size / 2; I < Size; ++I) Indexes[I] += Size / 2; } auto NewC = ConstantDataVector::get(V->getContext(), makeArrayRef(Indexes, Size)); auto V1 = II->getArgOperand(0); auto V2 = UndefValue::get(V1->getType()); auto Shuffle = Builder->CreateShuffleVector(V1, V2, NewC); return ReplaceInstUsesWith(CI, Shuffle); } case Intrinsic::x86_avx_vperm2f128_pd_256: case Intrinsic::x86_avx_vperm2f128_ps_256: case Intrinsic::x86_avx_vperm2f128_si_256: case Intrinsic::x86_avx2_vperm2i128: if (Value *V = SimplifyX86vperm2(*II, *Builder)) return ReplaceInstUsesWith(*II, V); break; case Intrinsic::ppc_altivec_vperm: // Turn vperm(V1,V2,mask) -> shuffle(V1,V2,mask) if mask is a constant. // Note that ppc_altivec_vperm has a big-endian bias, so when creating // a vectorshuffle for little endian, we must undo the transformation // performed on vec_perm in altivec.h. That is, we must complement // the permutation mask with respect to 31 and reverse the order of // V1 and V2. if (Constant *Mask = dyn_cast(II->getArgOperand(2))) { assert(Mask->getType()->getVectorNumElements() == 16 && "Bad type for intrinsic!"); // Check that all of the elements are integer constants or undefs. bool AllEltsOk = true; for (unsigned i = 0; i != 16; ++i) { Constant *Elt = Mask->getAggregateElement(i); if (!Elt || !(isa(Elt) || isa(Elt))) { AllEltsOk = false; break; } } if (AllEltsOk) { // Cast the input vectors to byte vectors. Value *Op0 = Builder->CreateBitCast(II->getArgOperand(0), Mask->getType()); Value *Op1 = Builder->CreateBitCast(II->getArgOperand(1), Mask->getType()); Value *Result = UndefValue::get(Op0->getType()); // Only extract each element once. Value *ExtractedElts[32]; memset(ExtractedElts, 0, sizeof(ExtractedElts)); for (unsigned i = 0; i != 16; ++i) { if (isa(Mask->getAggregateElement(i))) continue; unsigned Idx = cast(Mask->getAggregateElement(i))->getZExtValue(); Idx &= 31; // Match the hardware behavior. if (DL.isLittleEndian()) Idx = 31 - Idx; if (!ExtractedElts[Idx]) { Value *Op0ToUse = (DL.isLittleEndian()) ? Op1 : Op0; Value *Op1ToUse = (DL.isLittleEndian()) ? Op0 : Op1; ExtractedElts[Idx] = Builder->CreateExtractElement(Idx < 16 ? Op0ToUse : Op1ToUse, Builder->getInt32(Idx&15)); } // Insert this value into the result vector. Result = Builder->CreateInsertElement(Result, ExtractedElts[Idx], Builder->getInt32(i)); } return CastInst::Create(Instruction::BitCast, Result, CI.getType()); } } break; case Intrinsic::arm_neon_vld1: case Intrinsic::arm_neon_vld2: case Intrinsic::arm_neon_vld3: case Intrinsic::arm_neon_vld4: case Intrinsic::arm_neon_vld2lane: case Intrinsic::arm_neon_vld3lane: case Intrinsic::arm_neon_vld4lane: case Intrinsic::arm_neon_vst1: case Intrinsic::arm_neon_vst2: case Intrinsic::arm_neon_vst3: case Intrinsic::arm_neon_vst4: case Intrinsic::arm_neon_vst2lane: case Intrinsic::arm_neon_vst3lane: case Intrinsic::arm_neon_vst4lane: { unsigned MemAlign = getKnownAlignment(II->getArgOperand(0), DL, II, AC, DT); unsigned AlignArg = II->getNumArgOperands() - 1; ConstantInt *IntrAlign = dyn_cast(II->getArgOperand(AlignArg)); if (IntrAlign && IntrAlign->getZExtValue() < MemAlign) { II->setArgOperand(AlignArg, ConstantInt::get(Type::getInt32Ty(II->getContext()), MemAlign, false)); return II; } break; } case Intrinsic::arm_neon_vmulls: case Intrinsic::arm_neon_vmullu: case Intrinsic::aarch64_neon_smull: case Intrinsic::aarch64_neon_umull: { Value *Arg0 = II->getArgOperand(0); Value *Arg1 = II->getArgOperand(1); // Handle mul by zero first: if (isa(Arg0) || isa(Arg1)) { return ReplaceInstUsesWith(CI, ConstantAggregateZero::get(II->getType())); } // Check for constant LHS & RHS - in this case we just simplify. bool Zext = (II->getIntrinsicID() == Intrinsic::arm_neon_vmullu || II->getIntrinsicID() == Intrinsic::aarch64_neon_umull); VectorType *NewVT = cast(II->getType()); if (Constant *CV0 = dyn_cast(Arg0)) { if (Constant *CV1 = dyn_cast(Arg1)) { CV0 = ConstantExpr::getIntegerCast(CV0, NewVT, /*isSigned=*/!Zext); CV1 = ConstantExpr::getIntegerCast(CV1, NewVT, /*isSigned=*/!Zext); return ReplaceInstUsesWith(CI, ConstantExpr::getMul(CV0, CV1)); } // Couldn't simplify - canonicalize constant to the RHS. std::swap(Arg0, Arg1); } // Handle mul by one: if (Constant *CV1 = dyn_cast(Arg1)) if (ConstantInt *Splat = dyn_cast_or_null(CV1->getSplatValue())) if (Splat->isOne()) return CastInst::CreateIntegerCast(Arg0, II->getType(), /*isSigned=*/!Zext); break; } case Intrinsic::AMDGPU_rcp: { if (const ConstantFP *C = dyn_cast(II->getArgOperand(0))) { const APFloat &ArgVal = C->getValueAPF(); APFloat Val(ArgVal.getSemantics(), 1.0); APFloat::opStatus Status = Val.divide(ArgVal, APFloat::rmNearestTiesToEven); // Only do this if it was exact and therefore not dependent on the // rounding mode. if (Status == APFloat::opOK) return ReplaceInstUsesWith(CI, ConstantFP::get(II->getContext(), Val)); } break; } case Intrinsic::stackrestore: { // If the save is right next to the restore, remove the restore. This can // happen when variable allocas are DCE'd. if (IntrinsicInst *SS = dyn_cast(II->getArgOperand(0))) { if (SS->getIntrinsicID() == Intrinsic::stacksave) { BasicBlock::iterator BI = SS; if (&*++BI == II) return EraseInstFromFunction(CI); } } // Scan down this block to see if there is another stack restore in the // same block without an intervening call/alloca. BasicBlock::iterator BI = II; TerminatorInst *TI = II->getParent()->getTerminator(); bool CannotRemove = false; for (++BI; &*BI != TI; ++BI) { if (isa(BI)) { CannotRemove = true; break; } if (CallInst *BCI = dyn_cast(BI)) { if (IntrinsicInst *II = dyn_cast(BCI)) { // If there is a stackrestore below this one, remove this one. if (II->getIntrinsicID() == Intrinsic::stackrestore) return EraseInstFromFunction(CI); // Otherwise, ignore the intrinsic. } else { // If we found a non-intrinsic call, we can't remove the stack // restore. CannotRemove = true; break; } } } // If the stack restore is in a return, resume, or unwind block and if there // are no allocas or calls between the restore and the return, nuke the // restore. if (!CannotRemove && (isa(TI) || isa(TI))) return EraseInstFromFunction(CI); break; } case Intrinsic::assume: { // Canonicalize assume(a && b) -> assume(a); assume(b); // Note: New assumption intrinsics created here are registered by // the InstCombineIRInserter object. Value *IIOperand = II->getArgOperand(0), *A, *B, *AssumeIntrinsic = II->getCalledValue(); if (match(IIOperand, m_And(m_Value(A), m_Value(B)))) { Builder->CreateCall(AssumeIntrinsic, A, II->getName()); Builder->CreateCall(AssumeIntrinsic, B, II->getName()); return EraseInstFromFunction(*II); } // assume(!(a || b)) -> assume(!a); assume(!b); if (match(IIOperand, m_Not(m_Or(m_Value(A), m_Value(B))))) { Builder->CreateCall(AssumeIntrinsic, Builder->CreateNot(A), II->getName()); Builder->CreateCall(AssumeIntrinsic, Builder->CreateNot(B), II->getName()); return EraseInstFromFunction(*II); } // assume( (load addr) != null ) -> add 'nonnull' metadata to load // (if assume is valid at the load) if (ICmpInst* ICmp = dyn_cast(IIOperand)) { Value *LHS = ICmp->getOperand(0); Value *RHS = ICmp->getOperand(1); if (ICmpInst::ICMP_NE == ICmp->getPredicate() && isa(LHS) && isa(RHS) && RHS->getType()->isPointerTy() && cast(RHS)->isNullValue()) { LoadInst* LI = cast(LHS); if (isValidAssumeForContext(II, LI, DT)) { MDNode *MD = MDNode::get(II->getContext(), None); LI->setMetadata(LLVMContext::MD_nonnull, MD); return EraseInstFromFunction(*II); } } // TODO: apply nonnull return attributes to calls and invokes // TODO: apply range metadata for range check patterns? } // If there is a dominating assume with the same condition as this one, // then this one is redundant, and should be removed. APInt KnownZero(1, 0), KnownOne(1, 0); computeKnownBits(IIOperand, KnownZero, KnownOne, 0, II); if (KnownOne.isAllOnesValue()) return EraseInstFromFunction(*II); break; } case Intrinsic::experimental_gc_relocate: { // Translate facts known about a pointer before relocating into // facts about the relocate value, while being careful to // preserve relocation semantics. GCRelocateOperands Operands(II); Value *DerivedPtr = Operands.derivedPtr(); // Remove the relocation if unused, note that this check is required // to prevent the cases below from looping forever. if (II->use_empty()) return EraseInstFromFunction(*II); // Undef is undef, even after relocation. // TODO: provide a hook for this in GCStrategy. This is clearly legal for // most practical collectors, but there was discussion in the review thread // about whether it was legal for all possible collectors. if (isa(DerivedPtr)) return ReplaceInstUsesWith(*II, DerivedPtr); // The relocation of null will be null for most any collector. // TODO: provide a hook for this in GCStrategy. There might be some weird // collector this property does not hold for. if (isa(DerivedPtr)) return ReplaceInstUsesWith(*II, DerivedPtr); // isKnownNonNull -> nonnull attribute if (isKnownNonNull(DerivedPtr)) II->addAttribute(AttributeSet::ReturnIndex, Attribute::NonNull); // isDereferenceablePointer -> deref attribute if (DerivedPtr->isDereferenceablePointer(DL)) { if (Argument *A = dyn_cast(DerivedPtr)) { uint64_t Bytes = A->getDereferenceableBytes(); II->addDereferenceableAttr(AttributeSet::ReturnIndex, Bytes); } } // TODO: bitcast(relocate(p)) -> relocate(bitcast(p)) // Canonicalize on the type from the uses to the defs // TODO: relocate((gep p, C, C2, ...)) -> gep(relocate(p), C, C2, ...) } } return visitCallSite(II); } // InvokeInst simplification // Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) { return visitCallSite(&II); } /// isSafeToEliminateVarargsCast - If this cast does not affect the value /// passed through the varargs area, we can eliminate the use of the cast. static bool isSafeToEliminateVarargsCast(const CallSite CS, const DataLayout &DL, const CastInst *const CI, const int ix) { if (!CI->isLosslessCast()) return false; // If this is a GC intrinsic, avoid munging types. We need types for // statepoint reconstruction in SelectionDAG. // TODO: This is probably something which should be expanded to all // intrinsics since the entire point of intrinsics is that // they are understandable by the optimizer. if (isStatepoint(CS) || isGCRelocate(CS) || isGCResult(CS)) return false; // The size of ByVal or InAlloca arguments is derived from the type, so we // can't change to a type with a different size. If the size were // passed explicitly we could avoid this check. if (!CS.isByValOrInAllocaArgument(ix)) return true; Type* SrcTy = cast(CI->getOperand(0)->getType())->getElementType(); Type* DstTy = cast(CI->getType())->getElementType(); if (!SrcTy->isSized() || !DstTy->isSized()) return false; if (DL.getTypeAllocSize(SrcTy) != DL.getTypeAllocSize(DstTy)) return false; return true; } // Try to fold some different type of calls here. // Currently we're only working with the checking functions, memcpy_chk, // mempcpy_chk, memmove_chk, memset_chk, strcpy_chk, stpcpy_chk, strncpy_chk, // strcat_chk and strncat_chk. Instruction *InstCombiner::tryOptimizeCall(CallInst *CI) { if (!CI->getCalledFunction()) return nullptr; auto InstCombineRAUW = [this](Instruction *From, Value *With) { ReplaceInstUsesWith(*From, With); }; LibCallSimplifier Simplifier(DL, TLI, InstCombineRAUW); if (Value *With = Simplifier.optimizeCall(CI)) { ++NumSimplified; return CI->use_empty() ? CI : ReplaceInstUsesWith(*CI, With); } return nullptr; } static IntrinsicInst *FindInitTrampolineFromAlloca(Value *TrampMem) { // Strip off at most one level of pointer casts, looking for an alloca. This // is good enough in practice and simpler than handling any number of casts. Value *Underlying = TrampMem->stripPointerCasts(); if (Underlying != TrampMem && (!Underlying->hasOneUse() || Underlying->user_back() != TrampMem)) return nullptr; if (!isa(Underlying)) return nullptr; IntrinsicInst *InitTrampoline = nullptr; for (User *U : TrampMem->users()) { IntrinsicInst *II = dyn_cast(U); if (!II) return nullptr; if (II->getIntrinsicID() == Intrinsic::init_trampoline) { if (InitTrampoline) // More than one init_trampoline writes to this value. Give up. return nullptr; InitTrampoline = II; continue; } if (II->getIntrinsicID() == Intrinsic::adjust_trampoline) // Allow any number of calls to adjust.trampoline. continue; return nullptr; } // No call to init.trampoline found. if (!InitTrampoline) return nullptr; // Check that the alloca is being used in the expected way. if (InitTrampoline->getOperand(0) != TrampMem) return nullptr; return InitTrampoline; } static IntrinsicInst *FindInitTrampolineFromBB(IntrinsicInst *AdjustTramp, Value *TrampMem) { // Visit all the previous instructions in the basic block, and try to find a // init.trampoline which has a direct path to the adjust.trampoline. for (BasicBlock::iterator I = AdjustTramp, E = AdjustTramp->getParent()->begin(); I != E; ) { Instruction *Inst = --I; if (IntrinsicInst *II = dyn_cast(I)) if (II->getIntrinsicID() == Intrinsic::init_trampoline && II->getOperand(0) == TrampMem) return II; if (Inst->mayWriteToMemory()) return nullptr; } return nullptr; } // Given a call to llvm.adjust.trampoline, find and return the corresponding // call to llvm.init.trampoline if the call to the trampoline can be optimized // to a direct call to a function. Otherwise return NULL. // static IntrinsicInst *FindInitTrampoline(Value *Callee) { Callee = Callee->stripPointerCasts(); IntrinsicInst *AdjustTramp = dyn_cast(Callee); if (!AdjustTramp || AdjustTramp->getIntrinsicID() != Intrinsic::adjust_trampoline) return nullptr; Value *TrampMem = AdjustTramp->getOperand(0); if (IntrinsicInst *IT = FindInitTrampolineFromAlloca(TrampMem)) return IT; if (IntrinsicInst *IT = FindInitTrampolineFromBB(AdjustTramp, TrampMem)) return IT; return nullptr; } // visitCallSite - Improvements for call and invoke instructions. // Instruction *InstCombiner::visitCallSite(CallSite CS) { if (isAllocLikeFn(CS.getInstruction(), TLI)) return visitAllocSite(*CS.getInstruction()); bool Changed = false; // If the callee is a pointer to a function, attempt to move any casts to the // arguments of the call/invoke. Value *Callee = CS.getCalledValue(); if (!isa(Callee) && transformConstExprCastCall(CS)) return nullptr; if (Function *CalleeF = dyn_cast(Callee)) // If the call and callee calling conventions don't match, this call must // be unreachable, as the call is undefined. if (CalleeF->getCallingConv() != CS.getCallingConv() && // Only do this for calls to a function with a body. A prototype may // not actually end up matching the implementation's calling conv for a // variety of reasons (e.g. it may be written in assembly). !CalleeF->isDeclaration()) { Instruction *OldCall = CS.getInstruction(); new StoreInst(ConstantInt::getTrue(Callee->getContext()), UndefValue::get(Type::getInt1PtrTy(Callee->getContext())), OldCall); // If OldCall does not return void then replaceAllUsesWith undef. // This allows ValueHandlers and custom metadata to adjust itself. if (!OldCall->getType()->isVoidTy()) ReplaceInstUsesWith(*OldCall, UndefValue::get(OldCall->getType())); if (isa(OldCall)) return EraseInstFromFunction(*OldCall); // We cannot remove an invoke, because it would change the CFG, just // change the callee to a null pointer. cast(OldCall)->setCalledFunction( Constant::getNullValue(CalleeF->getType())); return nullptr; } if (isa(Callee) || isa(Callee)) { // If CS does not return void then replaceAllUsesWith undef. // This allows ValueHandlers and custom metadata to adjust itself. if (!CS.getInstruction()->getType()->isVoidTy()) ReplaceInstUsesWith(*CS.getInstruction(), UndefValue::get(CS.getInstruction()->getType())); if (isa(CS.getInstruction())) { // Can't remove an invoke because we cannot change the CFG. return nullptr; } // This instruction is not reachable, just remove it. We insert a store to // undef so that we know that this code is not reachable, despite the fact // that we can't modify the CFG here. new StoreInst(ConstantInt::getTrue(Callee->getContext()), UndefValue::get(Type::getInt1PtrTy(Callee->getContext())), CS.getInstruction()); return EraseInstFromFunction(*CS.getInstruction()); } if (IntrinsicInst *II = FindInitTrampoline(Callee)) return transformCallThroughTrampoline(CS, II); PointerType *PTy = cast(Callee->getType()); FunctionType *FTy = cast(PTy->getElementType()); if (FTy->isVarArg()) { int ix = FTy->getNumParams(); // See if we can optimize any arguments passed through the varargs area of // the call. for (CallSite::arg_iterator I = CS.arg_begin() + FTy->getNumParams(), E = CS.arg_end(); I != E; ++I, ++ix) { CastInst *CI = dyn_cast(*I); if (CI && isSafeToEliminateVarargsCast(CS, DL, CI, ix)) { *I = CI->getOperand(0); Changed = true; } } } if (isa(Callee) && !CS.doesNotThrow()) { // Inline asm calls cannot throw - mark them 'nounwind'. CS.setDoesNotThrow(); Changed = true; } // Try to optimize the call if possible, we require DataLayout for most of // this. None of these calls are seen as possibly dead so go ahead and // delete the instruction now. if (CallInst *CI = dyn_cast(CS.getInstruction())) { Instruction *I = tryOptimizeCall(CI); // If we changed something return the result, etc. Otherwise let // the fallthrough check. if (I) return EraseInstFromFunction(*I); } return Changed ? CS.getInstruction() : nullptr; } // transformConstExprCastCall - If the callee is a constexpr cast of a function, // attempt to move the cast to the arguments of the call/invoke. // bool InstCombiner::transformConstExprCastCall(CallSite CS) { Function *Callee = dyn_cast(CS.getCalledValue()->stripPointerCasts()); if (!Callee) return false; // The prototype of thunks are a lie, don't try to directly call such // functions. if (Callee->hasFnAttribute("thunk")) return false; Instruction *Caller = CS.getInstruction(); const AttributeSet &CallerPAL = CS.getAttributes(); // Okay, this is a cast from a function to a different type. Unless doing so // would cause a type conversion of one of our arguments, change this call to // be a direct call with arguments casted to the appropriate types. // FunctionType *FT = Callee->getFunctionType(); Type *OldRetTy = Caller->getType(); Type *NewRetTy = FT->getReturnType(); // Check to see if we are changing the return type... if (OldRetTy != NewRetTy) { if (NewRetTy->isStructTy()) return false; // TODO: Handle multiple return values. if (!CastInst::isBitOrNoopPointerCastable(NewRetTy, OldRetTy, DL)) { if (Callee->isDeclaration()) return false; // Cannot transform this return value. if (!Caller->use_empty() && // void -> non-void is handled specially !NewRetTy->isVoidTy()) return false; // Cannot transform this return value. } if (!CallerPAL.isEmpty() && !Caller->use_empty()) { AttrBuilder RAttrs(CallerPAL, AttributeSet::ReturnIndex); if (RAttrs. hasAttributes(AttributeFuncs:: typeIncompatible(NewRetTy, AttributeSet::ReturnIndex), AttributeSet::ReturnIndex)) return false; // Attribute not compatible with transformed value. } // If the callsite is an invoke instruction, and the return value is used by // a PHI node in a successor, we cannot change the return type of the call // because there is no place to put the cast instruction (without breaking // the critical edge). Bail out in this case. if (!Caller->use_empty()) if (InvokeInst *II = dyn_cast(Caller)) for (User *U : II->users()) if (PHINode *PN = dyn_cast(U)) if (PN->getParent() == II->getNormalDest() || PN->getParent() == II->getUnwindDest()) return false; } unsigned NumActualArgs = CS.arg_size(); unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs); // Prevent us turning: // declare void @takes_i32_inalloca(i32* inalloca) // call void bitcast (void (i32*)* @takes_i32_inalloca to void (i32)*)(i32 0) // // into: // call void @takes_i32_inalloca(i32* null) // // Similarly, avoid folding away bitcasts of byval calls. if (Callee->getAttributes().hasAttrSomewhere(Attribute::InAlloca) || Callee->getAttributes().hasAttrSomewhere(Attribute::ByVal)) return false; CallSite::arg_iterator AI = CS.arg_begin(); for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) { Type *ParamTy = FT->getParamType(i); Type *ActTy = (*AI)->getType(); if (!CastInst::isBitOrNoopPointerCastable(ActTy, ParamTy, DL)) return false; // Cannot transform this parameter value. if (AttrBuilder(CallerPAL.getParamAttributes(i + 1), i + 1). hasAttributes(AttributeFuncs:: typeIncompatible(ParamTy, i + 1), i + 1)) return false; // Attribute not compatible with transformed value. if (CS.isInAllocaArgument(i)) return false; // Cannot transform to and from inalloca. // If the parameter is passed as a byval argument, then we have to have a // sized type and the sized type has to have the same size as the old type. if (ParamTy != ActTy && CallerPAL.getParamAttributes(i + 1).hasAttribute(i + 1, Attribute::ByVal)) { PointerType *ParamPTy = dyn_cast(ParamTy); if (!ParamPTy || !ParamPTy->getElementType()->isSized()) return false; Type *CurElTy = ActTy->getPointerElementType(); if (DL.getTypeAllocSize(CurElTy) != DL.getTypeAllocSize(ParamPTy->getElementType())) return false; } } if (Callee->isDeclaration()) { // Do not delete arguments unless we have a function body. if (FT->getNumParams() < NumActualArgs && !FT->isVarArg()) return false; // If the callee is just a declaration, don't change the varargsness of the // call. We don't want to introduce a varargs call where one doesn't // already exist. PointerType *APTy = cast(CS.getCalledValue()->getType()); if (FT->isVarArg()!=cast(APTy->getElementType())->isVarArg()) return false; // If both the callee and the cast type are varargs, we still have to make // sure the number of fixed parameters are the same or we have the same // ABI issues as if we introduce a varargs call. if (FT->isVarArg() && cast(APTy->getElementType())->isVarArg() && FT->getNumParams() != cast(APTy->getElementType())->getNumParams()) return false; } if (FT->getNumParams() < NumActualArgs && FT->isVarArg() && !CallerPAL.isEmpty()) // In this case we have more arguments than the new function type, but we // won't be dropping them. Check that these extra arguments have attributes // that are compatible with being a vararg call argument. for (unsigned i = CallerPAL.getNumSlots(); i; --i) { unsigned Index = CallerPAL.getSlotIndex(i - 1); if (Index <= FT->getNumParams()) break; // Check if it has an attribute that's incompatible with varargs. AttributeSet PAttrs = CallerPAL.getSlotAttributes(i - 1); if (PAttrs.hasAttribute(Index, Attribute::StructRet)) return false; } // Okay, we decided that this is a safe thing to do: go ahead and start // inserting cast instructions as necessary. std::vector Args; Args.reserve(NumActualArgs); SmallVector attrVec; attrVec.reserve(NumCommonArgs); // Get any return attributes. AttrBuilder RAttrs(CallerPAL, AttributeSet::ReturnIndex); // If the return value is not being used, the type may not be compatible // with the existing attributes. Wipe out any problematic attributes. RAttrs. removeAttributes(AttributeFuncs:: typeIncompatible(NewRetTy, AttributeSet::ReturnIndex), AttributeSet::ReturnIndex); // Add the new return attributes. if (RAttrs.hasAttributes()) attrVec.push_back(AttributeSet::get(Caller->getContext(), AttributeSet::ReturnIndex, RAttrs)); AI = CS.arg_begin(); for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) { Type *ParamTy = FT->getParamType(i); if ((*AI)->getType() == ParamTy) { Args.push_back(*AI); } else { Args.push_back(Builder->CreateBitOrPointerCast(*AI, ParamTy)); } // Add any parameter attributes. AttrBuilder PAttrs(CallerPAL.getParamAttributes(i + 1), i + 1); if (PAttrs.hasAttributes()) attrVec.push_back(AttributeSet::get(Caller->getContext(), i + 1, PAttrs)); } // If the function takes more arguments than the call was taking, add them // now. for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i) Args.push_back(Constant::getNullValue(FT->getParamType(i))); // If we are removing arguments to the function, emit an obnoxious warning. if (FT->getNumParams() < NumActualArgs) { // TODO: if (!FT->isVarArg()) this call may be unreachable. PR14722 if (FT->isVarArg()) { // Add all of the arguments in their promoted form to the arg list. for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) { Type *PTy = getPromotedType((*AI)->getType()); if (PTy != (*AI)->getType()) { // Must promote to pass through va_arg area! Instruction::CastOps opcode = CastInst::getCastOpcode(*AI, false, PTy, false); Args.push_back(Builder->CreateCast(opcode, *AI, PTy)); } else { Args.push_back(*AI); } // Add any parameter attributes. AttrBuilder PAttrs(CallerPAL.getParamAttributes(i + 1), i + 1); if (PAttrs.hasAttributes()) attrVec.push_back(AttributeSet::get(FT->getContext(), i + 1, PAttrs)); } } } AttributeSet FnAttrs = CallerPAL.getFnAttributes(); if (CallerPAL.hasAttributes(AttributeSet::FunctionIndex)) attrVec.push_back(AttributeSet::get(Callee->getContext(), FnAttrs)); if (NewRetTy->isVoidTy()) Caller->setName(""); // Void type should not have a name. const AttributeSet &NewCallerPAL = AttributeSet::get(Callee->getContext(), attrVec); Instruction *NC; if (InvokeInst *II = dyn_cast(Caller)) { NC = Builder->CreateInvoke(Callee, II->getNormalDest(), II->getUnwindDest(), Args); NC->takeName(II); cast(NC)->setCallingConv(II->getCallingConv()); cast(NC)->setAttributes(NewCallerPAL); } else { CallInst *CI = cast(Caller); NC = Builder->CreateCall(Callee, Args); NC->takeName(CI); if (CI->isTailCall()) cast(NC)->setTailCall(); cast(NC)->setCallingConv(CI->getCallingConv()); cast(NC)->setAttributes(NewCallerPAL); } // Insert a cast of the return type as necessary. Value *NV = NC; if (OldRetTy != NV->getType() && !Caller->use_empty()) { if (!NV->getType()->isVoidTy()) { NV = NC = CastInst::CreateBitOrPointerCast(NC, OldRetTy); NC->setDebugLoc(Caller->getDebugLoc()); // If this is an invoke instruction, we should insert it after the first // non-phi, instruction in the normal successor block. if (InvokeInst *II = dyn_cast(Caller)) { BasicBlock::iterator I = II->getNormalDest()->getFirstInsertionPt(); InsertNewInstBefore(NC, *I); } else { // Otherwise, it's a call, just insert cast right after the call. InsertNewInstBefore(NC, *Caller); } Worklist.AddUsersToWorkList(*Caller); } else { NV = UndefValue::get(Caller->getType()); } } if (!Caller->use_empty()) ReplaceInstUsesWith(*Caller, NV); else if (Caller->hasValueHandle()) { if (OldRetTy == NV->getType()) ValueHandleBase::ValueIsRAUWd(Caller, NV); else // We cannot call ValueIsRAUWd with a different type, and the // actual tracked value will disappear. ValueHandleBase::ValueIsDeleted(Caller); } EraseInstFromFunction(*Caller); return true; } // transformCallThroughTrampoline - Turn a call to a function created by // init_trampoline / adjust_trampoline intrinsic pair into a direct call to the // underlying function. // Instruction * InstCombiner::transformCallThroughTrampoline(CallSite CS, IntrinsicInst *Tramp) { Value *Callee = CS.getCalledValue(); PointerType *PTy = cast(Callee->getType()); FunctionType *FTy = cast(PTy->getElementType()); const AttributeSet &Attrs = CS.getAttributes(); // If the call already has the 'nest' attribute somewhere then give up - // otherwise 'nest' would occur twice after splicing in the chain. if (Attrs.hasAttrSomewhere(Attribute::Nest)) return nullptr; assert(Tramp && "transformCallThroughTrampoline called with incorrect CallSite."); Function *NestF =cast(Tramp->getArgOperand(1)->stripPointerCasts()); PointerType *NestFPTy = cast(NestF->getType()); FunctionType *NestFTy = cast(NestFPTy->getElementType()); const AttributeSet &NestAttrs = NestF->getAttributes(); if (!NestAttrs.isEmpty()) { unsigned NestIdx = 1; Type *NestTy = nullptr; AttributeSet NestAttr; // Look for a parameter marked with the 'nest' attribute. for (FunctionType::param_iterator I = NestFTy->param_begin(), E = NestFTy->param_end(); I != E; ++NestIdx, ++I) if (NestAttrs.hasAttribute(NestIdx, Attribute::Nest)) { // Record the parameter type and any other attributes. NestTy = *I; NestAttr = NestAttrs.getParamAttributes(NestIdx); break; } if (NestTy) { Instruction *Caller = CS.getInstruction(); std::vector NewArgs; NewArgs.reserve(CS.arg_size() + 1); SmallVector NewAttrs; NewAttrs.reserve(Attrs.getNumSlots() + 1); // Insert the nest argument into the call argument list, which may // mean appending it. Likewise for attributes. // Add any result attributes. if (Attrs.hasAttributes(AttributeSet::ReturnIndex)) NewAttrs.push_back(AttributeSet::get(Caller->getContext(), Attrs.getRetAttributes())); { unsigned Idx = 1; CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end(); do { if (Idx == NestIdx) { // Add the chain argument and attributes. Value *NestVal = Tramp->getArgOperand(2); if (NestVal->getType() != NestTy) NestVal = Builder->CreateBitCast(NestVal, NestTy, "nest"); NewArgs.push_back(NestVal); NewAttrs.push_back(AttributeSet::get(Caller->getContext(), NestAttr)); } if (I == E) break; // Add the original argument and attributes. NewArgs.push_back(*I); AttributeSet Attr = Attrs.getParamAttributes(Idx); if (Attr.hasAttributes(Idx)) { AttrBuilder B(Attr, Idx); NewAttrs.push_back(AttributeSet::get(Caller->getContext(), Idx + (Idx >= NestIdx), B)); } ++Idx, ++I; } while (1); } // Add any function attributes. if (Attrs.hasAttributes(AttributeSet::FunctionIndex)) NewAttrs.push_back(AttributeSet::get(FTy->getContext(), Attrs.getFnAttributes())); // The trampoline may have been bitcast to a bogus type (FTy). // Handle this by synthesizing a new function type, equal to FTy // with the chain parameter inserted. std::vector NewTypes; NewTypes.reserve(FTy->getNumParams()+1); // Insert the chain's type into the list of parameter types, which may // mean appending it. { unsigned Idx = 1; FunctionType::param_iterator I = FTy->param_begin(), E = FTy->param_end(); do { if (Idx == NestIdx) // Add the chain's type. NewTypes.push_back(NestTy); if (I == E) break; // Add the original type. NewTypes.push_back(*I); ++Idx, ++I; } while (1); } // Replace the trampoline call with a direct call. Let the generic // code sort out any function type mismatches. FunctionType *NewFTy = FunctionType::get(FTy->getReturnType(), NewTypes, FTy->isVarArg()); Constant *NewCallee = NestF->getType() == PointerType::getUnqual(NewFTy) ? NestF : ConstantExpr::getBitCast(NestF, PointerType::getUnqual(NewFTy)); const AttributeSet &NewPAL = AttributeSet::get(FTy->getContext(), NewAttrs); Instruction *NewCaller; if (InvokeInst *II = dyn_cast(Caller)) { NewCaller = InvokeInst::Create(NewCallee, II->getNormalDest(), II->getUnwindDest(), NewArgs); cast(NewCaller)->setCallingConv(II->getCallingConv()); cast(NewCaller)->setAttributes(NewPAL); } else { NewCaller = CallInst::Create(NewCallee, NewArgs); if (cast(Caller)->isTailCall()) cast(NewCaller)->setTailCall(); cast(NewCaller)-> setCallingConv(cast(Caller)->getCallingConv()); cast(NewCaller)->setAttributes(NewPAL); } return NewCaller; } } // Replace the trampoline call with a direct call. Since there is no 'nest' // parameter, there is no need to adjust the argument list. Let the generic // code sort out any function type mismatches. Constant *NewCallee = NestF->getType() == PTy ? NestF : ConstantExpr::getBitCast(NestF, PTy); CS.setCalledFunction(NewCallee); return CS.getInstruction(); }