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Diffstat (limited to 'llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp')
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp | 546 |
1 files changed, 546 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp b/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp new file mode 100644 index 000000000000..cf6711adad48 --- /dev/null +++ b/llvm/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp @@ -0,0 +1,546 @@ +//===-- FunctionLoweringInfo.cpp ------------------------------------------===// +// +// 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 +// +//===----------------------------------------------------------------------===// +// +// This implements routines for translating functions from LLVM IR into +// Machine IR. +// +//===----------------------------------------------------------------------===// + +#include "llvm/CodeGen/FunctionLoweringInfo.h" +#include "llvm/Analysis/LegacyDivergenceAnalysis.h" +#include "llvm/CodeGen/Analysis.h" +#include "llvm/CodeGen/MachineFrameInfo.h" +#include "llvm/CodeGen/MachineFunction.h" +#include "llvm/CodeGen/MachineInstrBuilder.h" +#include "llvm/CodeGen/MachineRegisterInfo.h" +#include "llvm/CodeGen/TargetFrameLowering.h" +#include "llvm/CodeGen/TargetInstrInfo.h" +#include "llvm/CodeGen/TargetLowering.h" +#include "llvm/CodeGen/TargetRegisterInfo.h" +#include "llvm/CodeGen/TargetSubtargetInfo.h" +#include "llvm/CodeGen/WasmEHFuncInfo.h" +#include "llvm/CodeGen/WinEHFuncInfo.h" +#include "llvm/IR/DataLayout.h" +#include "llvm/IR/DerivedTypes.h" +#include "llvm/IR/Function.h" +#include "llvm/IR/Instructions.h" +#include "llvm/IR/IntrinsicInst.h" +#include "llvm/IR/LLVMContext.h" +#include "llvm/IR/Module.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/ErrorHandling.h" +#include "llvm/Support/MathExtras.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/Target/TargetOptions.h" +#include <algorithm> +using namespace llvm; + +#define DEBUG_TYPE "function-lowering-info" + +/// isUsedOutsideOfDefiningBlock - Return true if this instruction is used by +/// PHI nodes or outside of the basic block that defines it, or used by a +/// switch or atomic instruction, which may expand to multiple basic blocks. +static bool isUsedOutsideOfDefiningBlock(const Instruction *I) { + if (I->use_empty()) return false; + if (isa<PHINode>(I)) return true; + const BasicBlock *BB = I->getParent(); + for (const User *U : I->users()) + if (cast<Instruction>(U)->getParent() != BB || isa<PHINode>(U)) + return true; + + return false; +} + +static ISD::NodeType getPreferredExtendForValue(const Value *V) { + // For the users of the source value being used for compare instruction, if + // the number of signed predicate is greater than unsigned predicate, we + // prefer to use SIGN_EXTEND. + // + // With this optimization, we would be able to reduce some redundant sign or + // zero extension instruction, and eventually more machine CSE opportunities + // can be exposed. + ISD::NodeType ExtendKind = ISD::ANY_EXTEND; + unsigned NumOfSigned = 0, NumOfUnsigned = 0; + for (const User *U : V->users()) { + if (const auto *CI = dyn_cast<CmpInst>(U)) { + NumOfSigned += CI->isSigned(); + NumOfUnsigned += CI->isUnsigned(); + } + } + if (NumOfSigned > NumOfUnsigned) + ExtendKind = ISD::SIGN_EXTEND; + + return ExtendKind; +} + +void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf, + SelectionDAG *DAG) { + Fn = &fn; + MF = &mf; + TLI = MF->getSubtarget().getTargetLowering(); + RegInfo = &MF->getRegInfo(); + const TargetFrameLowering *TFI = MF->getSubtarget().getFrameLowering(); + unsigned StackAlign = TFI->getStackAlignment(); + DA = DAG->getDivergenceAnalysis(); + + // Check whether the function can return without sret-demotion. + SmallVector<ISD::OutputArg, 4> Outs; + CallingConv::ID CC = Fn->getCallingConv(); + + GetReturnInfo(CC, Fn->getReturnType(), Fn->getAttributes(), Outs, *TLI, + mf.getDataLayout()); + CanLowerReturn = + TLI->CanLowerReturn(CC, *MF, Fn->isVarArg(), Outs, Fn->getContext()); + + // If this personality uses funclets, we need to do a bit more work. + DenseMap<const AllocaInst *, TinyPtrVector<int *>> CatchObjects; + EHPersonality Personality = classifyEHPersonality( + Fn->hasPersonalityFn() ? Fn->getPersonalityFn() : nullptr); + if (isFuncletEHPersonality(Personality)) { + // Calculate state numbers if we haven't already. + WinEHFuncInfo &EHInfo = *MF->getWinEHFuncInfo(); + if (Personality == EHPersonality::MSVC_CXX) + calculateWinCXXEHStateNumbers(&fn, EHInfo); + else if (isAsynchronousEHPersonality(Personality)) + calculateSEHStateNumbers(&fn, EHInfo); + else if (Personality == EHPersonality::CoreCLR) + calculateClrEHStateNumbers(&fn, EHInfo); + + // Map all BB references in the WinEH data to MBBs. + for (WinEHTryBlockMapEntry &TBME : EHInfo.TryBlockMap) { + for (WinEHHandlerType &H : TBME.HandlerArray) { + if (const AllocaInst *AI = H.CatchObj.Alloca) + CatchObjects.insert({AI, {}}).first->second.push_back( + &H.CatchObj.FrameIndex); + else + H.CatchObj.FrameIndex = INT_MAX; + } + } + } + if (Personality == EHPersonality::Wasm_CXX) { + WasmEHFuncInfo &EHInfo = *MF->getWasmEHFuncInfo(); + calculateWasmEHInfo(&fn, EHInfo); + } + + // Initialize the mapping of values to registers. This is only set up for + // instruction values that are used outside of the block that defines + // them. + for (const BasicBlock &BB : *Fn) { + for (const Instruction &I : BB) { + if (const AllocaInst *AI = dyn_cast<AllocaInst>(&I)) { + Type *Ty = AI->getAllocatedType(); + unsigned Align = + std::max((unsigned)MF->getDataLayout().getPrefTypeAlignment(Ty), + AI->getAlignment()); + + // Static allocas can be folded into the initial stack frame + // adjustment. For targets that don't realign the stack, don't + // do this if there is an extra alignment requirement. + if (AI->isStaticAlloca() && + (TFI->isStackRealignable() || (Align <= StackAlign))) { + const ConstantInt *CUI = cast<ConstantInt>(AI->getArraySize()); + uint64_t TySize = MF->getDataLayout().getTypeAllocSize(Ty); + + TySize *= CUI->getZExtValue(); // Get total allocated size. + if (TySize == 0) TySize = 1; // Don't create zero-sized stack objects. + int FrameIndex = INT_MAX; + auto Iter = CatchObjects.find(AI); + if (Iter != CatchObjects.end() && TLI->needsFixedCatchObjects()) { + FrameIndex = MF->getFrameInfo().CreateFixedObject( + TySize, 0, /*IsImmutable=*/false, /*isAliased=*/true); + MF->getFrameInfo().setObjectAlignment(FrameIndex, Align); + } else { + FrameIndex = + MF->getFrameInfo().CreateStackObject(TySize, Align, false, AI); + } + + StaticAllocaMap[AI] = FrameIndex; + // Update the catch handler information. + if (Iter != CatchObjects.end()) { + for (int *CatchObjPtr : Iter->second) + *CatchObjPtr = FrameIndex; + } + } else { + // FIXME: Overaligned static allocas should be grouped into + // a single dynamic allocation instead of using a separate + // stack allocation for each one. + if (Align <= StackAlign) + Align = 0; + // Inform the Frame Information that we have variable-sized objects. + MF->getFrameInfo().CreateVariableSizedObject(Align ? Align : 1, AI); + } + } + + // Look for inline asm that clobbers the SP register. + if (isa<CallInst>(I) || isa<InvokeInst>(I)) { + ImmutableCallSite CS(&I); + if (isa<InlineAsm>(CS.getCalledValue())) { + unsigned SP = TLI->getStackPointerRegisterToSaveRestore(); + const TargetRegisterInfo *TRI = MF->getSubtarget().getRegisterInfo(); + std::vector<TargetLowering::AsmOperandInfo> Ops = + TLI->ParseConstraints(Fn->getParent()->getDataLayout(), TRI, CS); + for (TargetLowering::AsmOperandInfo &Op : Ops) { + if (Op.Type == InlineAsm::isClobber) { + // Clobbers don't have SDValue operands, hence SDValue(). + TLI->ComputeConstraintToUse(Op, SDValue(), DAG); + std::pair<unsigned, const TargetRegisterClass *> PhysReg = + TLI->getRegForInlineAsmConstraint(TRI, Op.ConstraintCode, + Op.ConstraintVT); + if (PhysReg.first == SP) + MF->getFrameInfo().setHasOpaqueSPAdjustment(true); + } + } + } + } + + // Look for calls to the @llvm.va_start intrinsic. We can omit some + // prologue boilerplate for variadic functions that don't examine their + // arguments. + if (const auto *II = dyn_cast<IntrinsicInst>(&I)) { + if (II->getIntrinsicID() == Intrinsic::vastart) + MF->getFrameInfo().setHasVAStart(true); + } + + // If we have a musttail call in a variadic function, we need to ensure we + // forward implicit register parameters. + if (const auto *CI = dyn_cast<CallInst>(&I)) { + if (CI->isMustTailCall() && Fn->isVarArg()) + MF->getFrameInfo().setHasMustTailInVarArgFunc(true); + } + + // Mark values used outside their block as exported, by allocating + // a virtual register for them. + if (isUsedOutsideOfDefiningBlock(&I)) + if (!isa<AllocaInst>(I) || !StaticAllocaMap.count(cast<AllocaInst>(&I))) + InitializeRegForValue(&I); + + // Decide the preferred extend type for a value. + PreferredExtendType[&I] = getPreferredExtendForValue(&I); + } + } + + // Create an initial MachineBasicBlock for each LLVM BasicBlock in F. This + // also creates the initial PHI MachineInstrs, though none of the input + // operands are populated. + for (const BasicBlock &BB : *Fn) { + // Don't create MachineBasicBlocks for imaginary EH pad blocks. These blocks + // are really data, and no instructions can live here. + if (BB.isEHPad()) { + const Instruction *PadInst = BB.getFirstNonPHI(); + // If this is a non-landingpad EH pad, mark this function as using + // funclets. + // FIXME: SEH catchpads do not create EH scope/funclets, so we could avoid + // setting this in such cases in order to improve frame layout. + if (!isa<LandingPadInst>(PadInst)) { + MF->setHasEHScopes(true); + MF->setHasEHFunclets(true); + MF->getFrameInfo().setHasOpaqueSPAdjustment(true); + } + if (isa<CatchSwitchInst>(PadInst)) { + assert(&*BB.begin() == PadInst && + "WinEHPrepare failed to remove PHIs from imaginary BBs"); + continue; + } + if (isa<FuncletPadInst>(PadInst)) + assert(&*BB.begin() == PadInst && "WinEHPrepare failed to demote PHIs"); + } + + MachineBasicBlock *MBB = mf.CreateMachineBasicBlock(&BB); + MBBMap[&BB] = MBB; + MF->push_back(MBB); + + // Transfer the address-taken flag. This is necessary because there could + // be multiple MachineBasicBlocks corresponding to one BasicBlock, and only + // the first one should be marked. + if (BB.hasAddressTaken()) + MBB->setHasAddressTaken(); + + // Mark landing pad blocks. + if (BB.isEHPad()) + MBB->setIsEHPad(); + + // Create Machine PHI nodes for LLVM PHI nodes, lowering them as + // appropriate. + for (const PHINode &PN : BB.phis()) { + if (PN.use_empty()) + continue; + + // Skip empty types + if (PN.getType()->isEmptyTy()) + continue; + + DebugLoc DL = PN.getDebugLoc(); + unsigned PHIReg = ValueMap[&PN]; + assert(PHIReg && "PHI node does not have an assigned virtual register!"); + + SmallVector<EVT, 4> ValueVTs; + ComputeValueVTs(*TLI, MF->getDataLayout(), PN.getType(), ValueVTs); + for (EVT VT : ValueVTs) { + unsigned NumRegisters = TLI->getNumRegisters(Fn->getContext(), VT); + const TargetInstrInfo *TII = MF->getSubtarget().getInstrInfo(); + for (unsigned i = 0; i != NumRegisters; ++i) + BuildMI(MBB, DL, TII->get(TargetOpcode::PHI), PHIReg + i); + PHIReg += NumRegisters; + } + } + } + + if (isFuncletEHPersonality(Personality)) { + WinEHFuncInfo &EHInfo = *MF->getWinEHFuncInfo(); + + // Map all BB references in the WinEH data to MBBs. + for (WinEHTryBlockMapEntry &TBME : EHInfo.TryBlockMap) { + for (WinEHHandlerType &H : TBME.HandlerArray) { + if (H.Handler) + H.Handler = MBBMap[H.Handler.get<const BasicBlock *>()]; + } + } + for (CxxUnwindMapEntry &UME : EHInfo.CxxUnwindMap) + if (UME.Cleanup) + UME.Cleanup = MBBMap[UME.Cleanup.get<const BasicBlock *>()]; + for (SEHUnwindMapEntry &UME : EHInfo.SEHUnwindMap) { + const auto *BB = UME.Handler.get<const BasicBlock *>(); + UME.Handler = MBBMap[BB]; + } + for (ClrEHUnwindMapEntry &CME : EHInfo.ClrEHUnwindMap) { + const auto *BB = CME.Handler.get<const BasicBlock *>(); + CME.Handler = MBBMap[BB]; + } + } + + else if (Personality == EHPersonality::Wasm_CXX) { + WasmEHFuncInfo &EHInfo = *MF->getWasmEHFuncInfo(); + // Map all BB references in the WinEH data to MBBs. + DenseMap<BBOrMBB, BBOrMBB> NewMap; + for (auto &KV : EHInfo.EHPadUnwindMap) { + const auto *Src = KV.first.get<const BasicBlock *>(); + const auto *Dst = KV.second.get<const BasicBlock *>(); + NewMap[MBBMap[Src]] = MBBMap[Dst]; + } + EHInfo.EHPadUnwindMap = std::move(NewMap); + } +} + +/// clear - Clear out all the function-specific state. This returns this +/// FunctionLoweringInfo to an empty state, ready to be used for a +/// different function. +void FunctionLoweringInfo::clear() { + MBBMap.clear(); + ValueMap.clear(); + VirtReg2Value.clear(); + StaticAllocaMap.clear(); + LiveOutRegInfo.clear(); + VisitedBBs.clear(); + ArgDbgValues.clear(); + DescribedArgs.clear(); + ByValArgFrameIndexMap.clear(); + RegFixups.clear(); + RegsWithFixups.clear(); + StatepointStackSlots.clear(); + StatepointSpillMaps.clear(); + PreferredExtendType.clear(); +} + +/// CreateReg - Allocate a single virtual register for the given type. +unsigned FunctionLoweringInfo::CreateReg(MVT VT, bool isDivergent) { + return RegInfo->createVirtualRegister( + MF->getSubtarget().getTargetLowering()->getRegClassFor(VT, isDivergent)); +} + +/// CreateRegs - Allocate the appropriate number of virtual registers of +/// the correctly promoted or expanded types. Assign these registers +/// consecutive vreg numbers and return the first assigned number. +/// +/// In the case that the given value has struct or array type, this function +/// will assign registers for each member or element. +/// +unsigned FunctionLoweringInfo::CreateRegs(Type *Ty, bool isDivergent) { + const TargetLowering *TLI = MF->getSubtarget().getTargetLowering(); + + SmallVector<EVT, 4> ValueVTs; + ComputeValueVTs(*TLI, MF->getDataLayout(), Ty, ValueVTs); + + unsigned FirstReg = 0; + for (unsigned Value = 0, e = ValueVTs.size(); Value != e; ++Value) { + EVT ValueVT = ValueVTs[Value]; + MVT RegisterVT = TLI->getRegisterType(Ty->getContext(), ValueVT); + + unsigned NumRegs = TLI->getNumRegisters(Ty->getContext(), ValueVT); + for (unsigned i = 0; i != NumRegs; ++i) { + unsigned R = CreateReg(RegisterVT, isDivergent); + if (!FirstReg) FirstReg = R; + } + } + return FirstReg; +} + +unsigned FunctionLoweringInfo::CreateRegs(const Value *V) { + return CreateRegs(V->getType(), DA && !TLI->requiresUniformRegister(*MF, V) && + DA->isDivergent(V)); +} + +/// GetLiveOutRegInfo - Gets LiveOutInfo for a register, returning NULL if the +/// register is a PHI destination and the PHI's LiveOutInfo is not valid. If +/// the register's LiveOutInfo is for a smaller bit width, it is extended to +/// the larger bit width by zero extension. The bit width must be no smaller +/// than the LiveOutInfo's existing bit width. +const FunctionLoweringInfo::LiveOutInfo * +FunctionLoweringInfo::GetLiveOutRegInfo(unsigned Reg, unsigned BitWidth) { + if (!LiveOutRegInfo.inBounds(Reg)) + return nullptr; + + LiveOutInfo *LOI = &LiveOutRegInfo[Reg]; + if (!LOI->IsValid) + return nullptr; + + if (BitWidth > LOI->Known.getBitWidth()) { + LOI->NumSignBits = 1; + LOI->Known = LOI->Known.zext(BitWidth, false /* => any extend */); + } + + return LOI; +} + +/// ComputePHILiveOutRegInfo - Compute LiveOutInfo for a PHI's destination +/// register based on the LiveOutInfo of its operands. +void FunctionLoweringInfo::ComputePHILiveOutRegInfo(const PHINode *PN) { + Type *Ty = PN->getType(); + if (!Ty->isIntegerTy() || Ty->isVectorTy()) + return; + + SmallVector<EVT, 1> ValueVTs; + ComputeValueVTs(*TLI, MF->getDataLayout(), Ty, ValueVTs); + assert(ValueVTs.size() == 1 && + "PHIs with non-vector integer types should have a single VT."); + EVT IntVT = ValueVTs[0]; + + if (TLI->getNumRegisters(PN->getContext(), IntVT) != 1) + return; + IntVT = TLI->getTypeToTransformTo(PN->getContext(), IntVT); + unsigned BitWidth = IntVT.getSizeInBits(); + + unsigned DestReg = ValueMap[PN]; + if (!Register::isVirtualRegister(DestReg)) + return; + LiveOutRegInfo.grow(DestReg); + LiveOutInfo &DestLOI = LiveOutRegInfo[DestReg]; + + Value *V = PN->getIncomingValue(0); + if (isa<UndefValue>(V) || isa<ConstantExpr>(V)) { + DestLOI.NumSignBits = 1; + DestLOI.Known = KnownBits(BitWidth); + return; + } + + if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { + APInt Val = CI->getValue().zextOrTrunc(BitWidth); + DestLOI.NumSignBits = Val.getNumSignBits(); + DestLOI.Known.Zero = ~Val; + DestLOI.Known.One = Val; + } else { + assert(ValueMap.count(V) && "V should have been placed in ValueMap when its" + "CopyToReg node was created."); + unsigned SrcReg = ValueMap[V]; + if (!Register::isVirtualRegister(SrcReg)) { + DestLOI.IsValid = false; + return; + } + const LiveOutInfo *SrcLOI = GetLiveOutRegInfo(SrcReg, BitWidth); + if (!SrcLOI) { + DestLOI.IsValid = false; + return; + } + DestLOI = *SrcLOI; + } + + assert(DestLOI.Known.Zero.getBitWidth() == BitWidth && + DestLOI.Known.One.getBitWidth() == BitWidth && + "Masks should have the same bit width as the type."); + + for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i) { + Value *V = PN->getIncomingValue(i); + if (isa<UndefValue>(V) || isa<ConstantExpr>(V)) { + DestLOI.NumSignBits = 1; + DestLOI.Known = KnownBits(BitWidth); + return; + } + + if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { + APInt Val = CI->getValue().zextOrTrunc(BitWidth); + DestLOI.NumSignBits = std::min(DestLOI.NumSignBits, Val.getNumSignBits()); + DestLOI.Known.Zero &= ~Val; + DestLOI.Known.One &= Val; + continue; + } + + assert(ValueMap.count(V) && "V should have been placed in ValueMap when " + "its CopyToReg node was created."); + unsigned SrcReg = ValueMap[V]; + if (!Register::isVirtualRegister(SrcReg)) { + DestLOI.IsValid = false; + return; + } + const LiveOutInfo *SrcLOI = GetLiveOutRegInfo(SrcReg, BitWidth); + if (!SrcLOI) { + DestLOI.IsValid = false; + return; + } + DestLOI.NumSignBits = std::min(DestLOI.NumSignBits, SrcLOI->NumSignBits); + DestLOI.Known.Zero &= SrcLOI->Known.Zero; + DestLOI.Known.One &= SrcLOI->Known.One; + } +} + +/// setArgumentFrameIndex - Record frame index for the byval +/// argument. This overrides previous frame index entry for this argument, +/// if any. +void FunctionLoweringInfo::setArgumentFrameIndex(const Argument *A, + int FI) { + ByValArgFrameIndexMap[A] = FI; +} + +/// getArgumentFrameIndex - Get frame index for the byval argument. +/// If the argument does not have any assigned frame index then 0 is +/// returned. +int FunctionLoweringInfo::getArgumentFrameIndex(const Argument *A) { + auto I = ByValArgFrameIndexMap.find(A); + if (I != ByValArgFrameIndexMap.end()) + return I->second; + LLVM_DEBUG(dbgs() << "Argument does not have assigned frame index!\n"); + return INT_MAX; +} + +unsigned FunctionLoweringInfo::getCatchPadExceptionPointerVReg( + const Value *CPI, const TargetRegisterClass *RC) { + MachineRegisterInfo &MRI = MF->getRegInfo(); + auto I = CatchPadExceptionPointers.insert({CPI, 0}); + unsigned &VReg = I.first->second; + if (I.second) + VReg = MRI.createVirtualRegister(RC); + assert(VReg && "null vreg in exception pointer table!"); + return VReg; +} + +const Value * +FunctionLoweringInfo::getValueFromVirtualReg(unsigned Vreg) { + if (VirtReg2Value.empty()) { + SmallVector<EVT, 4> ValueVTs; + for (auto &P : ValueMap) { + ValueVTs.clear(); + ComputeValueVTs(*TLI, Fn->getParent()->getDataLayout(), + P.first->getType(), ValueVTs); + unsigned Reg = P.second; + for (EVT VT : ValueVTs) { + unsigned NumRegisters = TLI->getNumRegisters(Fn->getContext(), VT); + for (unsigned i = 0, e = NumRegisters; i != e; ++i) + VirtReg2Value[Reg++] = P.first; + } + } + } + return VirtReg2Value.lookup(Vreg); +} |