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//===-- FunctionLoweringInfo.h - Lower functions from LLVM IR to CodeGen --===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This implements routines for translating functions from LLVM IR into
// Machine IR.
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/IndexedMap.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/CodeGen/ISDOpcodes.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/IR/InlineAsm.h"
#include "llvm/IR/Instructions.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include <vector>
namespace llvm {
class AllocaInst;
class BasicBlock;
class BranchProbabilityInfo;
class CallInst;
class Function;
class GlobalVariable;
class Instruction;
class MachineInstr;
class MachineBasicBlock;
class MachineFunction;
class MachineModuleInfo;
class MachineRegisterInfo;
class SelectionDAG;
class MVT;
class TargetLowering;
class Value;
/// FunctionLoweringInfo - This contains information that is global to a
/// function that is used when lowering a region of the function.
class FunctionLoweringInfo {
const Function *Fn;
MachineFunction *MF;
const TargetLowering *TLI;
MachineRegisterInfo *RegInfo;
BranchProbabilityInfo *BPI;
/// CanLowerReturn - true iff the function's return value can be lowered to
/// registers.
bool CanLowerReturn;
/// DemoteRegister - if CanLowerReturn is false, DemoteRegister is a vreg
/// allocated to hold a pointer to the hidden sret parameter.
unsigned DemoteRegister;
/// MBBMap - A mapping from LLVM basic blocks to their machine code entry.
DenseMap<const BasicBlock*, MachineBasicBlock *> MBBMap;
/// ValueMap - Since we emit code for the function a basic block at a time,
/// we must remember which virtual registers hold the values for
/// cross-basic-block values.
DenseMap<const Value*, unsigned> ValueMap;
// Keep track of frame indices allocated for statepoints as they could be used
// across basic block boundaries.
// Key of the map is statepoint instruction, value is a map from spilled
// llvm Value to the optional stack stack slot index.
// If optional is unspecified it means that we have visited this value
// but didn't spill it.
typedef DenseMap<const Value*, Optional<int>> StatepointSpilledValueMapTy;
DenseMap<const Instruction*, StatepointSpilledValueMapTy>
/// StaticAllocaMap - Keep track of frame indices for fixed sized allocas in
/// the entry block. This allows the allocas to be efficiently referenced
/// anywhere in the function.
DenseMap<const AllocaInst*, int> StaticAllocaMap;
/// ByValArgFrameIndexMap - Keep track of frame indices for byval arguments.
DenseMap<const Argument*, int> ByValArgFrameIndexMap;
/// ArgDbgValues - A list of DBG_VALUE instructions created during isel for
/// function arguments that are inserted after scheduling is completed.
SmallVector<MachineInstr*, 8> ArgDbgValues;
/// RegFixups - Registers which need to be replaced after isel is done.
DenseMap<unsigned, unsigned> RegFixups;
/// StatepointStackSlots - A list of temporary stack slots (frame indices)
/// used to spill values at a statepoint. We store them here to enable
/// reuse of the same stack slots across different statepoints in different
/// basic blocks.
SmallVector<unsigned, 50> StatepointStackSlots;
/// MBB - The current block.
MachineBasicBlock *MBB;
/// MBB - The current insert position inside the current block.
MachineBasicBlock::iterator InsertPt;
#ifndef NDEBUG
SmallPtrSet<const Instruction *, 8> CatchInfoLost;
SmallPtrSet<const Instruction *, 8> CatchInfoFound;
struct LiveOutInfo {
unsigned NumSignBits : 31;
bool IsValid : 1;
APInt KnownOne, KnownZero;
LiveOutInfo() : NumSignBits(0), IsValid(true), KnownOne(1, 0),
KnownZero(1, 0) {}
/// Record the preferred extend type (ISD::SIGN_EXTEND or ISD::ZERO_EXTEND)
/// for a value.
DenseMap<const Value *, ISD::NodeType> PreferredExtendType;
/// VisitedBBs - The set of basic blocks visited thus far by instruction
/// selection.
SmallPtrSet<const BasicBlock*, 4> VisitedBBs;
/// PHINodesToUpdate - A list of phi instructions whose operand list will
/// be updated after processing the current basic block.
/// TODO: This isn't per-function state, it's per-basic-block state. But
/// there's no other convenient place for it to live right now.
std::vector<std::pair<MachineInstr*, unsigned> > PHINodesToUpdate;
unsigned OrigNumPHINodesToUpdate;
/// If the current MBB is a landing pad, the exception pointer and exception
/// selector registers are copied into these virtual registers by
/// SelectionDAGISel::PrepareEHLandingPad().
unsigned ExceptionPointerVirtReg, ExceptionSelectorVirtReg;
/// set - Initialize this FunctionLoweringInfo with the given Function
/// and its associated MachineFunction.
void set(const Function &Fn, MachineFunction &MF, SelectionDAG *DAG);
/// 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 clear();
/// isExportedInst - Return true if the specified value is an instruction
/// exported from its block.
bool isExportedInst(const Value *V) {
return ValueMap.count(V);
unsigned CreateReg(MVT VT);
unsigned CreateRegs(Type *Ty);
unsigned InitializeRegForValue(const Value *V) {
unsigned &R = ValueMap[V];
assert(R == 0 && "Already initialized this value register!");
return R = CreateRegs(V->getType());
/// GetLiveOutRegInfo - Gets LiveOutInfo for a register, returning NULL if the
/// register is a PHI destination and the PHI's LiveOutInfo is not valid.
const LiveOutInfo *GetLiveOutRegInfo(unsigned Reg) {
if (!LiveOutRegInfo.inBounds(Reg))
return nullptr;
const LiveOutInfo *LOI = &LiveOutRegInfo[Reg];
if (!LOI->IsValid)
return nullptr;
return LOI;
/// 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 LiveOutInfo *GetLiveOutRegInfo(unsigned Reg, unsigned BitWidth);
/// AddLiveOutRegInfo - Adds LiveOutInfo for a register.
void AddLiveOutRegInfo(unsigned Reg, unsigned NumSignBits,
const APInt &KnownZero, const APInt &KnownOne) {
// Only install this information if it tells us something.
if (NumSignBits == 1 && KnownZero == 0 && KnownOne == 0)
LiveOutInfo &LOI = LiveOutRegInfo[Reg];
LOI.NumSignBits = NumSignBits;
LOI.KnownOne = KnownOne;
LOI.KnownZero = KnownZero;
/// ComputePHILiveOutRegInfo - Compute LiveOutInfo for a PHI's destination
/// register based on the LiveOutInfo of its operands.
void ComputePHILiveOutRegInfo(const PHINode*);
/// InvalidatePHILiveOutRegInfo - Invalidates a PHI's LiveOutInfo, to be
/// called when a block is visited before all of its predecessors.
void InvalidatePHILiveOutRegInfo(const PHINode *PN) {
// PHIs with no uses have no ValueMap entry.
DenseMap<const Value*, unsigned>::const_iterator It = ValueMap.find(PN);
if (It == ValueMap.end())
unsigned Reg = It->second;
if (Reg == 0)
LiveOutRegInfo[Reg].IsValid = false;
/// setArgumentFrameIndex - Record frame index for the byval
/// argument.
void setArgumentFrameIndex(const Argument *A, int FI);
/// getArgumentFrameIndex - Get frame index for the byval argument.
int getArgumentFrameIndex(const Argument *A);
void addSEHHandlersForLPads(ArrayRef<const LandingPadInst *> LPads);
/// LiveOutRegInfo - Information about live out vregs.
IndexedMap<LiveOutInfo, VirtReg2IndexFunctor> LiveOutRegInfo;
/// ComputeUsesVAFloatArgument - Determine if any floating-point values are
/// being passed to this variadic function, and set the MachineModuleInfo's
/// usesVAFloatArgument flag if so. This flag is used to emit an undefined
/// reference to _fltused on Windows, which will link in MSVCRT's
/// floating-point support.
void ComputeUsesVAFloatArgument(const CallInst &I, MachineModuleInfo *MMI);
/// AddLandingPadInfo - Extract the exception handling information from the
/// landingpad instruction and add them to the specified machine module info.
void AddLandingPadInfo(const LandingPadInst &I, MachineModuleInfo &MMI,
MachineBasicBlock *MBB);
} // end namespace llvm