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[DebugInfo][NFC] Move LiveDebugValues class to header 

This patch shifts the InstrRefBasedLDV class declaration to a header.
Partially because it's already massive, but mostly so that I can start
writing some unit tests for it. This patch also adds the boilerplate for
said unit tests.

Differential Revision: https://reviews.llvm.org/D110165
This commit is contained in:
Jeremy Morse 2021-10-12 15:55:46 +01:00
parent c8faeb1edd
commit 838b4a533e
4 changed files with 1115 additions and 964 deletions
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1141
llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
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llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.h Normal file
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//===- InstrRefBasedImpl.h - Tracking Debug Value MIs ---------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_CODEGEN_LIVEDEBUGVALUES_INSTRREFBASEDLDV_H
#define LLVM_LIB_CODEGEN_LIVEDEBUGVALUES_INSTRREFBASEDLDV_H
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/UniqueVector.h"
#include "llvm/CodeGen/LexicalScopes.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/TargetFrameLowering.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "LiveDebugValues.h"
class VLocTracker;
class TransferTracker;
// Forward dec of unit test class, so that we can peer into the LDV object.
class InstrRefLDVTest;
namespace LiveDebugValues {
class MLocTracker;
using namespace llvm;
/// Handle-class for a particular "location". This value-type uniquely
/// symbolises a register or stack location, allowing manipulation of locations
/// without concern for where that location is. Practically, this allows us to
/// treat the state of the machine at a particular point as an array of values,
/// rather than a map of values.
class LocIdx {
unsigned Location;
// Default constructor is private, initializing to an illegal location number.
// Use only for "not an entry" elements in IndexedMaps.
LocIdx() : Location(UINT_MAX) {}
public:
#define NUM_LOC_BITS 24
LocIdx(unsigned L) : Location(L) {
assert(L < (1 << NUM_LOC_BITS) && "Machine locations must fit in 24 bits");
}
static LocIdx MakeIllegalLoc() { return LocIdx(); }
bool isIllegal() const { return Location == UINT_MAX; }
uint64_t asU64() const { return Location; }
bool operator==(unsigned L) const { return Location == L; }
bool operator==(const LocIdx &L) const { return Location == L.Location; }
bool operator!=(unsigned L) const { return !(*this == L); }
bool operator!=(const LocIdx &L) const { return !(*this == L); }
bool operator<(const LocIdx &Other) const {
return Location < Other.Location;
}
};
// The location at which a spilled value resides. It consists of a register and
// an offset.
struct SpillLoc {
unsigned SpillBase;
StackOffset SpillOffset;
bool operator==(const SpillLoc &Other) const {
return std::make_pair(SpillBase, SpillOffset) ==
std::make_pair(Other.SpillBase, Other.SpillOffset);
}
bool operator<(const SpillLoc &Other) const {
return std::make_tuple(SpillBase, SpillOffset.getFixed(),
SpillOffset.getScalable()) <
std::make_tuple(Other.SpillBase, Other.SpillOffset.getFixed(),
Other.SpillOffset.getScalable());
}
};
/// Unique identifier for a value defined by an instruction, as a value type.
/// Casts back and forth to a uint64_t. Probably replacable with something less
/// bit-constrained. Each value identifies the instruction and machine location
/// where the value is defined, although there may be no corresponding machine
/// operand for it (ex: regmasks clobbering values). The instructions are
/// one-based, and definitions that are PHIs have instruction number zero.
///
/// The obvious limits of a 1M block function or 1M instruction blocks are
/// problematic; but by that point we should probably have bailed out of
/// trying to analyse the function.
class ValueIDNum {
uint64_t BlockNo : 20; /// The block where the def happens.
uint64_t InstNo : 20; /// The Instruction where the def happens.
/// One based, is distance from start of block.
uint64_t LocNo : NUM_LOC_BITS; /// The machine location where the def happens.
public:
// Default-initialize to EmptyValue. This is necessary to make IndexedMaps
// of values to work.
ValueIDNum() : BlockNo(0xFFFFF), InstNo(0xFFFFF), LocNo(0xFFFFFF) {}
ValueIDNum(uint64_t Block, uint64_t Inst, uint64_t Loc)
: BlockNo(Block), InstNo(Inst), LocNo(Loc) {}
ValueIDNum(uint64_t Block, uint64_t Inst, LocIdx Loc)
: BlockNo(Block), InstNo(Inst), LocNo(Loc.asU64()) {}
uint64_t getBlock() const { return BlockNo; }
uint64_t getInst() const { return InstNo; }
uint64_t getLoc() const { return LocNo; }
bool isPHI() const { return InstNo == 0; }
uint64_t asU64() const {
uint64_t TmpBlock = BlockNo;
uint64_t TmpInst = InstNo;
return TmpBlock << 44ull | TmpInst << NUM_LOC_BITS | LocNo;
}
static ValueIDNum fromU64(uint64_t v) {
uint64_t L = (v & 0x3FFF);
return {v >> 44ull, ((v >> NUM_LOC_BITS) & 0xFFFFF), L};
}
bool operator<(const ValueIDNum &Other) const {
return asU64() < Other.asU64();
}
bool operator==(const ValueIDNum &Other) const {
return std::tie(BlockNo, InstNo, LocNo) ==
std::tie(Other.BlockNo, Other.InstNo, Other.LocNo);
}
bool operator!=(const ValueIDNum &Other) const { return !(*this == Other); }
std::string asString(const std::string &mlocname) const {
return Twine("Value{bb: ")
.concat(Twine(BlockNo).concat(
Twine(", inst: ")
.concat((InstNo ? Twine(InstNo) : Twine("live-in"))
.concat(Twine(", loc: ").concat(Twine(mlocname)))
.concat(Twine("}")))))
.str();
}
static ValueIDNum EmptyValue;
};
/// Meta qualifiers for a value. Pair of whatever expression is used to qualify
/// the the value, and Boolean of whether or not it's indirect.
class DbgValueProperties {
public:
DbgValueProperties(const DIExpression *DIExpr, bool Indirect)
: DIExpr(DIExpr), Indirect(Indirect) {}
/// Extract properties from an existing DBG_VALUE instruction.
DbgValueProperties(const MachineInstr &MI) {
assert(MI.isDebugValue());
DIExpr = MI.getDebugExpression();
Indirect = MI.getOperand(1).isImm();
}
bool operator==(const DbgValueProperties &Other) const {
return std::tie(DIExpr, Indirect) == std::tie(Other.DIExpr, Other.Indirect);
}
bool operator!=(const DbgValueProperties &Other) const {
return !(*this == Other);
}
const DIExpression *DIExpr;
bool Indirect;
};
/// Class recording the (high level) _value_ of a variable. Identifies either
/// the value of the variable as a ValueIDNum, or a constant MachineOperand.
/// This class also stores meta-information about how the value is qualified.
/// Used to reason about variable values when performing the second
/// (DebugVariable specific) dataflow analysis.
class DbgValue {
public:
union {
/// If Kind is Def, the value number that this value is based on.
ValueIDNum ID;
/// If Kind is Const, the MachineOperand defining this value.
MachineOperand MO;
/// For a NoVal DbgValue, which block it was generated in.
unsigned BlockNo;
};
/// Qualifiers for the ValueIDNum above.
DbgValueProperties Properties;
typedef enum {
Undef, // Represents a DBG_VALUE $noreg in the transfer function only.
Def, // This value is defined by an inst, or is a PHI value.
Const, // A constant value contained in the MachineOperand field.
Proposed, // This is a tentative PHI value, which may be confirmed or
// invalidated later.
NoVal // Empty DbgValue, generated during dataflow. BlockNo stores
// which block this was generated in.
} KindT;
/// Discriminator for whether this is a constant or an in-program value.
KindT Kind;
DbgValue(const ValueIDNum &Val, const DbgValueProperties &Prop, KindT Kind)
: ID(Val), Properties(Prop), Kind(Kind) {
assert(Kind == Def || Kind == Proposed);
}
DbgValue(unsigned BlockNo, const DbgValueProperties &Prop, KindT Kind)
: BlockNo(BlockNo), Properties(Prop), Kind(Kind) {
assert(Kind == NoVal);
}
DbgValue(const MachineOperand &MO, const DbgValueProperties &Prop, KindT Kind)
: MO(MO), Properties(Prop), Kind(Kind) {
assert(Kind == Const);
}
DbgValue(const DbgValueProperties &Prop, KindT Kind)
: Properties(Prop), Kind(Kind) {
assert(Kind == Undef &&
"Empty DbgValue constructor must pass in Undef kind");
}
void dump(const MLocTracker *MTrack) const;
bool operator==(const DbgValue &Other) const {
if (std::tie(Kind, Properties) != std::tie(Other.Kind, Other.Properties))
return false;
else if (Kind == Proposed && ID != Other.ID)
return false;
else if (Kind == Def && ID != Other.ID)
return false;
else if (Kind == NoVal && BlockNo != Other.BlockNo)
return false;
else if (Kind == Const)
return MO.isIdenticalTo(Other.MO);
return true;
}
bool operator!=(const DbgValue &Other) const { return !(*this == Other); }
};
class LocIdxToIndexFunctor {
public:
using argument_type = LocIdx;
unsigned operator()(const LocIdx &L) const { return L.asU64(); }
};
/// Tracker for what values are in machine locations. Listens to the Things
/// being Done by various instructions, and maintains a table of what machine
/// locations have what values (as defined by a ValueIDNum).
///
/// There are potentially a much larger number of machine locations on the
/// target machine than the actual working-set size of the function. On x86 for
/// example, we're extremely unlikely to want to track values through control
/// or debug registers. To avoid doing so, MLocTracker has several layers of
/// indirection going on, with two kinds of ``location'':
/// * A LocID uniquely identifies a register or spill location, with a
/// predictable value.
/// * A LocIdx is a key (in the database sense) for a LocID and a ValueIDNum.
/// Whenever a location is def'd or used by a MachineInstr, we automagically
/// create a new LocIdx for a location, but not otherwise. This ensures we only
/// account for locations that are actually used or defined. The cost is another
/// vector lookup (of LocID -> LocIdx) over any other implementation. This is
/// fairly cheap, and the compiler tries to reduce the working-set at any one
/// time in the function anyway.
///
/// Register mask operands completely blow this out of the water; I've just
/// piled hacks on top of hacks to get around that.
class MLocTracker {
public:
MachineFunction &MF;
const TargetInstrInfo &TII;
const TargetRegisterInfo &TRI;
const TargetLowering &TLI;
/// IndexedMap type, mapping from LocIdx to ValueIDNum.
using LocToValueType = IndexedMap<ValueIDNum, LocIdxToIndexFunctor>;
/// Map of LocIdxes to the ValueIDNums that they store. This is tightly
/// packed, entries only exist for locations that are being tracked.
LocToValueType LocIdxToIDNum;
/// "Map" of machine location IDs (i.e., raw register or spill number) to the
/// LocIdx key / number for that location. There are always at least as many
/// as the number of registers on the target -- if the value in the register
/// is not being tracked, then the LocIdx value will be zero. New entries are
/// appended if a new spill slot begins being tracked.
/// This, and the corresponding reverse map persist for the analysis of the
/// whole function, and is necessarying for decoding various vectors of
/// values.
std::vector<LocIdx> LocIDToLocIdx;
/// Inverse map of LocIDToLocIdx.
IndexedMap<unsigned, LocIdxToIndexFunctor> LocIdxToLocID;
/// Unique-ification of spill slots. Used to number them -- their LocID
/// number is the index in SpillLocs minus one plus NumRegs.
UniqueVector<SpillLoc> SpillLocs;
// If we discover a new machine location, assign it an mphi with this
// block number.
unsigned CurBB;
/// Cached local copy of the number of registers the target has.
unsigned NumRegs;
/// Collection of register mask operands that have been observed. Second part
/// of pair indicates the instruction that they happened in. Used to
/// reconstruct where defs happened if we start tracking a location later
/// on.
SmallVector<std::pair<const MachineOperand *, unsigned>, 32> Masks;
/// Iterator for locations and the values they contain. Dereferencing
/// produces a struct/pair containing the LocIdx key for this location,
/// and a reference to the value currently stored. Simplifies the process
/// of seeking a particular location.
class MLocIterator {
LocToValueType &ValueMap;
LocIdx Idx;
public:
class value_type {
public:
value_type(LocIdx Idx, ValueIDNum &Value) : Idx(Idx), Value(Value) {}
const LocIdx Idx; /// Read-only index of this location.
ValueIDNum &Value; /// Reference to the stored value at this location.
};
MLocIterator(LocToValueType &ValueMap, LocIdx Idx)
: ValueMap(ValueMap), Idx(Idx) {}
bool operator==(const MLocIterator &Other) const {
assert(&ValueMap == &Other.ValueMap);
return Idx == Other.Idx;
}
bool operator!=(const MLocIterator &Other) const {
return !(*this == Other);
}
void operator++() { Idx = LocIdx(Idx.asU64() + 1); }
value_type operator*() { return value_type(Idx, ValueMap[LocIdx(Idx)]); }
};
MLocTracker(MachineFunction &MF, const TargetInstrInfo &TII,
const TargetRegisterInfo &TRI, const TargetLowering &TLI);
/// Produce location ID number for indexing LocIDToLocIdx. Takes the register
/// or spill number, and flag for whether it's a spill or not.
unsigned getLocID(Register RegOrSpill, bool isSpill) {
return (isSpill) ? RegOrSpill.id() + NumRegs - 1 : RegOrSpill.id();
}
/// Accessor for reading the value at Idx.
ValueIDNum getNumAtPos(LocIdx Idx) const {
assert(Idx.asU64() < LocIdxToIDNum.size());
return LocIdxToIDNum[Idx];
}
unsigned getNumLocs(void) const { return LocIdxToIDNum.size(); }
/// Reset all locations to contain a PHI value at the designated block. Used
/// sometimes for actual PHI values, othertimes to indicate the block entry
/// value (before any more information is known).
void setMPhis(unsigned NewCurBB) {
CurBB = NewCurBB;
for (auto Location : locations())
Location.Value = {CurBB, 0, Location.Idx};
}
/// Load values for each location from array of ValueIDNums. Take current
/// bbnum just in case we read a value from a hitherto untouched register.
void loadFromArray(ValueIDNum *Locs, unsigned NewCurBB) {
CurBB = NewCurBB;
// Iterate over all tracked locations, and load each locations live-in
// value into our local index.
for (auto Location : locations())
Location.Value = Locs[Location.Idx.asU64()];
}
/// Wipe any un-necessary location records after traversing a block.
void reset(void) {
// We could reset all the location values too; however either loadFromArray
// or setMPhis should be called before this object is re-used. Just
// clear Masks, they're definitely not needed.
Masks.clear();
}
/// Clear all data. Destroys the LocID <=> LocIdx map, which makes most of
/// the information in this pass uninterpretable.
void clear(void) {
reset();
LocIDToLocIdx.clear();
LocIdxToLocID.clear();
LocIdxToIDNum.clear();
// SpillLocs.reset(); XXX UniqueVector::reset assumes a SpillLoc casts from
// 0
SpillLocs = decltype(SpillLocs)();
LocIDToLocIdx.resize(NumRegs, LocIdx::MakeIllegalLoc());
}
/// Set a locaiton to a certain value.
void setMLoc(LocIdx L, ValueIDNum Num) {
assert(L.asU64() < LocIdxToIDNum.size());
LocIdxToIDNum[L] = Num;
}
/// Create a LocIdx for an untracked register ID. Initialize it to either an
/// mphi value representing a live-in, or a recent register mask clobber.
LocIdx trackRegister(unsigned ID);
LocIdx lookupOrTrackRegister(unsigned ID) {
LocIdx &Index = LocIDToLocIdx[ID];
if (Index.isIllegal())
Index = trackRegister(ID);
return Index;
}
/// Record a definition of the specified register at the given block / inst.
/// This doesn't take a ValueIDNum, because the definition and its location
/// are synonymous.
void defReg(Register R, unsigned BB, unsigned Inst) {
unsigned ID = getLocID(R, false);
LocIdx Idx = lookupOrTrackRegister(ID);
ValueIDNum ValueID = {BB, Inst, Idx};
LocIdxToIDNum[Idx] = ValueID;
}
/// Set a register to a value number. To be used if the value number is
/// known in advance.
void setReg(Register R, ValueIDNum ValueID) {
unsigned ID = getLocID(R, false);
LocIdx Idx = lookupOrTrackRegister(ID);
LocIdxToIDNum[Idx] = ValueID;
}
ValueIDNum readReg(Register R) {
unsigned ID = getLocID(R, false);
LocIdx Idx = lookupOrTrackRegister(ID);
return LocIdxToIDNum[Idx];
}
/// Reset a register value to zero / empty. Needed to replicate the
/// VarLoc implementation where a copy to/from a register effectively
/// clears the contents of the source register. (Values can only have one
/// machine location in VarLocBasedImpl).
void wipeRegister(Register R) {
unsigned ID = getLocID(R, false);
LocIdx Idx = LocIDToLocIdx[ID];
LocIdxToIDNum[Idx] = ValueIDNum::EmptyValue;
}
/// Determine the LocIdx of an existing register.
LocIdx getRegMLoc(Register R) {
unsigned ID = getLocID(R, false);
return LocIDToLocIdx[ID];
}
/// Record a RegMask operand being executed. Defs any register we currently
/// track, stores a pointer to the mask in case we have to account for it
/// later.
void writeRegMask(const MachineOperand *MO, unsigned CurBB, unsigned InstID);
/// Find LocIdx for SpillLoc \p L, creating a new one if it's not tracked.
LocIdx getOrTrackSpillLoc(SpillLoc L);
/// Set the value stored in a spill slot.
void setSpill(SpillLoc L, ValueIDNum ValueID) {
LocIdx Idx = getOrTrackSpillLoc(L);
LocIdxToIDNum[Idx] = ValueID;
}
/// Read whatever value is in a spill slot, or None if it isn't tracked.
Optional<ValueIDNum> readSpill(SpillLoc L) {
unsigned SpillID = SpillLocs.idFor(L);
if (SpillID == 0)
return None;
unsigned LocID = getLocID(SpillID, true);
LocIdx Idx = LocIDToLocIdx[LocID];
return LocIdxToIDNum[Idx];
}
/// Determine the LocIdx of a spill slot. Return None if it previously
/// hasn't had a value assigned.
Optional<LocIdx> getSpillMLoc(SpillLoc L) {
unsigned SpillID = SpillLocs.idFor(L);
if (SpillID == 0)
return None;
unsigned LocNo = getLocID(SpillID, true);
return LocIDToLocIdx[LocNo];
}
/// Return true if Idx is a spill machine location.
bool isSpill(LocIdx Idx) const { return LocIdxToLocID[Idx] >= NumRegs; }
MLocIterator begin() { return MLocIterator(LocIdxToIDNum, 0); }
MLocIterator end() {
return MLocIterator(LocIdxToIDNum, LocIdxToIDNum.size());
}
/// Return a range over all locations currently tracked.
iterator_range<MLocIterator> locations() {
return llvm::make_range(begin(), end());
}
std::string LocIdxToName(LocIdx Idx) const;
std::string IDAsString(const ValueIDNum &Num) const;
LLVM_DUMP_METHOD void dump();
LLVM_DUMP_METHOD void dump_mloc_map();
/// Create a DBG_VALUE based on machine location \p MLoc. Qualify it with the
/// information in \pProperties, for variable Var. Don't insert it anywhere,
/// just return the builder for it.
MachineInstrBuilder emitLoc(Optional<LocIdx> MLoc, const DebugVariable &Var,
const DbgValueProperties &Properties);
};
/// Types for recording sets of variable fragments that overlap. For a given
/// local variable, we record all other fragments of that variable that could
/// overlap it, to reduce search time.
using FragmentOfVar =
std::pair<const DILocalVariable *, DIExpression::FragmentInfo>;
using OverlapMap =
DenseMap<FragmentOfVar, SmallVector<DIExpression::FragmentInfo, 1>>;
// XXX XXX docs
class InstrRefBasedLDV : public LDVImpl {
private:
friend class ::InstrRefLDVTest;
using FragmentInfo = DIExpression::FragmentInfo;
using OptFragmentInfo = Optional<DIExpression::FragmentInfo>;
// Helper while building OverlapMap, a map of all fragments seen for a given
// DILocalVariable.
using VarToFragments =
DenseMap<const DILocalVariable *, SmallSet<FragmentInfo, 4>>;
/// Machine location/value transfer function, a mapping of which locations
/// are assigned which new values.
using MLocTransferMap = std::map<LocIdx, ValueIDNum>;
/// Live in/out structure for the variable values: a per-block map of
/// variables to their values. XXX, better name?
using LiveIdxT =
DenseMap<const MachineBasicBlock *, DenseMap<DebugVariable, DbgValue> *>;
using VarAndLoc = std::pair<DebugVariable, DbgValue>;
/// Type for a live-in value: the predecessor block, and its value.
using InValueT = std::pair<MachineBasicBlock *, DbgValue *>;
/// Vector (per block) of a collection (inner smallvector) of live-ins.
/// Used as the result type for the variable value dataflow problem.
using LiveInsT = SmallVector<SmallVector<VarAndLoc, 8>, 8>;
const TargetRegisterInfo *TRI;
const TargetInstrInfo *TII;
const TargetFrameLowering *TFI;
const MachineFrameInfo *MFI;
BitVector CalleeSavedRegs;
LexicalScopes LS;
TargetPassConfig *TPC;
/// Object to track machine locations as we step through a block. Could
/// probably be a field rather than a pointer, as it's always used.
MLocTracker *MTracker;
/// Number of the current block LiveDebugValues is stepping through.
unsigned CurBB;
/// Number of the current instruction LiveDebugValues is evaluating.
unsigned CurInst;
/// Variable tracker -- listens to DBG_VALUEs occurring as InstrRefBasedImpl
/// steps through a block. Reads the values at each location from the
/// MLocTracker object.
VLocTracker *VTracker;
/// Tracker for transfers, listens to DBG_VALUEs and transfers of values
/// between locations during stepping, creates new DBG_VALUEs when values move
/// location.
TransferTracker *TTracker;
/// Blocks which are artificial, i.e. blocks which exclusively contain
/// instructions without DebugLocs, or with line 0 locations.
SmallPtrSet<const MachineBasicBlock *, 16> ArtificialBlocks;
// Mapping of blocks to and from their RPOT order.
DenseMap<unsigned int, MachineBasicBlock *> OrderToBB;
DenseMap<MachineBasicBlock *, unsigned int> BBToOrder;
DenseMap<unsigned, unsigned> BBNumToRPO;
/// Pair of MachineInstr, and its 1-based offset into the containing block.
using InstAndNum = std::pair<const MachineInstr *, unsigned>;
/// Map from debug instruction number to the MachineInstr labelled with that
/// number, and its location within the function. Used to transform
/// instruction numbers in DBG_INSTR_REFs into machine value numbers.
std::map<uint64_t, InstAndNum> DebugInstrNumToInstr;
/// Record of where we observed a DBG_PHI instruction.
class DebugPHIRecord {
public:
uint64_t InstrNum; ///< Instruction number of this DBG_PHI.
MachineBasicBlock *MBB; ///< Block where DBG_PHI occurred.
ValueIDNum ValueRead; ///< The value number read by the DBG_PHI.
LocIdx ReadLoc; ///< Register/Stack location the DBG_PHI reads.
operator unsigned() const { return InstrNum; }
};
/// Map from instruction numbers defined by DBG_PHIs to a record of what that
/// DBG_PHI read and where. Populated and edited during the machine value
/// location problem -- we use LLVMs SSA Updater to fix changes by
/// optimizations that destroy PHI instructions.
SmallVector<DebugPHIRecord, 32> DebugPHINumToValue;
// Map of overlapping variable fragments.
OverlapMap OverlapFragments;
VarToFragments SeenFragments;
/// Tests whether this instruction is a spill to a stack slot.
bool isSpillInstruction(const MachineInstr &MI, MachineFunction *MF);
/// Decide if @MI is a spill instruction and return true if it is. We use 2
/// criteria to make this decision:
/// - Is this instruction a store to a spill slot?
/// - Is there a register operand that is both used and killed?
/// TODO: Store optimization can fold spills into other stores (including
/// other spills). We do not handle this yet (more than one memory operand).
bool isLocationSpill(const MachineInstr &MI, MachineFunction *MF,
unsigned &Reg);
/// If a given instruction is identified as a spill, return the spill slot
/// and set \p Reg to the spilled register.
Optional<SpillLoc> isRestoreInstruction(const MachineInstr &MI,
MachineFunction *MF, unsigned &Reg);
/// Given a spill instruction, extract the register and offset used to
/// address the spill slot in a target independent way.
SpillLoc extractSpillBaseRegAndOffset(const MachineInstr &MI);
/// Observe a single instruction while stepping through a block.
void process(MachineInstr &MI, ValueIDNum **MLiveOuts = nullptr,
ValueIDNum **MLiveIns = nullptr);
/// Examines whether \p MI is a DBG_VALUE and notifies trackers.
/// \returns true if MI was recognized and processed.
bool transferDebugValue(const MachineInstr &MI);
/// Examines whether \p MI is a DBG_INSTR_REF and notifies trackers.
/// \returns true if MI was recognized and processed.
bool transferDebugInstrRef(MachineInstr &MI, ValueIDNum **MLiveOuts,
ValueIDNum **MLiveIns);
/// Stores value-information about where this PHI occurred, and what
/// instruction number is associated with it.
/// \returns true if MI was recognized and processed.
bool transferDebugPHI(MachineInstr &MI);
/// Examines whether \p MI is copy instruction, and notifies trackers.
/// \returns true if MI was recognized and processed.
bool transferRegisterCopy(MachineInstr &MI);
/// Examines whether \p MI is stack spill or restore instruction, and
/// notifies trackers. \returns true if MI was recognized and processed.
bool transferSpillOrRestoreInst(MachineInstr &MI);
/// Examines \p MI for any registers that it defines, and notifies trackers.
void transferRegisterDef(MachineInstr &MI);
/// Copy one location to the other, accounting for movement of subregisters
/// too.
void performCopy(Register Src, Register Dst);
void accumulateFragmentMap(MachineInstr &MI);
/// Determine the machine value number referred to by (potentially several)
/// DBG_PHI instructions. Block duplication and tail folding can duplicate
/// DBG_PHIs, shifting the position where values in registers merge, and
/// forming another mini-ssa problem to solve.
/// \p Here the position of a DBG_INSTR_REF seeking a machine value number
/// \p InstrNum Debug instruction number defined by DBG_PHI instructions.
/// \returns The machine value number at position Here, or None.
Optional<ValueIDNum> resolveDbgPHIs(MachineFunction &MF,
ValueIDNum **MLiveOuts,
ValueIDNum **MLiveIns, MachineInstr &Here,
uint64_t InstrNum);
/// Step through the function, recording register definitions and movements
/// in an MLocTracker. Convert the observations into a per-block transfer
/// function in \p MLocTransfer, suitable for using with the machine value
/// location dataflow problem.
void
produceMLocTransferFunction(MachineFunction &MF,
SmallVectorImpl<MLocTransferMap> &MLocTransfer,
unsigned MaxNumBlocks);
/// Solve the machine value location dataflow problem. Takes as input the
/// transfer functions in \p MLocTransfer. Writes the output live-in and
/// live-out arrays to the (initialized to zero) multidimensional arrays in
/// \p MInLocs and \p MOutLocs. The outer dimension is indexed by block
/// number, the inner by LocIdx.
void mlocDataflow(ValueIDNum **MInLocs, ValueIDNum **MOutLocs,
SmallVectorImpl<MLocTransferMap> &MLocTransfer);
/// Perform a control flow join (lattice value meet) of the values in machine
/// locations at \p MBB. Follows the algorithm described in the file-comment,
/// reading live-outs of predecessors from \p OutLocs, the current live ins
/// from \p InLocs, and assigning the newly computed live ins back into
/// \p InLocs. \returns two bools -- the first indicates whether a change
/// was made, the second whether a lattice downgrade occurred. If the latter
/// is true, revisiting this block is necessary.
std::tuple<bool, bool>
mlocJoin(MachineBasicBlock &MBB,
SmallPtrSet<const MachineBasicBlock *, 16> &Visited,
ValueIDNum **OutLocs, ValueIDNum *InLocs);
/// Solve the variable value dataflow problem, for a single lexical scope.
/// Uses the algorithm from the file comment to resolve control flow joins,
/// although there are extra hacks, see vlocJoin. Reads the
/// locations of values from the \p MInLocs and \p MOutLocs arrays (see
/// mlocDataflow) and reads the variable values transfer function from
/// \p AllTheVlocs. Live-in and Live-out variable values are stored locally,
/// with the live-ins permanently stored to \p Output once the fixedpoint is
/// reached.
/// \p VarsWeCareAbout contains a collection of the variables in \p Scope
/// that we should be tracking.
/// \p AssignBlocks contains the set of blocks that aren't in \p Scope, but
/// which do contain DBG_VALUEs, which VarLocBasedImpl tracks locations
/// through.
void vlocDataflow(const LexicalScope *Scope, const DILocation *DILoc,
const SmallSet<DebugVariable, 4> &VarsWeCareAbout,
SmallPtrSetImpl<MachineBasicBlock *> &AssignBlocks,
LiveInsT &Output, ValueIDNum **MOutLocs,
ValueIDNum **MInLocs,
SmallVectorImpl<VLocTracker> &AllTheVLocs);
/// Compute the live-ins to a block, considering control flow merges according
/// to the method in the file comment. Live out and live in variable values
/// are stored in \p VLOCOutLocs and \p VLOCInLocs. The live-ins for \p MBB
/// are computed and stored into \p VLOCInLocs. \returns true if the live-ins
/// are modified.
/// \p InLocsT Output argument, storage for calculated live-ins.
/// \returns two bools -- the first indicates whether a change
/// was made, the second whether a lattice downgrade occurred. If the latter
/// is true, revisiting this block is necessary.
std::tuple<bool, bool>
vlocJoin(MachineBasicBlock &MBB, LiveIdxT &VLOCOutLocs, LiveIdxT &VLOCInLocs,
SmallPtrSet<const MachineBasicBlock *, 16> *VLOCVisited,
unsigned BBNum, const SmallSet<DebugVariable, 4> &AllVars,
ValueIDNum **MOutLocs, ValueIDNum **MInLocs,
SmallPtrSet<const MachineBasicBlock *, 8> &InScopeBlocks,
SmallPtrSet<const MachineBasicBlock *, 8> &BlocksToExplore,
DenseMap<DebugVariable, DbgValue> &InLocsT);
/// Continue exploration of the variable-value lattice, as explained in the
/// file-level comment. \p OldLiveInLocation contains the current
/// exploration position, from which we need to descend further. \p Values
/// contains the set of live-in values, \p CurBlockRPONum the RPO number of
/// the current block, and \p CandidateLocations a set of locations that
/// should be considered as PHI locations, if we reach the bottom of the
/// lattice. \returns true if we should downgrade; the value is the agreeing
/// value number in a non-backedge predecessor.
bool vlocDowngradeLattice(const MachineBasicBlock &MBB,
const DbgValue &OldLiveInLocation,
const SmallVectorImpl<InValueT> &Values,
unsigned CurBlockRPONum);
/// For the given block and live-outs feeding into it, try to find a
/// machine location where they all join. If a solution for all predecessors
/// can't be found, a location where all non-backedge-predecessors join
/// will be returned instead. While this method finds a join location, this
/// says nothing as to whether it should be used.
/// \returns Pair of value ID if found, and true when the correct value
/// is available on all predecessor edges, or false if it's only available
/// for non-backedge predecessors.
std::tuple<Optional<ValueIDNum>, bool>
pickVPHILoc(MachineBasicBlock &MBB, const DebugVariable &Var,
const LiveIdxT &LiveOuts, ValueIDNum **MOutLocs,
ValueIDNum **MInLocs,
const SmallVectorImpl<MachineBasicBlock *> &BlockOrders);
/// Given the solutions to the two dataflow problems, machine value locations
/// in \p MInLocs and live-in variable values in \p SavedLiveIns, runs the
/// TransferTracker class over the function to produce live-in and transfer
/// DBG_VALUEs, then inserts them. Groups of DBG_VALUEs are inserted in the
/// order given by AllVarsNumbering -- this could be any stable order, but
/// right now "order of appearence in function, when explored in RPO", so
/// that we can compare explictly against VarLocBasedImpl.
void emitLocations(MachineFunction &MF, LiveInsT SavedLiveIns,
ValueIDNum **MOutLocs, ValueIDNum **MInLocs,
DenseMap<DebugVariable, unsigned> &AllVarsNumbering,
const TargetPassConfig &TPC);
/// Boilerplate computation of some initial sets, artifical blocks and
/// RPOT block ordering.
void initialSetup(MachineFunction &MF);
bool ExtendRanges(MachineFunction &MF, TargetPassConfig *TPC,
unsigned InputBBLimit, unsigned InputDbgValLimit) override;
public:
/// Default construct and initialize the pass.
InstrRefBasedLDV();
LLVM_DUMP_METHOD
void dump_mloc_transfer(const MLocTransferMap &mloc_transfer) const;
bool isCalleeSaved(LocIdx L) const;
};
} // namespace LiveDebugValues
#endif /* LLVM_LIB_CODEGEN_LIVEDEBUGVALUES_INSTRREFBASEDLDV_H */

1
llvm/unittests/CodeGen/CMakeLists.txt
View File

@ -20,6 +20,7 @@ add_llvm_unittest(CodeGenTests
AsmPrinterDwarfTest.cpp
DIEHashTest.cpp
DIETest.cpp
InstrRefLDVTest.cpp
LowLevelTypeTest.cpp
LexicalScopesTest.cpp
MachineInstrBundleIteratorTest.cpp

99
llvm/unittests/CodeGen/InstrRefLDVTest.cpp Normal file
View File

@ -0,0 +1,99 @@
//===------------- llvm/unittest/CodeGen/InstrRefLDVTest.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
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/TargetLowering.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/IR/DIBuilder.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/MC/TargetRegistry.h"
#include "llvm/Support/TargetSelect.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include "../lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.h"
#include "gtest/gtest.h"
using namespace llvm;
using namespace LiveDebugValues;
// Include helper functions to ease the manipulation of MachineFunctions
#include "MFCommon.inc"
class InstrRefLDVTest : public testing::Test {
public:
LLVMContext Ctx;
Module Mod;
std::unique_ptr<MachineFunction> MF;
DICompileUnit *OurCU;
DIFile *OurFile;
DISubprogram *OurFunc;
DILexicalBlock *OurBlock, *AnotherBlock;
DISubprogram *ToInlineFunc;
DILexicalBlock *ToInlineBlock;
DebugLoc OutermostLoc, InBlockLoc, NotNestedBlockLoc, InlinedLoc;
MachineBasicBlock *MBB1, *MBB2, *MBB3, *MBB4;
InstrRefLDVTest() : Ctx(), Mod("beehives", Ctx) {
// Boilerplate that creates a MachineFunction and associated blocks.
MF = createMachineFunction(Ctx, Mod);
llvm::Function &F = const_cast<llvm::Function &>(MF->getFunction());
auto BB1 = BasicBlock::Create(Ctx, "a", &F);
auto BB2 = BasicBlock::Create(Ctx, "b", &F);
auto BB3 = BasicBlock::Create(Ctx, "c", &F);
auto BB4 = BasicBlock::Create(Ctx, "d", &F);
IRBuilder<> IRB1(BB1), IRB2(BB2), IRB3(BB3), IRB4(BB4);
IRB1.CreateBr(BB2);
IRB2.CreateBr(BB3);
IRB3.CreateBr(BB4);
IRB4.CreateRetVoid();
MBB1 = MF->CreateMachineBasicBlock(BB1);
MF->insert(MF->end(), MBB1);
MBB2 = MF->CreateMachineBasicBlock(BB2);
MF->insert(MF->end(), MBB2);
MBB3 = MF->CreateMachineBasicBlock(BB3);
MF->insert(MF->end(), MBB3);
MBB4 = MF->CreateMachineBasicBlock(BB4);
MF->insert(MF->end(), MBB4);
MBB1->addSuccessor(MBB2);
MBB1->addSuccessor(MBB3);
MBB2->addSuccessor(MBB4);
MBB3->addSuccessor(MBB4);
// Create metadata: CU, subprogram, some blocks and an inline function
// scope.
DIBuilder DIB(Mod);
OurFile = DIB.createFile("xyzzy.c", "/cave");
OurCU =
DIB.createCompileUnit(dwarf::DW_LANG_C99, OurFile, "nou", false, "", 0);
auto OurSubT = DIB.createSubroutineType(DIB.getOrCreateTypeArray(None));
OurFunc =
DIB.createFunction(OurCU, "bees", "", OurFile, 1, OurSubT, 1,
DINode::FlagZero, DISubprogram::SPFlagDefinition);
F.setSubprogram(OurFunc);
OurBlock = DIB.createLexicalBlock(OurFunc, OurFile, 2, 3);
AnotherBlock = DIB.createLexicalBlock(OurFunc, OurFile, 2, 6);
ToInlineFunc =
DIB.createFunction(OurFile, "shoes", "", OurFile, 10, OurSubT, 10,
DINode::FlagZero, DISubprogram::SPFlagDefinition);
// Make some nested scopes.
OutermostLoc = DILocation::get(Ctx, 3, 1, OurFunc);
InBlockLoc = DILocation::get(Ctx, 4, 1, OurBlock);
InlinedLoc = DILocation::get(Ctx, 10, 1, ToInlineFunc, InBlockLoc.get());
// Make a scope that isn't nested within the others.
NotNestedBlockLoc = DILocation::get(Ctx, 4, 1, AnotherBlock);
DIB.finalize();
}
};