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llvm-mirror/lib/CodeGen/LiveDebugVariables.cpp
OCHyams 5a42c7fbee [NFC] Fix performance issue in LiveDebugVariables 
When compiling AMDGPUDisassembler.cpp in a stage 1 trunk build with
CMAKE_BUILD_TYPE=RelWithDebInfo LLVM_USE_SANITIZER=Address LiveDebugVariables
accounts for 21.5% wall clock time. This fix reduces that to 1.2% by switching
out a linked list lookup with a map lookup.

Note that the linked list is still used to group UserValues by vreg. The vreg
lookups don't cause any problems in this pathological case.

This is the same idea as D68816, which was reverted, except that it is a less
intrusive fix.

Reviewed By: vsk

Differential Revision: https://reviews.llvm.org/D77226
2020-04-02 09:39:33 +01:00

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52 KiB
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//===- LiveDebugVariables.cpp - Tracking debug info variables -------------===//
//
// 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 file implements the LiveDebugVariables analysis.
//
// Remove all DBG_VALUE instructions referencing virtual registers and replace
// them with a data structure tracking where live user variables are kept - in a
// virtual register or in a stack slot.
//
// Allow the data structure to be updated during register allocation when values
// are moved between registers and stack slots. Finally emit new DBG_VALUE
// instructions after register allocation is complete.
//
//===----------------------------------------------------------------------===//
#include "LiveDebugVariables.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/IntervalMap.h"
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/CodeGen/LexicalScopes.h"
#include "llvm/CodeGen/LiveInterval.h"
#include "llvm/CodeGen/LiveIntervals.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/SlotIndexes.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/CodeGen/TargetOpcodes.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/CodeGen/VirtRegMap.h"
#include "llvm/Config/llvm-config.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Metadata.h"
#include "llvm/InitializePasses.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/Pass.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cassert>
#include <iterator>
#include <memory>
#include <utility>
using namespace llvm;
#define DEBUG_TYPE "livedebugvars"
static cl::opt<bool>
EnableLDV("live-debug-variables", cl::init(true),
cl::desc("Enable the live debug variables pass"), cl::Hidden);
STATISTIC(NumInsertedDebugValues, "Number of DBG_VALUEs inserted");
STATISTIC(NumInsertedDebugLabels, "Number of DBG_LABELs inserted");
char LiveDebugVariables::ID = 0;
INITIALIZE_PASS_BEGIN(LiveDebugVariables, DEBUG_TYPE,
"Debug Variable Analysis", false, false)
INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
INITIALIZE_PASS_DEPENDENCY(LiveIntervals)
INITIALIZE_PASS_END(LiveDebugVariables, DEBUG_TYPE,
"Debug Variable Analysis", false, false)
void LiveDebugVariables::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<MachineDominatorTree>();
AU.addRequiredTransitive<LiveIntervals>();
AU.setPreservesAll();
MachineFunctionPass::getAnalysisUsage(AU);
}
LiveDebugVariables::LiveDebugVariables() : MachineFunctionPass(ID) {
initializeLiveDebugVariablesPass(*PassRegistry::getPassRegistry());
}
enum : unsigned { UndefLocNo = ~0U };
/// Describes a debug variable value by location number and expression along
/// with some flags about the original usage of the location.
class DbgVariableValue {
public:
DbgVariableValue(unsigned LocNo, bool WasIndirect,
const DIExpression &Expression)
: LocNo(LocNo), WasIndirect(WasIndirect), Expression(&Expression) {
assert(getLocNo() == LocNo && "location truncation");
}
DbgVariableValue() : LocNo(0), WasIndirect(0) {}
const DIExpression *getExpression() const { return Expression; }
unsigned getLocNo() const {
// Fix up the undef location number, which gets truncated.
return LocNo == INT_MAX ? UndefLocNo : LocNo;
}
bool getWasIndirect() const { return WasIndirect; }
bool isUndef() const { return getLocNo() == UndefLocNo; }
DbgVariableValue changeLocNo(unsigned NewLocNo) const {
return DbgVariableValue(NewLocNo, WasIndirect, *Expression);
}
friend inline bool operator==(const DbgVariableValue &LHS,
const DbgVariableValue &RHS) {
return LHS.LocNo == RHS.LocNo && LHS.WasIndirect == RHS.WasIndirect &&
LHS.Expression == RHS.Expression;
}
friend inline bool operator!=(const DbgVariableValue &LHS,
const DbgVariableValue &RHS) {
return !(LHS == RHS);
}
private:
unsigned LocNo : 31;
unsigned WasIndirect : 1;
const DIExpression *Expression = nullptr;
};
/// Map of where a user value is live to that value.
using LocMap = IntervalMap<SlotIndex, DbgVariableValue, 4>;
/// Map of stack slot offsets for spilled locations.
/// Non-spilled locations are not added to the map.
using SpillOffsetMap = DenseMap<unsigned, unsigned>;
namespace {
class LDVImpl;
/// A user value is a part of a debug info user variable.
///
/// A DBG_VALUE instruction notes that (a sub-register of) a virtual register
/// holds part of a user variable. The part is identified by a byte offset.
///
/// UserValues are grouped into equivalence classes for easier searching. Two
/// user values are related if they are held by the same virtual register. The
/// equivalence class is the transitive closure of that relation.
class UserValue {
const DILocalVariable *Variable; ///< The debug info variable we are part of.
/// The part of the variable we describe.
const Optional<DIExpression::FragmentInfo> Fragment;
DebugLoc dl; ///< The debug location for the variable. This is
///< used by dwarf writer to find lexical scope.
UserValue *leader; ///< Equivalence class leader.
UserValue *next = nullptr; ///< Next value in equivalence class, or null.
/// Numbered locations referenced by locmap.
SmallVector<MachineOperand, 4> locations;
/// Map of slot indices where this value is live.
LocMap locInts;
/// Set of interval start indexes that have been trimmed to the
/// lexical scope.
SmallSet<SlotIndex, 2> trimmedDefs;
/// Insert a DBG_VALUE into MBB at Idx for DbgValue.
void insertDebugValue(MachineBasicBlock *MBB, SlotIndex StartIdx,
SlotIndex StopIdx, DbgVariableValue DbgValue,
bool Spilled, unsigned SpillOffset, LiveIntervals &LIS,
const TargetInstrInfo &TII,
const TargetRegisterInfo &TRI);
/// Replace OldLocNo ranges with NewRegs ranges where NewRegs
/// is live. Returns true if any changes were made.
bool splitLocation(unsigned OldLocNo, ArrayRef<unsigned> NewRegs,
LiveIntervals &LIS);
public:
/// Create a new UserValue.
UserValue(const DILocalVariable *var,
Optional<DIExpression::FragmentInfo> Fragment, DebugLoc L,
LocMap::Allocator &alloc)
: Variable(var), Fragment(Fragment), dl(std::move(L)), leader(this),
locInts(alloc) {}
/// Get the leader of this value's equivalence class.
UserValue *getLeader() {
UserValue *l = leader;
while (l != l->leader)
l = l->leader;
return leader = l;
}
/// Return the next UserValue in the equivalence class.
UserValue *getNext() const { return next; }
/// Merge equivalence classes.
static UserValue *merge(UserValue *L1, UserValue *L2) {
L2 = L2->getLeader();
if (!L1)
return L2;
L1 = L1->getLeader();
if (L1 == L2)
return L1;
// Splice L2 before L1's members.
UserValue *End = L2;
while (End->next) {
End->leader = L1;
End = End->next;
}
End->leader = L1;
End->next = L1->next;
L1->next = L2;
return L1;
}
/// Return the location number that matches Loc.
///
/// For undef values we always return location number UndefLocNo without
/// inserting anything in locations. Since locations is a vector and the
/// location number is the position in the vector and UndefLocNo is ~0,
/// we would need a very big vector to put the value at the right position.
unsigned getLocationNo(const MachineOperand &LocMO) {
if (LocMO.isReg()) {
if (LocMO.getReg() == 0)
return UndefLocNo;
// For register locations we dont care about use/def and other flags.
for (unsigned i = 0, e = locations.size(); i != e; ++i)
if (locations[i].isReg() &&
locations[i].getReg() == LocMO.getReg() &&
locations[i].getSubReg() == LocMO.getSubReg())
return i;
} else
for (unsigned i = 0, e = locations.size(); i != e; ++i)
if (LocMO.isIdenticalTo(locations[i]))
return i;
locations.push_back(LocMO);
// We are storing a MachineOperand outside a MachineInstr.
locations.back().clearParent();
// Don't store def operands.
if (locations.back().isReg()) {
if (locations.back().isDef())
locations.back().setIsDead(false);
locations.back().setIsUse();
}
return locations.size() - 1;
}
/// Remove (recycle) a location number. If \p LocNo still is used by the
/// locInts nothing is done.
void removeLocationIfUnused(unsigned LocNo) {
// Bail out if LocNo still is used.
for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I) {
DbgVariableValue DbgValue = I.value();
if (DbgValue.getLocNo() == LocNo)
return;
}
// Remove the entry in the locations vector, and adjust all references to
// location numbers above the removed entry.
locations.erase(locations.begin() + LocNo);
for (LocMap::iterator I = locInts.begin(); I.valid(); ++I) {
DbgVariableValue DbgValue = I.value();
if (!DbgValue.isUndef() && DbgValue.getLocNo() > LocNo)
I.setValueUnchecked(DbgValue.changeLocNo(DbgValue.getLocNo() - 1));
}
}
/// Ensure that all virtual register locations are mapped.
void mapVirtRegs(LDVImpl *LDV);
/// Add a definition point to this user value.
void addDef(SlotIndex Idx, const MachineOperand &LocMO, bool IsIndirect,
const DIExpression &Expr) {
DbgVariableValue DbgValue(getLocationNo(LocMO), IsIndirect, Expr);
// Add a singular (Idx,Idx) -> value mapping.
LocMap::iterator I = locInts.find(Idx);
if (!I.valid() || I.start() != Idx)
I.insert(Idx, Idx.getNextSlot(), DbgValue);
else
// A later DBG_VALUE at the same SlotIndex overrides the old location.
I.setValue(DbgValue);
}
/// Extend the current definition as far as possible down.
///
/// Stop when meeting an existing def or when leaving the live
/// range of VNI. End points where VNI is no longer live are added to Kills.
///
/// We only propagate DBG_VALUES locally here. LiveDebugValues performs a
/// data-flow analysis to propagate them beyond basic block boundaries.
///
/// \param Idx Starting point for the definition.
/// \param DbgValue value to propagate.
/// \param LR Restrict liveness to where LR has the value VNI. May be null.
/// \param VNI When LR is not null, this is the value to restrict to.
/// \param [out] Kills Append end points of VNI's live range to Kills.
/// \param LIS Live intervals analysis.
void extendDef(SlotIndex Idx, DbgVariableValue DbgValue, LiveRange *LR,
const VNInfo *VNI, SmallVectorImpl<SlotIndex> *Kills,
LiveIntervals &LIS);
/// The value in LI may be copies to other registers. Determine if
/// any of the copies are available at the kill points, and add defs if
/// possible.
///
/// \param LI Scan for copies of the value in LI->reg.
/// \param DbgValue Location number of LI->reg, and DIExpression.
/// \param Kills Points where the range of DbgValue could be extended.
/// \param [in,out] NewDefs Append (Idx, DbgValue) of inserted defs here.
void addDefsFromCopies(
LiveInterval *LI, DbgVariableValue DbgValue,
const SmallVectorImpl<SlotIndex> &Kills,
SmallVectorImpl<std::pair<SlotIndex, DbgVariableValue>> &NewDefs,
MachineRegisterInfo &MRI, LiveIntervals &LIS);
/// Compute the live intervals of all locations after collecting all their
/// def points.
void computeIntervals(MachineRegisterInfo &MRI, const TargetRegisterInfo &TRI,
LiveIntervals &LIS, LexicalScopes &LS);
/// Replace OldReg ranges with NewRegs ranges where NewRegs is
/// live. Returns true if any changes were made.
bool splitRegister(unsigned OldReg, ArrayRef<unsigned> NewRegs,
LiveIntervals &LIS);
/// Rewrite virtual register locations according to the provided virtual
/// register map. Record the stack slot offsets for the locations that
/// were spilled.
void rewriteLocations(VirtRegMap &VRM, const MachineFunction &MF,
const TargetInstrInfo &TII,
const TargetRegisterInfo &TRI,
SpillOffsetMap &SpillOffsets);
/// Recreate DBG_VALUE instruction from data structures.
void emitDebugValues(VirtRegMap *VRM, LiveIntervals &LIS,
const TargetInstrInfo &TII,
const TargetRegisterInfo &TRI,
const SpillOffsetMap &SpillOffsets);
/// Return DebugLoc of this UserValue.
DebugLoc getDebugLoc() { return dl;}
void print(raw_ostream &, const TargetRegisterInfo *);
};
/// A user label is a part of a debug info user label.
class UserLabel {
const DILabel *Label; ///< The debug info label we are part of.
DebugLoc dl; ///< The debug location for the label. This is
///< used by dwarf writer to find lexical scope.
SlotIndex loc; ///< Slot used by the debug label.
/// Insert a DBG_LABEL into MBB at Idx.
void insertDebugLabel(MachineBasicBlock *MBB, SlotIndex Idx,
LiveIntervals &LIS, const TargetInstrInfo &TII);
public:
/// Create a new UserLabel.
UserLabel(const DILabel *label, DebugLoc L, SlotIndex Idx)
: Label(label), dl(std::move(L)), loc(Idx) {}
/// Does this UserLabel match the parameters?
bool matches(const DILabel *L, const DILocation *IA,
const SlotIndex Index) const {
return Label == L && dl->getInlinedAt() == IA && loc == Index;
}
/// Recreate DBG_LABEL instruction from data structures.
void emitDebugLabel(LiveIntervals &LIS, const TargetInstrInfo &TII);
/// Return DebugLoc of this UserLabel.
DebugLoc getDebugLoc() { return dl; }
void print(raw_ostream &, const TargetRegisterInfo *);
};
/// Implementation of the LiveDebugVariables pass.
class LDVImpl {
LiveDebugVariables &pass;
LocMap::Allocator allocator;
MachineFunction *MF = nullptr;
LiveIntervals *LIS;
const TargetRegisterInfo *TRI;
/// Whether emitDebugValues is called.
bool EmitDone = false;
/// Whether the machine function is modified during the pass.
bool ModifiedMF = false;
/// All allocated UserValue instances.
SmallVector<std::unique_ptr<UserValue>, 8> userValues;
/// All allocated UserLabel instances.
SmallVector<std::unique_ptr<UserLabel>, 2> userLabels;
/// Map virtual register to eq class leader.
using VRMap = DenseMap<unsigned, UserValue *>;
VRMap virtRegToEqClass;
/// Map to find existing UserValue instances.
using UVMap = DenseMap<DebugVariable, UserValue *>;
UVMap userVarMap;
/// Find or create a UserValue.
UserValue *getUserValue(const DILocalVariable *Var,
Optional<DIExpression::FragmentInfo> Fragment,
const DebugLoc &DL);
/// Find the EC leader for VirtReg or null.
UserValue *lookupVirtReg(unsigned VirtReg);
/// Add DBG_VALUE instruction to our maps.
///
/// \param MI DBG_VALUE instruction
/// \param Idx Last valid SLotIndex before instruction.
///
/// \returns True if the DBG_VALUE instruction should be deleted.
bool handleDebugValue(MachineInstr &MI, SlotIndex Idx);
/// Add DBG_LABEL instruction to UserLabel.
///
/// \param MI DBG_LABEL instruction
/// \param Idx Last valid SlotIndex before instruction.
///
/// \returns True if the DBG_LABEL instruction should be deleted.
bool handleDebugLabel(MachineInstr &MI, SlotIndex Idx);
/// Collect and erase all DBG_VALUE instructions, adding a UserValue def
/// for each instruction.
///
/// \param mf MachineFunction to be scanned.
///
/// \returns True if any debug values were found.
bool collectDebugValues(MachineFunction &mf);
/// Compute the live intervals of all user values after collecting all
/// their def points.
void computeIntervals();
public:
LDVImpl(LiveDebugVariables *ps) : pass(*ps) {}
bool runOnMachineFunction(MachineFunction &mf);
/// Release all memory.
void clear() {
MF = nullptr;
userValues.clear();
userLabels.clear();
virtRegToEqClass.clear();
userVarMap.clear();
// Make sure we call emitDebugValues if the machine function was modified.
assert((!ModifiedMF || EmitDone) &&
"Dbg values are not emitted in LDV");
EmitDone = false;
ModifiedMF = false;
}
/// Map virtual register to an equivalence class.
void mapVirtReg(unsigned VirtReg, UserValue *EC);
/// Replace all references to OldReg with NewRegs.
void splitRegister(unsigned OldReg, ArrayRef<unsigned> NewRegs);
/// Recreate DBG_VALUE instruction from data structures.
void emitDebugValues(VirtRegMap *VRM);
void print(raw_ostream&);
};
} // end anonymous namespace
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
static void printDebugLoc(const DebugLoc &DL, raw_ostream &CommentOS,
const LLVMContext &Ctx) {
if (!DL)
return;
auto *Scope = cast<DIScope>(DL.getScope());
// Omit the directory, because it's likely to be long and uninteresting.
CommentOS << Scope->getFilename();
CommentOS << ':' << DL.getLine();
if (DL.getCol() != 0)
CommentOS << ':' << DL.getCol();
DebugLoc InlinedAtDL = DL.getInlinedAt();
if (!InlinedAtDL)
return;
CommentOS << " @[ ";
printDebugLoc(InlinedAtDL, CommentOS, Ctx);
CommentOS << " ]";
}
static void printExtendedName(raw_ostream &OS, const DINode *Node,
const DILocation *DL) {
const LLVMContext &Ctx = Node->getContext();
StringRef Res;
unsigned Line = 0;
if (const auto *V = dyn_cast<const DILocalVariable>(Node)) {
Res = V->getName();
Line = V->getLine();
} else if (const auto *L = dyn_cast<const DILabel>(Node)) {
Res = L->getName();
Line = L->getLine();
}
if (!Res.empty())
OS << Res << "," << Line;
auto *InlinedAt = DL ? DL->getInlinedAt() : nullptr;
if (InlinedAt) {
if (DebugLoc InlinedAtDL = InlinedAt) {
OS << " @[";
printDebugLoc(InlinedAtDL, OS, Ctx);
OS << "]";
}
}
}
void UserValue::print(raw_ostream &OS, const TargetRegisterInfo *TRI) {
OS << "!\"";
printExtendedName(OS, Variable, dl);
OS << "\"\t";
for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I) {
OS << " [" << I.start() << ';' << I.stop() << "):";
if (I.value().isUndef())
OS << "undef";
else {
OS << I.value().getLocNo();
if (I.value().getWasIndirect())
OS << " ind";
}
}
for (unsigned i = 0, e = locations.size(); i != e; ++i) {
OS << " Loc" << i << '=';
locations[i].print(OS, TRI);
}
OS << '\n';
}
void UserLabel::print(raw_ostream &OS, const TargetRegisterInfo *TRI) {
OS << "!\"";
printExtendedName(OS, Label, dl);
OS << "\"\t";
OS << loc;
OS << '\n';
}
void LDVImpl::print(raw_ostream &OS) {
OS << "********** DEBUG VARIABLES **********\n";
for (auto &userValue : userValues)
userValue->print(OS, TRI);
OS << "********** DEBUG LABELS **********\n";
for (auto &userLabel : userLabels)
userLabel->print(OS, TRI);
}
#endif
void UserValue::mapVirtRegs(LDVImpl *LDV) {
for (unsigned i = 0, e = locations.size(); i != e; ++i)
if (locations[i].isReg() &&
Register::isVirtualRegister(locations[i].getReg()))
LDV->mapVirtReg(locations[i].getReg(), this);
}
UserValue *LDVImpl::getUserValue(const DILocalVariable *Var,
Optional<DIExpression::FragmentInfo> Fragment,
const DebugLoc &DL) {
// FIXME: Handle partially overlapping fragments. See
// https://reviews.llvm.org/D70121#1849741.
DebugVariable ID(Var, Fragment, DL->getInlinedAt());
UserValue *&UV = userVarMap[ID];
if (!UV) {
userValues.push_back(
std::make_unique<UserValue>(Var, Fragment, DL, allocator));
UV = userValues.back().get();
}
return UV;
}
void LDVImpl::mapVirtReg(unsigned VirtReg, UserValue *EC) {
assert(Register::isVirtualRegister(VirtReg) && "Only map VirtRegs");
UserValue *&Leader = virtRegToEqClass[VirtReg];
Leader = UserValue::merge(Leader, EC);
}
UserValue *LDVImpl::lookupVirtReg(unsigned VirtReg) {
if (UserValue *UV = virtRegToEqClass.lookup(VirtReg))
return UV->getLeader();
return nullptr;
}
bool LDVImpl::handleDebugValue(MachineInstr &MI, SlotIndex Idx) {
// DBG_VALUE loc, offset, variable
if (MI.getNumOperands() != 4 ||
!(MI.getOperand(1).isReg() || MI.getOperand(1).isImm()) ||
!MI.getOperand(2).isMetadata()) {
LLVM_DEBUG(dbgs() << "Can't handle " << MI);
return false;
}
// Detect invalid DBG_VALUE instructions, with a debug-use of a virtual
// register that hasn't been defined yet. If we do not remove those here, then
// the re-insertion of the DBG_VALUE instruction after register allocation
// will be incorrect.
// TODO: If earlier passes are corrected to generate sane debug information
// (and if the machine verifier is improved to catch this), then these checks
// could be removed or replaced by asserts.
bool Discard = false;
if (MI.getOperand(0).isReg() &&
Register::isVirtualRegister(MI.getOperand(0).getReg())) {
const Register Reg = MI.getOperand(0).getReg();
if (!LIS->hasInterval(Reg)) {
// The DBG_VALUE is described by a virtual register that does not have a
// live interval. Discard the DBG_VALUE.
Discard = true;
LLVM_DEBUG(dbgs() << "Discarding debug info (no LIS interval): " << Idx
<< " " << MI);
} else {
// The DBG_VALUE is only valid if either Reg is live out from Idx, or Reg
// is defined dead at Idx (where Idx is the slot index for the instruction
// preceding the DBG_VALUE).
const LiveInterval &LI = LIS->getInterval(Reg);
LiveQueryResult LRQ = LI.Query(Idx);
if (!LRQ.valueOutOrDead()) {
// We have found a DBG_VALUE with the value in a virtual register that
// is not live. Discard the DBG_VALUE.
Discard = true;
LLVM_DEBUG(dbgs() << "Discarding debug info (reg not live): " << Idx
<< " " << MI);
}
}
}
// Get or create the UserValue for (variable,offset) here.
bool IsIndirect = MI.getOperand(1).isImm();
if (IsIndirect)
assert(MI.getOperand(1).getImm() == 0 && "DBG_VALUE with nonzero offset");
const DILocalVariable *Var = MI.getDebugVariable();
const DIExpression *Expr = MI.getDebugExpression();
UserValue *UV = getUserValue(Var, Expr->getFragmentInfo(), MI.getDebugLoc());
if (!Discard)
UV->addDef(Idx, MI.getOperand(0), IsIndirect, *Expr);
else {
MachineOperand MO = MachineOperand::CreateReg(0U, false);
MO.setIsDebug();
UV->addDef(Idx, MO, false, *Expr);
}
return true;
}
bool LDVImpl::handleDebugLabel(MachineInstr &MI, SlotIndex Idx) {
// DBG_LABEL label
if (MI.getNumOperands() != 1 || !MI.getOperand(0).isMetadata()) {
LLVM_DEBUG(dbgs() << "Can't handle " << MI);
return false;
}
// Get or create the UserLabel for label here.
const DILabel *Label = MI.getDebugLabel();
const DebugLoc &DL = MI.getDebugLoc();
bool Found = false;
for (auto const &L : userLabels) {
if (L->matches(Label, DL->getInlinedAt(), Idx)) {
Found = true;
break;
}
}
if (!Found)
userLabels.push_back(std::make_unique<UserLabel>(Label, DL, Idx));
return true;
}
bool LDVImpl::collectDebugValues(MachineFunction &mf) {
bool Changed = false;
for (MachineFunction::iterator MFI = mf.begin(), MFE = mf.end(); MFI != MFE;
++MFI) {
MachineBasicBlock *MBB = &*MFI;
for (MachineBasicBlock::iterator MBBI = MBB->begin(), MBBE = MBB->end();
MBBI != MBBE;) {
// Use the first debug instruction in the sequence to get a SlotIndex
// for following consecutive debug instructions.
if (!MBBI->isDebugInstr()) {
++MBBI;
continue;
}
// Debug instructions has no slot index. Use the previous
// non-debug instruction's SlotIndex as its SlotIndex.
SlotIndex Idx =
MBBI == MBB->begin()
? LIS->getMBBStartIdx(MBB)
: LIS->getInstructionIndex(*std::prev(MBBI)).getRegSlot();
// Handle consecutive debug instructions with the same slot index.
do {
// Only handle DBG_VALUE in handleDebugValue(). Skip all other
// kinds of debug instructions.
if ((MBBI->isDebugValue() && handleDebugValue(*MBBI, Idx)) ||
(MBBI->isDebugLabel() && handleDebugLabel(*MBBI, Idx))) {
MBBI = MBB->erase(MBBI);
Changed = true;
} else
++MBBI;
} while (MBBI != MBBE && MBBI->isDebugInstr());
}
}
return Changed;
}
void UserValue::extendDef(SlotIndex Idx, DbgVariableValue DbgValue, LiveRange *LR,
const VNInfo *VNI, SmallVectorImpl<SlotIndex> *Kills,
LiveIntervals &LIS) {
SlotIndex Start = Idx;
MachineBasicBlock *MBB = LIS.getMBBFromIndex(Start);
SlotIndex Stop = LIS.getMBBEndIdx(MBB);
LocMap::iterator I = locInts.find(Start);
// Limit to VNI's live range.
bool ToEnd = true;
if (LR && VNI) {
LiveInterval::Segment *Segment = LR->getSegmentContaining(Start);
if (!Segment || Segment->valno != VNI) {
if (Kills)
Kills->push_back(Start);
return;
}
if (Segment->end < Stop) {
Stop = Segment->end;
ToEnd = false;
}
}
// There could already be a short def at Start.
if (I.valid() && I.start() <= Start) {
// Stop when meeting a different location or an already extended interval.
Start = Start.getNextSlot();
if (I.value() != DbgValue || I.stop() != Start)
return;
// This is a one-slot placeholder. Just skip it.
++I;
}
// Limited by the next def.
if (I.valid() && I.start() < Stop)
Stop = I.start();
// Limited by VNI's live range.
else if (!ToEnd && Kills)
Kills->push_back(Stop);
if (Start < Stop)
I.insert(Start, Stop, DbgValue);
}
void UserValue::addDefsFromCopies(
LiveInterval *LI, DbgVariableValue DbgValue,
const SmallVectorImpl<SlotIndex> &Kills,
SmallVectorImpl<std::pair<SlotIndex, DbgVariableValue>> &NewDefs,
MachineRegisterInfo &MRI, LiveIntervals &LIS) {
if (Kills.empty())
return;
// Don't track copies from physregs, there are too many uses.
if (!Register::isVirtualRegister(LI->reg))
return;
// Collect all the (vreg, valno) pairs that are copies of LI.
SmallVector<std::pair<LiveInterval*, const VNInfo*>, 8> CopyValues;
for (MachineOperand &MO : MRI.use_nodbg_operands(LI->reg)) {
MachineInstr *MI = MO.getParent();
// Copies of the full value.
if (MO.getSubReg() || !MI->isCopy())
continue;
Register DstReg = MI->getOperand(0).getReg();
// Don't follow copies to physregs. These are usually setting up call
// arguments, and the argument registers are always call clobbered. We are
// better off in the source register which could be a callee-saved register,
// or it could be spilled.
if (!Register::isVirtualRegister(DstReg))
continue;
// Is the value extended to reach this copy? If not, another def may be
// blocking it, or we are looking at a wrong value of LI.
SlotIndex Idx = LIS.getInstructionIndex(*MI);
LocMap::iterator I = locInts.find(Idx.getRegSlot(true));
if (!I.valid() || I.value() != DbgValue)
continue;
if (!LIS.hasInterval(DstReg))
continue;
LiveInterval *DstLI = &LIS.getInterval(DstReg);
const VNInfo *DstVNI = DstLI->getVNInfoAt(Idx.getRegSlot());
assert(DstVNI && DstVNI->def == Idx.getRegSlot() && "Bad copy value");
CopyValues.push_back(std::make_pair(DstLI, DstVNI));
}
if (CopyValues.empty())
return;
LLVM_DEBUG(dbgs() << "Got " << CopyValues.size() << " copies of " << *LI
<< '\n');
// Try to add defs of the copied values for each kill point.
for (unsigned i = 0, e = Kills.size(); i != e; ++i) {
SlotIndex Idx = Kills[i];
for (unsigned j = 0, e = CopyValues.size(); j != e; ++j) {
LiveInterval *DstLI = CopyValues[j].first;
const VNInfo *DstVNI = CopyValues[j].second;
if (DstLI->getVNInfoAt(Idx) != DstVNI)
continue;
// Check that there isn't already a def at Idx
LocMap::iterator I = locInts.find(Idx);
if (I.valid() && I.start() <= Idx)
continue;
LLVM_DEBUG(dbgs() << "Kill at " << Idx << " covered by valno #"
<< DstVNI->id << " in " << *DstLI << '\n');
MachineInstr *CopyMI = LIS.getInstructionFromIndex(DstVNI->def);
assert(CopyMI && CopyMI->isCopy() && "Bad copy value");
unsigned LocNo = getLocationNo(CopyMI->getOperand(0));
DbgVariableValue NewValue = DbgValue.changeLocNo(LocNo);
I.insert(Idx, Idx.getNextSlot(), NewValue);
NewDefs.push_back(std::make_pair(Idx, NewValue));
break;
}
}
}
void UserValue::computeIntervals(MachineRegisterInfo &MRI,
const TargetRegisterInfo &TRI,
LiveIntervals &LIS, LexicalScopes &LS) {
SmallVector<std::pair<SlotIndex, DbgVariableValue>, 16> Defs;
// Collect all defs to be extended (Skipping undefs).
for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I)
if (!I.value().isUndef())
Defs.push_back(std::make_pair(I.start(), I.value()));
// Extend all defs, and possibly add new ones along the way.
for (unsigned i = 0; i != Defs.size(); ++i) {
SlotIndex Idx = Defs[i].first;
DbgVariableValue DbgValue = Defs[i].second;
const MachineOperand &LocMO = locations[DbgValue.getLocNo()];
if (!LocMO.isReg()) {
extendDef(Idx, DbgValue, nullptr, nullptr, nullptr, LIS);
continue;
}
// Register locations are constrained to where the register value is live.
if (Register::isVirtualRegister(LocMO.getReg())) {
LiveInterval *LI = nullptr;
const VNInfo *VNI = nullptr;
if (LIS.hasInterval(LocMO.getReg())) {
LI = &LIS.getInterval(LocMO.getReg());
VNI = LI->getVNInfoAt(Idx);
}
SmallVector<SlotIndex, 16> Kills;
extendDef(Idx, DbgValue, LI, VNI, &Kills, LIS);
// FIXME: Handle sub-registers in addDefsFromCopies. The problem is that
// if the original location for example is %vreg0:sub_hi, and we find a
// full register copy in addDefsFromCopies (at the moment it only handles
// full register copies), then we must add the sub1 sub-register index to
// the new location. However, that is only possible if the new virtual
// register is of the same regclass (or if there is an equivalent
// sub-register in that regclass). For now, simply skip handling copies if
// a sub-register is involved.
if (LI && !LocMO.getSubReg())
addDefsFromCopies(LI, DbgValue, Kills, Defs, MRI, LIS);
continue;
}
// For physregs, we only mark the start slot idx. DwarfDebug will see it
// as if the DBG_VALUE is valid up until the end of the basic block, or
// the next def of the physical register. So we do not need to extend the
// range. It might actually happen that the DBG_VALUE is the last use of
// the physical register (e.g. if this is an unused input argument to a
// function).
}
// The computed intervals may extend beyond the range of the debug
// location's lexical scope. In this case, splitting of an interval
// can result in an interval outside of the scope being created,
// causing extra unnecessary DBG_VALUEs to be emitted. To prevent
// this, trim the intervals to the lexical scope.
LexicalScope *Scope = LS.findLexicalScope(dl);
if (!Scope)
return;
SlotIndex PrevEnd;
LocMap::iterator I = locInts.begin();
// Iterate over the lexical scope ranges. Each time round the loop
// we check the intervals for overlap with the end of the previous
// range and the start of the next. The first range is handled as
// a special case where there is no PrevEnd.
for (const InsnRange &Range : Scope->getRanges()) {
SlotIndex RStart = LIS.getInstructionIndex(*Range.first);
SlotIndex REnd = LIS.getInstructionIndex(*Range.second);
// Variable locations at the first instruction of a block should be
// based on the block's SlotIndex, not the first instruction's index.
if (Range.first == Range.first->getParent()->begin())
RStart = LIS.getSlotIndexes()->getIndexBefore(*Range.first);
// At the start of each iteration I has been advanced so that
// I.stop() >= PrevEnd. Check for overlap.
if (PrevEnd && I.start() < PrevEnd) {
SlotIndex IStop = I.stop();
DbgVariableValue DbgValue = I.value();
// Stop overlaps previous end - trim the end of the interval to
// the scope range.
I.setStopUnchecked(PrevEnd);
++I;
// If the interval also overlaps the start of the "next" (i.e.
// current) range create a new interval for the remainder (which
// may be further trimmed).
if (RStart < IStop)
I.insert(RStart, IStop, DbgValue);
}
// Advance I so that I.stop() >= RStart, and check for overlap.
I.advanceTo(RStart);
if (!I.valid())
return;
if (I.start() < RStart) {
// Interval start overlaps range - trim to the scope range.
I.setStartUnchecked(RStart);
// Remember that this interval was trimmed.
trimmedDefs.insert(RStart);
}
// The end of a lexical scope range is the last instruction in the
// range. To convert to an interval we need the index of the
// instruction after it.
REnd = REnd.getNextIndex();
// Advance I to first interval outside current range.
I.advanceTo(REnd);
if (!I.valid())
return;
PrevEnd = REnd;
}
// Check for overlap with end of final range.
if (PrevEnd && I.start() < PrevEnd)
I.setStopUnchecked(PrevEnd);
}
void LDVImpl::computeIntervals() {
LexicalScopes LS;
LS.initialize(*MF);
for (unsigned i = 0, e = userValues.size(); i != e; ++i) {
userValues[i]->computeIntervals(MF->getRegInfo(), *TRI, *LIS, LS);
userValues[i]->mapVirtRegs(this);
}
}
bool LDVImpl::runOnMachineFunction(MachineFunction &mf) {
clear();
MF = &mf;
LIS = &pass.getAnalysis<LiveIntervals>();
TRI = mf.getSubtarget().getRegisterInfo();
LLVM_DEBUG(dbgs() << "********** COMPUTING LIVE DEBUG VARIABLES: "
<< mf.getName() << " **********\n");
bool Changed = collectDebugValues(mf);
computeIntervals();
LLVM_DEBUG(print(dbgs()));
ModifiedMF = Changed;
return Changed;
}
static void removeDebugValues(MachineFunction &mf) {
for (MachineBasicBlock &MBB : mf) {
for (auto MBBI = MBB.begin(), MBBE = MBB.end(); MBBI != MBBE; ) {
if (!MBBI->isDebugValue()) {
++MBBI;
continue;
}
MBBI = MBB.erase(MBBI);
}
}
}
bool LiveDebugVariables::runOnMachineFunction(MachineFunction &mf) {
if (!EnableLDV)
return false;
if (!mf.getFunction().getSubprogram()) {
removeDebugValues(mf);
return false;
}
if (!pImpl)
pImpl = new LDVImpl(this);
return static_cast<LDVImpl*>(pImpl)->runOnMachineFunction(mf);
}
void LiveDebugVariables::releaseMemory() {
if (pImpl)
static_cast<LDVImpl*>(pImpl)->clear();
}
LiveDebugVariables::~LiveDebugVariables() {
if (pImpl)
delete static_cast<LDVImpl*>(pImpl);
}
//===----------------------------------------------------------------------===//
// Live Range Splitting
//===----------------------------------------------------------------------===//
bool
UserValue::splitLocation(unsigned OldLocNo, ArrayRef<unsigned> NewRegs,
LiveIntervals& LIS) {
LLVM_DEBUG({
dbgs() << "Splitting Loc" << OldLocNo << '\t';
print(dbgs(), nullptr);
});
bool DidChange = false;
LocMap::iterator LocMapI;
LocMapI.setMap(locInts);
for (unsigned i = 0; i != NewRegs.size(); ++i) {
LiveInterval *LI = &LIS.getInterval(NewRegs[i]);
if (LI->empty())
continue;
// Don't allocate the new LocNo until it is needed.
unsigned NewLocNo = UndefLocNo;
// Iterate over the overlaps between locInts and LI.
LocMapI.find(LI->beginIndex());
if (!LocMapI.valid())
continue;
LiveInterval::iterator LII = LI->advanceTo(LI->begin(), LocMapI.start());
LiveInterval::iterator LIE = LI->end();
while (LocMapI.valid() && LII != LIE) {
// At this point, we know that LocMapI.stop() > LII->start.
LII = LI->advanceTo(LII, LocMapI.start());
if (LII == LIE)
break;
// Now LII->end > LocMapI.start(). Do we have an overlap?
if (LocMapI.value().getLocNo() == OldLocNo &&
LII->start < LocMapI.stop()) {
// Overlapping correct location. Allocate NewLocNo now.
if (NewLocNo == UndefLocNo) {
MachineOperand MO = MachineOperand::CreateReg(LI->reg, false);
MO.setSubReg(locations[OldLocNo].getSubReg());
NewLocNo = getLocationNo(MO);
DidChange = true;
}
SlotIndex LStart = LocMapI.start();
SlotIndex LStop = LocMapI.stop();
DbgVariableValue OldDbgValue = LocMapI.value();
// Trim LocMapI down to the LII overlap.
if (LStart < LII->start)
LocMapI.setStartUnchecked(LII->start);
if (LStop > LII->end)
LocMapI.setStopUnchecked(LII->end);
// Change the value in the overlap. This may trigger coalescing.
LocMapI.setValue(OldDbgValue.changeLocNo(NewLocNo));
// Re-insert any removed OldDbgValue ranges.
if (LStart < LocMapI.start()) {
LocMapI.insert(LStart, LocMapI.start(), OldDbgValue);
++LocMapI;
assert(LocMapI.valid() && "Unexpected coalescing");
}
if (LStop > LocMapI.stop()) {
++LocMapI;
LocMapI.insert(LII->end, LStop, OldDbgValue);
--LocMapI;
}
}
// Advance to the next overlap.
if (LII->end < LocMapI.stop()) {
if (++LII == LIE)
break;
LocMapI.advanceTo(LII->start);
} else {
++LocMapI;
if (!LocMapI.valid())
break;
LII = LI->advanceTo(LII, LocMapI.start());
}
}
}
// Finally, remove OldLocNo unless it is still used by some interval in the
// locInts map. One case when OldLocNo still is in use is when the register
// has been spilled. In such situations the spilled register is kept as a
// location until rewriteLocations is called (VirtRegMap is mapping the old
// register to the spill slot). So for a while we can have locations that map
// to virtual registers that have been removed from both the MachineFunction
// and from LiveIntervals.
//
// We may also just be using the location for a value with a different
// expression.
removeLocationIfUnused(OldLocNo);
LLVM_DEBUG({
dbgs() << "Split result: \t";
print(dbgs(), nullptr);
});
return DidChange;
}
bool
UserValue::splitRegister(unsigned OldReg, ArrayRef<unsigned> NewRegs,
LiveIntervals &LIS) {
bool DidChange = false;
// Split locations referring to OldReg. Iterate backwards so splitLocation can
// safely erase unused locations.
for (unsigned i = locations.size(); i ; --i) {
unsigned LocNo = i-1;
const MachineOperand *Loc = &locations[LocNo];
if (!Loc->isReg() || Loc->getReg() != OldReg)
continue;
DidChange |= splitLocation(LocNo, NewRegs, LIS);
}
return DidChange;
}
void LDVImpl::splitRegister(unsigned OldReg, ArrayRef<unsigned> NewRegs) {
bool DidChange = false;
for (UserValue *UV = lookupVirtReg(OldReg); UV; UV = UV->getNext())
DidChange |= UV->splitRegister(OldReg, NewRegs, *LIS);
if (!DidChange)
return;
// Map all of the new virtual registers.
UserValue *UV = lookupVirtReg(OldReg);
for (unsigned i = 0; i != NewRegs.size(); ++i)
mapVirtReg(NewRegs[i], UV);
}
void LiveDebugVariables::
splitRegister(unsigned OldReg, ArrayRef<unsigned> NewRegs, LiveIntervals &LIS) {
if (pImpl)
static_cast<LDVImpl*>(pImpl)->splitRegister(OldReg, NewRegs);
}
void UserValue::rewriteLocations(VirtRegMap &VRM, const MachineFunction &MF,
const TargetInstrInfo &TII,
const TargetRegisterInfo &TRI,
SpillOffsetMap &SpillOffsets) {
// Build a set of new locations with new numbers so we can coalesce our
// IntervalMap if two vreg intervals collapse to the same physical location.
// Use MapVector instead of SetVector because MapVector::insert returns the
// position of the previously or newly inserted element. The boolean value
// tracks if the location was produced by a spill.
// FIXME: This will be problematic if we ever support direct and indirect
// frame index locations, i.e. expressing both variables in memory and
// 'int x, *px = &x'. The "spilled" bit must become part of the location.
MapVector<MachineOperand, std::pair<bool, unsigned>> NewLocations;
SmallVector<unsigned, 4> LocNoMap(locations.size());
for (unsigned I = 0, E = locations.size(); I != E; ++I) {
bool Spilled = false;
unsigned SpillOffset = 0;
MachineOperand Loc = locations[I];
// Only virtual registers are rewritten.
if (Loc.isReg() && Loc.getReg() &&
Register::isVirtualRegister(Loc.getReg())) {
Register VirtReg = Loc.getReg();
if (VRM.isAssignedReg(VirtReg) &&
Register::isPhysicalRegister(VRM.getPhys(VirtReg))) {
// This can create a %noreg operand in rare cases when the sub-register
// index is no longer available. That means the user value is in a
// non-existent sub-register, and %noreg is exactly what we want.
Loc.substPhysReg(VRM.getPhys(VirtReg), TRI);
} else if (VRM.getStackSlot(VirtReg) != VirtRegMap::NO_STACK_SLOT) {
// Retrieve the stack slot offset.
unsigned SpillSize;
const MachineRegisterInfo &MRI = MF.getRegInfo();
const TargetRegisterClass *TRC = MRI.getRegClass(VirtReg);
bool Success = TII.getStackSlotRange(TRC, Loc.getSubReg(), SpillSize,
SpillOffset, MF);
// FIXME: Invalidate the location if the offset couldn't be calculated.
(void)Success;
Loc = MachineOperand::CreateFI(VRM.getStackSlot(VirtReg));
Spilled = true;
} else {
Loc.setReg(0);
Loc.setSubReg(0);
}
}
// Insert this location if it doesn't already exist and record a mapping
// from the old number to the new number.
auto InsertResult = NewLocations.insert({Loc, {Spilled, SpillOffset}});
unsigned NewLocNo = std::distance(NewLocations.begin(), InsertResult.first);
LocNoMap[I] = NewLocNo;
}
// Rewrite the locations and record the stack slot offsets for spills.
locations.clear();
SpillOffsets.clear();
for (auto &Pair : NewLocations) {
bool Spilled;
unsigned SpillOffset;
std::tie(Spilled, SpillOffset) = Pair.second;
locations.push_back(Pair.first);
if (Spilled) {
unsigned NewLocNo = std::distance(&*NewLocations.begin(), &Pair);
SpillOffsets[NewLocNo] = SpillOffset;
}
}
// Update the interval map, but only coalesce left, since intervals to the
// right use the old location numbers. This should merge two contiguous
// DBG_VALUE intervals with different vregs that were allocated to the same
// physical register.
for (LocMap::iterator I = locInts.begin(); I.valid(); ++I) {
DbgVariableValue DbgValue = I.value();
// Undef values don't exist in locations (and thus not in LocNoMap either)
// so skip over them. See getLocationNo().
if (DbgValue.isUndef())
continue;
unsigned NewLocNo = LocNoMap[DbgValue.getLocNo()];
I.setValueUnchecked(DbgValue.changeLocNo(NewLocNo));
I.setStart(I.start());
}
}
/// Find an iterator for inserting a DBG_VALUE instruction.
static MachineBasicBlock::iterator
findInsertLocation(MachineBasicBlock *MBB, SlotIndex Idx,
LiveIntervals &LIS) {
SlotIndex Start = LIS.getMBBStartIdx(MBB);
Idx = Idx.getBaseIndex();
// Try to find an insert location by going backwards from Idx.
MachineInstr *MI;
while (!(MI = LIS.getInstructionFromIndex(Idx))) {
// We've reached the beginning of MBB.
if (Idx == Start) {
MachineBasicBlock::iterator I = MBB->SkipPHIsLabelsAndDebug(MBB->begin());
return I;
}
Idx = Idx.getPrevIndex();
}
// Don't insert anything after the first terminator, though.
return MI->isTerminator() ? MBB->getFirstTerminator() :
std::next(MachineBasicBlock::iterator(MI));
}
/// Find an iterator for inserting the next DBG_VALUE instruction
/// (or end if no more insert locations found).
static MachineBasicBlock::iterator
findNextInsertLocation(MachineBasicBlock *MBB,
MachineBasicBlock::iterator I,
SlotIndex StopIdx, MachineOperand &LocMO,
LiveIntervals &LIS,
const TargetRegisterInfo &TRI) {
if (!LocMO.isReg())
return MBB->instr_end();
Register Reg = LocMO.getReg();
// Find the next instruction in the MBB that define the register Reg.
while (I != MBB->end() && !I->isTerminator()) {
if (!LIS.isNotInMIMap(*I) &&
SlotIndex::isEarlierEqualInstr(StopIdx, LIS.getInstructionIndex(*I)))
break;
if (I->definesRegister(Reg, &TRI))
// The insert location is directly after the instruction/bundle.
return std::next(I);
++I;
}
return MBB->end();
}
void UserValue::insertDebugValue(MachineBasicBlock *MBB, SlotIndex StartIdx,
SlotIndex StopIdx, DbgVariableValue DbgValue,
bool Spilled, unsigned SpillOffset,
LiveIntervals &LIS, const TargetInstrInfo &TII,
const TargetRegisterInfo &TRI) {
SlotIndex MBBEndIdx = LIS.getMBBEndIdx(&*MBB);
// Only search within the current MBB.
StopIdx = (MBBEndIdx < StopIdx) ? MBBEndIdx : StopIdx;
MachineBasicBlock::iterator I = findInsertLocation(MBB, StartIdx, LIS);
// Undef values don't exist in locations so create new "noreg" register MOs
// for them. See getLocationNo().
MachineOperand MO =
!DbgValue.isUndef()
? locations[DbgValue.getLocNo()]
: MachineOperand::CreateReg(
/* Reg */ 0, /* isDef */ false, /* isImp */ false,
/* isKill */ false, /* isDead */ false,
/* isUndef */ false, /* isEarlyClobber */ false,
/* SubReg */ 0, /* isDebug */ true);
++NumInsertedDebugValues;
assert(cast<DILocalVariable>(Variable)
->isValidLocationForIntrinsic(getDebugLoc()) &&
"Expected inlined-at fields to agree");
// If the location was spilled, the new DBG_VALUE will be indirect. If the
// original DBG_VALUE was indirect, we need to add DW_OP_deref to indicate
// that the original virtual register was a pointer. Also, add the stack slot
// offset for the spilled register to the expression.
const DIExpression *Expr = DbgValue.getExpression();
uint8_t DIExprFlags = DIExpression::ApplyOffset;
bool IsIndirect = DbgValue.getWasIndirect();
if (Spilled) {
if (IsIndirect)
DIExprFlags |= DIExpression::DerefAfter;
Expr =
DIExpression::prepend(Expr, DIExprFlags, SpillOffset);
IsIndirect = true;
}
assert((!Spilled || MO.isFI()) && "a spilled location must be a frame index");
do {
BuildMI(*MBB, I, getDebugLoc(), TII.get(TargetOpcode::DBG_VALUE),
IsIndirect, MO, Variable, Expr);
// Continue and insert DBG_VALUES after every redefinition of register
// associated with the debug value within the range
I = findNextInsertLocation(MBB, I, StopIdx, MO, LIS, TRI);
} while (I != MBB->end());
}
void UserLabel::insertDebugLabel(MachineBasicBlock *MBB, SlotIndex Idx,
LiveIntervals &LIS,
const TargetInstrInfo &TII) {
MachineBasicBlock::iterator I = findInsertLocation(MBB, Idx, LIS);
++NumInsertedDebugLabels;
BuildMI(*MBB, I, getDebugLoc(), TII.get(TargetOpcode::DBG_LABEL))
.addMetadata(Label);
}
void UserValue::emitDebugValues(VirtRegMap *VRM, LiveIntervals &LIS,
const TargetInstrInfo &TII,
const TargetRegisterInfo &TRI,
const SpillOffsetMap &SpillOffsets) {
MachineFunction::iterator MFEnd = VRM->getMachineFunction().end();
for (LocMap::const_iterator I = locInts.begin(); I.valid();) {
SlotIndex Start = I.start();
SlotIndex Stop = I.stop();
DbgVariableValue DbgValue = I.value();
auto SpillIt = !DbgValue.isUndef() ? SpillOffsets.find(DbgValue.getLocNo())
: SpillOffsets.end();
bool Spilled = SpillIt != SpillOffsets.end();
unsigned SpillOffset = Spilled ? SpillIt->second : 0;
// If the interval start was trimmed to the lexical scope insert the
// DBG_VALUE at the previous index (otherwise it appears after the
// first instruction in the range).
if (trimmedDefs.count(Start))
Start = Start.getPrevIndex();
LLVM_DEBUG(dbgs() << "\t[" << Start << ';' << Stop
<< "):" << DbgValue.getLocNo());
MachineFunction::iterator MBB = LIS.getMBBFromIndex(Start)->getIterator();
SlotIndex MBBEnd = LIS.getMBBEndIdx(&*MBB);
LLVM_DEBUG(dbgs() << ' ' << printMBBReference(*MBB) << '-' << MBBEnd);
insertDebugValue(&*MBB, Start, Stop, DbgValue, Spilled, SpillOffset, LIS,
TII, TRI);
// This interval may span multiple basic blocks.
// Insert a DBG_VALUE into each one.
while (Stop > MBBEnd) {
// Move to the next block.
Start = MBBEnd;
if (++MBB == MFEnd)
break;
MBBEnd = LIS.getMBBEndIdx(&*MBB);
LLVM_DEBUG(dbgs() << ' ' << printMBBReference(*MBB) << '-' << MBBEnd);
insertDebugValue(&*MBB, Start, Stop, DbgValue, Spilled, SpillOffset, LIS,
TII, TRI);
}
LLVM_DEBUG(dbgs() << '\n');
if (MBB == MFEnd)
break;
++I;
}
}
void UserLabel::emitDebugLabel(LiveIntervals &LIS, const TargetInstrInfo &TII) {
LLVM_DEBUG(dbgs() << "\t" << loc);
MachineFunction::iterator MBB = LIS.getMBBFromIndex(loc)->getIterator();
LLVM_DEBUG(dbgs() << ' ' << printMBBReference(*MBB));
insertDebugLabel(&*MBB, loc, LIS, TII);
LLVM_DEBUG(dbgs() << '\n');
}
void LDVImpl::emitDebugValues(VirtRegMap *VRM) {
LLVM_DEBUG(dbgs() << "********** EMITTING LIVE DEBUG VARIABLES **********\n");
if (!MF)
return;
const TargetInstrInfo *TII = MF->getSubtarget().getInstrInfo();
SpillOffsetMap SpillOffsets;
for (auto &userValue : userValues) {
LLVM_DEBUG(userValue->print(dbgs(), TRI));
userValue->rewriteLocations(*VRM, *MF, *TII, *TRI, SpillOffsets);
userValue->emitDebugValues(VRM, *LIS, *TII, *TRI, SpillOffsets);
}
LLVM_DEBUG(dbgs() << "********** EMITTING LIVE DEBUG LABELS **********\n");
for (auto &userLabel : userLabels) {
LLVM_DEBUG(userLabel->print(dbgs(), TRI));
userLabel->emitDebugLabel(*LIS, *TII);
}
EmitDone = true;
}
void LiveDebugVariables::emitDebugValues(VirtRegMap *VRM) {
if (pImpl)
static_cast<LDVImpl*>(pImpl)->emitDebugValues(VRM);
}
bool LiveDebugVariables::doInitialization(Module &M) {
return Pass::doInitialization(M);
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
LLVM_DUMP_METHOD void LiveDebugVariables::dump() const {
if (pImpl)
static_cast<LDVImpl*>(pImpl)->print(dbgs());
}
#endif
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