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llvm-mirror/lib/CodeGen/LiveDebugVariables.cpp
Robert Lougher dae8861924 [LiveDebugVariables] Strip all debug instructions from nodebug functions 
A crash/assertion failure in the greedy register allocator was tracked
down to a debug instr being passed to LiveIntervals::getInstructionIndex.
Normally this should not occur as debug instructions are collected and
removed by LiveDebugVariables before RA, and reinserted afterwards.
However, when a function has no debug info, LiveDebugVariables simply
strips any debug values that are present as they're not needed (this
situation will occur when a function with debug info is inlined into a
nodebug function). The problem is, it only removes DBG_VALUE instructions,
leaving DBG_LABELs (the cause of the crash).

This patch updates the LiveDebugVariables nodebug path to remove all debug
instructions. The test case verifies that DBG_VALUE/DBG_LABEL instructions
are present, and that they are stripped.

When -experimental-debug-variable-locations is enabled, certain variable
locations are represented by DBG_INSTR_REF instead of DBG_VALUE. The test
case verifies that a DBG_INSTR_REF is emitted by the option, and that it
is also stripped.

Differential Revision: https://reviews.llvm.org/D92127
2020-11-26 14:30:18 +00:00

1504 lines
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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/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 };
namespace {
/// 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;
};
} // namespace
/// 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<Register> 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(Register OldReg, ArrayRef<Register> 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;
using StashedInstrRef =
std::tuple<unsigned, unsigned, const DILocalVariable *,
const DIExpression *, DebugLoc>;
std::map<SlotIndex, std::vector<StashedInstrRef>> StashedInstrReferences;
/// 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(Register 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);
/// Track a DBG_INSTR_REF. This needs to be removed from the MachineFunction
/// during regalloc -- but there's no need to maintain live ranges, as we
/// refer to a value rather than a location.
///
/// \param MI DBG_INSTR_REF instruction
/// \param Idx Last valid SlotIndex before instruction
///
/// \returns True if the DBG_VALUE instruction should be deleted.
bool handleDebugInstrRef(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;
StashedInstrReferences.clear();
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(Register VirtReg, UserValue *EC);
/// Replace all references to OldReg with NewRegs.
void splitRegister(Register OldReg, ArrayRef<Register> 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(Register VirtReg, UserValue *EC) {
assert(Register::isVirtualRegister(VirtReg) && "Only map VirtRegs");
UserValue *&Leader = virtRegToEqClass[VirtReg];
Leader = UserValue::merge(Leader, EC);
}
UserValue *LDVImpl::lookupVirtReg(Register 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.getDebugOffset().isReg() || MI.getDebugOffset().isImm()) ||
!MI.getDebugVariableOp().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.getDebugOperand(0).isReg() &&
Register::isVirtualRegister(MI.getDebugOperand(0).getReg())) {
const Register Reg = MI.getDebugOperand(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.isDebugOffsetImm();
if (IsIndirect)
assert(MI.getDebugOffset().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.getDebugOperand(0), IsIndirect, *Expr);
else {
MachineOperand MO = MachineOperand::CreateReg(0U, false);
MO.setIsDebug();
UV->addDef(Idx, MO, false, *Expr);
}
return true;
}
bool LDVImpl::handleDebugInstrRef(MachineInstr &MI, SlotIndex Idx) {
assert(MI.isDebugRef());
unsigned InstrNum = MI.getOperand(0).getImm();
unsigned OperandNum = MI.getOperand(1).getImm();
auto *Var = MI.getDebugVariable();
auto *Expr = MI.getDebugExpression();
auto &DL = MI.getDebugLoc();
StashedInstrRef Stashed =
std::make_tuple(InstrNum, OperandNum, Var, Expr, DL);
StashedInstrReferences[Idx].push_back(Stashed);
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->isDebugRef() && handleDebugInstrRef(*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 removeDebugInstrs(MachineFunction &mf) {
for (MachineBasicBlock &MBB : mf) {
for (auto MBBI = MBB.begin(), MBBE = MBB.end(); MBBI != MBBE; ) {
if (!MBBI->isDebugInstr()) {
++MBBI;
continue;
}
MBBI = MBB.erase(MBBI);
}
}
}
bool LiveDebugVariables::runOnMachineFunction(MachineFunction &mf) {
if (!EnableLDV)
return false;
if (!mf.getFunction().getSubprogram()) {
removeDebugInstrs(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<Register> 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(Register OldReg, ArrayRef<Register> 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(Register OldReg, ArrayRef<Register> 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(Register OldReg, ArrayRef<Register> 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);
}
LLVM_DEBUG(dbgs() << "********** EMITTING INSTR REFERENCES **********\n");
// Re-insert any DBG_INSTR_REFs back in the position they were. Ordering
// is preserved by vector.
auto Slots = LIS->getSlotIndexes();
const MCInstrDesc &RefII = TII->get(TargetOpcode::DBG_INSTR_REF);
for (auto &P : StashedInstrReferences) {
const SlotIndex &Idx = P.first;
auto *MBB = Slots->getMBBFromIndex(Idx);
MachineBasicBlock::iterator insertPos = findInsertLocation(MBB, Idx, *LIS);
for (auto &Stashed : P.second) {
auto MIB = BuildMI(*MF, std::get<4>(Stashed), RefII);
MIB.addImm(std::get<0>(Stashed));
MIB.addImm(std::get<1>(Stashed));
MIB.addMetadata(std::get<2>(Stashed));
MIB.addMetadata(std::get<3>(Stashed));
MachineInstr *New = MIB;
MBB->insert(insertPos, New);
}
}
EmitDone = true;
}
void LiveDebugVariables::emitDebugValues(VirtRegMap *VRM) {
if (pImpl)
static_cast<LDVImpl*>(pImpl)->emitDebugValues(VRM);
}
#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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