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llvm/lib/CodeGen/LiveDebugVariables.cpp
Adrian Prantl 02474a32eb Move the complex address expression out of DIVariable and into an extra 
argument of the llvm.dbg.declare/llvm.dbg.value intrinsics.

Previously, DIVariable was a variable-length field that has an optional
reference to a Metadata array consisting of a variable number of
complex address expressions. In the case of OpPiece expressions this is
wasting a lot of storage in IR, because when an aggregate type is, e.g.,
SROA'd into all of its n individual members, the IR will contain n copies
of the DIVariable, all alike, only differing in the complex address
reference at the end.

By making the complex address into an extra argument of the
dbg.value/dbg.declare intrinsics, all of the pieces can reference the
same variable and the complex address expressions can be uniqued across
the CU, too.
Down the road, this will allow us to move other flags, such as
"indirection" out of the DIVariable, too.

The new intrinsics look like this:
declare void @llvm.dbg.declare(metadata %storage, metadata %var, metadata %expr)
declare void @llvm.dbg.value(metadata %storage, i64 %offset, metadata %var, metadata %expr)

This patch adds a new LLVM-local tag to DIExpressions, so we can detect
and pretty-print DIExpression metadata nodes.

What this patch doesn't do:

This patch does not touch the "Indirect" field in DIVariable; but moving
that into the expression would be a natural next step.

http://reviews.llvm.org/D4919
rdar://problem/17994491

Thanks to dblaikie and dexonsmith for reviewing this patch!

Note: I accidentally committed a bogus older version of this patch previously.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218787 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-01 18:55:02 +00:00

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//===- LiveDebugVariables.cpp - Tracking debug info variables -------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// 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/IntervalMap.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/LexicalScopes.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/VirtRegMap.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/Metadata.h"
#include "llvm/IR/Value.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetSubtargetInfo.h"
#include <memory>
using namespace llvm;
#define DEBUG_TYPE "livedebug"
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");
char LiveDebugVariables::ID = 0;
INITIALIZE_PASS_BEGIN(LiveDebugVariables, "livedebugvars",
"Debug Variable Analysis", false, false)
INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
INITIALIZE_PASS_DEPENDENCY(LiveIntervals)
INITIALIZE_PASS_END(LiveDebugVariables, "livedebugvars",
"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), pImpl(nullptr) {
initializeLiveDebugVariablesPass(*PassRegistry::getPassRegistry());
}
/// LocMap - Map of where a user value is live, and its location.
typedef IntervalMap<SlotIndex, unsigned, 4> LocMap;
namespace {
/// UserValueScopes - Keeps track of lexical scopes associated with a
/// user value's source location.
class UserValueScopes {
DebugLoc DL;
LexicalScopes &LS;
SmallPtrSet<const MachineBasicBlock *, 4> LBlocks;
public:
UserValueScopes(DebugLoc D, LexicalScopes &L) : DL(D), LS(L) {}
/// dominates - Return true if current scope dominates at least one machine
/// instruction in a given machine basic block.
bool dominates(MachineBasicBlock *MBB) {
if (LBlocks.empty())
LS.getMachineBasicBlocks(DL, LBlocks);
if (LBlocks.count(MBB) != 0 || LS.dominates(DL, MBB))
return true;
return false;
}
};
} // end anonymous namespace
/// UserValue - 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 refer to the same variable, or if they are
/// held by the same virtual register. The equivalence class is the transitive
/// closure of that relation.
namespace {
class LDVImpl;
class UserValue {
const MDNode *Variable; ///< The debug info variable we are part of.
const MDNode *Expression; ///< Any complex address expression.
unsigned offset; ///< Byte offset into variable.
bool IsIndirect; ///< true if this is a register-indirect+offset value.
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; ///< 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;
/// coalesceLocation - After LocNo was changed, check if it has become
/// identical to another location, and coalesce them. This may cause LocNo or
/// a later location to be erased, but no earlier location will be erased.
void coalesceLocation(unsigned LocNo);
/// insertDebugValue - Insert a DBG_VALUE into MBB at Idx for LocNo.
void insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx, unsigned LocNo,
LiveIntervals &LIS, const TargetInstrInfo &TII);
/// splitLocation - 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:
/// UserValue - Create a new UserValue.
UserValue(const MDNode *var, const MDNode *expr, unsigned o, bool i,
DebugLoc L, LocMap::Allocator &alloc)
: Variable(var), Expression(expr), offset(o), IsIndirect(i), dl(L),
leader(this), next(nullptr), locInts(alloc) {}
/// getLeader - Get the leader of this value's equivalence class.
UserValue *getLeader() {
UserValue *l = leader;
while (l != l->leader)
l = l->leader;
return leader = l;
}
/// getNext - Return the next UserValue in the equivalence class.
UserValue *getNext() const { return next; }
/// match - Does this UserValue match the parameters?
bool match(const MDNode *Var, const MDNode *Expr, unsigned Offset,
bool indirect) const {
return Var == Variable && Expr == Expression && Offset == offset &&
indirect == IsIndirect;
}
/// merge - 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;
}
/// getLocationNo - Return the location number that matches Loc.
unsigned getLocationNo(const MachineOperand &LocMO) {
if (LocMO.isReg()) {
if (LocMO.getReg() == 0)
return ~0u;
// 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())
locations.back().setIsUse();
return locations.size() - 1;
}
/// mapVirtRegs - Ensure that all virtual register locations are mapped.
void mapVirtRegs(LDVImpl *LDV);
/// addDef - Add a definition point to this value.
void addDef(SlotIndex Idx, const MachineOperand &LocMO) {
// Add a singular (Idx,Idx) -> Loc mapping.
LocMap::iterator I = locInts.find(Idx);
if (!I.valid() || I.start() != Idx)
I.insert(Idx, Idx.getNextSlot(), getLocationNo(LocMO));
else
// A later DBG_VALUE at the same SlotIndex overrides the old location.
I.setValue(getLocationNo(LocMO));
}
/// extendDef - Extend the current definition as far as possible down the
/// dominator tree. 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.
/// @param Idx Starting point for the definition.
/// @param LocNo Location number 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 Kills Append end points of VNI's live range to Kills.
/// @param LIS Live intervals analysis.
/// @param MDT Dominator tree.
void extendDef(SlotIndex Idx, unsigned LocNo,
LiveRange *LR, const VNInfo *VNI,
SmallVectorImpl<SlotIndex> *Kills,
LiveIntervals &LIS, MachineDominatorTree &MDT,
UserValueScopes &UVS);
/// addDefsFromCopies - The value in LI/LocNo 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 LocNo Location number of LI->reg.
/// @param Kills Points where the range of LocNo could be extended.
/// @param NewDefs Append (Idx, LocNo) of inserted defs here.
void addDefsFromCopies(LiveInterval *LI, unsigned LocNo,
const SmallVectorImpl<SlotIndex> &Kills,
SmallVectorImpl<std::pair<SlotIndex, unsigned> > &NewDefs,
MachineRegisterInfo &MRI,
LiveIntervals &LIS);
/// computeIntervals - Compute the live intervals of all locations after
/// collecting all their def points.
void computeIntervals(MachineRegisterInfo &MRI, const TargetRegisterInfo &TRI,
LiveIntervals &LIS, MachineDominatorTree &MDT,
UserValueScopes &UVS);
/// splitRegister - Replace OldReg ranges with NewRegs ranges where NewRegs is
/// live. Returns true if any changes were made.
bool splitRegister(unsigned OldLocNo, ArrayRef<unsigned> NewRegs,
LiveIntervals &LIS);
/// rewriteLocations - Rewrite virtual register locations according to the
/// provided virtual register map.
void rewriteLocations(VirtRegMap &VRM, const TargetRegisterInfo &TRI);
/// emitDebugValues - Recreate DBG_VALUE instruction from data structures.
void emitDebugValues(VirtRegMap *VRM,
LiveIntervals &LIS, const TargetInstrInfo &TRI);
/// findDebugLoc - Return DebugLoc used for this DBG_VALUE instruction. A
/// variable may have more than one corresponding DBG_VALUE instructions.
/// Only first one needs DebugLoc to identify variable's lexical scope
/// in source file.
DebugLoc findDebugLoc();
/// getDebugLoc - Return DebugLoc of this UserValue.
DebugLoc getDebugLoc() { return dl;}
void print(raw_ostream&, const TargetMachine*);
};
} // namespace
/// LDVImpl - Implementation of the LiveDebugVariables pass.
namespace {
class LDVImpl {
LiveDebugVariables &pass;
LocMap::Allocator allocator;
MachineFunction *MF;
LiveIntervals *LIS;
LexicalScopes LS;
MachineDominatorTree *MDT;
const TargetRegisterInfo *TRI;
/// Whether emitDebugValues is called.
bool EmitDone;
/// Whether the machine function is modified during the pass.
bool ModifiedMF;
/// userValues - All allocated UserValue instances.
SmallVector<std::unique_ptr<UserValue>, 8> userValues;
/// Map virtual register to eq class leader.
typedef DenseMap<unsigned, UserValue*> VRMap;
VRMap virtRegToEqClass;
/// Map user variable to eq class leader.
typedef DenseMap<const MDNode *, UserValue*> UVMap;
UVMap userVarMap;
/// getUserValue - Find or create a UserValue.
UserValue *getUserValue(const MDNode *Var, const MDNode *Expr,
unsigned Offset, bool IsIndirect, DebugLoc DL);
/// lookupVirtReg - Find the EC leader for VirtReg or null.
UserValue *lookupVirtReg(unsigned VirtReg);
/// handleDebugValue - Add DBG_VALUE instruction to our maps.
/// @param MI DBG_VALUE instruction
/// @param Idx Last valid SLotIndex before instruction.
/// @return True if the DBG_VALUE instruction should be deleted.
bool handleDebugValue(MachineInstr *MI, SlotIndex Idx);
/// collectDebugValues - Collect and erase all DBG_VALUE instructions, adding
/// a UserValue def for each instruction.
/// @param mf MachineFunction to be scanned.
/// @return True if any debug values were found.
bool collectDebugValues(MachineFunction &mf);
/// computeIntervals - Compute the live intervals of all user values after
/// collecting all their def points.
void computeIntervals();
public:
LDVImpl(LiveDebugVariables *ps)
: pass(*ps), MF(nullptr), EmitDone(false), ModifiedMF(false) {}
bool runOnMachineFunction(MachineFunction &mf);
/// clear - Release all memory.
void clear() {
MF = nullptr;
userValues.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;
}
/// mapVirtReg - Map virtual register to an equivalence class.
void mapVirtReg(unsigned VirtReg, UserValue *EC);
/// splitRegister - Replace all references to OldReg with NewRegs.
void splitRegister(unsigned OldReg, ArrayRef<unsigned> NewRegs);
/// emitDebugValues - Recreate DBG_VALUE instruction from data structures.
void emitDebugValues(VirtRegMap *VRM);
void print(raw_ostream&);
};
} // namespace
void UserValue::print(raw_ostream &OS, const TargetMachine *TM) {
DIVariable DV(Variable);
OS << "!\"";
DV.printExtendedName(OS);
OS << "\"\t";
if (offset)
OS << '+' << offset;
for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I) {
OS << " [" << I.start() << ';' << I.stop() << "):";
if (I.value() == ~0u)
OS << "undef";
else
OS << I.value();
}
for (unsigned i = 0, e = locations.size(); i != e; ++i) {
OS << " Loc" << i << '=';
locations[i].print(OS, TM);
}
OS << '\n';
}
void LDVImpl::print(raw_ostream &OS) {
OS << "********** DEBUG VARIABLES **********\n";
for (unsigned i = 0, e = userValues.size(); i != e; ++i)
userValues[i]->print(OS, &MF->getTarget());
}
void UserValue::coalesceLocation(unsigned LocNo) {
unsigned KeepLoc = 0;
for (unsigned e = locations.size(); KeepLoc != e; ++KeepLoc) {
if (KeepLoc == LocNo)
continue;
if (locations[KeepLoc].isIdenticalTo(locations[LocNo]))
break;
}
// No matches.
if (KeepLoc == locations.size())
return;
// Keep the smaller location, erase the larger one.
unsigned EraseLoc = LocNo;
if (KeepLoc > EraseLoc)
std::swap(KeepLoc, EraseLoc);
locations.erase(locations.begin() + EraseLoc);
// Rewrite values.
for (LocMap::iterator I = locInts.begin(); I.valid(); ++I) {
unsigned v = I.value();
if (v == EraseLoc)
I.setValue(KeepLoc); // Coalesce when possible.
else if (v > EraseLoc)
I.setValueUnchecked(v-1); // Avoid coalescing with untransformed values.
}
}
void UserValue::mapVirtRegs(LDVImpl *LDV) {
for (unsigned i = 0, e = locations.size(); i != e; ++i)
if (locations[i].isReg() &&
TargetRegisterInfo::isVirtualRegister(locations[i].getReg()))
LDV->mapVirtReg(locations[i].getReg(), this);
}
UserValue *LDVImpl::getUserValue(const MDNode *Var, const MDNode *Expr,
unsigned Offset, bool IsIndirect,
DebugLoc DL) {
UserValue *&Leader = userVarMap[Var];
if (Leader) {
UserValue *UV = Leader->getLeader();
Leader = UV;
for (; UV; UV = UV->getNext())
if (UV->match(Var, Expr, Offset, IsIndirect))
return UV;
}
userValues.push_back(
make_unique<UserValue>(Var, Expr, Offset, IsIndirect, DL, allocator));
UserValue *UV = userValues.back().get();
Leader = UserValue::merge(Leader, UV);
return UV;
}
void LDVImpl::mapVirtReg(unsigned VirtReg, UserValue *EC) {
assert(TargetRegisterInfo::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()) {
DEBUG(dbgs() << "Can't handle " << *MI);
return false;
}
// Get or create the UserValue for (variable,offset).
bool IsIndirect = MI->isIndirectDebugValue();
unsigned Offset = IsIndirect ? MI->getOperand(1).getImm() : 0;
const MDNode *Var = MI->getDebugVariable();
const MDNode *Expr = MI->getDebugExpression();
//here.
UserValue *UV =
getUserValue(Var, Expr, Offset, IsIndirect, MI->getDebugLoc());
UV->addDef(Idx, MI->getOperand(0));
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;) {
if (!MBBI->isDebugValue()) {
++MBBI;
continue;
}
// DBG_VALUE has no slot index, use the previous instruction instead.
SlotIndex Idx = MBBI == MBB->begin() ?
LIS->getMBBStartIdx(MBB) :
LIS->getInstructionIndex(std::prev(MBBI)).getRegSlot();
// Handle consecutive DBG_VALUE instructions with the same slot index.
do {
if (handleDebugValue(MBBI, Idx)) {
MBBI = MBB->erase(MBBI);
Changed = true;
} else
++MBBI;
} while (MBBI != MBBE && MBBI->isDebugValue());
}
}
return Changed;
}
void UserValue::extendDef(SlotIndex Idx, unsigned LocNo,
LiveRange *LR, const VNInfo *VNI,
SmallVectorImpl<SlotIndex> *Kills,
LiveIntervals &LIS, MachineDominatorTree &MDT,
UserValueScopes &UVS) {
SmallVector<SlotIndex, 16> Todo;
Todo.push_back(Idx);
do {
SlotIndex Start = Todo.pop_back_val();
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);
continue;
}
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() != LocNo || I.stop() != Start)
continue;
// This is a one-slot placeholder. Just skip it.
++I;
}
// Limited by the next def.
if (I.valid() && I.start() < Stop)
Stop = I.start(), ToEnd = false;
// Limited by VNI's live range.
else if (!ToEnd && Kills)
Kills->push_back(Stop);
if (Start >= Stop)
continue;
I.insert(Start, Stop, LocNo);
// If we extended to the MBB end, propagate down the dominator tree.
if (!ToEnd)
continue;
const std::vector<MachineDomTreeNode*> &Children =
MDT.getNode(MBB)->getChildren();
for (unsigned i = 0, e = Children.size(); i != e; ++i) {
MachineBasicBlock *MBB = Children[i]->getBlock();
if (UVS.dominates(MBB))
Todo.push_back(LIS.getMBBStartIdx(MBB));
}
} while (!Todo.empty());
}
void
UserValue::addDefsFromCopies(LiveInterval *LI, unsigned LocNo,
const SmallVectorImpl<SlotIndex> &Kills,
SmallVectorImpl<std::pair<SlotIndex, unsigned> > &NewDefs,
MachineRegisterInfo &MRI, LiveIntervals &LIS) {
if (Kills.empty())
return;
// Don't track copies from physregs, there are too many uses.
if (!TargetRegisterInfo::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;
unsigned 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 (!TargetRegisterInfo::isVirtualRegister(DstReg))
continue;
// Is LocNo 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() != LocNo)
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;
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;
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));
I.insert(Idx, Idx.getNextSlot(), LocNo);
NewDefs.push_back(std::make_pair(Idx, LocNo));
break;
}
}
}
void
UserValue::computeIntervals(MachineRegisterInfo &MRI,
const TargetRegisterInfo &TRI,
LiveIntervals &LIS,
MachineDominatorTree &MDT,
UserValueScopes &UVS) {
SmallVector<std::pair<SlotIndex, unsigned>, 16> Defs;
// Collect all defs to be extended (Skipping undefs).
for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I)
if (I.value() != ~0u)
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;
unsigned LocNo = Defs[i].second;
const MachineOperand &Loc = locations[LocNo];
if (!Loc.isReg()) {
extendDef(Idx, LocNo, nullptr, nullptr, nullptr, LIS, MDT, UVS);
continue;
}
// Register locations are constrained to where the register value is live.
if (TargetRegisterInfo::isVirtualRegister(Loc.getReg())) {
LiveInterval *LI = nullptr;
const VNInfo *VNI = nullptr;
if (LIS.hasInterval(Loc.getReg())) {
LI = &LIS.getInterval(Loc.getReg());
VNI = LI->getVNInfoAt(Idx);
}
SmallVector<SlotIndex, 16> Kills;
extendDef(Idx, LocNo, LI, VNI, &Kills, LIS, MDT, UVS);
if (LI)
addDefsFromCopies(LI, LocNo, Kills, Defs, MRI, LIS);
continue;
}
// For physregs, use the live range of the first regunit as a guide.
unsigned Unit = *MCRegUnitIterator(Loc.getReg(), &TRI);
LiveRange *LR = &LIS.getRegUnit(Unit);
const VNInfo *VNI = LR->getVNInfoAt(Idx);
// Don't track copies from physregs, it is too expensive.
extendDef(Idx, LocNo, LR, VNI, nullptr, LIS, MDT, UVS);
}
// Finally, erase all the undefs.
for (LocMap::iterator I = locInts.begin(); I.valid();)
if (I.value() == ~0u)
I.erase();
else
++I;
}
void LDVImpl::computeIntervals() {
for (unsigned i = 0, e = userValues.size(); i != e; ++i) {
UserValueScopes UVS(userValues[i]->getDebugLoc(), LS);
userValues[i]->computeIntervals(MF->getRegInfo(), *TRI, *LIS, *MDT, UVS);
userValues[i]->mapVirtRegs(this);
}
}
bool LDVImpl::runOnMachineFunction(MachineFunction &mf) {
clear();
MF = &mf;
LIS = &pass.getAnalysis<LiveIntervals>();
MDT = &pass.getAnalysis<MachineDominatorTree>();
TRI = mf.getSubtarget().getRegisterInfo();
LS.initialize(mf);
DEBUG(dbgs() << "********** COMPUTING LIVE DEBUG VARIABLES: "
<< mf.getName() << " **********\n");
bool Changed = collectDebugValues(mf);
computeIntervals();
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 (!FunctionDIs.count(mf.getFunction())) {
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) {
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 = ~0u;
// 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() == OldLocNo && LII->start < LocMapI.stop()) {
// Overlapping correct location. Allocate NewLocNo now.
if (NewLocNo == ~0u) {
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();
// 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(NewLocNo);
// Re-insert any removed OldLocNo ranges.
if (LStart < LocMapI.start()) {
LocMapI.insert(LStart, LocMapI.start(), OldLocNo);
++LocMapI;
assert(LocMapI.valid() && "Unexpected coalescing");
}
if (LStop > LocMapI.stop()) {
++LocMapI;
LocMapI.insert(LII->end, LStop, OldLocNo);
--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 any remaining OldLocNo intervals and OldLocNo itself.
locations.erase(locations.begin() + OldLocNo);
LocMapI.goToBegin();
while (LocMapI.valid()) {
unsigned v = LocMapI.value();
if (v == OldLocNo) {
DEBUG(dbgs() << "Erasing [" << LocMapI.start() << ';'
<< LocMapI.stop() << ")\n");
LocMapI.erase();
} else {
if (v > OldLocNo)
LocMapI.setValueUnchecked(v-1);
++LocMapI;
}
}
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 TargetRegisterInfo &TRI) {
// Iterate over locations in reverse makes it easier to handle coalescing.
for (unsigned i = locations.size(); i ; --i) {
unsigned LocNo = i-1;
MachineOperand &Loc = locations[LocNo];
// Only virtual registers are rewritten.
if (!Loc.isReg() || !Loc.getReg() ||
!TargetRegisterInfo::isVirtualRegister(Loc.getReg()))
continue;
unsigned VirtReg = Loc.getReg();
if (VRM.isAssignedReg(VirtReg) &&
TargetRegisterInfo::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) {
// FIXME: Translate SubIdx to a stackslot offset.
Loc = MachineOperand::CreateFI(VRM.getStackSlot(VirtReg));
} else {
Loc.setReg(0);
Loc.setSubReg(0);
}
coalesceLocation(LocNo);
}
}
/// findInsertLocation - 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->SkipPHIsAndLabels(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));
}
DebugLoc UserValue::findDebugLoc() {
DebugLoc D = dl;
dl = DebugLoc();
return D;
}
void UserValue::insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx,
unsigned LocNo,
LiveIntervals &LIS,
const TargetInstrInfo &TII) {
MachineBasicBlock::iterator I = findInsertLocation(MBB, Idx, LIS);
MachineOperand &Loc = locations[LocNo];
++NumInsertedDebugValues;
if (Loc.isReg())
BuildMI(*MBB, I, findDebugLoc(), TII.get(TargetOpcode::DBG_VALUE),
IsIndirect, Loc.getReg(), offset, Variable, Expression);
else
BuildMI(*MBB, I, findDebugLoc(), TII.get(TargetOpcode::DBG_VALUE))
.addOperand(Loc)
.addImm(offset)
.addMetadata(Variable)
.addMetadata(Expression);
}
void UserValue::emitDebugValues(VirtRegMap *VRM, LiveIntervals &LIS,
const TargetInstrInfo &TII) {
MachineFunction::iterator MFEnd = VRM->getMachineFunction().end();
for (LocMap::const_iterator I = locInts.begin(); I.valid();) {
SlotIndex Start = I.start();
SlotIndex Stop = I.stop();
unsigned LocNo = I.value();
DEBUG(dbgs() << "\t[" << Start << ';' << Stop << "):" << LocNo);
MachineFunction::iterator MBB = LIS.getMBBFromIndex(Start);
SlotIndex MBBEnd = LIS.getMBBEndIdx(MBB);
DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd);
insertDebugValue(MBB, Start, LocNo, LIS, TII);
// 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);
DEBUG(dbgs() << " BB#" << MBB->getNumber() << '-' << MBBEnd);
insertDebugValue(MBB, Start, LocNo, LIS, TII);
}
DEBUG(dbgs() << '\n');
if (MBB == MFEnd)
break;
++I;
}
}
void LDVImpl::emitDebugValues(VirtRegMap *VRM) {
DEBUG(dbgs() << "********** EMITTING LIVE DEBUG VARIABLES **********\n");
if (!MF)
return;
const TargetInstrInfo *TII = MF->getSubtarget().getInstrInfo();
for (unsigned i = 0, e = userValues.size(); i != e; ++i) {
DEBUG(userValues[i]->print(dbgs(), &MF->getTarget()));
userValues[i]->rewriteLocations(*VRM, *TRI);
userValues[i]->emitDebugValues(VRM, *LIS, *TII);
}
EmitDone = true;
}
void LiveDebugVariables::emitDebugValues(VirtRegMap *VRM) {
if (pImpl)
static_cast<LDVImpl*>(pImpl)->emitDebugValues(VRM);
}
bool LiveDebugVariables::doInitialization(Module &M) {
FunctionDIs = makeSubprogramMap(M);
return Pass::doInitialization(M);
}
#ifndef NDEBUG
void LiveDebugVariables::dump() {
if (pImpl)
static_cast<LDVImpl*>(pImpl)->print(dbgs());
}
#endif
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