third_party/LLVM/lib/VMCore/DebugLoc.cpp - SwiftShader - Git at Google

 //===-- DebugLoc.cpp - Implement DebugLoc class ---------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//

 #include "llvm/Support/DebugLoc.h"
 #include "llvm/ADT/DenseMapInfo.h"
 #include "LLVMContextImpl.h"
 using namespace llvm;

 //===----------------------------------------------------------------------===//
 // DebugLoc Implementation
 //===----------------------------------------------------------------------===//

 MDNode *DebugLoc::getScope(const LLVMContext &Ctx) const {
   if (ScopeIdx == 0) return 0;

   if (ScopeIdx > 0) {
     // Positive ScopeIdx is an index into ScopeRecords, which has no inlined-at
     // position specified.
     assert(unsigned(ScopeIdx) <= Ctx.pImpl->ScopeRecords.size() &&
            "Invalid ScopeIdx!");
     return Ctx.pImpl->ScopeRecords[ScopeIdx-1].get();
   }

   // Otherwise, the index is in the ScopeInlinedAtRecords array.
   assert(unsigned(-ScopeIdx) <= Ctx.pImpl->ScopeInlinedAtRecords.size() &&
          "Invalid ScopeIdx");
   return Ctx.pImpl->ScopeInlinedAtRecords[-ScopeIdx-1].first.get();
 }

 MDNode *DebugLoc::getInlinedAt(const LLVMContext &Ctx) const {
   // Positive ScopeIdx is an index into ScopeRecords, which has no inlined-at
   // position specified.  Zero is invalid.
   if (ScopeIdx >= 0) return 0;

   // Otherwise, the index is in the ScopeInlinedAtRecords array.
   assert(unsigned(-ScopeIdx) <= Ctx.pImpl->ScopeInlinedAtRecords.size() &&
          "Invalid ScopeIdx");
   return Ctx.pImpl->ScopeInlinedAtRecords[-ScopeIdx-1].second.get();
 }

 /// Return both the Scope and the InlinedAt values.
 void DebugLoc::getScopeAndInlinedAt(MDNode *&Scope, MDNode *&IA,
                                     const LLVMContext &Ctx) const {
   if (ScopeIdx == 0) {
     Scope = IA = 0;
     return;
   }

   if (ScopeIdx > 0) {
     // Positive ScopeIdx is an index into ScopeRecords, which has no inlined-at
     // position specified.
     assert(unsigned(ScopeIdx) <= Ctx.pImpl->ScopeRecords.size() &&
            "Invalid ScopeIdx!");
     Scope = Ctx.pImpl->ScopeRecords[ScopeIdx-1].get();
     IA = 0;
     return;
   }

   // Otherwise, the index is in the ScopeInlinedAtRecords array.
   assert(unsigned(-ScopeIdx) <= Ctx.pImpl->ScopeInlinedAtRecords.size() &&
          "Invalid ScopeIdx");
   Scope = Ctx.pImpl->ScopeInlinedAtRecords[-ScopeIdx-1].first.get();
   IA    = Ctx.pImpl->ScopeInlinedAtRecords[-ScopeIdx-1].second.get();
 }


 DebugLoc DebugLoc::get(unsigned Line, unsigned Col,
                        MDNode *Scope, MDNode *InlinedAt) {
   DebugLoc Result;

   // If no scope is available, this is an unknown location.
   if (Scope == 0) return Result;

   // Saturate line and col to "unknown".
   if (Col > 255) Col = 0;
   if (Line >= (1 << 24)) Line = 0;
   Result.LineCol = Line | (Col << 24);

   LLVMContext &Ctx = Scope->getContext();

   // If there is no inlined-at location, use the ScopeRecords array.
   if (InlinedAt == 0)
     Result.ScopeIdx = Ctx.pImpl->getOrAddScopeRecordIdxEntry(Scope, 0);
   else
     Result.ScopeIdx = Ctx.pImpl->getOrAddScopeInlinedAtIdxEntry(Scope,
                                                                 InlinedAt, 0);

   return Result;
 }

 /// getAsMDNode - This method converts the compressed DebugLoc node into a
 /// DILocation compatible MDNode.
 MDNode *DebugLoc::getAsMDNode(const LLVMContext &Ctx) const {
   if (isUnknown()) return 0;

   MDNode *Scope, *IA;
   getScopeAndInlinedAt(Scope, IA, Ctx);
   assert(Scope && "If scope is null, this should be isUnknown()");

   LLVMContext &Ctx2 = Scope->getContext();
   Type *Int32 = Type::getInt32Ty(Ctx2);
   Value *Elts[] = {
     ConstantInt::get(Int32, getLine()), ConstantInt::get(Int32, getCol()),
     Scope, IA
   };
   return MDNode::get(Ctx2, Elts);
 }

 /// getFromDILocation - Translate the DILocation quad into a DebugLoc.
 DebugLoc DebugLoc::getFromDILocation(MDNode *N) {
   if (N == 0 || N->getNumOperands() != 4) return DebugLoc();

   MDNode *Scope = dyn_cast_or_null<MDNode>(N->getOperand(2));
   if (Scope == 0) return DebugLoc();

   unsigned LineNo = 0, ColNo = 0;
   if (ConstantInt *Line = dyn_cast_or_null<ConstantInt>(N->getOperand(0)))
     LineNo = Line->getZExtValue();
   if (ConstantInt *Col = dyn_cast_or_null<ConstantInt>(N->getOperand(1)))
     ColNo = Col->getZExtValue();

   return get(LineNo, ColNo, Scope, dyn_cast_or_null<MDNode>(N->getOperand(3)));
 }

 /// getFromDILexicalBlock - Translate the DILexicalBlock into a DebugLoc.
 DebugLoc DebugLoc::getFromDILexicalBlock(MDNode *N) {
   if (N == 0 || N->getNumOperands() < 3) return DebugLoc();

   MDNode *Scope = dyn_cast_or_null<MDNode>(N->getOperand(1));
   if (Scope == 0) return DebugLoc();

   unsigned LineNo = 0, ColNo = 0;
   if (ConstantInt *Line = dyn_cast_or_null<ConstantInt>(N->getOperand(2)))
     LineNo = Line->getZExtValue();
   if (ConstantInt *Col = dyn_cast_or_null<ConstantInt>(N->getOperand(3)))
     ColNo = Col->getZExtValue();

   return get(LineNo, ColNo, Scope, NULL);
 }

 void DebugLoc::dump(const LLVMContext &Ctx) const {
 #ifndef NDEBUG
   if (!isUnknown()) {
     dbgs() << getLine();
     if (getCol() != 0)
       dbgs() << ',' << getCol();
     DebugLoc InlinedAtDL = DebugLoc::getFromDILocation(getInlinedAt(Ctx));
     if (!InlinedAtDL.isUnknown()) {
       dbgs() << " @ ";
       InlinedAtDL.dump(Ctx);
     } else
       dbgs() << "\n";
   }
 #endif
 }

 //===----------------------------------------------------------------------===//
 // DenseMap specialization
 //===----------------------------------------------------------------------===//

 DebugLoc DenseMapInfo<DebugLoc>::getEmptyKey() {
   return DebugLoc::getEmptyKey();
 }

 DebugLoc DenseMapInfo<DebugLoc>::getTombstoneKey() {
   return DebugLoc::getTombstoneKey();
 }

 unsigned DenseMapInfo<DebugLoc>::getHashValue(const DebugLoc &Key) {
   FoldingSetNodeID ID;
   ID.AddInteger(Key.LineCol);
   ID.AddInteger(Key.ScopeIdx);
   return ID.ComputeHash();
 }

 bool DenseMapInfo<DebugLoc>::isEqual(const DebugLoc &LHS, const DebugLoc &RHS) {
   return LHS == RHS;
 }

 //===----------------------------------------------------------------------===//
 // LLVMContextImpl Implementation
 //===----------------------------------------------------------------------===//

 int LLVMContextImpl::getOrAddScopeRecordIdxEntry(MDNode *Scope,
                                                  int ExistingIdx) {
   // If we already have an entry for this scope, return it.
   int &Idx = ScopeRecordIdx[Scope];
   if (Idx) return Idx;

   // If we don't have an entry, but ExistingIdx is specified, use it.
   if (ExistingIdx)
     return Idx = ExistingIdx;

   // Otherwise add a new entry.

   // Start out ScopeRecords with a minimal reasonable size to avoid
   // excessive reallocation starting out.
   if (ScopeRecords.empty())
     ScopeRecords.reserve(128);

   // Index is biased by 1 for index.
   Idx = ScopeRecords.size()+1;
   ScopeRecords.push_back(DebugRecVH(Scope, this, Idx));
   return Idx;
 }

 int LLVMContextImpl::getOrAddScopeInlinedAtIdxEntry(MDNode *Scope, MDNode *IA,
                                                     int ExistingIdx) {
   // If we already have an entry, return it.
   int &Idx = ScopeInlinedAtIdx[std::make_pair(Scope, IA)];
   if (Idx) return Idx;

   // If we don't have an entry, but ExistingIdx is specified, use it.
   if (ExistingIdx)
     return Idx = ExistingIdx;

   // Start out ScopeInlinedAtRecords with a minimal reasonable size to avoid
   // excessive reallocation starting out.
   if (ScopeInlinedAtRecords.empty())
     ScopeInlinedAtRecords.reserve(128);

   // Index is biased by 1 and negated.
   Idx = -ScopeInlinedAtRecords.size()-1;
   ScopeInlinedAtRecords.push_back(std::make_pair(DebugRecVH(Scope, this, Idx),
                                                  DebugRecVH(IA, this, Idx)));
   return Idx;
 }


 //===----------------------------------------------------------------------===//
 // DebugRecVH Implementation
 //===----------------------------------------------------------------------===//

 /// deleted - The MDNode this is pointing to got deleted, so this pointer needs
 /// to drop to null and we need remove our entry from the DenseMap.
 void DebugRecVH::deleted() {
   // If this is a non-canonical reference, just drop the value to null, we know
   // it doesn't have a map entry.
   if (Idx == 0) {
     setValPtr(0);
     return;
   }

   MDNode *Cur = get();

   // If the index is positive, it is an entry in ScopeRecords.
   if (Idx > 0) {
     assert(Ctx->ScopeRecordIdx[Cur] == Idx && "Mapping out of date!");
     Ctx->ScopeRecordIdx.erase(Cur);
     // Reset this VH to null and we're done.
     setValPtr(0);
     Idx = 0;
     return;
   }

   // Otherwise, it is an entry in ScopeInlinedAtRecords, we don't know if it
   // is the scope or the inlined-at record entry.
   assert(unsigned(-Idx-1) < Ctx->ScopeInlinedAtRecords.size());
   std::pair<DebugRecVH, DebugRecVH> &Entry = Ctx->ScopeInlinedAtRecords[-Idx-1];
   assert((this == &Entry.first || this == &Entry.second) &&
          "Mapping out of date!");

   MDNode *OldScope = Entry.first.get();
   MDNode *OldInlinedAt = Entry.second.get();
   assert(OldScope != 0 && OldInlinedAt != 0 &&
          "Entry should be non-canonical if either val dropped to null");

   // Otherwise, we do have an entry in it, nuke it and we're done.
   assert(Ctx->ScopeInlinedAtIdx[std::make_pair(OldScope, OldInlinedAt)] == Idx&&
          "Mapping out of date");
   Ctx->ScopeInlinedAtIdx.erase(std::make_pair(OldScope, OldInlinedAt));

   // Reset this VH to null.  Drop both 'Idx' values to null to indicate that
   // we're in non-canonical form now.
   setValPtr(0);
   Entry.first.Idx = Entry.second.Idx = 0;
 }

 void DebugRecVH::allUsesReplacedWith(Value *NewVa) {
   // If being replaced with a non-mdnode value (e.g. undef) handle this as if
   // the mdnode got deleted.
   MDNode *NewVal = dyn_cast<MDNode>(NewVa);
   if (NewVal == 0) return deleted();

   // If this is a non-canonical reference, just change it, we know it already
   // doesn't have a map entry.
   if (Idx == 0) {
     setValPtr(NewVa);
     return;
   }

   MDNode *OldVal = get();
   assert(OldVal != NewVa && "Node replaced with self?");

   // If the index is positive, it is an entry in ScopeRecords.
   if (Idx > 0) {
     assert(Ctx->ScopeRecordIdx[OldVal] == Idx && "Mapping out of date!");
     Ctx->ScopeRecordIdx.erase(OldVal);
     setValPtr(NewVal);

     int NewEntry = Ctx->getOrAddScopeRecordIdxEntry(NewVal, Idx);

     // If NewVal already has an entry, this becomes a non-canonical reference,
     // just drop Idx to 0 to signify this.
     if (NewEntry != Idx)
       Idx = 0;
     return;
   }

   // Otherwise, it is an entry in ScopeInlinedAtRecords, we don't know if it
   // is the scope or the inlined-at record entry.
   assert(unsigned(-Idx-1) < Ctx->ScopeInlinedAtRecords.size());
   std::pair<DebugRecVH, DebugRecVH> &Entry = Ctx->ScopeInlinedAtRecords[-Idx-1];
   assert((this == &Entry.first || this == &Entry.second) &&
          "Mapping out of date!");

   MDNode *OldScope = Entry.first.get();
   MDNode *OldInlinedAt = Entry.second.get();
   assert(OldScope != 0 && OldInlinedAt != 0 &&
          "Entry should be non-canonical if either val dropped to null");

   // Otherwise, we do have an entry in it, nuke it and we're done.
   assert(Ctx->ScopeInlinedAtIdx[std::make_pair(OldScope, OldInlinedAt)] == Idx&&
          "Mapping out of date");
   Ctx->ScopeInlinedAtIdx.erase(std::make_pair(OldScope, OldInlinedAt));

   // Reset this VH to the new value.
   setValPtr(NewVal);

   int NewIdx = Ctx->getOrAddScopeInlinedAtIdxEntry(Entry.first.get(),
                                                    Entry.second.get(), Idx);
   // If NewVal already has an entry, this becomes a non-canonical reference,
   // just drop Idx to 0 to signify this.
   if (NewIdx != Idx) {
     std::pair<DebugRecVH, DebugRecVH> &Entry=Ctx->ScopeInlinedAtRecords[-Idx-1];
     Entry.first.Idx = Entry.second.Idx = 0;
   }
 }
	//===-- DebugLoc.cpp - Implement DebugLoc class ---------------------------===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//

	#include "llvm/Support/DebugLoc.h"
	#include "llvm/ADT/DenseMapInfo.h"
	#include "LLVMContextImpl.h"
	using namespace llvm;

	//===----------------------------------------------------------------------===//
	// DebugLoc Implementation
	//===----------------------------------------------------------------------===//

	MDNode *DebugLoc::getScope(const LLVMContext &Ctx) const {
	if (ScopeIdx == 0) return 0;

	if (ScopeIdx > 0) {
	// Positive ScopeIdx is an index into ScopeRecords, which has no inlined-at
	// position specified.
	assert(unsigned(ScopeIdx) <= Ctx.pImpl->ScopeRecords.size() &&
	"Invalid ScopeIdx!");
	return Ctx.pImpl->ScopeRecords[ScopeIdx-1].get();
	}

	// Otherwise, the index is in the ScopeInlinedAtRecords array.
	assert(unsigned(-ScopeIdx) <= Ctx.pImpl->ScopeInlinedAtRecords.size() &&
	"Invalid ScopeIdx");
	return Ctx.pImpl->ScopeInlinedAtRecords[-ScopeIdx-1].first.get();
	}

	MDNode *DebugLoc::getInlinedAt(const LLVMContext &Ctx) const {
	// Positive ScopeIdx is an index into ScopeRecords, which has no inlined-at
	// position specified. Zero is invalid.
	if (ScopeIdx >= 0) return 0;

	// Otherwise, the index is in the ScopeInlinedAtRecords array.
	assert(unsigned(-ScopeIdx) <= Ctx.pImpl->ScopeInlinedAtRecords.size() &&
	"Invalid ScopeIdx");
	return Ctx.pImpl->ScopeInlinedAtRecords[-ScopeIdx-1].second.get();
	}

	/// Return both the Scope and the InlinedAt values.
	void DebugLoc::getScopeAndInlinedAt(MDNode &Scope, MDNode &IA,
	const LLVMContext &Ctx) const {
	if (ScopeIdx == 0) {
	Scope = IA = 0;
	return;
	}

	if (ScopeIdx > 0) {
	// Positive ScopeIdx is an index into ScopeRecords, which has no inlined-at
	// position specified.
	assert(unsigned(ScopeIdx) <= Ctx.pImpl->ScopeRecords.size() &&
	"Invalid ScopeIdx!");
	Scope = Ctx.pImpl->ScopeRecords[ScopeIdx-1].get();
	IA = 0;
	return;
	}

	// Otherwise, the index is in the ScopeInlinedAtRecords array.
	assert(unsigned(-ScopeIdx) <= Ctx.pImpl->ScopeInlinedAtRecords.size() &&
	"Invalid ScopeIdx");
	Scope = Ctx.pImpl->ScopeInlinedAtRecords[-ScopeIdx-1].first.get();
	IA = Ctx.pImpl->ScopeInlinedAtRecords[-ScopeIdx-1].second.get();
	}


	DebugLoc DebugLoc::get(unsigned Line, unsigned Col,
	MDNode Scope, MDNode InlinedAt) {
	DebugLoc Result;

	// If no scope is available, this is an unknown location.
	if (Scope == 0) return Result;

	// Saturate line and col to "unknown".
	if (Col > 255) Col = 0;
	if (Line >= (1 << 24)) Line = 0;
	Result.LineCol = Line \| (Col << 24);

	LLVMContext &Ctx = Scope->getContext();

	// If there is no inlined-at location, use the ScopeRecords array.
	if (InlinedAt == 0)
	Result.ScopeIdx = Ctx.pImpl->getOrAddScopeRecordIdxEntry(Scope, 0);
	else
	Result.ScopeIdx = Ctx.pImpl->getOrAddScopeInlinedAtIdxEntry(Scope,
	InlinedAt, 0);

	return Result;
	}

	/// getAsMDNode - This method converts the compressed DebugLoc node into a
	/// DILocation compatible MDNode.
	MDNode *DebugLoc::getAsMDNode(const LLVMContext &Ctx) const {
	if (isUnknown()) return 0;

	MDNode Scope, IA;
	getScopeAndInlinedAt(Scope, IA, Ctx);
	assert(Scope && "If scope is null, this should be isUnknown()");

	LLVMContext &Ctx2 = Scope->getContext();
	Type *Int32 = Type::getInt32Ty(Ctx2);
	Value *Elts[] = {
	ConstantInt::get(Int32, getLine()), ConstantInt::get(Int32, getCol()),
	Scope, IA
	};
	return MDNode::get(Ctx2, Elts);
	}

	/// getFromDILocation - Translate the DILocation quad into a DebugLoc.
	DebugLoc DebugLoc::getFromDILocation(MDNode *N) {
	if (N == 0 \|\| N->getNumOperands() != 4) return DebugLoc();

	MDNode *Scope = dyn_cast_or_null<MDNode>(N->getOperand(2));
	if (Scope == 0) return DebugLoc();

	unsigned LineNo = 0, ColNo = 0;
	if (ConstantInt *Line = dyn_cast_or_null<ConstantInt>(N->getOperand(0)))
	LineNo = Line->getZExtValue();
	if (ConstantInt *Col = dyn_cast_or_null<ConstantInt>(N->getOperand(1)))
	ColNo = Col->getZExtValue();

	return get(LineNo, ColNo, Scope, dyn_cast_or_null<MDNode>(N->getOperand(3)));
	}

	/// getFromDILexicalBlock - Translate the DILexicalBlock into a DebugLoc.
	DebugLoc DebugLoc::getFromDILexicalBlock(MDNode *N) {
	if (N == 0 \|\| N->getNumOperands() < 3) return DebugLoc();

	MDNode *Scope = dyn_cast_or_null<MDNode>(N->getOperand(1));
	if (Scope == 0) return DebugLoc();

	unsigned LineNo = 0, ColNo = 0;
	if (ConstantInt *Line = dyn_cast_or_null<ConstantInt>(N->getOperand(2)))
	LineNo = Line->getZExtValue();
	if (ConstantInt *Col = dyn_cast_or_null<ConstantInt>(N->getOperand(3)))
	ColNo = Col->getZExtValue();

	return get(LineNo, ColNo, Scope, NULL);
	}

	void DebugLoc::dump(const LLVMContext &Ctx) const {
	#ifndef NDEBUG
	if (!isUnknown()) {
	dbgs() << getLine();
	if (getCol() != 0)
	dbgs() << ',' << getCol();
	DebugLoc InlinedAtDL = DebugLoc::getFromDILocation(getInlinedAt(Ctx));
	if (!InlinedAtDL.isUnknown()) {
	dbgs() << " @ ";
	InlinedAtDL.dump(Ctx);
	} else
	dbgs() << "\n";
	}
	#endif
	}

	//===----------------------------------------------------------------------===//
	// DenseMap specialization
	//===----------------------------------------------------------------------===//

	DebugLoc DenseMapInfo<DebugLoc>::getEmptyKey() {
	return DebugLoc::getEmptyKey();
	}

	DebugLoc DenseMapInfo<DebugLoc>::getTombstoneKey() {
	return DebugLoc::getTombstoneKey();
	}

	unsigned DenseMapInfo<DebugLoc>::getHashValue(const DebugLoc &Key) {
	FoldingSetNodeID ID;
	ID.AddInteger(Key.LineCol);
	ID.AddInteger(Key.ScopeIdx);
	return ID.ComputeHash();
	}

	bool DenseMapInfo<DebugLoc>::isEqual(const DebugLoc &LHS, const DebugLoc &RHS) {
	return LHS == RHS;
	}

	//===----------------------------------------------------------------------===//
	// LLVMContextImpl Implementation
	//===----------------------------------------------------------------------===//

	int LLVMContextImpl::getOrAddScopeRecordIdxEntry(MDNode *Scope,
	int ExistingIdx) {
	// If we already have an entry for this scope, return it.
	int &Idx = ScopeRecordIdx[Scope];
	if (Idx) return Idx;

	// If we don't have an entry, but ExistingIdx is specified, use it.
	if (ExistingIdx)
	return Idx = ExistingIdx;

	// Otherwise add a new entry.

	// Start out ScopeRecords with a minimal reasonable size to avoid
	// excessive reallocation starting out.
	if (ScopeRecords.empty())
	ScopeRecords.reserve(128);

	// Index is biased by 1 for index.
	Idx = ScopeRecords.size()+1;
	ScopeRecords.push_back(DebugRecVH(Scope, this, Idx));
	return Idx;
	}

	int LLVMContextImpl::getOrAddScopeInlinedAtIdxEntry(MDNode Scope, MDNode IA,
	int ExistingIdx) {
	// If we already have an entry, return it.
	int &Idx = ScopeInlinedAtIdx[std::make_pair(Scope, IA)];
	if (Idx) return Idx;

	// If we don't have an entry, but ExistingIdx is specified, use it.
	if (ExistingIdx)
	return Idx = ExistingIdx;

	// Start out ScopeInlinedAtRecords with a minimal reasonable size to avoid
	// excessive reallocation starting out.
	if (ScopeInlinedAtRecords.empty())
	ScopeInlinedAtRecords.reserve(128);

	// Index is biased by 1 and negated.
	Idx = -ScopeInlinedAtRecords.size()-1;
	ScopeInlinedAtRecords.push_back(std::make_pair(DebugRecVH(Scope, this, Idx),
	DebugRecVH(IA, this, Idx)));
	return Idx;
	}


	//===----------------------------------------------------------------------===//
	// DebugRecVH Implementation
	//===----------------------------------------------------------------------===//

	/// deleted - The MDNode this is pointing to got deleted, so this pointer needs
	/// to drop to null and we need remove our entry from the DenseMap.
	void DebugRecVH::deleted() {
	// If this is a non-canonical reference, just drop the value to null, we know
	// it doesn't have a map entry.
	if (Idx == 0) {
	setValPtr(0);
	return;
	}

	MDNode *Cur = get();

	// If the index is positive, it is an entry in ScopeRecords.
	if (Idx > 0) {
	assert(Ctx->ScopeRecordIdx[Cur] == Idx && "Mapping out of date!");
	Ctx->ScopeRecordIdx.erase(Cur);
	// Reset this VH to null and we're done.
	setValPtr(0);
	Idx = 0;
	return;
	}

	// Otherwise, it is an entry in ScopeInlinedAtRecords, we don't know if it
	// is the scope or the inlined-at record entry.
	assert(unsigned(-Idx-1) < Ctx->ScopeInlinedAtRecords.size());
	std::pair<DebugRecVH, DebugRecVH> &Entry = Ctx->ScopeInlinedAtRecords[-Idx-1];
	assert((this == &Entry.first \|\| this == &Entry.second) &&
	"Mapping out of date!");

	MDNode *OldScope = Entry.first.get();
	MDNode *OldInlinedAt = Entry.second.get();
	assert(OldScope != 0 && OldInlinedAt != 0 &&
	"Entry should be non-canonical if either val dropped to null");

	// Otherwise, we do have an entry in it, nuke it and we're done.
	assert(Ctx->ScopeInlinedAtIdx[std::make_pair(OldScope, OldInlinedAt)] == Idx&&
	"Mapping out of date");
	Ctx->ScopeInlinedAtIdx.erase(std::make_pair(OldScope, OldInlinedAt));

	// Reset this VH to null. Drop both 'Idx' values to null to indicate that
	// we're in non-canonical form now.
	setValPtr(0);
	Entry.first.Idx = Entry.second.Idx = 0;
	}

	void DebugRecVH::allUsesReplacedWith(Value *NewVa) {
	// If being replaced with a non-mdnode value (e.g. undef) handle this as if
	// the mdnode got deleted.
	MDNode *NewVal = dyn_cast<MDNode>(NewVa);
	if (NewVal == 0) return deleted();

	// If this is a non-canonical reference, just change it, we know it already
	// doesn't have a map entry.
	if (Idx == 0) {
	setValPtr(NewVa);
	return;
	}

	MDNode *OldVal = get();
	assert(OldVal != NewVa && "Node replaced with self?");

	// If the index is positive, it is an entry in ScopeRecords.
	if (Idx > 0) {
	assert(Ctx->ScopeRecordIdx[OldVal] == Idx && "Mapping out of date!");
	Ctx->ScopeRecordIdx.erase(OldVal);
	setValPtr(NewVal);

	int NewEntry = Ctx->getOrAddScopeRecordIdxEntry(NewVal, Idx);

	// If NewVal already has an entry, this becomes a non-canonical reference,
	// just drop Idx to 0 to signify this.
	if (NewEntry != Idx)
	Idx = 0;
	return;
	}

	// Otherwise, it is an entry in ScopeInlinedAtRecords, we don't know if it
	// is the scope or the inlined-at record entry.
	assert(unsigned(-Idx-1) < Ctx->ScopeInlinedAtRecords.size());
	std::pair<DebugRecVH, DebugRecVH> &Entry = Ctx->ScopeInlinedAtRecords[-Idx-1];
	assert((this == &Entry.first \|\| this == &Entry.second) &&
	"Mapping out of date!");

	MDNode *OldScope = Entry.first.get();
	MDNode *OldInlinedAt = Entry.second.get();
	assert(OldScope != 0 && OldInlinedAt != 0 &&
	"Entry should be non-canonical if either val dropped to null");

	// Otherwise, we do have an entry in it, nuke it and we're done.
	assert(Ctx->ScopeInlinedAtIdx[std::make_pair(OldScope, OldInlinedAt)] == Idx&&
	"Mapping out of date");
	Ctx->ScopeInlinedAtIdx.erase(std::make_pair(OldScope, OldInlinedAt));

	// Reset this VH to the new value.
	setValPtr(NewVal);

	int NewIdx = Ctx->getOrAddScopeInlinedAtIdxEntry(Entry.first.get(),
	Entry.second.get(), Idx);
	// If NewVal already has an entry, this becomes a non-canonical reference,
	// just drop Idx to 0 to signify this.
	if (NewIdx != Idx) {
	std::pair<DebugRecVH, DebugRecVH> &Entry=Ctx->ScopeInlinedAtRecords[-Idx-1];
	Entry.first.Idx = Entry.second.Idx = 0;
	}
	}