Add a new "NewDebugLoc" class which will eventually replace DebugLoc,

and will replace the 'DbgInfo' member in Instruction.

The benefit of NewDebugLoc is that it is compact (8 bytes vs 12/24 
bytes for the DbgInfo member in Instruction on a 32/64 bit system),
it means that we will end up not having to allocate MDNodes to 
represent the "DILocations" in common cases of -O0 -g, and it is
much more efficient to get things out of than the MDNode.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100072 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 314 insertions, 1 deletions

diff --git a/lib/VMCore/DebugLoc.cpp b/lib/VMCore/DebugLoc.cpp
new file mode 100644
index 0000000000..0fcbf2653a
--- /dev/null
+++ b/lib/VMCore/DebugLoc.cpp
@@ -0,0 +1,270 @@
+//===-- 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 "LLVMContextImpl.h"
+using namespace llvm;
+
+//===----------------------------------------------------------------------===//
+// DebugLoc Implementation
+//===----------------------------------------------------------------------===//
+
+MDNode *NewDebugLoc::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 *NewDebugLoc::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 NewDebugLoc::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();
+}
+
+
+NewDebugLoc NewDebugLoc::get(unsigned Line, unsigned Col,
+                             MDNode *Scope, MDNode *InlinedAt) {
+  NewDebugLoc 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 *NewDebugLoc::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();
+  const Type *Int32 = Type::getInt32Ty(Ctx2);
+  Value *Elts[] = {
+    ConstantInt::get(Int32, getLine()), ConstantInt::get(Int32, getCol()),
+    Scope, IA
+  };
+  return MDNode::get(Ctx2, &Elts[0], 4);
+}
+
+
+//===----------------------------------------------------------------------===//
+// 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.
+  setValPtr(0);
+  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)
+    Idx = 0;
+}
diff --git a/lib/VMCore/LLVMContextImpl.h b/lib/VMCore/LLVMContextImpl.h
index 8666f45f4a..d4ebf8044d 100644
--- a/lib/VMCore/LLVMContextImpl.h
+++ b/lib/VMCore/LLVMContextImpl.h
@@ -90,6 +90,29 @@ struct DenseMapAPFloatKeyInfo {
   }
 };
 
+/// DebugRecVH - This is a CallbackVH used to keep the Scope -> index maps
+/// up to date as MDNodes mutate.  This class is implemented in DebugLoc.cpp.
+class DebugRecVH : public CallbackVH {
+  /// Ctx - This is the LLVM Context being referenced.
+  LLVMContextImpl *Ctx;
+  
+  /// Idx - The index into either ScopeRecordIdx or ScopeInlinedAtRecords that
+  /// this reference lives in.  If this is zero, then it represents a
+  /// non-canonical entry that has no DenseMap value.  This can happen due to
+  /// RAUW.
+  int Idx;
+public:
+  DebugRecVH(MDNode *n, LLVMContextImpl *ctx, int idx)
+    : CallbackVH(n), Ctx(ctx), Idx(idx) {}
+  
+  MDNode *get() const {
+    return cast_or_null<MDNode>(getValPtr());
+  }
+  
+  virtual void deleted();
+  virtual void allUsesReplacedWith(Value *VNew);
+};
+  
 class LLVMContextImpl {
 public:
   typedef DenseMap<DenseMapAPIntKeyInfo::KeyTy, ConstantInt*, 
@@ -128,7 +151,6 @@ public:
   VectorConstantsTy VectorConstants;
   
   ConstantUniqueMap<char, PointerType, ConstantPointerNull> NullPtrConstants;
-  
   ConstantUniqueMap<char, Type, UndefValue> UndefValueConstants;
   
   DenseMap<std::pair<Function*, BasicBlock*> , BlockAddress*> BlockAddresses;
@@ -195,6 +217,27 @@ public:
   /// context.
   DenseMap<const Instruction *, MDMapTy> MetadataStore;
   
+  /// ScopeRecordIdx - This is the index in ScopeRecords for an MDNode scope
+  /// entry with no "inlined at" element.
+  DenseMap<MDNode*, int> ScopeRecordIdx;
+  
+  /// ScopeRecords - These are the actual mdnodes (in a value handle) for an
+  /// index.  The ValueHandle ensures that ScopeRecordIdx stays up to date if
+  /// the MDNode is RAUW'd.
+  std::vector<DebugRecVH> ScopeRecords;
+  
+  /// ScopeInlinedAtIdx - This is the index in ScopeInlinedAtRecords for an
+  /// scope/inlined-at pair.
+  DenseMap<std::pair<MDNode*, MDNode*>, int> ScopeInlinedAtIdx;
+  
+  /// ScopeInlinedAtRecords - These are the actual mdnodes (in value handles)
+  /// for an index.  The ValueHandle ensures that ScopeINlinedAtIdx stays up
+  /// to date.
+  std::vector<std::pair<DebugRecVH, DebugRecVH> > ScopeInlinedAtRecords;
+  
+  int getOrAddScopeRecordIdxEntry(MDNode *N, int ExistingIdx);
+  int getOrAddScopeInlinedAtIdxEntry(MDNode *Scope, MDNode *IA,int ExistingIdx);
+  
   LLVMContextImpl(LLVMContext &C);
   ~LLVMContextImpl();
 };