Reduce malloc traffic in DwarfAccelTable

- Don't copy offsets into HashData, the underlying vector won't change once the table is finalized.
- Allocate HashData and HashDataContents in a BumpPtrAllocator.
- Allocate string map entries in the same allocator.
- Random cleanups.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154694 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/AsmPrinter/DwarfAccelTable.cpp

@@ -36,35 +36,20 @@ const char *DwarfAccelTable::Atom::AtomTypeString(enum AtomType AT) {
   llvm_unreachable("invalid AtomType!");
 }
 
-// The general case would need to have a less hard coded size for the
-// length of the HeaderData, however, if we're constructing based on a
-// single Atom then we know it will always be: 4 + 4 + 2 + 2.
-DwarfAccelTable::DwarfAccelTable(DwarfAccelTable::Atom atom) :
-  Header(12),
-  HeaderData(atom) {
-}
-
 // The length of the header data is always going to be 4 + 4 + 4*NumAtoms.
-DwarfAccelTable::DwarfAccelTable(std::vector<DwarfAccelTable::Atom> &atomList) :
+DwarfAccelTable::DwarfAccelTable(ArrayRef<DwarfAccelTable::Atom> atomList) :
   Header(8 + (atomList.size() * 4)),
-  HeaderData(atomList) {
-}
+  HeaderData(atomList),
+  Entries(Allocator) { }
 
-DwarfAccelTable::~DwarfAccelTable() {
-  for (size_t i = 0, e = Data.size(); i < e; ++i)
-    delete Data[i];
-  for (StringMap<DataArray>::iterator
-         EI = Entries.begin(), EE = Entries.end(); EI != EE; ++EI)
-    for (DataArray::iterator DI = EI->second.begin(),
-           DE = EI->second.end(); DI != DE; ++DI)
-      delete (*DI);
-}
+DwarfAccelTable::~DwarfAccelTable() { }
 
 void DwarfAccelTable::AddName(StringRef Name, DIE* die, char Flags) {
+  assert(Data.empty() && "Already finalized!");
   // If the string is in the list already then add this die to the list
   // otherwise add a new one.
   DataArray &DIEs = Entries[Name];
-  DIEs.push_back(new HashDataContents(die, Flags));
+  DIEs.push_back(new (Allocator) HashDataContents(die, Flags));
 }
 
 void DwarfAccelTable::ComputeBucketCount(void) {
@@ -85,31 +70,23 @@ void DwarfAccelTable::ComputeBucketCount(void) {
   Header.hashes_count = num;
 }
 
-namespace {
-  // DIESorter - comparison predicate that sorts DIEs by their offset.
-  struct DIESorter {
-    bool operator()(const struct DwarfAccelTable::HashDataContents *A,
-                    const struct DwarfAccelTable::HashDataContents *B) const {
-      return A->Die->getOffset() < B->Die->getOffset();
-    }
-  };
+// compareDIEs - comparison predicate that sorts DIEs by their offset.
+static bool compareDIEs(const DwarfAccelTable::HashDataContents *A,
+                        const DwarfAccelTable::HashDataContents *B) {
+  return A->Die->getOffset() < B->Die->getOffset();
 }
 
 void DwarfAccelTable::FinalizeTable(AsmPrinter *Asm, const char *Prefix) {
   // Create the individual hash data outputs.
   for (StringMap<DataArray>::iterator
          EI = Entries.begin(), EE = Entries.end(); EI != EE; ++EI) {
-    struct HashData *Entry = new HashData((*EI).getKeyData());
 
     // Unique the entries.
-    std::stable_sort(EI->second.begin(), EI->second.end(), DIESorter());
+    std::stable_sort(EI->second.begin(), EI->second.end(), compareDIEs);
     EI->second.erase(std::unique(EI->second.begin(), EI->second.end()),
                        EI->second.end());
 
-    for (DataArray::const_iterator DI = EI->second.begin(),
-           DE = EI->second.end();
-         DI != DE; ++DI)
-      Entry->addData((*DI));
+    HashData *Entry = new (Allocator) HashData(EI->getKey(), EI->second);
     Data.push_back(Entry);
   }
 
@@ -216,7 +193,7 @@ void DwarfAccelTable::EmitData(AsmPrinter *Asm, DwarfDebug *D) {
                              D->getStringPool());
       Asm->OutStreamer.AddComment("Num DIEs");
       Asm->EmitInt32((*HI)->Data.size());
-      for (std::vector<struct HashDataContents*>::const_iterator
+      for (ArrayRef<HashDataContents*>::const_iterator
              DI = (*HI)->Data.begin(), DE = (*HI)->Data.end();
            DI != DE; ++DI) {
         // Emit the DIE offset

lib/CodeGen/AsmPrinter/DwarfAccelTable.h

@@ -15,6 +15,7 @@
 #define CODEGEN_ASMPRINTER_DWARFACCELTABLE_H__
 
 #include "llvm/ADT/StringMap.h"
+#include "llvm/ADT/ArrayRef.h"
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/Support/Dwarf.h"
 #include "llvm/Support/DataTypes.h"
@@ -164,22 +165,12 @@ public:
 
  private:
   struct TableHeaderData {
-    
     uint32_t die_offset_base;
-    std::vector<Atom> Atoms;
+    SmallVector<Atom, 1> Atoms;
+
+    TableHeaderData(ArrayRef<Atom> AtomList, uint32_t offset = 0)
+      : die_offset_base(offset), Atoms(AtomList.begin(), AtomList.end()) { }
 
-    TableHeaderData(std::vector<DwarfAccelTable::Atom> &AtomList,
-                    uint32_t offset = 0) :
-      die_offset_base(offset) {
-      for (size_t i = 0, e = AtomList.size(); i != e; ++i)
-        Atoms.push_back(AtomList[i]);
-    }
-    
-    TableHeaderData(DwarfAccelTable::Atom Atom, uint32_t offset = 0)
-    : die_offset_base(offset) {
-      Atoms.push_back(Atom);
-    }
-    
 #ifndef NDEBUG
     void print (raw_ostream &O) {
       O << "die_offset_base: " << die_offset_base << "\n";
@@ -221,11 +212,11 @@ private:
     StringRef Str;
     uint32_t HashValue;
     MCSymbol *Sym;
-    std::vector<struct HashDataContents*> Data; // offsets
-    HashData(StringRef S) : Str(S) {
+    ArrayRef<HashDataContents*> Data; // offsets
+    HashData(StringRef S, ArrayRef<HashDataContents*> Data)
+      : Str(S), Data(Data) {
       HashValue = DwarfAccelTable::HashDJB(S);
     }
-    void addData(struct HashDataContents *Datum) { Data.push_back(Datum); }
     #ifndef NDEBUG
     void print(raw_ostream &O) {
       O << "Name: " << Str << "\n";
@@ -255,15 +246,18 @@ private:
   void EmitHashes(AsmPrinter *);
   void EmitOffsets(AsmPrinter *, MCSymbol *);
   void EmitData(AsmPrinter *, DwarfDebug *D);
-  
+
+  // Allocator for HashData and HashDataContents.
+  BumpPtrAllocator Allocator;
+
   // Output Variables
   TableHeader Header;
   TableHeaderData HeaderData;
   std::vector<HashData*> Data;
 
   // String Data
-  typedef std::vector<struct HashDataContents*> DataArray;
-  typedef StringMap<DataArray> StringEntries;
+  typedef std::vector<HashDataContents*> DataArray;
+  typedef StringMap<DataArray, BumpPtrAllocator&> StringEntries;
   StringEntries Entries;
 
   // Buckets/Hashes/Offsets
@@ -274,8 +268,7 @@ private:
   
   // Public Implementation
  public:
-  DwarfAccelTable(DwarfAccelTable::Atom);
-  DwarfAccelTable(std::vector<DwarfAccelTable::Atom> &);
+  DwarfAccelTable(ArrayRef<DwarfAccelTable::Atom>);
   ~DwarfAccelTable();
   void AddName(StringRef, DIE*, char = 0);
   void FinalizeTable(AsmPrinter *, const char *);