Imported Upstream version 5.18.0.179

Former-commit-id: 67aa10e65b237e1c4537630979ee99ebe1374215

external/llvm/lib/CodeGen/AsmPrinter/DwarfAccelTable.cpp

@@ -0,0 +1,293 @@
+//===- llvm/CodeGen/DwarfAccelTable.cpp - Dwarf Accelerator Tables --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains support for writing dwarf accelerator tables.
+//
+//===----------------------------------------------------------------------===//
+
+#include "DwarfAccelTable.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/ADT/Twine.h"
+#include "llvm/BinaryFormat/Dwarf.h"
+#include "llvm/CodeGen/AsmPrinter.h"
+#include "llvm/CodeGen/DIE.h"
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCStreamer.h"
+#include "llvm/Support/raw_ostream.h"
+#include <algorithm>
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <iterator>
+#include <limits>
+#include <vector>
+
+using namespace llvm;
+
+// The length of the header data is always going to be 4 + 4 + 4*NumAtoms.
+DwarfAccelTable::DwarfAccelTable(ArrayRef<DwarfAccelTable::Atom> atomList)
+    : Header(8 + (atomList.size() * 4)), HeaderData(atomList),
+      Entries(Allocator) {}
+
+void DwarfAccelTable::AddName(DwarfStringPoolEntryRef Name, const 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.getString()];
+  assert(!DIEs.Name || DIEs.Name == Name);
+  DIEs.Name = Name;
+  DIEs.Values.push_back(new (Allocator) HashDataContents(die, Flags));
+}
+
+void DwarfAccelTable::ComputeBucketCount() {
+  // First get the number of unique hashes.
+  std::vector<uint32_t> uniques(Data.size());
+  for (size_t i = 0, e = Data.size(); i < e; ++i)
+    uniques[i] = Data[i]->HashValue;
+  array_pod_sort(uniques.begin(), uniques.end());
+  std::vector<uint32_t>::iterator p =
+      std::unique(uniques.begin(), uniques.end());
+  uint32_t num = std::distance(uniques.begin(), p);
+
+  // Then compute the bucket size, minimum of 1 bucket.
+  if (num > 1024)
+    Header.bucket_count = num / 4;
+  else if (num > 16)
+    Header.bucket_count = num / 2;
+  else
+    Header.bucket_count = num > 0 ? num : 1;
+
+  Header.hashes_count = num;
+}
+
+// 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, StringRef Prefix) {
+  // Create the individual hash data outputs.
+  Data.reserve(Entries.size());
+  for (StringMap<DataArray>::iterator EI = Entries.begin(), EE = Entries.end();
+       EI != EE; ++EI) {
+
+    // Unique the entries.
+    std::stable_sort(EI->second.Values.begin(), EI->second.Values.end(), compareDIEs);
+    EI->second.Values.erase(
+        std::unique(EI->second.Values.begin(), EI->second.Values.end()),
+        EI->second.Values.end());
+
+    HashData *Entry = new (Allocator) HashData(EI->getKey(), EI->second);
+    Data.push_back(Entry);
+  }
+
+  // Figure out how many buckets we need, then compute the bucket
+  // contents and the final ordering. We'll emit the hashes and offsets
+  // by doing a walk during the emission phase. We add temporary
+  // symbols to the data so that we can reference them during the offset
+  // later, we'll emit them when we emit the data.
+  ComputeBucketCount();
+
+  // Compute bucket contents and final ordering.
+  Buckets.resize(Header.bucket_count);
+  for (size_t i = 0, e = Data.size(); i < e; ++i) {
+    uint32_t bucket = Data[i]->HashValue % Header.bucket_count;
+    Buckets[bucket].push_back(Data[i]);
+    Data[i]->Sym = Asm->createTempSymbol(Prefix);
+  }
+
+  // Sort the contents of the buckets by hash value so that hash
+  // collisions end up together. Stable sort makes testing easier and
+  // doesn't cost much more.
+  for (size_t i = 0; i < Buckets.size(); ++i)
+    std::stable_sort(Buckets[i].begin(), Buckets[i].end(),
+                     [] (HashData *LHS, HashData *RHS) {
+                       return LHS->HashValue < RHS->HashValue;
+                     });
+}
+
+// Emits the header for the table via the AsmPrinter.
+void DwarfAccelTable::EmitHeader(AsmPrinter *Asm) {
+  Asm->OutStreamer->AddComment("Header Magic");
+  Asm->EmitInt32(Header.magic);
+  Asm->OutStreamer->AddComment("Header Version");
+  Asm->EmitInt16(Header.version);
+  Asm->OutStreamer->AddComment("Header Hash Function");
+  Asm->EmitInt16(Header.hash_function);
+  Asm->OutStreamer->AddComment("Header Bucket Count");
+  Asm->EmitInt32(Header.bucket_count);
+  Asm->OutStreamer->AddComment("Header Hash Count");
+  Asm->EmitInt32(Header.hashes_count);
+  Asm->OutStreamer->AddComment("Header Data Length");
+  Asm->EmitInt32(Header.header_data_len);
+  Asm->OutStreamer->AddComment("HeaderData Die Offset Base");
+  Asm->EmitInt32(HeaderData.die_offset_base);
+  Asm->OutStreamer->AddComment("HeaderData Atom Count");
+  Asm->EmitInt32(HeaderData.Atoms.size());
+  for (size_t i = 0; i < HeaderData.Atoms.size(); i++) {
+    Atom A = HeaderData.Atoms[i];
+    Asm->OutStreamer->AddComment(dwarf::AtomTypeString(A.type));
+    Asm->EmitInt16(A.type);
+    Asm->OutStreamer->AddComment(dwarf::FormEncodingString(A.form));
+    Asm->EmitInt16(A.form);
+  }
+}
+
+// Walk through and emit the buckets for the table. Each index is
+// an offset into the list of hashes.
+void DwarfAccelTable::EmitBuckets(AsmPrinter *Asm) {
+  unsigned index = 0;
+  for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
+    Asm->OutStreamer->AddComment("Bucket " + Twine(i));
+    if (!Buckets[i].empty())
+      Asm->EmitInt32(index);
+    else
+      Asm->EmitInt32(std::numeric_limits<uint32_t>::max());
+    // Buckets point in the list of hashes, not to the data. Do not
+    // increment the index multiple times in case of hash collisions.
+    uint64_t PrevHash = std::numeric_limits<uint64_t>::max();
+    for (auto *HD : Buckets[i]) {
+      uint32_t HashValue = HD->HashValue;
+      if (PrevHash != HashValue)
+        ++index;
+      PrevHash = HashValue;
+    }
+  }
+}
+
+// Walk through the buckets and emit the individual hashes for each
+// bucket.
+void DwarfAccelTable::EmitHashes(AsmPrinter *Asm) {
+  uint64_t PrevHash = std::numeric_limits<uint64_t>::max();
+  for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
+    for (HashList::const_iterator HI = Buckets[i].begin(),
+                                  HE = Buckets[i].end();
+         HI != HE; ++HI) {
+      uint32_t HashValue = (*HI)->HashValue;
+      if (PrevHash == HashValue)
+        continue;
+      Asm->OutStreamer->AddComment("Hash in Bucket " + Twine(i));
+      Asm->EmitInt32(HashValue);
+      PrevHash = HashValue;
+    }
+  }
+}
+
+// Walk through the buckets and emit the individual offsets for each
+// element in each bucket. This is done via a symbol subtraction from the
+// beginning of the section. The non-section symbol will be output later
+// when we emit the actual data.
+void DwarfAccelTable::emitOffsets(AsmPrinter *Asm, const MCSymbol *SecBegin) {
+  uint64_t PrevHash = std::numeric_limits<uint64_t>::max();
+  for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
+    for (HashList::const_iterator HI = Buckets[i].begin(),
+                                  HE = Buckets[i].end();
+         HI != HE; ++HI) {
+      uint32_t HashValue = (*HI)->HashValue;
+      if (PrevHash == HashValue)
+        continue;
+      PrevHash = HashValue;
+      Asm->OutStreamer->AddComment("Offset in Bucket " + Twine(i));
+      MCContext &Context = Asm->OutStreamer->getContext();
+      const MCExpr *Sub = MCBinaryExpr::createSub(
+          MCSymbolRefExpr::create((*HI)->Sym, Context),
+          MCSymbolRefExpr::create(SecBegin, Context), Context);
+      Asm->OutStreamer->EmitValue(Sub, sizeof(uint32_t));
+    }
+  }
+}
+
+// Walk through the buckets and emit the full data for each element in
+// the bucket. For the string case emit the dies and the various offsets.
+// Terminate each HashData bucket with 0.
+void DwarfAccelTable::EmitData(AsmPrinter *Asm, DwarfDebug *D) {
+  for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
+    uint64_t PrevHash = std::numeric_limits<uint64_t>::max();
+    for (HashList::const_iterator HI = Buckets[i].begin(),
+                                  HE = Buckets[i].end();
+         HI != HE; ++HI) {
+      // Terminate the previous entry if there is no hash collision
+      // with the current one.
+      if (PrevHash != std::numeric_limits<uint64_t>::max() &&
+          PrevHash != (*HI)->HashValue)
+        Asm->EmitInt32(0);
+      // Remember to emit the label for our offset.
+      Asm->OutStreamer->EmitLabel((*HI)->Sym);
+      Asm->OutStreamer->AddComment((*HI)->Str);
+      Asm->emitDwarfStringOffset((*HI)->Data.Name);
+      Asm->OutStreamer->AddComment("Num DIEs");
+      Asm->EmitInt32((*HI)->Data.Values.size());
+      for (HashDataContents *HD : (*HI)->Data.Values) {
+        // Emit the DIE offset
+        Asm->EmitInt32(HD->Die->getDebugSectionOffset());
+        // If we have multiple Atoms emit that info too.
+        // FIXME: A bit of a hack, we either emit only one atom or all info.
+        if (HeaderData.Atoms.size() > 1) {
+          Asm->EmitInt16(HD->Die->getTag());
+          Asm->EmitInt8(HD->Flags);
+        }
+      }
+      PrevHash = (*HI)->HashValue;
+    }
+    // Emit the final end marker for the bucket.
+    if (!Buckets[i].empty())
+      Asm->EmitInt32(0);
+  }
+}
+
+// Emit the entire data structure to the output file.
+void DwarfAccelTable::emit(AsmPrinter *Asm, const MCSymbol *SecBegin,
+                           DwarfDebug *D) {
+  // Emit the header.
+  EmitHeader(Asm);
+
+  // Emit the buckets.
+  EmitBuckets(Asm);
+
+  // Emit the hashes.
+  EmitHashes(Asm);
+
+  // Emit the offsets.
+  emitOffsets(Asm, SecBegin);
+
+  // Emit the hash data.
+  EmitData(Asm, D);
+}
+
+#ifndef NDEBUG
+void DwarfAccelTable::print(raw_ostream &OS) {
+  Header.print(OS);
+  HeaderData.print(OS);
+
+  OS << "Entries: \n";
+  for (StringMap<DataArray>::const_iterator EI = Entries.begin(),
+                                            EE = Entries.end();
+       EI != EE; ++EI) {
+    OS << "Name: " << EI->getKeyData() << "\n";
+    for (HashDataContents *HD : EI->second.Values)
+      HD->print(OS);
+  }
+
+  OS << "Buckets and Hashes: \n";
+  for (size_t i = 0, e = Buckets.size(); i < e; ++i)
+    for (HashList::const_iterator HI = Buckets[i].begin(),
+                                  HE = Buckets[i].end();
+         HI != HE; ++HI)
+      (*HI)->print(OS);
+
+  OS << "Data: \n";
+  for (std::vector<HashData *>::const_iterator DI = Data.begin(),
+                                               DE = Data.end();
+       DI != DE; ++DI)
+    (*DI)->print(OS);
+}
+#endif