llvm/lib/CodeGen/AsmPrinter/DwarfAccelTable.cpp - toolchain/llvm-project - Gitiles

 //=-- llvm/CodeGen/DwarfAccelTable.cpp - Dwarf Accelerator Tables -*- C++ -*-=//
 //
 //                     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 "DwarfCompileUnit.h"
 #include "DwarfDebug.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/CodeGen/AsmPrinter.h"
 #include "llvm/CodeGen/DIE.h"
 #include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCStreamer.h"
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/Support/Debug.h"

 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(StringRef Name, MCSymbol *StrSym, 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];
   assert(!DIEs.StrSym || DIEs.StrSym == StrSym);
   DIEs.StrSym = StrSym;
   DIEs.Values.push_back(new (Allocator) HashDataContents(die, Flags));
 }

 void DwarfAccelTable::ComputeBucketCount(void) {
   // 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].size() != 0)
       Asm->EmitInt32(index);
     else
       Asm->EmitInt32(UINT32_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 = UINT64_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 = UINT64_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 = UINT64_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 = UINT64_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 != UINT64_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->emitSectionOffset((*HI)->Data.StrSym);
       Asm->OutStreamer->AddComment("Num DIEs");
       Asm->EmitInt32((*HI)->Data.Values.size());
       for (HashDataContents *HD : (*HI)->Data.Values) {
         // Emit the DIE offset
         DwarfCompileUnit *CU = D->lookupUnit(HD->Die->getUnit());
         assert(CU && "Accelerated DIE should belong to a CU.");
         Asm->EmitInt32(HD->Die->getOffset() + CU->getDebugInfoOffset());
         // 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 &O) {

   Header.print(O);
   HeaderData.print(O);

   O << "Entries: \n";
   for (StringMap<DataArray>::const_iterator EI = Entries.begin(),
                                             EE = Entries.end();
        EI != EE; ++EI) {
     O << "Name: " << EI->getKeyData() << "\n";
     for (HashDataContents *HD : EI->second.Values)
       HD->print(O);
   }

   O << "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(O);

   O << "Data: \n";
   for (std::vector<HashData *>::const_iterator DI = Data.begin(),
                                                DE = Data.end();
        DI != DE; ++DI)
     (*DI)->print(O);
 }
 #endif
	//=-- llvm/CodeGen/DwarfAccelTable.cpp - Dwarf Accelerator Tables -- C++ --=//
	//
	// 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 "DwarfCompileUnit.h"
	#include "DwarfDebug.h"
	#include "llvm/ADT/STLExtras.h"
	#include "llvm/ADT/Twine.h"
	#include "llvm/CodeGen/AsmPrinter.h"
	#include "llvm/CodeGen/DIE.h"
	#include "llvm/MC/MCExpr.h"
	#include "llvm/MC/MCStreamer.h"
	#include "llvm/MC/MCSymbol.h"
	#include "llvm/Support/Debug.h"

	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(StringRef Name, MCSymbol StrSym, 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];
	assert(!DIEs.StrSym \|\| DIEs.StrSym == StrSym);
	DIEs.StrSym = StrSym;
	DIEs.Values.push_back(new (Allocator) HashDataContents(die, Flags));
	}

	void DwarfAccelTable::ComputeBucketCount(void) {
	// 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].size() != 0)
	Asm->EmitInt32(index);
	else
	Asm->EmitInt32(UINT32_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 = UINT64_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 = UINT64_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 = UINT64_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 = UINT64_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 != UINT64_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->emitSectionOffset((*HI)->Data.StrSym);
	Asm->OutStreamer->AddComment("Num DIEs");
	Asm->EmitInt32((*HI)->Data.Values.size());
	for (HashDataContents HD : (HI)->Data.Values) {
	// Emit the DIE offset
	DwarfCompileUnit *CU = D->lookupUnit(HD->Die->getUnit());
	assert(CU && "Accelerated DIE should belong to a CU.");
	Asm->EmitInt32(HD->Die->getOffset() + CU->getDebugInfoOffset());
	// 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 &O) {

	Header.print(O);
	HeaderData.print(O);

	O << "Entries: \n";
	for (StringMap<DataArray>::const_iterator EI = Entries.begin(),
	EE = Entries.end();
	EI != EE; ++EI) {
	O << "Name: " << EI->getKeyData() << "\n";
	for (HashDataContents *HD : EI->second.Values)
	HD->print(O);
	}

	O << "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(O);

	O << "Data: \n";
	for (std::vector<HashData *>::const_iterator DI = Data.begin(),
	DE = Data.end();
	DI != DE; ++DI)
	(*DI)->print(O);
	}
	#endif