llvm-project/llvm/lib/MC/StringTableBuilder.cpp

117 lines
3.0 KiB
C++

//===-- StringTableBuilder.cpp - String table building utility ------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/StringTableBuilder.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/COFF.h"
#include "llvm/Support/Endian.h"
#include <vector>
using namespace llvm;
StringTableBuilder::StringTableBuilder(Kind K) : K(K) {}
static int compareBySuffix(std::pair<StringRef, size_t> *const *AP,
std::pair<StringRef, size_t> *const *BP) {
StringRef A = (*AP)->first;
StringRef B = (*BP)->first;
size_t SizeA = A.size();
size_t SizeB = B.size();
size_t Len = std::min(SizeA, SizeB);
for (size_t I = 0; I < Len; ++I) {
char CA = A[SizeA - I - 1];
char CB = B[SizeB - I - 1];
if (CA != CB)
return CB - CA;
}
return SizeB - SizeA;
}
void StringTableBuilder::finalize() {
std::vector<std::pair<StringRef, size_t> *> Strings;
Strings.reserve(StringIndexMap.size());
for (std::pair<StringRef, size_t> &P : StringIndexMap)
Strings.push_back(&P);
array_pod_sort(Strings.begin(), Strings.end(), compareBySuffix);
switch (K) {
case RAW:
break;
case ELF:
case MachO:
// Start the table with a NUL byte.
StringTable += '\x00';
break;
case WinCOFF:
// Make room to write the table size later.
StringTable.append(4, '\x00');
break;
}
StringRef Previous;
for (std::pair<StringRef, size_t> *P : Strings) {
StringRef S = P->first;
if (K == WinCOFF)
assert(S.size() > COFF::NameSize && "Short string in COFF string table!");
if (Previous.endswith(S)) {
P->second = StringTable.size() - S.size() - (K != RAW);
continue;
}
P->second = StringTable.size();
StringTable += S;
if (K != RAW)
StringTable += '\x00';
Previous = S;
}
switch (K) {
case RAW:
case ELF:
break;
case MachO:
// Pad to multiple of 4.
while (StringTable.size() % 4)
StringTable += '\x00';
break;
case WinCOFF:
// Write the table size in the first word.
assert(StringTable.size() <= std::numeric_limits<uint32_t>::max());
uint32_t Size = static_cast<uint32_t>(StringTable.size());
support::endian::write<uint32_t, support::little, support::unaligned>(
StringTable.data(), Size);
break;
}
Size = StringTable.size();
}
void StringTableBuilder::clear() {
StringTable.clear();
StringIndexMap.clear();
}
size_t StringTableBuilder::getOffset(StringRef S) const {
assert(isFinalized());
auto I = StringIndexMap.find(S);
assert(I != StringIndexMap.end() && "String is not in table!");
return I->second;
}
size_t StringTableBuilder::add(StringRef S) {
assert(!isFinalized());
auto P = StringIndexMap.insert(std::make_pair(S, Size));
if (P.second)
Size += S.size() + (K != RAW);
return P.first->second;
}