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Embed the offset of the PTH table inside the prologue of the PTH file. This will help improve gradual versioning of PTH files instead of relying that the PTH table is at a fixed offset. 

llvm-svn: 63045
This commit is contained in:
Ted Kremenek 2009-01-26 21:43:14 +00:00
parent a26699211d
commit eb8c8fbd63
2 changed files with 20 additions and 9 deletions
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10
clang/Driver/CacheTokens.cpp
View File

@ -454,6 +454,11 @@ void PTHWriter::EmitCachedSpellings() {
}
void PTHWriter::GeneratePTH() {
// Generate the prologue.
Out << "cfe-pth";
Offset JumpOffset = Out.tell();
Emit32(0);
// Iterate over all the files in SourceManager. Create a lexer
// for each file and cache the tokens.
SourceManager &SM = PP.getSourceManager();
@ -490,10 +495,15 @@ void PTHWriter::GeneratePTH() {
Offset FileTableOff = EmitFileTable();
// Finally, write out the offset table at the end.
Offset JumpTargetOffset = Out.tell();
Emit32(IdTableOff.first);
Emit32(IdTableOff.second.first);
Emit32(IdTableOff.second.second);
Emit32(FileTableOff);
// Now write the offset in the prologue.
Out.seek(JumpOffset);
Emit32(JumpTargetOffset);
}
void clang::CacheTokens(Preprocessor& PP, const std::string& OutFile) {

19
clang/lib/Lex/PTHLexer.cpp
View File

@ -520,17 +520,18 @@ PTHManager* PTHManager::Create(const std::string& file) {
// words at the end of the file.
const unsigned char* BufBeg = (unsigned char*)File->getBufferStart();
const unsigned char* BufEnd = (unsigned char*)File->getBufferEnd();
if(!(BufEnd > BufBeg + sizeof(uint32_t)*3)) {
assert(false && "Invalid PTH file.");
return 0; // FIXME: Proper error diagnostic?
}
// Check the prologue of the file.
if ((BufEnd - BufBeg) < (unsigned) (sizeof("cfe-pth") + 3) ||
memcmp(BufBeg, "cfe-pth", sizeof("cfe-pth") - 1) != 0)
return 0;
// Compute the address of the index table at the end of the PTH file.
// This table contains the offset of the file lookup table, the
// persistent ID -> identifer data table.
// FIXME: We should just embed this offset in the PTH file.
const unsigned char* EndTable = BufEnd - sizeof(uint32_t)*4;
const unsigned char *p = BufBeg + (sizeof("cfe-pth") - 1);
const unsigned char *EndTable = BufBeg + ReadLE32(p);
if (EndTable >= BufEnd)
return 0;
// Construct the file lookup table. This will be used for mapping from
// FileEntry*'s to cached tokens.