Bitcode: Simplify emission of METADATA_BLOCK

Refactor logic so that we know up-front whether to open a block and
whether we need an MDString abbreviation.

This is almost NFC, but will start emitting `MDString` abbreviations
when the first record is not an `MDString`.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225712 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan P. N. Exon Smith
2015-01-12 22:30:34 +00:00
parent 0c51e0a826
commit 8d86cef92f
3 changed files with 33 additions and 37 deletions

View File

@@ -783,52 +783,44 @@ static void WriteModuleMetadata(const Module *M,
const ValueEnumerator &VE,
BitstreamWriter &Stream) {
const auto &MDs = VE.getMDs();
bool StartedMetadataBlock = false;
if (MDs.empty() && M->named_metadata_empty())
return;
Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
unsigned MDSAbbrev = 0;
if (VE.hasMDString()) {
// Abbrev for METADATA_STRING.
BitCodeAbbrev *Abbv = new BitCodeAbbrev();
Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRING));
Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
MDSAbbrev = Stream.EmitAbbrev(Abbv);
}
SmallVector<uint64_t, 64> Record;
for (unsigned i = 0, e = MDs.size(); i != e; ++i) {
if (const MDNode *N = dyn_cast<MDNode>(MDs[i])) {
if (!StartedMetadataBlock) {
Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
StartedMetadataBlock = true;
}
WriteMDNode(N, VE, Stream, Record);
} else if (const auto *MDC = dyn_cast<ConstantAsMetadata>(MDs[i])) {
if (!StartedMetadataBlock) {
Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
StartedMetadataBlock = true;
}
WriteValueAsMetadata(MDC, VE, Stream, Record);
} else if (const MDString *MDS = dyn_cast<MDString>(MDs[i])) {
if (!StartedMetadataBlock) {
Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
// Abbrev for METADATA_STRING.
BitCodeAbbrev *Abbv = new BitCodeAbbrev();
Abbv->Add(BitCodeAbbrevOp(bitc::METADATA_STRING));
Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 8));
MDSAbbrev = Stream.EmitAbbrev(Abbv);
StartedMetadataBlock = true;
}
// Code: [strchar x N]
Record.append(MDS->bytes_begin(), MDS->bytes_end());
// Emit the finished record.
Stream.EmitRecord(bitc::METADATA_STRING, Record, MDSAbbrev);
Record.clear();
continue;
}
if (const auto *MDC = dyn_cast<ConstantAsMetadata>(MDs[i])) {
WriteValueAsMetadata(MDC, VE, Stream, Record);
continue;
}
const MDString *MDS = cast<MDString>(MDs[i]);
// Code: [strchar x N]
Record.append(MDS->bytes_begin(), MDS->bytes_end());
// Emit the finished record.
Stream.EmitRecord(bitc::METADATA_STRING, Record, MDSAbbrev);
Record.clear();
}
// Write named metadata.
for (Module::const_named_metadata_iterator I = M->named_metadata_begin(),
E = M->named_metadata_end(); I != E; ++I) {
const NamedMDNode *NMD = I;
if (!StartedMetadataBlock) {
Stream.EnterSubblock(bitc::METADATA_BLOCK_ID, 3);
StartedMetadataBlock = true;
}
// Write name.
StringRef Str = NMD->getName();
@@ -844,8 +836,7 @@ static void WriteModuleMetadata(const Module *M,
Record.clear();
}
if (StartedMetadataBlock)
Stream.ExitBlock();
Stream.ExitBlock();
}
static void WriteFunctionLocalMetadata(const Function &F,