IR: Add assembly/bitcode support for function metadata attachments

Add serialization support for function metadata attachments (added in
r235783).  The syntax is:

    define @foo() !attach !0 {

Metadata attachments are only allowed on functions with bodies.  Since
they come before the `{`, they're not really part of the body; since
they require a body, they're not really part of the header.  In
`LLParser` I gave them a separate function called from `ParseDefine()`,
`ParseOptionalFunctionMetadata()`.

In bitcode, I'm using the same `METADATA_ATTACHMENT` record used by
instructions.  Instruction metadata attachments are included in a
special "attachment" block at the end of a `Function`.  The attachment
records are laid out like this:

    InstID (KindID MetadataID)+

Note that these records always have an odd number of fields.  The new
code takes advantage of this to recognize function attachments (which
don't need an instruction ID):

    (KindID MetadataID)+

This means we can use the same attachment block already used for
instructions.

This is part of PR23340.

llvm-svn: 235785

1 files changed, 17 insertions, 4 deletions

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index 5f7a5ea1291..b6528cbbecc 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -370,7 +370,7 @@ private:
   std::error_code GlobalCleanup();
   std::error_code ResolveGlobalAndAliasInits();
   std::error_code ParseMetadata();
-  std::error_code ParseMetadataAttachment();
+  std::error_code ParseMetadataAttachment(Function &F);
   ErrorOr<std::string> parseModuleTriple();
   std::error_code ParseUseLists();
   std::error_code InitStream();
@@ -3215,7 +3215,7 @@ ErrorOr<std::string> BitcodeReader::parseTriple() {
 }
 
 /// ParseMetadataAttachment - Parse metadata attachments.
-std::error_code BitcodeReader::ParseMetadataAttachment() {
+std::error_code BitcodeReader::ParseMetadataAttachment(Function &F) {
   if (Stream.EnterSubBlock(bitc::METADATA_ATTACHMENT_ID))
     return Error("Invalid record");
 
@@ -3241,8 +3241,21 @@ std::error_code BitcodeReader::ParseMetadataAttachment() {
       break;
     case bitc::METADATA_ATTACHMENT: {
       unsigned RecordLength = Record.size();
-      if (Record.empty() || (RecordLength - 1) % 2 == 1)
+      if (Record.empty())
         return Error("Invalid record");
+      if (RecordLength % 2 == 0) {
+        // A function attachment.
+        for (unsigned I = 0; I != RecordLength; I += 2) {
+          auto K = MDKindMap.find(Record[I]);
+          if (K == MDKindMap.end())
+            return Error("Invalid ID");
+          Metadata *MD = MDValueList.getValueFwdRef(Record[I + 1]);
+          F.setMetadata(K->second, cast<MDNode>(MD));
+        }
+        continue;
+      }
+
+      // An instruction attachment.
       Instruction *Inst = InstructionList[Record[0]];
       for (unsigned i = 1; i != RecordLength; i = i+2) {
         unsigned Kind = Record[i];
@@ -3319,7 +3332,7 @@ std::error_code BitcodeReader::ParseFunctionBody(Function *F) {
           return EC;
         break;
       case bitc::METADATA_ATTACHMENT_ID:
-        if (std::error_code EC = ParseMetadataAttachment())
+        if (std::error_code EC = ParseMetadataAttachment(*F))
           return EC;
         break;
       case bitc::METADATA_BLOCK_ID: