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, 1 insertions, 0 deletions

diff --git a/llvm/lib/AsmParser/LLParser.h b/llvm/lib/AsmParser/LLParser.h
index ea18b58d32f..a43a4b06a94 100644
--- a/llvm/lib/AsmParser/LLParser.h
+++ b/llvm/lib/AsmParser/LLParser.h
@@ -394,6 +394,7 @@ namespace llvm {
     bool ParseMDNodeVector(SmallVectorImpl<Metadata *> &MDs);
     bool ParseMetadataAttachment(unsigned &Kind, MDNode *&MD);
     bool ParseInstructionMetadata(Instruction &Inst);
+    bool ParseOptionalFunctionMetadata(Function &F);
 
     template <class FieldTy>
     bool ParseMDField(LocTy Loc, StringRef Name, FieldTy &Result);