IR: add optional type to 'byval' function parameters

When we switch to opaque pointer types we will need some way to describe
how many bytes a 'byval' parameter should occupy on the stack. This adds
a (for now) optional extra type parameter.

If present, the type must match the pointee type of the argument.

Note to front-end maintainers: if this causes test failures, it's probably
because the "byval" attribute is printed after attributes without any parameter
after this change.

llvm-svn: 362012

llvm/lib/Bitcode/Writer/BitcodeWriter.cpp

@@ -747,7 +747,7 @@ void ModuleBitcodeWriter::writeAttributeGroupTable() {
         Record.push_back(1);
         Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
         Record.push_back(Attr.getValueAsInt());
-      } else {
+      } else if (Attr.isStringAttribute()) {
         StringRef Kind = Attr.getKindAsString();
         StringRef Val = Attr.getValueAsString();
 
@@ -758,6 +758,13 @@ void ModuleBitcodeWriter::writeAttributeGroupTable() {
           Record.append(Val.begin(), Val.end());
           Record.push_back(0);
         }
+      } else {
+        assert(Attr.isTypeAttribute());
+        Type *Ty = Attr.getValueAsType();
+        Record.push_back(Ty ? 6 : 5);
+        Record.push_back(getAttrKindEncoding(Attr.getKindAsEnum()));
+        if (Ty)
+          Record.push_back(VE.getTypeID(Attr.getValueAsType()));
       }
     }
 
@@ -4126,15 +4133,15 @@ void ModuleBitcodeWriter::write() {
   // Emit blockinfo, which defines the standard abbreviations etc.
   writeBlockInfo();
 
+  // Emit information describing all of the types in the module.
+  writeTypeTable();
+
   // Emit information about attribute groups.
   writeAttributeGroupTable();
 
   // Emit information about parameter attributes.
   writeAttributeTable();
 
-  // Emit information describing all of the types in the module.
-  writeTypeTable();
-
   writeComdats();
 
   // Emit top-level description of module, including target triple, inline asm,