Add methods to merge an AttrBuilder into another builder.

This is useful when parsing an object that references multiple attribute groups.

N.B. If both builders have alignments specified, then they should match!

llvm-svn: 174480

llvm/include/llvm/IR/Attributes.h

@@ -373,6 +373,10 @@ public:
     addAttribute(A);
   }
   AttrBuilder(AttributeSet AS, unsigned Idx);
+  AttrBuilder(const AttrBuilder &B)
+    : Attrs(B.Attrs),
+      TargetDepAttrs(B.TargetDepAttrs.begin(), B.TargetDepAttrs.end()),
+      Alignment(B.Alignment), StackAlignment(B.StackAlignment) {}
 
   void clear();
 
@@ -394,6 +398,9 @@ public:
   /// \brief Remove the target-dependent attribute to the builder.
   AttrBuilder &removeAttribute(StringRef A);
 
+  /// \brief Add the attributes from the builder.
+  AttrBuilder &merge(const AttrBuilder &B);
+
   /// \brief Return true if the builder has the specified attribute.
   bool contains(Attribute::AttrKind A) const;
 

llvm/lib/IR/Attributes.cpp

@@ -956,6 +956,23 @@ AttrBuilder &AttrBuilder::addStackAlignmentAttr(unsigned Align) {
   return *this;
 }
 
+AttrBuilder &AttrBuilder::merge(const AttrBuilder &B) {
+  // FIXME: What if both have alignments, but they don't match?!
+  if (!Alignment)
+    Alignment = B.Alignment;
+
+  if (!StackAlignment)
+    StackAlignment = B.StackAlignment;
+
+  Attrs.insert(B.Attrs.begin(), B.Attrs.end());
+
+  for (td_const_iterator I = B.TargetDepAttrs.begin(),
+         E = B.TargetDepAttrs.end(); I != E; ++I)
+    TargetDepAttrs[I->first] = I->second;
+
+  return *this;
+}
+
 bool AttrBuilder::contains(Attribute::AttrKind A) const {
   return Attrs.count(A);
 }