Add initial support for the convergent attribute.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238264 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Bitcode/Reader/BitcodeReader.cpp

@@ -1095,6 +1095,8 @@ static Attribute::AttrKind GetAttrFromCode(uint64_t Code) {
     return Attribute::InAlloca;
   case bitc::ATTR_KIND_COLD:
     return Attribute::Cold;
+  case bitc::ATTR_KIND_CONVERGENT:
+    return Attribute::Convergent;
   case bitc::ATTR_KIND_INLINE_HINT:
     return Attribute::InlineHint;
   case bitc::ATTR_KIND_IN_REG: