[IR] Take func, ret, and arg attrs separately in AttributeList::get

This seems like a much more natural API, based on Derek Schuff's
comments on r300015. It further hides the implementation detail of
AttributeList that function attributes come last and appear at index
~0U, which is easy for the user to screw up. git diff says it saves code
as well: 97 insertions(+), 137 deletions(-)

This also makes it easier to change the implementation, which I want to
do next.

llvm-svn: 300153

1 files changed, 7 insertions, 10 deletions

diff --git a/llvm/lib/Transforms/Utils/CloneFunction.cpp b/llvm/lib/Transforms/Utils/CloneFunction.cpp
index ae58d61..0577026 100644
--- a/llvm/lib/Transforms/Utils/CloneFunction.cpp
+++ b/llvm/lib/Transforms/Utils/CloneFunction.cpp
@@ -103,23 +103,20 @@ void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
                  ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
                  TypeMapper, Materializer));
 
-  SmallVector<AttributeSet, 4> AttrVec(NewFunc->arg_size() + 2);
+  SmallVector<AttributeSet, 4> NewArgAttrs(NewFunc->arg_size());
   AttributeList OldAttrs = OldFunc->getAttributes();
 
-  // Copy the return attributes.
-  AttrVec[0] = OldAttrs.getRetAttributes();
-
   // Clone any argument attributes that are present in the VMap.
-  for (const Argument &OldArg : OldFunc->args())
+  for (const Argument &OldArg : OldFunc->args()) {
     if (Argument *NewArg = dyn_cast<Argument>(VMap[&OldArg])) {
-      AttrVec[NewArg->getArgNo() + 1] =
+      NewArgAttrs[NewArg->getArgNo()] =
           OldAttrs.getParamAttributes(OldArg.getArgNo() + 1);
     }
+  }
 
-  // Copy any function attributes.
-  AttrVec.back() = OldAttrs.getFnAttributes();
-
-  NewFunc->setAttributes(AttributeList::get(NewFunc->getContext(), AttrVec));
+  NewFunc->setAttributes(
+      AttributeList::get(NewFunc->getContext(), OldAttrs.getFnAttributes(),
+                         OldAttrs.getRetAttributes(), NewArgAttrs));
 
   SmallVector<std::pair<unsigned, MDNode *>, 1> MDs;
   OldFunc->getAllMetadata(MDs);