[IR] Make AttributeSetNode public, avoid temporary AttributeList copies

Summary:
AttributeList::get(Fn|Ret|Param)Attributes no longer creates a temporary
AttributeList just to hide the AttributeSetNode type.

I've also added a factory method to create AttributeLists from a
parallel array of AttributeSetNodes. I think this simplifies
construction of AttributeLists when rewriting function prototypes.
Previously we would test if a particular index had attributes, and
conditionally add a temporary attribute list to a vector. Now the
attribute set vector is parallel to the argument vector already that
these passes already construct.

My long term vision is to wrap AttributeSetNode* inside an AttributeSet
type that holds the enum attributes, but that will come in a follow up
change.

I haven't done any performance measurements for this change because
profiling hasn't shown that any of the affected code is hot.

Reviewers: pete, chandlerc, sanjoy, hfinkel

Reviewed By: pete

Subscribers: jfb, llvm-commits

Differential Revision: https://reviews.llvm.org/D31198

llvm-svn: 299875

1 files changed, 1 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/Utils/CodeExtractor.cpp b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
index 755427cace2..3bc33d0c666 100644
--- a/llvm/lib/Transforms/Utils/CodeExtractor.cpp
+++ b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
@@ -362,8 +362,7 @@ Function *CodeExtractor::constructFunction(const ValueSet &inputs,
   //  "target-features" attribute allowing it to be lowered.
   // FIXME: This should be changed to check to see if a specific
   //           attribute can not be inherited.
-  AttributeList OldFnAttrs = oldFunction->getAttributes().getFnAttributes();
-  AttrBuilder AB(OldFnAttrs, AttributeList::FunctionIndex);
+  AttrBuilder AB(oldFunction->getAttributes().getFnAttributes());
   for (const auto &Attr : AB.td_attrs())
     newFunction->addFnAttr(Attr.first, Attr.second);