Add CodeGen support for functions that always return arguments via a new parameter attribute 'returned', which is taken advantage of in target-independent tail call opportunity detection and in ARM call lowering (when placed on an integral first parameter).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179925 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 7 insertions, 0 deletions

diff --git a/lib/IR/Function.cpp b/lib/IR/Function.cpp
index 1e72b90a13..7f7efabf76 100644
--- a/lib/IR/Function.cpp
+++ b/lib/IR/Function.cpp
@@ -124,6 +124,13 @@ bool Argument::hasStructRetAttr() const {
     hasAttribute(1, Attribute::StructRet);
 }
 
+/// hasReturnedAttr - Return true if this argument has the returned attribute on
+/// it in its containing function.
+bool Argument::hasReturnedAttr() const {
+  return getParent()->getAttributes().
+    hasAttribute(getArgNo()+1, Attribute::Returned);
+}
+
 /// addAttr - Add attributes to an argument.
 void Argument::addAttr(AttributeSet AS) {
   assert(AS.getNumSlots() <= 1 &&