Extend 'readonly' and 'readnone' to work on function arguments as well as

functions. Make the function attributes pass add it to known library functions
and when it can deduce it.

llvm-svn: 185735

1 files changed, 9 insertions, 1 deletions

diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
index 7f7efabf..bf9d949b 100644
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -131,6 +131,15 @@ bool Argument::hasReturnedAttr() const {
     hasAttribute(getArgNo()+1, Attribute::Returned);
 }
 
+/// Return true if this argument has the readonly or readnone attribute on it
+/// in its containing function.
+bool Argument::onlyReadsMemory() const {
+  return getParent()->getAttributes().
+      hasAttribute(getArgNo()+1, Attribute::ReadOnly) ||
+      getParent()->getAttributes().
+      hasAttribute(getArgNo()+1, Attribute::ReadNone);
+}
+
 /// addAttr - Add attributes to an argument.
 void Argument::addAttr(AttributeSet AS) {
   assert(AS.getNumSlots() <= 1 &&
@@ -711,4 +720,3 @@ bool Function::callsFunctionThatReturnsTwice() const {
 
   return false;
 }
-