[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, 11 insertions, 11 deletions

diff --git a/llvm/lib/IR/Attributes.cpp b/llvm/lib/IR/Attributes.cpp
index 7faac60208f..2e3d7bdf709 100644
--- a/llvm/lib/IR/Attributes.cpp
+++ b/llvm/lib/IR/Attributes.cpp
@@ -778,7 +778,7 @@ AttributeList AttributeList::getImpl(
 #ifndef NDEBUG
   unsigned LastIndex = 0;
   bool IsFirst = true;
-  for (const auto &AttrPair : Attrs) {
+  for (auto &&AttrPair : Attrs) {
     assert((IsFirst || LastIndex < AttrPair.first) &&
            "unsorted or duplicate AttributeList indices");
     assert(AttrPair.second.hasAttributes() && "pointless AttributeList slot");
@@ -855,20 +855,20 @@ AttributeList::get(LLVMContext &C,
   return getImpl(C, Attrs);
 }
 
-AttributeList AttributeList::get(LLVMContext &C, ArrayRef<AttributeSet> Attrs) {
-  assert(Attrs.size() >= 2 &&
-         "should always have function and return attr slots");
+AttributeList AttributeList::get(LLVMContext &C, AttributeSet FnAttrs,
+                                 AttributeSet RetAttrs,
+                                 ArrayRef<AttributeSet> ArgAttrs) {
   SmallVector<std::pair<unsigned, AttributeSet>, 8> AttrPairs;
-  size_t Index = 0;
-  for (AttributeSet AS : Attrs) {
-    if (AS.hasAttributes()) {
-      // If this is the last AttributeSetNode, it's for the function.
-      if (Index == Attrs.size() - 1)
-        Index = AttributeList::FunctionIndex;
+  if (RetAttrs.hasAttributes())
+    AttrPairs.emplace_back(ReturnIndex, RetAttrs);
+  size_t Index = 1;
+  for (AttributeSet AS : ArgAttrs) {
+    if (AS.hasAttributes())
       AttrPairs.emplace_back(Index, AS);
-    }
     ++Index;
   }
+  if (FnAttrs.hasAttributes())
+    AttrPairs.emplace_back(FunctionIndex, FnAttrs);
   if (AttrPairs.empty())
     return AttributeList();
   return getImpl(C, AttrPairs);