Reland "[IR] Make AttributeSetNode public, avoid temporary AttributeList copies"

This re-lands r299875.

I introduced a bug in Clang code responsible for replacing K&R, no
prototype declarations with a real function definition with a prototype.
The bug was here:

       // Collect any return attributes from the call.
  -    if (oldAttrs.hasAttributes(llvm::AttributeList::ReturnIndex))
  -      newAttrs.push_back(llvm::AttributeList::get(newFn->getContext(),
  -                                                  oldAttrs.getRetAttributes()));
  +    newAttrs.push_back(oldAttrs.getRetAttributes());

Previously getRetAttributes() carried AttributeList::ReturnIndex in its
AttributeList. Now that we return the AttributeSetNode* directly, it no
longer carries that index, and we call this overload with a single node:
  AttributeList::get(LLVMContext&, ArrayRef<AttributeSetNode*>)

That aborted with an assertion on x86_32 targets. I added an explicit
triple to the test and added CHECKs to help find issues like this in the
future sooner.

llvm-svn: 299899

1 files changed, 1 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/IPO/MergeFunctions.cpp b/llvm/lib/Transforms/IPO/MergeFunctions.cpp
index dc73902..5d41ca9 100644
--- a/llvm/lib/Transforms/IPO/MergeFunctions.cpp
+++ b/llvm/lib/Transforms/IPO/MergeFunctions.cpp
@@ -439,8 +439,7 @@ void MergeFunctions::replaceDirectCallers(Function *Old, Function *New) {
           Context, AttributeList::ReturnIndex, NewFuncAttrs.getRetAttributes());
 
       for (unsigned argIdx = 0; argIdx < CS.arg_size(); argIdx++) {
-        AttributeList Attrs = NewFuncAttrs.getParamAttributes(argIdx);
-        if (Attrs.getNumSlots())
+        if (AttributeSetNode *Attrs = NewFuncAttrs.getParamAttributes(argIdx))
           CallSiteAttrs = CallSiteAttrs.addAttributes(Context, argIdx, Attrs);
       }