[IR] Make getParamAttributes take argument numbers, not ArgNo+1

Add hasParamAttribute() and use it instead of hasAttribute(ArgNo+1,
Kind) everywhere.

The fact that the AttributeList index for an argument is ArgNo+1 should
be a hidden implementation detail.

NFC

llvm-svn: 300272

1 files changed, 9 insertions, 13 deletions

diff --git a/llvm/lib/Transforms/IPO/MergeFunctions.cpp b/llvm/lib/Transforms/IPO/MergeFunctions.cpp
index 4ce4de1..771770d 100644
--- a/llvm/lib/Transforms/IPO/MergeFunctions.cpp
+++ b/llvm/lib/Transforms/IPO/MergeFunctions.cpp
@@ -432,19 +432,15 @@ void MergeFunctions::replaceDirectCallers(Function *Old, Function *New) {
       // Transferring other attributes may help other optimizations, but that
       // should be done uniformly and not in this ad-hoc way.
       auto &Context = New->getContext();
-      auto NewFuncAttrs = New->getAttributes();
-      auto CallSiteAttrs = CS.getAttributes();
-
-      CallSiteAttrs = CallSiteAttrs.addAttributes(
-          Context, AttributeList::ReturnIndex, NewFuncAttrs.getRetAttributes());
-
-      for (unsigned argIdx = 0; argIdx < CS.arg_size(); argIdx++) {
-        AttributeSet Attrs = NewFuncAttrs.getParamAttributes(argIdx);
-        if (Attrs.hasAttributes())
-          CallSiteAttrs = CallSiteAttrs.addAttributes(Context, argIdx, Attrs);
-      }
-
-      CS.setAttributes(CallSiteAttrs);
+      auto NewPAL = New->getAttributes();
+      SmallVector<AttributeSet, 4> NewArgAttrs;
+      for (unsigned argIdx = 0; argIdx < CS.arg_size(); argIdx++)
+        NewArgAttrs.push_back(NewPAL.getParamAttributes(argIdx));
+      // Don't transfer attributes from the function to the callee. Function
+      // attributes typically aren't relevant to the calling convention or ABI.
+      CS.setAttributes(AttributeList::get(Context, /*FnAttrs=*/AttributeSet(),
+                                          NewPAL.getRetAttributes(),
+                                          NewArgAttrs));
 
       remove(CS.getInstruction()->getParent()->getParent());
       U->set(BitcastNew);