[IR] Optimize no-op removal from AttributeSet (NFC)

When removing an AttrBuilder from an AttributeSet, first check
whether there is any overlap. If nothing is being removed, we can
directly return the original set.

1 files changed, 5 insertions, 1 deletions

diff --git a/llvm/lib/IR/Attributes.cpp b/llvm/lib/IR/Attributes.cpp
index adf8e6d..450543d 100644
--- a/llvm/lib/IR/Attributes.cpp
+++ b/llvm/lib/IR/Attributes.cpp
@@ -781,8 +781,12 @@ AttributeSet AttributeSet::removeAttribute(LLVMContext &C,
 }
 
 AttributeSet AttributeSet::removeAttributes(LLVMContext &C,
-                                              const AttrBuilder &Attrs) const {
+                                            const AttrBuilder &Attrs) const {
   AttrBuilder B(*this);
+  // If there is nothing to remove, directly return the original set.
+  if (!B.overlaps(Attrs))
+    return *this;
+
   B.remove(Attrs);
   return get(C, B);
 }