[GVN] Handle empty attrs in Expression ==

Author: macurtis-amd

llvm/lib/Transforms/Scalar/GVN.cpp

@@ -156,7 +156,7 @@ struct llvm::GVNPass::Expression {
       return false;
     if (varargs != other.varargs)
       return false;
-    if (!attrs.isEmpty() && !other.attrs.isEmpty() &&
+    if ((!attrs.isEmpty() || !other.attrs.isEmpty()) &&
         !attrs.intersectWith(type->getContext(), other.attrs).has_value())
       return false;
     return true;

llvm/test/Transforms/GVN/intersect-empty-attr.ll

@@ -0,0 +1,19 @@
+; RUN: opt -S -passes=gvn < %s | FileCheck %s
+
+declare i32 @bar() #0
+
+define i32 @foo() {
+entry:
+  %0 = tail call i32 @bar() #1
+  %1 = tail call i32 @bar()
+  ret i32 1
+}
+
+; CHECK-LABEL:    define i32 @foo(
+; CHECK:            %0 = tail call i32 @bar() #1
+; CHECK-NEXT:       %1 = tail call i32 @bar()
+; CHECK-NEXT:       ret i32 1
+; CHECK-NEXT:     }
+
+attributes #0 = { memory(none) }
+attributes #1 = { "llvm.assume"="ompx_no_call_asm" }