IR: Drop uniquing for self-referencing MDNodes
It doesn't make sense to unique self-referencing nodes. Drop uniquing
for them.
Note that `MDNode::intersect()` occasionally returns self-referencing
nodes. Previously these would be returned by `MDNode::get()`. I'm not
convinced this was intended behaviour -- to me it seems it should return
a node whose only operand is the self-reference -- but I don't know much
about alias scopes so I'm preserving it for now.
This is part of PR21532.
llvm-svn: 223618
diff --git a/llvm/unittests/IR/MetadataTest.cpp b/llvm/unittests/IR/MetadataTest.cpp
index 1a6f3d2..0e25990 100644
--- a/llvm/unittests/IR/MetadataTest.cpp
+++ b/llvm/unittests/IR/MetadataTest.cpp
@@ -123,6 +123,46 @@
delete I;
}
+TEST_F(MDNodeTest, SelfReference) {
+ // !0 = metadata !{metadata !0}
+ // !1 = metadata !{metadata !0}
+ {
+ MDNode *Temp = MDNode::getTemporary(Context, None);
+ Value *Args[] = {Temp};
+ MDNode *Self = MDNode::get(Context, Args);
+ Self->replaceOperandWith(0, Self);
+ MDNode::deleteTemporary(Temp);
+ ASSERT_EQ(Self, Self->getOperand(0));
+
+ // Self-references should be distinct, so MDNode::get() should grab a
+ // uniqued node that references Self, not Self.
+ Args[0] = Self;
+ MDNode *Ref1 = MDNode::get(Context, Args);
+ MDNode *Ref2 = MDNode::get(Context, Args);
+ EXPECT_NE(Self, Ref1);
+ EXPECT_EQ(Ref1, Ref2);
+ }
+
+ // !0 = metadata !{metadata !0, metadata !{}}
+ // !1 = metadata !{metadata !0, metadata !{}}
+ {
+ MDNode *Temp = MDNode::getTemporary(Context, None);
+ Value *Args[] = {Temp, MDNode::get(Context, None)};
+ MDNode *Self = MDNode::get(Context, Args);
+ Self->replaceOperandWith(0, Self);
+ MDNode::deleteTemporary(Temp);
+ ASSERT_EQ(Self, Self->getOperand(0));
+
+ // Self-references should be distinct, so MDNode::get() should grab a
+ // uniqued node that references Self, not Self itself.
+ Args[0] = Self;
+ MDNode *Ref1 = MDNode::get(Context, Args);
+ MDNode *Ref2 = MDNode::get(Context, Args);
+ EXPECT_NE(Self, Ref1);
+ EXPECT_EQ(Ref1, Ref2);
+ }
+}
+
TEST(NamedMDNodeTest, Search) {
LLVMContext Context;
Constant *C = ConstantInt::get(Type::getInt32Ty(Context), 1);