[llvm] r225223 - IR: Don't drop MDNode uniquing on null operands
Duncan P. N. Exon Smith
dexonsmith at apple.com
Mon Jan 5 15:31:54 PST 2015
Author: dexonsmith
Date: Mon Jan 5 17:31:54 2015
New Revision: 225223
URL: http://llvm.org/viewvc/llvm-project?rev=225223&view=rev
Log:
IR: Don't drop MDNode uniquing on null operands
Now that `LLVMContextImpl` can call `MDNode::dropAllReferences()` to
prevent teardown madness, stop dropping uniquing just because an operand
drops to null.
Part of PR21532.
Modified:
llvm/trunk/lib/IR/Metadata.cpp
llvm/trunk/unittests/IR/MetadataTest.cpp
Modified: llvm/trunk/lib/IR/Metadata.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/Metadata.cpp?rev=225223&r1=225222&r2=225223&view=diff
==============================================================================
--- llvm/trunk/lib/IR/Metadata.cpp (original)
+++ llvm/trunk/lib/IR/Metadata.cpp Mon Jan 5 17:31:54 2015
@@ -515,13 +515,8 @@ void GenericMDNode::handleChangedOperand
Metadata *Old = getOperand(Op);
setOperand(Op, New);
- // Drop uniquing for self-reference cycles or if an operand drops to null.
- //
- // FIXME: Stop dropping uniquing when an operand drops to null. The original
- // motivation was to prevent madness during teardown of LLVMContextImpl, but
- // dropAllReferences() fixes that problem in a better way. (It's just here
- // now for better staging of semantic changes.)
- if (New == this || !New) {
+ // Drop uniquing for self-reference cycles.
+ if (New == this) {
storeDistinctInContext();
setHash(0);
if (!isResolved())
Modified: llvm/trunk/unittests/IR/MetadataTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/IR/MetadataTest.cpp?rev=225223&r1=225222&r2=225223&view=diff
==============================================================================
--- llvm/trunk/unittests/IR/MetadataTest.cpp (original)
+++ llvm/trunk/unittests/IR/MetadataTest.cpp Mon Jan 5 17:31:54 2015
@@ -202,6 +202,26 @@ TEST_F(MDNodeTest, Print) {
EXPECT_EQ(Expected, Actual);
}
+TEST_F(MDNodeTest, NullOperand) {
+ // metadata !{}
+ MDNode *Empty = MDNode::get(Context, None);
+
+ // metadata !{metadata !{}}
+ Metadata *Ops[] = {Empty};
+ MDNode *N = MDNode::get(Context, Ops);
+ ASSERT_EQ(Empty, N->getOperand(0));
+
+ // metadata !{metadata !{}} => metadata !{null}
+ N->replaceOperandWith(0, nullptr);
+ ASSERT_EQ(nullptr, N->getOperand(0));
+
+ // metadata !{null}
+ Ops[0] = nullptr;
+ MDNode *NullOp = MDNode::get(Context, Ops);
+ ASSERT_EQ(nullptr, NullOp->getOperand(0));
+ EXPECT_EQ(N, NullOp);
+}
+
typedef MetadataTest MetadataAsValueTest;
TEST_F(MetadataAsValueTest, MDNode) {
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