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IR: Don't track nullptr on metadata RAUW

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The RAUW support in `Metadata` supports going to `nullptr` specifically
to handle values being deleted, causing `ValueAsMetadata` to be deleted.

Fix the case where the reference is from a `TrackingMDRef` (as opposed
to an `MDOperand` or a `MetadataAsValue`).

This is surprisingly rare -- metadata tracked by `TrackingMDRef` going
to null -- but it came up in an openSUSE bootstrap during inlining.  The
tracking ref was held by the `ValueMap` because it was referencing a
local, the basic block containing the local became dead after it had
been merged in, and when the local was deleted, the tracking ref
asserted in an `isa`.

llvm-svn: 224146
This commit is contained in:
Duncan P. N. Exon Smith 2014-12-12 19:24:33 +00:00
parent 8851da85ea
commit 77f50da5c2
2 changed files with 49 additions and 1 deletions
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3
lib/IR/Metadata.cpp
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@ -173,7 +173,8 @@ void ReplaceableMetadataImpl::replaceAllUsesWith(Metadata *MD) {
// Update unowned tracking references directly.
Metadata *&Ref = *static_cast<Metadata **>(Pair.first);
Ref = MD;
MetadataTracking::track(Ref);
if (MD)
MetadataTracking::track(Ref);
UseMap.erase(Pair.first);
continue;
}

47
unittests/IR/MetadataTest.cpp
View File

@ -207,6 +207,53 @@ TEST_F(MetadataAsValueTest, MDNodeConstant) {
EXPECT_EQ(V, V2);
}
typedef MetadataTest ValueAsMetadataTest;
TEST_F(ValueAsMetadataTest, UpdatesOnRAUW) {
Type *Ty = Type::getInt1PtrTy(Context);
std::unique_ptr<GlobalVariable> GV0(
new GlobalVariable(Ty, false, GlobalValue::ExternalLinkage));
auto *MD = ValueAsMetadata::get(GV0.get());
EXPECT_TRUE(MD->getValue() == GV0.get());
ASSERT_TRUE(GV0->use_empty());
std::unique_ptr<GlobalVariable> GV1(
new GlobalVariable(Ty, false, GlobalValue::ExternalLinkage));
GV0->replaceAllUsesWith(GV1.get());
EXPECT_TRUE(MD->getValue() == GV1.get());
}
typedef MetadataTest TrackingMDRefTest;
TEST_F(TrackingMDRefTest, UpdatesOnRAUW) {
Type *Ty = Type::getInt1PtrTy(Context);
std::unique_ptr<GlobalVariable> GV0(
new GlobalVariable(Ty, false, GlobalValue::ExternalLinkage));
TypedTrackingMDRef<ValueAsMetadata> MD(ValueAsMetadata::get(GV0.get()));
EXPECT_TRUE(MD->getValue() == GV0.get());
ASSERT_TRUE(GV0->use_empty());
std::unique_ptr<GlobalVariable> GV1(
new GlobalVariable(Ty, false, GlobalValue::ExternalLinkage));
GV0->replaceAllUsesWith(GV1.get());
EXPECT_TRUE(MD->getValue() == GV1.get());
// Reset it, so we don't inadvertently test deletion.
MD.reset();
}
TEST_F(TrackingMDRefTest, UpdatesOnDeletion) {
Type *Ty = Type::getInt1PtrTy(Context);
std::unique_ptr<GlobalVariable> GV(
new GlobalVariable(Ty, false, GlobalValue::ExternalLinkage));
TypedTrackingMDRef<ValueAsMetadata> MD(ValueAsMetadata::get(GV.get()));
EXPECT_TRUE(MD->getValue() == GV.get());
ASSERT_TRUE(GV->use_empty());
GV.reset();
EXPECT_TRUE(!MD);
}
TEST(NamedMDNodeTest, Search) {
LLVMContext Context;
ConstantAsMetadata *C =