Duncan P. N. Exon Smith 8fa25a1082 IR: Drop uniquing when an MDNode Value operand is deleted ... This is a fix for PR28697. An MDNode can indirectly refer to a GlobalValue, through a ConstantAsMetadata. When the GlobalValue is deleted, the MDNode operand is reset to `nullptr`. If the node is uniqued, this can lead to a hard-to-detect cache invalidation in a Metadata map that's shared across an LLVMContext. Consider: 1. A map from Metadata* to `T` called RemappedMDs. 2. A node that references a global variable, `!{i1* @GV}`. 3. Insert `!{i1* @GV} -> SomeT` in the map. 4. Delete `@GV`, leaving behind `!{null} -> SomeT`. Looking up the generic and uninteresting `!{null}` gives you `SomeT`, which is likely related to `@GV`. Worse, `SomeT`'s lifetime may be tied to the deleted `@GV`. This occurs in practice in the shared ValueMap used since r266579 in the IRMover. Other code that handles more than one Module (with different lifetimes) in the same LLVMContext could hit it too. The fix here is a partial revert of r225223: in the rare case that an MDNode operand is a ConstantAsMetadata (i.e., wrapping a node from the Value hierarchy), drop uniquing if it gets replaced with `nullptr`. This changes step #4 above to leave behind `distinct !{null} -> SomeT`, which can't be confused with the generic `!{null}`. In theory, this can cause some churn in the LLVMContext's MDNode uniquing map when Values are being deleted. However: - The number of GlobalValues referenced from uniqued MDNodes is expected to be quite small. E.g., the debug info metadata schema only references GlobalValues from distinct nodes. - Other Constants have the lifetime of the LLVMContext, whose teardown is careful to drop references before deleting the constants. As a result, I don't expect a compile time regression from this change. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@277625 91177308-0d34-0410-b5e6-96231b3b80d8		2016-08-03 18:19:43 +00:00
..
Inputs	IR: Drop uniquing when an MDNode Value operand is deleted	2016-08-03 18:19:43 +00:00
2002-07-17-GlobalFail.ll
2002-07-17-LinkTest2.ll
2002-08-20-ConstantExpr.ll
2003-01-30-LinkerRename.ll
2003-01-30-LinkerTypeRename.ll
2003-04-23-LinkOnceLost.ll
2003-04-26-NullPtrLinkProblem.ll
2003-05-15-TypeProblem.ll
2003-05-31-LinkerRename.ll
2003-06-02-TypeResolveProblem2.ll
2003-06-02-TypeResolveProblem.ll
2003-08-20-OpaqueTypeResolve.ll
2003-08-23-GlobalVarLinking.ll
2003-08-23-RecursiveOpaqueTypeResolve.ll
2003-08-24-InheritPtrSize.ll
2003-08-28-TypeResolvesGlobal2.ll
2003-08-28-TypeResolvesGlobal3.ll	Make "@name =" mandatory for globals in .ll files.	2016-05-10 18:22:45 +00:00
2003-08-28-TypeResolvesGlobal.ll
2003-10-27-LinkOncePromote.ll
2003-11-18-TypeResolution.ll
2004-02-17-WeakStrongLinkage.ll
2004-05-07-TypeResolution1.ll
2004-05-07-TypeResolution2.ll
2004-12-03-DisagreeingType.ll
2005-02-12-ConstantGlobals-2.ll
2005-02-12-ConstantGlobals.ll
2005-12-06-AppendingZeroLengthArrays.ll
2006-01-19-ConstantPacked.ll
2008-03-05-AliasReference2.ll
2008-03-05-AliasReference.ll
2008-03-07-DroppedSection_a.ll
2008-03-07-DroppedSection_b.ll
2008-06-13-LinkOnceRedefinition.ll
2008-06-26-AddressSpace.ll
2008-07-06-AliasFnDecl2.ll
2008-07-06-AliasFnDecl.ll
2008-07-06-AliasWeakDest2.ll
2008-07-06-AliasWeakDest.ll
2009-09-03-mdnode2.ll	[PR27284] Reverse the ownership between DICompileUnit and DISubprogram.	2016-04-15 15:57:41 +00:00
2009-09-03-mdnode.ll	[PR27284] Reverse the ownership between DICompileUnit and DISubprogram.	2016-04-15 15:57:41 +00:00
2011-08-04-DebugLoc2.ll	[PR27284] Reverse the ownership between DICompileUnit and DISubprogram.	2016-04-15 15:57:41 +00:00
2011-08-04-DebugLoc.ll	[PR27284] Reverse the ownership between DICompileUnit and DISubprogram.	2016-04-15 15:57:41 +00:00
2011-08-04-Metadata2.ll	[PR27284] Reverse the ownership between DICompileUnit and DISubprogram.	2016-04-15 15:57:41 +00:00
2011-08-04-Metadata.ll	[PR27284] Reverse the ownership between DICompileUnit and DISubprogram.	2016-04-15 15:57:41 +00:00
2011-08-18-unique-class-type2.ll	[PR27284] Reverse the ownership between DICompileUnit and DISubprogram.	2016-04-15 15:57:41 +00:00
2011-08-18-unique-class-type.ll	[PR27284] Reverse the ownership between DICompileUnit and DISubprogram.	2016-04-15 15:57:41 +00:00
2011-08-18-unique-debug-type2.ll	[PR27284] Reverse the ownership between DICompileUnit and DISubprogram.	2016-04-15 15:57:41 +00:00
2011-08-18-unique-debug-type.ll	[PR27284] Reverse the ownership between DICompileUnit and DISubprogram.	2016-04-15 15:57:41 +00:00
alias-2.ll	Fix PR26152.	2016-01-20 22:05:50 +00:00
alias-3.ll	IRLinker: fix double scheduling of mapping a global value because of an alias	2016-05-25 21:00:44 +00:00
alias.ll
alignment.ll
AppendingLinkage2.ll
AppendingLinkage.ll
apple-version.ll
available_externally_a.ll
available_externally_b.ll
available_externally_over_decl.ll
basiclink.ll
broken.ll	Don't verify inputs to the Linker if ODR merging.	2016-06-29 18:31:48 +00:00
comdat2.ll
comdat4.ll
comdat5.ll
comdat6.ll
comdat7.ll
comdat8.ll
comdat9.ll	Fix lazy linking of comdat members.	2016-03-24 00:06:03 +00:00
comdat10.ll
comdat11.ll
comdat12.ll
comdat13.ll
comdat14.ll	ModuleLinker: Do not import linkonce/weak as "external_weak"	2016-04-19 16:11:05 +00:00
comdat15.ll
comdat16.ll	Fix logic for which symbols to keep with comdats.	2016-03-23 21:16:33 +00:00
comdat_group.ll
comdat-rm-dst.ll	Drop comdats from the dst module if they are not selected.	2016-03-22 21:35:47 +00:00
comdat.ll
ConstantGlobals.ll
constructor-comdat.ll	Fix logic for which symbols to keep with comdats.	2016-03-23 21:16:33 +00:00
ctors2.ll
ctors3.ll
ctors4.ll
ctors5.ll
ctors.ll
datalayout.ll
DbgDeclare2.ll	[PR27284] Reverse the ownership between DICompileUnit and DISubprogram.	2016-04-15 15:57:41 +00:00
DbgDeclare.ll	[PR27284] Reverse the ownership between DICompileUnit and DISubprogram.	2016-04-15 15:57:41 +00:00
debug-info-version-a.ll	[PR27284] Reverse the ownership between DICompileUnit and DISubprogram.	2016-04-15 15:57:41 +00:00
debug-info-version-b.ll
dicompositetype-unique.ll	IR: Enable debug info type ODR uniquing for forward decls	2016-04-19 18:00:19 +00:00
distinct-cycles.ll
distinct.ll
dllstorage-a.ll
dllstorage-b.ll
drop-debug.ll
func-attrs-a.ll
func-attrs-b.ll
funcimport2.ll	ThinLTO/ModuleLinker: add a flag to not always pull-in linkonce when performing importing	2016-04-21 01:59:39 +00:00
funcimport_appending_global.ll	Move summary creation out of llvm-as into opt	2016-04-12 21:35:18 +00:00
funcimport_comdat.ll	Move summary creation out of llvm-as into opt	2016-04-12 21:35:18 +00:00
funcimport.ll	ThinLTO: never promote as external weak	2016-04-20 04:18:11 +00:00
global_ctors.ll
ident.ll
inlineasm.ll
internalize-lazy.ll
link-flags.ll
link-global-to-func.ll
link-type-names.ll
linkage2.ll
linkage.ll
linkmdnode2.ll
linkmdnode.ll
linknamedmdnode2.ll
linknamedmdnode.ll
LinkOnce.ll
lto-attributes.ll
mdlocation.ll	[PR27284] Reverse the ownership between DICompileUnit and DISubprogram.	2016-04-15 15:57:41 +00:00
metadata-a.ll
metadata-attach.ll	Linker: Copy metadata when linking declarations.	2016-06-24 17:42:21 +00:00
metadata-b.ll
metadata-function.ll
metadata-with-global-value-operand.ll	IR: Drop uniquing when an MDNode Value operand is deleted	2016-08-03 18:19:43 +00:00
module-flags-1-a.ll
module-flags-1-b.ll
module-flags-2-a.ll
module-flags-2-b.ll
module-flags-3-a.ll
module-flags-3-b.ll
module-flags-4-a.ll	Linker: teach the IR mover to return llvm::Error.	2016-05-27 05:21:35 +00:00
module-flags-4-b.ll	Linker: teach the IR mover to return llvm::Error.	2016-05-27 05:21:35 +00:00
module-flags-5-a.ll
module-flags-5-b.ll
module-flags-6-a.ll
module-flags-6-b.ll
module-flags-7-a.ll
module-flags-7-b.ll
module-flags-8-a.ll
module-flags-8-b.ll
module-flags-dont-change-others.ll
module-flags-pic-1-a.ll
module-flags-pic-2-a.ll
multiple-merged-structs.ll
null_mapping_constant.ll	ValueMapper: fix assertion when null-mapping a constant for linking metadata	2016-05-28 17:26:03 +00:00
odr.ll	Don't verify inputs to the Linker if ODR merging.	2016-06-29 18:31:48 +00:00
only-needed-debug-metadata.ll	[PR27284] Reverse the ownership between DICompileUnit and DISubprogram.	2016-04-15 15:57:41 +00:00
only-needed-named-metadata.ll	Revert obsolete llvm-link -preserve-modules option/test	2016-01-21 14:28:52 +00:00
only-needed-recurse.ll	Fix recursive -only-needed.	2016-04-21 14:56:33 +00:00
opaque.ll
override-different-linkage.ll
override-with-internal-linkage-2.ll
override-with-internal-linkage.ll
override.ll
partial-type-refinement-link.ll
partial-type-refinement.ll
pr21374.ll
pr21494.ll
pr22807.ll
pr26037.ll	[PR27284] Reverse the ownership between DICompileUnit and DISubprogram.	2016-04-15 15:57:41 +00:00
pr27044.ll	Fix another case where we were unconditionally linking linkonce GVs.	2016-03-24 15:23:01 +00:00
PR8300.ll
prologuedata.ll
redefinition.ll
replaced-function-matches-first-subprogram.ll	[PR27284] Reverse the ownership between DICompileUnit and DISubprogram.	2016-04-15 15:57:41 +00:00
subprogram-linkonce-weak.ll	[PR27284] Reverse the ownership between DICompileUnit and DISubprogram.	2016-04-15 15:57:41 +00:00
targettriple.ll
testlink.ll
thinlto_funcimport_debug.ll	[PR27284] Reverse the ownership between DICompileUnit and DISubprogram.	2016-04-15 15:57:41 +00:00
transitive-lazy-link.ll
type-unique-alias.ll
type-unique-dst-types.ll
type-unique-inheritance.ll
type-unique-name.ll
type-unique-odr-a.ll	DebugInfo: Remove MDString-based type references	2016-04-23 21:08:00 +00:00
type-unique-odr-b.ll	DebugInfo: Remove MDString-based type references	2016-04-23 21:08:00 +00:00
type-unique-opaque.ll
type-unique-simple2-a.ll	DebugInfo: Remove MDString-based type references	2016-04-23 21:08:00 +00:00
type-unique-simple2-b.ll	DebugInfo: Remove MDString-based type references	2016-04-23 21:08:00 +00:00
type-unique-simple2.ll
type-unique-simple-a.ll	DebugInfo: Remove MDString-based type references	2016-04-23 21:08:00 +00:00
type-unique-simple-b.ll	DebugInfo: Remove MDString-based type references	2016-04-23 21:08:00 +00:00
type-unique-src-type.ll
type-unique-type-array-a.ll	DebugInfo: Remove MDString-based type references	2016-04-23 21:08:00 +00:00
type-unique-type-array-b.ll	DebugInfo: Remove MDString-based type references	2016-04-23 21:08:00 +00:00
type-unique-unrelated.ll
unique-fwd-decl-a.ll
unique-fwd-decl-order.ll
uniqued-distinct-cycles.ll
unnamed-addr1-a.ll
unnamed-addr1-b.ll
unnamed-addr-err-a.ll
unnamed-addr-err-b.ll
visibility.ll
weakextern.ll