llvm::MDNode

Synopsis

Declared in <llvm/IR/Metadata.h>

class MDNode
    : public Metadata

Description

Metadata nodes can be uniqued, like constants, or distinct. Temporary metadata nodes (with full support for RAUW) can be used to delay uniquing until forward references are known. The basic metadata node is an MDTuple.

There is limited support for RAUW at construction time. At construction time, if any operand is a temporary node (or an unresolved uniqued node, which indicates a transitive temporary operand), the node itself will be unresolved. As soon as all operands become resolved, it will drop RAUW support permanently.

If an unresolved node is part of a cycle, resolveCycles() needs to be called on some member of the cycle once all temporary nodes have been replaced.

MDNodes can be large or small, as well as resizable or non-resizable. Large MDNodes' operands are allocated in a separate storage vector, whereas small MDNodes' operands are co-allocated. Distinct and temporary MDnodes are resizable, but only MDTuples support this capability.

Clients can add operands to resizable MDNodes using push_back().

Base Classes

Name	Description
`Metadata`	Root of the metadata hierarchy.

Type Aliases

Name
`op_iterator`
`op_range`

Enums

Name
`MetadataKind`

Member Functions

Name	Description
`MDNode` [constructor] [deleted]	Copy constructor
`operator=` [deleted]
`clone`	Create a (temporary) clone of this.
`dump`	User-friendly dump.
`dumpTree`	User-friendly dump in tree shape.
`getContext`
`getMetadataID`
`getNumOperands`	Return number of MDNode operands.
`getNumTemporaryUses`
`getOperand`
`isAlwaysReplaceable`
`isDistinct`
`isReplaceable`
`isResolved`	Check if node is fully resolved.
`isTBAAVtableAccess`	Check whether MDNode is a vtable access.
`isTemporary`
`isUniqued`
`op_begin`
`op_end`
`operands`
`operator new` [deleted]
`print`	Print.
`printAsOperand`	Print as operand.
`printTree`	Print in tree shape.
`replaceAllUsesWith`	RAUW a temporary.
`replaceOperandWith`	Replace a specific operand.
`resolve`	Resolve a unique, unresolved node.
`resolveCycles`	Resolve cycles.

Static Member Functions

Name	Description
`classof`	Methods for support type inquiry through isa, cast, and dyn_cast:
`concatenate`	Methods for metadata merging.
`deleteTemporary`	Deallocate a node created by getTemporary.
`fromCaptureComponents`	Convert CaptureComponents to !captures metadata. The return value may be nullptr.
`get`
`getDistinct`
`getIfExists`
`getMergedAllocTokenMetadata`
`getMergedCalleeTypeMetadata`
`getMergedCallsiteMetadata`
`getMergedMemProfMetadata`
`getMergedProfMetadata`	Merge !prof metadata from two instructions. Currently only implemented with direct callsites with branch weights.
`getMostGenericAliasScope`
`getMostGenericAlignmentOrDereferenceable`
`getMostGenericFPMath`
`getMostGenericNoFPClass`
`getMostGenericNoaliasAddrspace`
`getMostGenericRange`
`getMostGenericTBAA`
`getTemporary`
`intersect`
`replaceWithDistinct`	Replace a temporary node with a distinct one.
`replaceWithPermanent`	Replace a temporary node with a permanent one.
`replaceWithUniqued`	Replace a temporary node with a uniqued one.
`toCaptureComponents`	Convert !captures metadata to CaptureComponents. MD may be nullptr.

Static Data Members

Name	Description
`PoisonGeneratingIDs`	Metadata IDs that may generate poison.

Protected Type Aliases

Name
`mutable_op_range`

Protected Enums

Name	Description
`StorageType`	Active type of storage.

Protected Member Functions

Name	Description
`MDNode` [constructor]
`~MDNode` [destructor]	Destructor
`dropAllReferences`
`getNumUnresolved`
`handleChangedOperand`	Default handling of a changed operand, which asserts.
`mutable_begin`
`mutable_end`
`mutable_operands`
`operator delete`	Required by std, but never called.
`operator new`
`resize`	Resize the node to hold NumOps operands.
`setNumUnresolved`
`setOperand`	Set an operand.
`storeDistinctInContext`

Protected Static Member Functions

Name
`storeImpl`

Protected Data Members

Name	Description
`Storage`	Storage flag for non-uniqued, otherwise unowned, metadata.
`SubclassData1`
`SubclassData16`
`SubclassData32`

Friends

Name	Description
`llvm::DIAssignID`	Assignment ID. Used to link stores (as an attachment) and dbg.assigns (as an operand). DIAssignID metadata is never uniqued as we compare instances using referential equality (the instance/address is the ID).
`llvm::LLVMContextImpl`
`llvm::ReplaceableMetadataImpl`	Shared implementation of use-lists for replaceable metadata.

Non-Member Functions

Name	Description
`MapMetadata`	Lookup or compute a mapping for a piece of metadata.
`MapMetadata`	Version of MapMetadata with type safety for MDNode.
`UpgradeTBAANode`	If the given TBAA tag uses the scalar TBAA format, create a new node corresponding to the upgrade to the struct-path aware TBAA format. Otherwise return the `TBAANode` itself.
`computeKnownBitsFromRangeMetadata`	Compute known bits from the range metadata. `KnownZero` the set of bits that are known to be zero `KnownOne` the set of bits that are known to be one
`extractBranchWeights`	Extract branch weights from MD_prof metadata
`extractFromBranchWeightMD32`	Faster version of extractBranchWeights() that skips checks and must only be called with "branch_weights" metadata nodes. Supports uint32_t.
`extractFromBranchWeightMD64`	Faster version of extractBranchWeights() that skips checks and must only be called with "branch_weights" metadata nodes. Supports uint64_t.
`extractProfTotalWeight`	Retrieve the total of all weights from MD_prof data.
`findOptionMDForLoop`	Find string metadata for a loop.
`findOptionMDForLoopID`	Find and return the loop attribute node for the attribute `Name` in `LoopID.` Return nullptr if there is no such attribute.
`getBranchWeightMDNode`	Get the branch weights metadata node
`getBranchWeightOffset`	Return the offset to the first branch weight data
`getConstantRangeFromMetadata`	Parse out a conservative ConstantRange from !range metadata.
`getDISubprogram`	Find subprogram that is enclosing this scope.
`getExplicitlyUnknownBranchWeightsIfProfiled`	Returns a metadata node containing unknown branch weights if the function has an entry count, otherwise returns nullptr.
`getMemCacheHintMetadata`	Return the cache hint metadata node for memory operand `OperandNo` on `I,` or nullptr when the instruction has no hint for that operand. For a `CallBase,` `OperandNo` is an argument index; otherwise it is an instruction operand index.
`getPGOFuncNameMetadata`	Return the PGOFuncName meta data associated with a function.
`getValidBranchWeightMDNode`	Get the valid branch weights metadata node
`hasBranchWeightOrigin`	Check if Branch Weight Metadata has an "expected" field from an llvm.expect* intrinsic
`intersectAccessGroups`	Compute the access-group list of access groups that `Inst1` and `Inst2` are both in. If either instruction does not access memory at all, it is considered to be in every list.
`isBranchWeightMD`	Checks if an MDNode contains Branch Weight Metadata
`isValidAsAccessGroup`	Return whether an MDNode might represent an access group.
`isValueProfileMD`	Checks if an MDNode contains value profiling Metadata
`makeFollowupLoopID`	Create a new loop identifier for a loop created from a loop transformation.
`makePostTransformationMetadata`	Create a new LoopID after the loop has been transformed.
`uniteAccessGroups`	Compute the union of two access-group lists.
`upgradeInstructionLoopAttachment`	Upgrade the loop attachment metadata node.
`memprof::buildCallstackMetadata`	Build callstack metadata from the provided list of call stack ids. Returns the resulting metadata node.
`memprof::getMIBAllocType`	Returns the allocation type from an MIB metadata node.
`memprof::getMIBStackNode`	Returns the stack node from an MIB metadata node.

Derived Classes

Name	Description
`DIAssignID`	Assignment ID. Used to link stores (as an attachment) and dbg.assigns (as an operand). DIAssignID metadata is never uniqued as we compare instances using referential equality (the instance/address is the ID).
`DIExpression`	DWARF expression.
`DIGlobalVariableExpression`	A pair of DIGlobalVariable and DIExpression.
`DILocation`	Debug location.
`DIMacroNode`	Macro Info DWARF-like metadata node.
`DINode`	Tagged DWARF-like metadata node.
`MDTuple`	Tuple of metadata.