Module metadata 

pliron representation of LLVM metadata.

LLVM’s metadata graph is made of MDNodes. The graph may be cyclic, including self referential nodes (like !0 = distinct !{!0, !"llvm.loop.unroll.disable"}). Nodes have an identity: structural equivalence does not imply identity equivalence.

In pliron, every MDNode lives in a module level metadata table, and the index in that table identifies the node. This is similar to LLVM’s textual format, where every node is printed at module level and referred to by number:

%10 = load i32, ptr %9, !tbaa !5, !alias.scope !12
!5  = !{!6, !6, i64 0}
!12 = distinct !{!12, !"copy: argument 1"}

becomes, in pliron:

v10 = llvm.load v9 : builtin.integer si32 !0

outlined_attributes:
!0 = [llvm_metadata = llvm.md_attachments ["tbaa" = #5, "alias.scope" = #12]]

with the definitions of #5 and #12 in the module’s MdTableAttr.

Metadata attachments on an [Operation] (MdAttachmentsAttr), and the module’s named metadata (NamedMdAttr), both refer to nodes by MdNodeId too. All of MdTableAttr, MdAttachmentsAttr and NamedMdAttr are [OutlinedAttr]s, ensuring better readability and simpler formatters (custom printers and parsers don’t need to be responsible for metadata, it’s automatically taken care of).

TODO: Only generic nodes (LLVM’s MDTuple) are supported. LLVM’s specialized debug info nodes (DILocation, DISubprogram, …) need extensions in MdNodeAttr; until then, conversion from LLVM-IR drops them, with a warning.

Structs

MdAttachmentsAttr

Metadata attached to an [Operation], keyed by LLVM’s metadata kind name ("tbaa", "llvm.loop", …), the way %v = load ..., !tbaa !5 attaches node !5 under kind tbaa.

MdTableAttr

The module level table of metadata node definitions. A node is referred to, from anywhere in the module, by its index in this table.

MdTableParseErr

NamedMdAttr

LLVM’s named metadata: a module level list of nodes under a name, such as !llvm.module.flags = !{!0, !1}.

Enums

MdAddErr

Error enum for metadata addition.

MdNodeAttr

A metadata node: an entry in the module’s metadata table (MdTableAttr).

MdOperandAttr

An operand of a metadata node (MdNodeAttr).

MetadataVerifyErr

Statics

ATTR_KEY_MD_ATTACHMENTS

The MdAttachmentsAttr on an [Operation].

ATTR_KEY_MD_TABLE

The module level MdTableAttr holding every metadata node’s definition.

ATTR_KEY_NAMED_MD

The module level NamedMdAttr, LLVM’s named metadata.

Functions

add_metadata_node

Add node to the metadata table of the module enclosing op, creating the table if the module doesn’t have one yet, and get the MdNodeId to refer to it by.

attach_metadata

Attach the node node to op under the LLVM metadata kind kind.

attach_new_metadata

Add node to the metadata table of the module enclosing op, and attach it to op under the LLVM metadata kind kind, replacing any existing attachment for that kind.

find_enclosing_module

Starting at op and walking up its ancestors, find the enclosing [ModuleOp].

find_metadata_table

Starting at op and walking up its ancestors, find the metadata table of the enclosing [ModuleOp].

get_attachments

Get the metadata attached to op.

get_metadata_table

Get the metadata table of module_op.

get_named_metadata

Get the named metadata of module_op.

set_attachments

Attach attachments to op, replacing whatever was attached to it.

set_metadata_table

Set the metadata table on module_op.

set_named_metadata

Set the named metadata on module_op.

verify_metadata

Verify that

Type Aliases

MdNodeId

Index of a metadata node in the module’s metadata table (MdTableAttr).