Differential D29104 Diff 88967 docs/LangRef.rst

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Show First 20 Lines • Show All 5,095 Lines • ▼ Show 20 Lines	.. code-block:: llvm
!0 = !{!"magic ptr"}		!0 = !{!"magic ptr"}
!1 = !{!"other ptr"}		!1 = !{!"other ptr"}

'``type``' Metadata		'``type``' Metadata
^^^^^^^^^^^^^^^^^^^		^^^^^^^^^^^^^^^^^^^

See :doc:`TypeMetadata`.		See :doc:`TypeMetadata`.

		'``associated``' Metadata
		^^^^^^^^^^^^^^^^^^^

		The ``associated`` metadata may be attached to a global object
		declaration with a single argument that references another global object.

		This metadata prevents discarding of the global object in linker GC
		mehdi_aminiUnsubmitted Not Done Reply Inline Actions 80 cols. mehdi_amini: 80 cols.
		unless the referenced object is also discarded. The linker support for
		this feature is spotty. For best compatibility, globals carrying this
		mehdi_aminiUnsubmitted Not Done Reply Inline Actions I don't think this is an OK property of metadata. Have you look for another representation that would not have this constraint? mehdi_amini: I don't think this is an OK property of metadata. Have you look for another representation that…
		eugenisAuthorUnsubmitted Not Done Reply Inline Actions It does not seem to be that bad. After all, !type and !absolute_symbol already have that property, they just don't document it. eugenis: It does not seem to be that bad. After all, !type and !absolute_symbol already have that…
		eugenisAuthorUnsubmitted Not Done Reply Inline Actions How about now? Under this list of conditions the metadata can be discarded, which will make the global non-discardable. eugenis: How about now? Under this list of conditions the metadata can be discarded, which will make the…
		mehdi_aminiUnsubmitted Not Done Reply Inline Actions From LangRef: A transformation is required to drop any metadata attachment that it does not know or know it can’t preserve. Currently there is an exception for metadata attachment to globals for !type and !absolute_symbol which can’t be unconditionally dropped unless the global is itself deleted. mehdi_amini: From LangRef: ``` A transformation is required to drop any metadata attachment that it does…
		eugenisAuthorUnsubmitted Not Done Reply Inline Actions Ah thanks, I was expecting to find this in the individual metadata type's sections. eugenis: Ah thanks, I was expecting to find this in the individual metadata type's sections.
		metadata must also
		mehdi_aminiUnsubmitted Not Done Reply Inline Actions colon? Also, since it seems to be advisory and not mandatory I wouldn't use "must" but "may". mehdi_amini: colon? Also, since it seems to be advisory and not mandatory I wouldn't use "must" but "may".

		- Be in a comdat with the referenced global.
		- Be in @llvm.compiler.used.
		- Have an explicit section with a name which is a valid C identifier.
		mehdi_aminiUnsubmitted Done Reply Inline Actions From the sentence this list is just "guidelines", correct? Is it still "valid" to use the `associated` MD without a section? In different comdats? mehdi_amini: From the sentence this list is just "guidelines", correct? Is it still "valid" to use the…

		It does not have any effect on non-ELF targets.

		Example:

		.. code-block:: llvm
		$a = comdat any
		@a = global i32 1, comdat $a
		@b = internal global i32 2, comdat $a, section "abc", !associated !0
		!0 = !{i32* @a}


Module Flags Metadata		Module Flags Metadata
=====================		=====================

Information about the module as a whole is difficult to convey to LLVM's		Information about the module as a whole is difficult to convey to LLVM's
subsystems. The LLVM IR isn't sufficient to transmit this information.		subsystems. The LLVM IR isn't sufficient to transmit this information.
The ``llvm.module.flags`` named metadata exists in order to facilitate		The ``llvm.module.flags`` named metadata exists in order to facilitate
this. These flags are in the form of key / value pairs --- much like a		this. These flags are in the form of key / value pairs --- much like a
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