[PATCH] D78952: [LangRef] Describe linkage types, allocation size of declarations for global variables

[Matthias Schiffer via Phabricator via llvm-commits]

NeoRaider updated this revision to Diff 260712.
NeoRaider added a comment.

- Changed wording as suggested by review
- Mention overlap
- Mention alignment


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D78952/new/

https://reviews.llvm.org/D78952

Files:
  llvm/docs/LangRef.rst


Index: llvm/docs/LangRef.rst
===================================================================
--- llvm/docs/LangRef.rst
+++ llvm/docs/LangRef.rst
@@ -272,8 +272,8 @@
     visible, meaning that it participates in linkage and can be used to
     resolve external symbol references.
 
-It is illegal for a function *declaration* to have any linkage type
-other than ``external`` or ``extern_weak``.
+It is illegal for a global variable or function *declaration* to have any
+linkage type other than ``external`` or ``extern_weak``.
 
 .. _callingconv:
 
@@ -615,6 +615,8 @@
 Global variables in other translation units can also be declared, in which
 case they don't have an initializer.
 
+Global variables can optionally specify a :ref:`linkage type <linkage>`.
+
 Either global variable definitions or declarations may have an explicit section
 to be placed in and may have an optional explicit alignment specified. If there
 is a mismatch between the explicit or inferred section information for the
@@ -686,6 +688,13 @@
 iterate over them as an array, alignment padding would break this
 iteration. The maximum alignment is ``1 << 29``.
 
+For global variables declarations, as well as definitions that may be
+replaced at link time (``linkonce``, ``weak``, ``extern_weak`` and ``common``
+linkage types), LLVM makes no assumptions about the allocation size of the
+variables, except that they may not overlap. The alignment of a global variable
+declaration or replaceable definition must not be greater than the alignment of
+the definition it resolves to.
+
 Globals can also have a :ref:`DLL storage class <dllstorageclass>`,
 an optional :ref:`runtime preemption specifier <runtime_preemption_model>`,
 an optional :ref:`global attributes <glattrs>` and


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