[PATCH] D49042: [LangRef] Clarify alloca of zero bytes.

[Eli Friedman via Phabricator via llvm-commits]

efriedma created this revision.
efriedma added reviewers: nlopes, hfinkel, sanjoy, rsmith, rjmccall.

Let's be conservative here; it matches what we actually implement, and it should be rare in practice anyway.


Repository:
  rL LLVM

https://reviews.llvm.org/D49042

Files:
  docs/LangRef.rst


Index: docs/LangRef.rst
===================================================================
--- docs/LangRef.rst
+++ docs/LangRef.rst
@@ -7854,9 +7854,9 @@
 '``alloca``' instruction is commonly used to represent automatic
 variables that must have an address available. When the function returns
 (either with the ``ret`` or ``resume`` instructions), the memory is
-reclaimed. Allocating zero bytes is legal, but the result is undefined.
-The order in which memory is allocated (ie., which way the stack grows)
-is not specified.
+reclaimed. Allocating zero bytes is legal, but the returned pointer may not
+be unique. The order in which memory is allocated (ie., which way the stack
+grows) is not specified.
 
 Example:
 """"""""


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