[llvm] r354394 - [LangRef] add to description of alloca instruction

[Sanjay Patel via llvm-commits]

Author: spatel
Date: Tue Feb 19 14:35:12 2019
New Revision: 354394

URL: http://llvm.org/viewvc/llvm-project?rev=354394&view=rev
Log:
[LangRef] add to description of alloca instruction

As mentioned in D58359, we can explicitly state that the
memory allocated is uninitialized and reading that memory
produces undef.

Modified:
    llvm/trunk/docs/LangRef.rst

Modified: llvm/trunk/docs/LangRef.rst
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/LangRef.rst?rev=354394&r1=354393&r2=354394&view=diff
==============================================================================
--- llvm/trunk/docs/LangRef.rst (original)
+++ llvm/trunk/docs/LangRef.rst Tue Feb 19 14:35:12 2019
@@ -8364,15 +8364,16 @@ boundary compatible with the type.
 Semantics:
 """"""""""
 
-Memory is allocated; a pointer is returned. The operation is undefined
-if there is insufficient stack space for the allocation. '``alloca``'d
-memory is automatically released when the function returns. The
-'``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 returned pointer may not
-be unique. The order in which memory is allocated (ie., which way the stack
-grows) is not specified.
+Memory is allocated; a pointer is returned. The allocated memory is
+uninitialized, and loading from uninitialized memory produces an undefined
+value. The operation itself is undefined if there is insufficient stack
+space for the allocation.'``alloca``'d memory is automatically released
+when the function returns. The '``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 returned
+pointer may not be unique. The order in which memory is allocated (ie.,
+which way the stack grows) is not specified.
 
 Example:
 """"""""