explain that NumElements in alloca and malloc defaults to one

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46912 91177308-0d34-0410-b5e6-96231b3b80d8

docs/LangRef.html

@@ -2760,10 +2760,10 @@ <h5>Arguments:</h5>
 <tt>sizeof(&lt;type&gt;)*NumElements</tt>
 bytes of memory from the operating system and returns a pointer of the
 appropriate type to the program.  If "NumElements" is specified, it is the
-number of elements allocated.  If an alignment is specified, the value result
-of the allocation is guaranteed to be aligned to at least that boundary.  If
-not specified, or if zero, the target can choose to align the allocation on any
-convenient boundary.</p>
+number of elements allocated, otherwise "NumElements" is defaulted to be one.
+If an alignment is specified, the value result of the allocation is guaranteed to
+be aligned to at least that boundary.  If not specified, or if zero, the target can
+choose to align the allocation on any convenient boundary.</p>
 
 <p>'<tt>type</tt>' must be a sized type.</p>
 
@@ -2846,11 +2846,11 @@ <h5>Arguments:</h5>
 
 <p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
 bytes of memory on the runtime stack, returning a pointer of the
-appropriate type to the program.    If "NumElements" is specified, it is the
-number of elements allocated.  If an alignment is specified, the value result
-of the allocation is guaranteed to be aligned to at least that boundary.  If
-not specified, or if zero, the target can choose to align the allocation on any
-convenient boundary.</p>
+appropriate type to the program.  If "NumElements" is specified, it is the
+number of elements allocated, otherwise "NumElements" is defaulted to be one.
+If an alignment is specified, the value result of the allocation is guaranteed
+to be aligned to at least that boundary.  If not specified, or if zero, the target
+can choose to align the allocation on any convenient boundary.</p>
 
 <p>'<tt>type</tt>' may be any sized type.</p>