[llvm-commits] [llvm] r119914 - /llvm/trunk/docs/LangRef.html

[Chris Lattner]

Author: lattner
Date: Sat Nov 20 17:49:06 2010
New Revision: 119914

URL: http://llvm.org/viewvc/llvm-project?rev=119914&view=rev
Log:
a byval argument without an align can have an arbitrary alignment
requirement on the input pointer.

Modified:
    llvm/trunk/docs/LangRef.html

Modified: llvm/trunk/docs/LangRef.html
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/LangRef.html?rev=119914&r1=119913&r2=119914&view=diff
==============================================================================
--- llvm/trunk/docs/LangRef.html (original)
+++ llvm/trunk/docs/LangRef.html Sat Nov 20 17:49:06 2010
@@ -1021,8 +1021,9 @@
       registers).  Use of this attribute is target-specific.</dd>
 
   <dt><tt><b><a name="byval">byval</a></b></tt></dt>
-  <dd>This indicates that the pointer parameter should really be passed by value
-      to the function.  The attribute implies that a hidden copy of the pointee
+  <dd><p>This indicates that the pointer parameter should really be passed by
+      value to the function.  The attribute implies that a hidden copy of the
+      pointee
       is made between the caller and the callee, so the callee is unable to
       modify the value in the callee.  This attribute is only valid on LLVM
       pointer arguments.  It is generally used to pass structs and arrays by
@@ -1030,10 +1031,13 @@
       to belong to the caller not the callee (for example,
       <tt><a href="#readonly">readonly</a></tt> functions should not write to
       <tt>byval</tt> parameters). This is not a valid attribute for return
-      values.  The byval attribute also supports specifying an alignment with
-      the align attribute.  This has a target-specific effect on the code
-      generator that usually indicates a desired alignment for the synthesized
-      stack slot.</dd>
+      values.</p>
+      
+      <p>The byval attribute also supports specifying an alignment with
+      the align attribute.  It indicates the alignment of the stack slot to
+      form and the known alignment of the pointer specified to the call site. If
+      the alignment is not specified, then the code generator makes a
+      target-specific assumption.</p></dd>
 
   <dt><tt><b><a name="sret">sret</a></b></tt></dt>
   <dd>This indicates that the pointer parameter specifies the address of a