Introduce !align metadata for load instruction

Reviewed By: hfinkel

Differential Revision: http://reviews.llvm.org/D12853

llvm-svn: 248721

1 files changed, 10 insertions, 1 deletions

diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index 9b8aaa7a1fd..bc4df058646 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -6860,10 +6860,11 @@ Syntax:
 
 ::
 
-      <result> = load [volatile] <ty>, <ty>* <pointer>[, align <alignment>][, !nontemporal !<index>][, !invariant.load !<index>][, !invariant.group !<index>][, !nonnull !<index>][, !dereferenceable !<deref_bytes_node>][, !dereferenceable_or_null !<deref_bytes_node>]
+      <result> = load [volatile] <ty>, <ty>* <pointer>[, align <alignment>][, !nontemporal !<index>][, !invariant.load !<index>][, !invariant.group !<index>][, !nonnull !<index>][, !dereferenceable !<deref_bytes_node>][, !dereferenceable_or_null !<deref_bytes_node>][, !align !<align_node>]
       <result> = load atomic [volatile] <ty>* <pointer> [singlethread] <ordering>, align <alignment> [, !invariant.group !<index>]
       !<index> = !{ i32 1 }
       !<deref_bytes_node> = !{i64 <dereferenceable_bytes>}
+      !<align_node> = !{ i64 <value_alignment> }
 
 Overview:
 """""""""
@@ -6948,6 +6949,14 @@ value in the metadata node. This is analogous to the ''dereferenceable_or_null''
 attribute on parameters and return values. This metadata can only be applied
 to loads of a pointer type.
 
+The optional ``!align`` metadata must reference a single metadata name
+``<align_node>`` corresponding to a metadata node with one ``i64`` entry.
+The existence of the ``!align`` metadata on the instruction tells the
+optimizer that the value loaded is known to be aligned to a boundary specified
+by the integer value in the metadata node. The alignment must be a power of 2.
+This is analogous to the ''align'' attribute on parameters and return values.
+This metadata can only be applied to loads of a pointer type.
+
 Semantics:
 """"""""""