Dissallow non-empty metadata for invariant.group
Summary:
This feature is not needed, but it might be usefull in the future
to use metadata to mark what which function should support it
(and strip it when not).
Reviewers: rsmith, sanjoy, amharc, kuhar
Subscribers: hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D45419
llvm-svn: 332787
diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index ba13d8e..455dd42 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -5314,10 +5314,10 @@
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The experimental ``invariant.group`` metadata may be attached to
-``load``/``store`` instructions.
+``load``/``store`` instructions referencing a single metadata with no entries.
The existence of the ``invariant.group`` metadata on the instruction tells
the optimizer that every ``load`` and ``store`` to the same pointer operand
-within the same invariant group can be assumed to load or store the same
+can be assumed to load or store the same
value (but see the ``llvm.launder.invariant.group`` intrinsic which affects
when two pointers are considered the same). Pointers returned by bitcast or
getelementptr with only zero indices are considered the same.
@@ -5334,7 +5334,6 @@
%a = load i8, i8* %ptr, !invariant.group !0 ; Can assume that value under %ptr didn't change
call void @foo(i8* %ptr)
- %b = load i8, i8* %ptr, !invariant.group !1 ; Can't assume anything, because group changed
%newPtr = call i8* @getPointer(i8* %ptr)
%c = load i8, i8* %newPtr, !invariant.group !0 ; Can't assume anything, because we only have information about %ptr
@@ -5351,8 +5350,7 @@
declare i8* @getPointer(i8*)
declare i8* @llvm.launder.invariant.group(i8*)
- !0 = !{!"magic ptr"}
- !1 = !{!"other ptr"}
+ !0 = !{}
The invariant.group metadata must be dropped when replacing one pointer by
another based on aliasing information. This is because invariant.group is tied
@@ -7637,7 +7635,8 @@
program where the memory location is known to be dereferenceable.
The optional ``!invariant.group`` metadata must reference a single metadata name
- ``<index>`` corresponding to a metadata node. See ``invariant.group`` metadata.
+ ``<index>`` corresponding to a metadata node with no entries.
+ See ``invariant.group`` metadata.
The optional ``!nonnull`` metadata must reference a single
metadata name ``<index>`` corresponding to a metadata node with no
diff --git a/llvm/docs/ReleaseNotes.rst b/llvm/docs/ReleaseNotes.rst
index b8da194..614c63a 100644
--- a/llvm/docs/ReleaseNotes.rst
+++ b/llvm/docs/ReleaseNotes.rst
@@ -109,6 +109,8 @@
* invariant.group.barrier has been renamed to launder.invariant.group.
+* invariant.group metadata can now refer only empty metadata nodes.
+
Changes to the ARM Backend
--------------------------