RPCS3/llvm
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm.git synced 2024-11-27 13:40:43 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

Invariant.group and mustalias docs fixes

Browse Source 
Summary:
Alias analysis would like to know that
invariant.group.barrier returns pointer that mustalias,
but this can't imply that we can replace one pointer with another

Reviewers: dberlin, sanjoy

Subscribers: llvm-commits, chandlerc, hfinkel, nlewycky, amharc

Differential Revision: https://reviews.llvm.org/D31758

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@300033 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Piotr Padlewski 2017-04-12 07:59:35 +00:00
parent ddfada260a
commit 3512d22fea
2 changed files with 11 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
docs/AliasAnalysis.rst
View File

@ -136,7 +136,7 @@ be overlapping in some way, but do not start at the same address.
The ``MustAlias`` response may only be returned if the two memory objects are The ``MustAlias`` response may only be returned if the two memory objects are
guaranteed to always start at exactly the same location. A ``MustAlias`` guaranteed to always start at exactly the same location. A ``MustAlias``
response implies that the pointers compare equal. response does not imply that the pointers compare equal.
The ``getModRefInfo`` methods The ``getModRefInfo`` methods
----------------------------- -----------------------------

10
docs/LangRef.rst
View File

@ -5121,6 +5121,16 @@ Examples:
!0 = !{!"magic ptr"} !0 = !{!"magic ptr"}
!1 = !{!"other ptr"} !1 = !{!"other ptr"}
The invariant.group metadata must be dropped when replacing one pointer by
another based on aliasing information. This is because invariant.group is tied
to the SSA value of the pointer operand.
.. code-block:: llvm
%v = load i8, i8* %x, !invariant.group !0
; if %x mustalias %y then we can replace the above instruction with
%v = load i8, i8* %y
'``type``' Metadata '``type``' Metadata
^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^