maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

LangRef: Note expectations when loading with extra alignment 

llvm-svn: 272914
This commit is contained in:
Matt Arsenault 2016-06-16 16:33:41 +00:00
parent 4a90f57ef2
commit 7020f255b1
1 changed files with 14 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
llvm/docs/LangRef.rst
View File

@ -7019,7 +7019,12 @@ alignment for the target. It is the responsibility of the code emitter
to ensure that the alignment information is correct. Overestimating the
alignment results in undefined behavior. Underestimating the alignment
may produce less efficient code. An alignment of 1 is always safe. The
maximum possible alignment is ``1 << 29``.
maximum possible alignment is ``1 << 29``. An alignment value higher
than the size of the loaded type implies memory up to the alignment
value bytes can be safely loaded without trapping in the default
address space. Access of the high bytes can interfere with debugging
tools, so should not be accessed if the function has the
``sanitize_thread`` or ``sanitize_address`` attributes.
The optional ``!nontemporal`` metadata must reference a single
metadata name ``<index>`` corresponding to a metadata node with one
@ -7144,7 +7149,14 @@ alignment for the target. It is the responsibility of the code emitter
to ensure that the alignment information is correct. Overestimating the
alignment results in undefined behavior. Underestimating the
alignment may produce less efficient code. An alignment of 1 is always
safe. The maximum possible alignment is ``1 << 29``.
safe. The maximum possible alignment is ``1 << 29``. An alignment
value higher than the size of the stored type implies memory up to the
alignment value bytes can be stored to without trapping in the default
address space. Storing to the higher bytes however may result in data
races if another thread can access the same address. Introducing a
data race is not allowed. Storing to the extra bytes is not allowed
even in situations where a data race is known to not exist if the
function has the ``sanitize_address`` attribute.
The optional ``!nontemporal`` metadata must reference a single metadata
name ``<index>`` corresponding to a metadata node with one ``i32`` entry of