This is apart of a series of patches to encapsulate PtrState.RRI and
make PtrState.RRI a private field of PtrState.
*NOTE* This is actually the second commit in the patch stream. I should
have put this note on the first such commit r184528.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184532 91177308-0d34-0410-b5e6-96231b3b80d8
In the presense of a block being initialized, the frontend will emit the
objc_retain on the original pointer and the release on the pointer loaded from
the alloca. The optimizer will through the provenance analysis realize that the
two are related (albiet different), but since we only require KnownSafe in one
direction, will match the inner retain on the original pointer with the guard
release on the original pointer. This is fixed by ensuring that in the presense
of allocas we only unconditionally remove pointers if both our retain and our
release are KnownSafe (i.e. we are KnownSafe in both directions) since we must
deal with the possibility that the frontend will emit what (to the optimizer)
appears to be unbalanced retain/releases.
An example of the miscompile is:
%A = alloca
retain(%x)
retain(%x) <--- Inner Retain
store %x, %A
%y = load %A
... DO STUFF ...
release(%y)
call void @use(%x)
release(%x) <--- Guarding Release
getting optimized to:
%A = alloca
retain(%x)
store %x, %A
%y = load %A
... DO STUFF ...
release(%y)
call void @use(%x)
rdar://13750319
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181743 91177308-0d34-0410-b5e6-96231b3b80d8
This makes the statistics gathering completely independent of the actual
optimization occuring, preventing any sort of bleeding over from occuring.
Additionally, it simplifies a switch statement in the non-statistic gathering case.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181719 91177308-0d34-0410-b5e6-96231b3b80d8
the things, and renames it to CBindingWrapping.h. I also moved
CBindingWrapping.h into Support/.
This new file just contains the macros for defining different wrap/unwrap
methods.
The calls to those macros, as well as any custom wrap/unwrap definitions
(like for array of Values for example), are put into corresponding C++
headers.
Doing this required some #include surgery, since some .cpp files relied
on the fact that including Wrap.h implicitly caused the inclusion of a
bunch of other things.
This also now means that the C++ headers will include their corresponding
C API headers; for example Value.h must include llvm-c/Core.h. I think
this is harmless, since the C API headers contain just external function
declarations and some C types, so I don't believe there should be any
nasty dependency issues here.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180881 91177308-0d34-0410-b5e6-96231b3b80d8
Turning retains into retainRV calls disrupts the data flow analysis in
ObjCARCOpts. Thus we move it as late as we can by moving it into
ObjCARCContract.
We leave in the conversion from retainRV -> retain in ObjCARCOpt since
it enables the dataflow analysis.
rdar://10813093
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180698 91177308-0d34-0410-b5e6-96231b3b80d8
This reverts commit r180222.
I think this might tie in with a different problem which will require a
different approach potentially. I am reverting this in the case I need to go
down that second path.
My apologies for the noise. = /.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180590 91177308-0d34-0410-b5e6-96231b3b80d8
Due to the semantics of ARC, we must be extremely conservative with autorelease
calls inserted by the frontend since ARC gaurantees that said object will be in
the autorelease pool after that point, an optimization invariant that the
optimizer must respect.
On the other hand, we are allowed significantly more flexibility with
autoreleaseRV instructions.
Often times though this flexibility is disrupted by early transformations which
transform objc_autoreleaseRV => objc_autorelease if said instruction is no
longer being used as part of an RV pair (generally due to inlining). Since we
can not tell the difference in between an autorelease put into place by the
frontend and one created through said ``strength reduction'' we can not perform
these optimizations.
The addition of this set gets around said issues by allowing us to differentiate
in between said two cases.
rdar://problem/13697741.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180222 91177308-0d34-0410-b5e6-96231b3b80d8
This will make it clearer when we are actually resetting a sequence's progress
vs just changing state. This is an important distinction because the former case
clears any pointers that we are tracking while the later does not.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179963 91177308-0d34-0410-b5e6-96231b3b80d8
This occurs due to an alloca representing a separate ownership from the
original pointer. Thus consider the following pseudo-IR:
objc_retain(%a)
for (...) {
objc_retain(%a)
%block <- %a
F(%block)
objc_release(%block)
}
objc_release(%a)
From the perspective of the optimizer, the %block is a separate
provenance from the original %a. Thus the optimizer pairs up the inner
retain for %a and the outer release from %a, resulting in segfaults.
This is fixed by noting that the signature of a mismatch of
retain/releases inside the for loop is a Use/CanRelease top down with an
None bottom up (since bottom up the Retain-CanRelease-Use-Release
sequence is completed by the inner objc_retain, but top down due to the
differing provenance from the objc_release said sequence is not
completed). In said case in CheckForCFGHazards, we now clear the state
of %a implying that no pairing will occur.
Additionally a test case is included.
rdar://12969722
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179747 91177308-0d34-0410-b5e6-96231b3b80d8
This is the counterpart to commit r160637, except it performs the action
in the bottomup portion of the data flow analysis.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178922 91177308-0d34-0410-b5e6-96231b3b80d8
The normal dataflow sequence in the ARC optimizer consists of the following
states:
Retain -> CanRelease -> Use -> Release
The optimizer before this patch stored the uses that determine the lifetime of
the retainable object pointer when it bottom up hits a retain or when top down
it hits a release. This is correct for an imprecise lifetime scenario since what
we are trying to do is remove retains/releases while making sure that no
``CanRelease'' (which is usually a call) deallocates the given pointer before we
get to the ``Use'' (since that would cause a segfault).
If we are considering the precise lifetime scenario though, this is not
correct. In such a situation, we *DO* care about the previous sequence, but
additionally, we wish to track the uses resulting from the following incomplete
sequences:
Retain -> CanRelease -> Release (TopDown)
Retain <- Use <- Release (BottomUp)
*NOTE* This patch looks large but the most of it consists of updating
test cases. Additionally this fix exposed an additional bug. I removed
the test case that expressed said bug and will recommit it with the fix
in a little bit.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178921 91177308-0d34-0410-b5e6-96231b3b80d8
