Commit Graph

70 Commits

Author SHA1 Message Date
Michael Gottesman
3f4613310d [objc-arc] Added ImpreciseAutoreleaseSet to track autorelease calls that were once autoreleaseRV instructions.
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
2013-04-24 22:18:18 +00:00
Michael Gottesman
0eb5e45e4b Fixed comment typo.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180221 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-24 22:18:15 +00:00
Eric Christopher
3e39731e88 Move C++ code out of the C headers and into either C++ headers
or the C++ files themselves. This enables people to use
just a C compiler to interoperate with LLVM.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180063 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-22 22:47:22 +00:00
Michael Gottesman
fca9d95523 When we strength reduce an objc_retainBlock call to objc_retain, increment NumPeeps and make sure that Changed is set to true.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179968 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-21 00:50:27 +00:00
Michael Gottesman
8c87177f2c Fixed comment typo.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179967 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-21 00:44:46 +00:00
Michael Gottesman
d4adf8a886 [objc-arc] Fixed typo in debug message.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179966 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-21 00:30:50 +00:00
Michael Gottesman
ee37359762 [objc-arc] Fixed comment typo.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179965 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-21 00:25:04 +00:00
Michael Gottesman
9f2b618ac5 [objc-arc] Refactored OptimizeReturns so that it uses continue instead of a large multi-level nested if statement.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179964 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-21 00:25:01 +00:00
Michael Gottesman
7e48a92829 [objc-arc] Added debug statement saying when we are resetting a sequence's progress.
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
2013-04-20 23:36:57 +00:00
Michael Gottesman
0556900b26 [objc-arc] Do not mismatch up retains inside a for loop with releases outside said for loop in the presense of differing provenance caused by escaping blocks.
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
2013-04-18 05:39:45 +00:00
Michael Gottesman
8a709208ed Removed trailing whitespace.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179746 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-18 04:34:11 +00:00
Michael Gottesman
f92bf40ced [objc-arc] Added annotation option to only emit annotations for a specific ssa identifier.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179729 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-17 21:59:41 +00:00
Michael Gottesman
9739b65264 Fixed typo.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179721 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-17 21:03:53 +00:00
Michael Gottesman
b271b120d0 [objc-arc] Added descriptions for EnableARCAnnotations, EnableCheckForCFGHazards, EnableARCOptimizations.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179718 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-17 20:48:03 +00:00
Michael Gottesman
ba5d950518 [objc-arc] Added an option to arc-annotations for turning off CheckForCFGHazard.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179717 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-17 20:48:01 +00:00
Bob Wilson
58ddf52892 Fix some comment typos.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179132 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-09 22:15:51 +00:00
Michael Gottesman
310f2665e8 Removed trailing whitespace.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178932 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-05 23:46:45 +00:00
Michael Gottesman
e8b3c2e48a An objc_retain can serve as a use for a different pointer.
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
2013-04-05 22:54:32 +00:00
Michael Gottesman
e7ce2b3f75 Properly model precise lifetime when given an incomplete dataflow sequence.
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
2013-04-05 22:54:28 +00:00
Michael Gottesman
5c762e0c25 Added two debug logging messages to VisitInstructionsTopDown to match VisitInstructionsBottomUp.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178895 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-05 18:26:08 +00:00
Michael Gottesman
5789a86f5c Cleaned up whitespace and made debug logging less verbose.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178893 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-05 18:10:41 +00:00
Michael Gottesman
296ffab562 Refactored out the helper method FindPredecessorAutoreleaseWithSafePath from ObjCARCOpt::OptimizeReturns.
Now ObjCARCOpt::OptimizeReturns is easy to read and reason about.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178715 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-03 23:39:14 +00:00
Michael Gottesman
681f258ae3 Refactored out the helper function FindPredecessorRetainWithSafePath from ObjCARCOpt::OptimizeReturns.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178714 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-03 23:16:05 +00:00
Michael Gottesman
9bede89bbe Small cleanups.
Cleaned up trailing whitespace and added extra slashes in front of a
function level comment so that it follow the convention of having 3
slashes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178712 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-03 23:07:45 +00:00
Michael Gottesman
ca4cb5b6df Refactored out a part of ObjCARCOpt::OptimizeReturns into its own method HasSafePathToPredecessorCall.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178710 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-03 23:04:28 +00:00
Michael Gottesman
60d1c0bca3 Removed an old comment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178709 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-03 23:04:24 +00:00
Michael Gottesman
7a424bd5de Clean up arc annotations by moving the top/bottom BB annotations into conditional macros that no-op in Release mode instead of #ifdef sections of the code.
This is to follow the example of the DEBUG macro.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178705 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-03 22:41:59 +00:00
Michael Gottesman
a67a20c95f Remove an optimization where we were changing an objc_autorelease into an objc_autoreleaseReturnValue.
The semantics of ARC implies that a pointer passed into an objc_autorelease
must live until some point (potentially down the stack) where an
autorelease pool is popped. On the other hand, an
objc_autoreleaseReturnValue just signifies that the object must live
until the end of the given function at least.

Thus objc_autorelease is stronger than objc_autoreleaseReturnValue in
terms of the semantics of ARC* implying that performing the given
strength reduction without any knowledge of how this relates to
the autorelease pool pop that is further up the stack violates the
semantics of ARC.

*Even though objc_autoreleaseReturnValue if you know that no RV
optimization will occur is more computationally expensive.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178612 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-03 02:57:24 +00:00
Michael Gottesman
003d5f946d Improved comment. No functionality change.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178605 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-03 01:57:16 +00:00
Michael Gottesman
3e9f3a0389 Add clang.arc.used to ModuleHasARC so ARC always runs if said call is present in a module.
clang.arc.used is an interesting call for ARC since ObjCARCContract
needs to run to remove said intrinsic to avoid a linker error (since the
call does not exist).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178369 91177308-0d34-0410-b5e6-96231b3b80d8
2013-03-29 21:15:23 +00:00
Michael Gottesman
ae07bf3ad3 Removed trailing whitespace.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178329 91177308-0d34-0410-b5e6-96231b3b80d8
2013-03-29 05:13:07 +00:00
Michael Gottesman
d02e46be1a Removed dead code from ObjCARCOpts relating to tracking objc_retainBlocks through the ARC Dataflow analysis. By the time we get to the ARC dataflow analysis, any objc_retainBlock calls are not optimizable.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178306 91177308-0d34-0410-b5e6-96231b3b80d8
2013-03-28 23:08:44 +00:00
Michael Gottesman
3832eff354 Non optimizable objc_retainBlock calls are not forwarding.
Since we handle optimizable objc_retainBlocks through strength reduction
in OptimizableIndividualCalls, we know that all code after that point
will only see non-optimizable objc_retainBlock calls. IsForwarding is
only called by functions after that point, so it is ok to just classify
objc_retainBlock as non-forwarding.

<rdar://problem/13249661>.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178285 91177308-0d34-0410-b5e6-96231b3b80d8
2013-03-28 20:11:30 +00:00
Michael Gottesman
0d92a3c600 [ObjCARC] Strength reduce objc_retainBlock -> objc_retain if the objc_retainBlock is optimizable.
If an objc_retainBlock has the copy_on_escape metadata attached to it
AND if the block pointer argument only escapes down the stack, we are
allowed to strength reduce the objc_retainBlock to to an objc_retain and
thus optimize it.

Current there is logic in the ARC data flow analysis to handle
this case which is complicated and involved making distinctions in
between objc_retainBlock and objc_retain in certain places and
considering them the same in others.

This patch simplifies said code by:

1. Performing the strength reduction in the initial ARC peephole
analysis (ObjCARCOpts::OptimizeIndividualCalls).

2. Changes the ARC dataflow analysis (which runs after the peephole
analysis) to consider all objc_retainBlock calls to not be optimizable
(since if the call was optimizable, we would have strength reduced it
already).

This patch leaves in the infrastructure in the ARC dataflow analysis to
handle this case, which due to 2 will just be dead code. I am doing this
on purpose to separate the removal of the old code from the testing of
the new code.

<rdar://problem/13249661>.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178284 91177308-0d34-0410-b5e6-96231b3b80d8
2013-03-28 20:11:19 +00:00
Michael Gottesman
26dbfb6a78 [ObjCARC Annotations] Added support for displaying the state of pointers at the bottom/top of BBs of the ARC dataflow analysis for both bottomup and topdown analyses.
This will allow for verification and analysis of the merge function of
the data flow analyses in the ARC optimizer.

The actual implementation of this feature is by introducing calls to
the functions llvm.arc.annotation.{bottomup,topdown}.{bbstart,bbend}
which are only declared. Each such call takes in a pointer to a global
with the same name as the pointer whose provenance is being tracked and
a pointer whose name is one of our Sequence states and points to a
string that contains the same name.

To ensure that the optimizer does not consider these annotations in any
way, I made it so that the annotations are considered to be of IC_None
type.

A test case is included for this commit and the previous
ObjCARCAnnotation commit.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177952 91177308-0d34-0410-b5e6-96231b3b80d8
2013-03-26 00:42:09 +00:00
Michael Gottesman
7bef073622 [ObjCARC Annotations] Implemented ARC annotation metadata to expose the ARC data flow analysis state in the IR via metadata.
Previously the inner works of the data flow analysis in ObjCARCOpts was hard to
get out of the optimizer for analysis of bugs or testing. All of the current ARC
unit tests are based off of testing the effect of the data flow
analysis (i.e. what statements are removed or moved, etc.). This creates
weakness in the current unit testing regimem since we are not actually testing
what effects various instructions have on the modeled pointer state.
Additionally in order to analyze a bug in the optimizer, one would need to track
by hand what the optimizer was actually doing either through use of DEBUG
statements or through the usage of a debugger, both yielding large loses in
developer productivity.

This patch deals with these two issues by providing ARC annotation
metadata that annotates instructions with the state changes that they cause in
various pointers as well as provides metadata to annotate provenance sources.

Specifically, we introduce the following metadata types:

1. llvm.arc.annotation.bottomup.
2. llvm.arc.annotation.topdown.
3. llvm.arc.annotation.provenancesource.

llvm.arc.annotation.{bottomup,topdown}: These annotations describes a state
change in a pointer when we are visiting instructions bottomup/topdown
respectively. The output format for both is the same:

  !1 = metadata !{metadata !"(test,%x)", metadata !"S_Release", metadata !"S_Use"}

The first element is a string tuple with the following format:

  (function,variable name)

The second two elements of the metadata show the previous state of the
pointer (in this case S_Release) and the new state of the pointer (S_Use). We
write the metadata in such a manner to ensure that it is easy for outside tools
to parse. This is important since I am currently working on a tool for taking
this information and pretty printing it besides the IR and that can be used for
LIT style testing via the generation of an index.

llvm.arc.annotation.provenancesource: This metadata is used to annotate
instructions which act as provenance sources, i.e. ones that introduce a
new (from the optimizer's perspective) non-argument pointer to track. This
enables cross-referencing in between provenance sources and the state changes
that occur to them.

This is still a work in progress. Additionally I plan on committing
later today additions to the annotations that annotate at the top/bottom
of basic blocks the state of the various pointers being tracked.

*NOTE* The metadata support is conditionally compiled into libObjCARCOpts only
when we are producing a debug build of llvm/clang and even so are
disabled by default. To enable the annotation metadata, pass in
-enable-objc-arc-annotations to opt.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177951 91177308-0d34-0410-b5e6-96231b3b80d8
2013-03-26 00:42:04 +00:00
Michael Gottesman
f0a15d88af Changed isNullOrUndef => IsNullOrUndef and isNoopInstruction => IsNoopInstruction so that all helper functions are named similarly in ObjCARC.h.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177855 91177308-0d34-0410-b5e6-96231b3b80d8
2013-03-25 09:27:43 +00:00
Michael Gottesman
31881c235f Change method name ClearRefCount => ClearKnownPositiveRefCount to match the name of the member that it is modifying.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177818 91177308-0d34-0410-b5e6-96231b3b80d8
2013-03-23 05:46:19 +00:00
Michael Gottesman
4df66f74d9 Changed the method name PtrState.IsKnownIncremented() to PtrState.HasKnownPositiveRefCount().
Now said method matches namewise every other method which refers to
the member KnownPositiveRefCount of the class PtrState.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177816 91177308-0d34-0410-b5e6-96231b3b80d8
2013-03-23 05:31:01 +00:00
John McCall
1f9c4407c0 Kill every call to @clang.arc.use in the ARC contract phase.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177769 91177308-0d34-0410-b5e6-96231b3b80d8
2013-03-22 21:38:36 +00:00
Michael Gottesman
3603e9aa5e Fixed a careless mistake.
rdar://13273675.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175939 91177308-0d34-0410-b5e6-96231b3b80d8
2013-02-23 00:31:32 +00:00
Benjamin Kramer
74b3c8da48 Make helpers static. Add missing include so LLVMInitializeObjCARCOpts gets C linkage.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175264 91177308-0d34-0410-b5e6-96231b3b80d8
2013-02-15 12:30:38 +00:00
Michael Gottesman
49b5bb4cb4 Changed isStoredObjCPointer => IsStoredObjCPointer. No functionality change.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175017 91177308-0d34-0410-b5e6-96231b3b80d8
2013-02-12 23:35:08 +00:00
Michael Gottesman
65c46b0cff Moved some comments due to the recent refactoring of ObjCARC.
1. Moved a comment from ObjCARCOpts.cpp -> ObjCARCContract.cpp.
2. Removed a comment from ObjCARCOpts.cpp that was already moved to
ObjCARCAliasAnalysis.h/.cpp.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174581 91177308-0d34-0410-b5e6-96231b3b80d8
2013-02-07 04:12:57 +00:00
Michael Gottesman
da6bf1d8bb Removed explicit inline as per the LLVM style guide.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174432 91177308-0d34-0410-b5e6-96231b3b80d8
2013-02-05 19:32:18 +00:00
Michael Gottesman
5500943771 Made certain small functions in PtrState inlined.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173842 91177308-0d34-0410-b5e6-96231b3b80d8
2013-01-29 22:29:59 +00:00
Michael Gottesman
485da64848 Removed trailing comma in last element of enum declaration.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173836 91177308-0d34-0410-b5e6-96231b3b80d8
2013-01-29 21:41:44 +00:00
Michael Gottesman
b82d200dcb Moved S_Stop back to its previous position in the sequence order.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173834 91177308-0d34-0410-b5e6-96231b3b80d8
2013-01-29 21:39:02 +00:00
Michael Gottesman
02c953ea8b Fixed a few debug messages and some 80+ violations.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173832 91177308-0d34-0410-b5e6-96231b3b80d8
2013-01-29 21:07:53 +00:00
Michael Gottesman
a519c97b42 Added some periods to some comments and added an overload for operator<< for type Sequence so I can print out Sequences in debug statements.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173831 91177308-0d34-0410-b5e6-96231b3b80d8
2013-01-29 21:07:51 +00:00