Commit Graph

31 Commits

Author SHA1 Message Date
Michael Gottesman 54dc7fdefb Refactored out a part of ObjCARCOpt::OptimizeReturns into its own method HasSafePathToPredecessorCall.
llvm-svn: 178710
2013-04-03 23:04:28 +00:00
Michael Gottesman 0a1748bb8c Removed an old comment.
llvm-svn: 178709
2013-04-03 23:04:24 +00:00
Michael Gottesman 43e7e00a68 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.

llvm-svn: 178705
2013-04-03 22:41:59 +00:00
Michael Gottesman b8c8836594 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.

llvm-svn: 178612
2013-04-03 02:57:24 +00:00
Michael Gottesman 624243914f Improved comment. No functionality change.
llvm-svn: 178605
2013-04-03 01:57:16 +00:00
Michael Gottesman 60f6b28c58 Removed trailing whitespace.
llvm-svn: 178329
2013-03-29 05:13:07 +00:00
Michael Gottesman ba64859e6e 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.
llvm-svn: 178306
2013-03-28 23:08:44 +00:00
Michael Gottesman 158fdf699e [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>.

llvm-svn: 178284
2013-03-28 20:11:19 +00:00
Michael Gottesman cd4de0f9bb [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.

llvm-svn: 177952
2013-03-26 00:42:09 +00:00
Michael Gottesman 81b1d43783 [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.

llvm-svn: 177951
2013-03-26 00:42:04 +00:00
Michael Gottesman 65c2481d09 Changed isNullOrUndef => IsNullOrUndef and isNoopInstruction => IsNoopInstruction so that all helper functions are named similarly in ObjCARC.h.
llvm-svn: 177855
2013-03-25 09:27:43 +00:00
Michael Gottesman 764b1cfced Change method name ClearRefCount => ClearKnownPositiveRefCount to match the name of the member that it is modifying.
llvm-svn: 177818
2013-03-23 05:46:19 +00:00
Michael Gottesman 07beea47b8 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.

llvm-svn: 177816
2013-03-23 05:31:01 +00:00
John McCall 20182ac0c7 Kill every call to @clang.arc.use in the ARC contract phase.
llvm-svn: 177769
2013-03-22 21:38:36 +00:00
Michael Gottesman f4b7761ed7 Fixed a careless mistake.
rdar://13273675.

llvm-svn: 175939
2013-02-23 00:31:32 +00:00
Michael Gottesman 697d8b9a26 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.

llvm-svn: 174581
2013-02-07 04:12:57 +00:00
Michael Gottesman 415ddd7e13 Removed explicit inline as per the LLVM style guide.
llvm-svn: 174432
2013-02-05 19:32:18 +00:00
Michael Gottesman e52dec1695 Made certain small functions in PtrState inlined.
llvm-svn: 173842
2013-01-29 22:29:59 +00:00
Michael Gottesman 9bdab2bf6b Removed trailing comma in last element of enum declaration.
llvm-svn: 173836
2013-01-29 21:41:44 +00:00
Michael Gottesman 386241ce5b Moved S_Stop back to its previous position in the sequence order.
llvm-svn: 173834
2013-01-29 21:39:02 +00:00
Michael Gottesman 23cda0cd39 Fixed a few debug messages and some 80+ violations.
llvm-svn: 173832
2013-01-29 21:07:53 +00:00
Michael Gottesman 53fd20bdbd Added some periods to some comments and added an overload for operator<< for type Sequence so I can print out Sequences in debug statements.
llvm-svn: 173831
2013-01-29 21:07:51 +00:00
Michael Gottesman 774d2c014e Changed DoesObjCBlockEscape => DoesRetainableObjPtrEscape so I can use it to perform escape analysis of other retainable object pointers in other locations.
llvm-svn: 173829
2013-01-29 21:00:52 +00:00
Timur Iskhodzhanov 5d7ff00456 Hopefully fix the Windows build failure introduced in r173769
llvm-svn: 173781
2013-01-29 09:09:27 +00:00
Michael Gottesman 13a5f1a8b7 Juggled Debug.h from ObjCARC.h to only the including cpp files that
actually have DEBUG statements. Also changed raw_ostream in said header
to be a forward declaration (removing an include).

llvm-svn: 173769
2013-01-29 04:51:59 +00:00
Michael Gottesman 278266faa8 Sorted includes using utils/sort_includes.
llvm-svn: 173767
2013-01-29 04:20:52 +00:00
Michael Gottesman 778138e960 Extracted ObjCARCContract from ObjCARCOpts into its own file.
This also required adding 2x headers Dependency Analysis.h/Provenance Analysis.h
and a .cpp file DependencyAnalysis.cpp to unentangle the dependencies inbetween
ObjCARCContract and ObjCARCOpts.

llvm-svn: 173760
2013-01-29 03:03:03 +00:00
Michael Gottesman 294e7daaac Refactor ObjCARCAliasAnalysis into its own file.
llvm-svn: 173662
2013-01-28 05:51:54 +00:00
Michael Gottesman fa0939f790 Refactored out pass ObjCARCAPElim from ObjCARCOpts.cpp => ObjCARCAPElim.cpp.
llvm-svn: 173654
2013-01-28 04:12:07 +00:00
Michael Gottesman 08904e3ba4 Extracted pass ObjCARCExpand from ObjCARC.cpp => ObjCARCExpand.cpp.
I also added the local header ObjCARC.h for common functions used by the
various passes.

llvm-svn: 173651
2013-01-28 03:28:38 +00:00
Michael Gottesman 79d8d81226 Extracted ObjCARC.cpp into its own library libLLVMObjCARCOpts in preparation for refactoring the ARC Optimizer.
llvm-svn: 173647
2013-01-28 01:35:51 +00:00