[llvm] r178921 - Properly model precise lifetime when given an incomplete dataflow sequence.

[Bob Wilson]

On Apr 5, 2013, at 3:54 PM, Michael Gottesman <mgottesman at apple.com> wrote:

> Author: mgottesman
> Date: Fri Apr  5 17:54:28 2013
> New Revision: 178921
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=178921&view=rev
> Log:
> Properly model precise lifetime when given an incomplete dataflow sequence.
> 
> Modified: llvm/trunk/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/ObjCARC/ObjCARCOpts.cpp?rev=178921&r1=178920&r2=178921&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/ObjCARC/ObjCARCOpts.cpp (original)
> +++ llvm/trunk/lib/Transforms/ObjCARC/ObjCARCOpts.cpp Fri Apr  5 17:54:28 2013
> @@ -408,6 +408,10 @@ namespace {
>       KnownSafe(false), IsTailCallRelease(false), ReleaseMetadata(0) {}
> 
>     void clear();
> +    

Please remove the trailing whitespace here.

> +    bool IsTrackingImpreciseReleases() {
> +      return ReleaseMetadata != 0;
> +    }
>   };
> }
> 
> @@ -1746,7 +1750,9 @@ ObjCARCOpt::VisitInstructionBottomUp(Ins
>   bool NestingDetected = false;
>   InstructionClass Class = GetInstructionClass(Inst);
>   const Value *Arg = 0;
> -
> +  
> +  DEBUG(dbgs() << "Class: " << Class << "\n");
> +  

…and here, and also on most of the other blank lines added to this file in this patch.

>   switch (Class) {
>   case IC_Release: {
>     Arg = GetObjCArg(Inst);
> @@ -1794,7 +1800,10 @@ ObjCARCOpt::VisitInstructionBottomUp(Ins
>     case S_Release:
>     case S_MovableRelease:
>     case S_Use:
> -      S.RRI.ReverseInsertPts.clear();
> +      // If OldSeq is not S_Use or OldSeq is S_Use and we are tracking an
> +      // imprecise release, clear our reverse insertion points.
> +      if (OldSeq != S_Use || S.RRI.IsTrackingImpreciseReleases())
> +        S.RRI.ReverseInsertPts.clear();
>       // FALL THROUGH
>     case S_CanRelease:
>       // Don't do retain+release tracking for IC_RetainRV, because it's
> @@ -2017,14 +2026,19 @@ ObjCARCOpt::VisitInstructionTopDown(Inst
> 
>     PtrState &S = MyStates.getPtrTopDownState(Arg);
>     S.ClearKnownPositiveRefCount();
> -
> -    switch (S.GetSeq()) {
> +    
> +    Sequence OldSeq = S.GetSeq();
> +    
> +    MDNode *ReleaseMetadata = Inst->getMetadata(ImpreciseReleaseMDKind);
> +    
> +    switch (OldSeq) {
>     case S_Retain:
>     case S_CanRelease:
> -      S.RRI.ReverseInsertPts.clear();
> +      if (OldSeq == S_Retain || ReleaseMetadata != 0)
> +        S.RRI.ReverseInsertPts.clear();
>       // FALL THROUGH
>     case S_Use:
> -      S.RRI.ReleaseMetadata = Inst->getMetadata(ImpreciseReleaseMDKind);
> +      S.RRI.ReleaseMetadata = ReleaseMetadata;
>       S.RRI.IsTailCallRelease = cast<CallInst>(Inst)->isTailCall();
>       Releases[Inst] = S.RRI;
>       ANNOTATE_TOPDOWN(Inst, Arg, S.GetSeq(), S_None)
> ;
> 
> 

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