[llvm-commits] [llvm] r172599 - /llvm/trunk/lib/Transforms/Scalar/ObjCARC.cpp

[Michael Gottesman]

*note* I was tired when I committed this so I forgot to add a test case. I am going to do that later today and in that commit reference this commit and the pr this fixes.

On Jan 15, 2013, at 10:32 PM, Michael Gottesman <mgottesman at apple.com> wrote:

> Author: mgottesman
> Date: Wed Jan 16 00:32:39 2013
> New Revision: 172599
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=172599&view=rev
> Log:
> [ObjCARC] Turn off ignoring unwind edges in ObjCARC when -fno-objc-arc-exception is enabled due to it's affect on correctness.
> 
> Specifically according to the semantics of ARC -fno-objc-arc-exception simply
> states that it is expected that the unwind path out of a call *MAY* not release
> objects. Thus we can have the situation where a release gets moved into a catch
> block which we ignore when we remove a retain/release pair resulting in (even
> though we assume the program is exiting anyways) the cleanup code path
> potentially blowing up before program exit.
> 
> Modified:
>    llvm/trunk/lib/Transforms/Scalar/ObjCARC.cpp
> 
> Modified: llvm/trunk/lib/Transforms/Scalar/ObjCARC.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/ObjCARC.cpp?rev=172599&r1=172598&r2=172599&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Scalar/ObjCARC.cpp (original)
> +++ llvm/trunk/lib/Transforms/Scalar/ObjCARC.cpp Wed Jan 16 00:32:39 2013
> @@ -2675,17 +2675,6 @@
>       PtrState &S = I->second;
>       succ_const_iterator SI(TI), SE(TI, false);
> 
> -      // If the terminator is an invoke marked with the
> -      // clang.arc.no_objc_arc_exceptions metadata, the unwind edge can be
> -      // ignored, for ARC purposes.
> -      if (isa<InvokeInst>(TI) && TI->getMetadata(NoObjCARCExceptionsMDKind)) {
> -        DEBUG(dbgs() << "ObjCARCOpt::CheckForCFGHazards: Found an invoke "
> -                        "terminator marked with "
> -                        "clang.arc.no_objc_arc_exceptions. Ignoring unwind "
> -                        "edge.\n");
> -        --SE;
> -      }
> -
>       for (; SI != SE; ++SI) {
>         Sequence SuccSSeq = S_None;
>         bool SuccSRRIKnownSafe = false;
> @@ -2734,17 +2723,6 @@
>       PtrState &S = I->second;
>       succ_const_iterator SI(TI), SE(TI, false);
> 
> -      // If the terminator is an invoke marked with the
> -      // clang.arc.no_objc_arc_exceptions metadata, the unwind edge can be
> -      // ignored, for ARC purposes.
> -      if (isa<InvokeInst>(TI) && TI->getMetadata(NoObjCARCExceptionsMDKind)) {
> -        DEBUG(dbgs() << "ObjCARCOpt::CheckForCFGHazards: Found an invoke "
> -                        "terminator marked with "
> -                        "clang.arc.no_objc_arc_exceptions. Ignoring unwind "
> -                        "edge.\n");
> -        --SE;
> -      }
> -
>       for (; SI != SE; ++SI) {
>         Sequence SuccSSeq = S_None;
>         bool SuccSRRIKnownSafe = false;
> @@ -3199,17 +3177,6 @@
>     TerminatorInst *TI = cast<TerminatorInst>(&CurrBB->back());
>     succ_iterator SE(TI, false);
> 
> -    // If the terminator is an invoke marked with the
> -    // clang.arc.no_objc_arc_exceptions metadata, the unwind edge can be
> -    // ignored, for ARC purposes.
> -    if (isa<InvokeInst>(TI) && TI->getMetadata(NoObjCARCExceptionsMDKind)) {
> -        DEBUG(dbgs() << "ObjCARCOpt::ComputePostOrders: Found an invoke "
> -                        "terminator marked with "
> -                        "clang.arc.no_objc_arc_exceptions. Ignoring unwind "
> -                        "edge.\n");
> -      --SE;
> -    }
> -
>     while (SuccStack.back().second != SE) {
>       BasicBlock *SuccBB = *SuccStack.back().second++;
>       if (Visited.insert(SuccBB)) {
> 
> 
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