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0556900b26
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
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| .. | ||
| ADCE | ||
| ArgumentPromotion | ||
| BBVectorize | ||
| BlockPlacement | ||
| BranchFolding | ||
| CodeExtractor | ||
| CodeGenPrepare | ||
| ConstantMerge | ||
| ConstProp | ||
| CorrelatedValuePropagation | ||
| DeadArgElim | ||
| DeadStoreElimination | ||
| EarlyCSE | ||
| FunctionAttrs | ||
| GCOVProfiling | ||
| GlobalDCE | ||
| GlobalOpt | ||
| GVN | ||
| IndVarSimplify | ||
| Inline | ||
| InstCombine | ||
| InstSimplify | ||
| Internalize | ||
| IPConstantProp | ||
| JumpThreading | ||
| LCSSA | ||
| LICM | ||
| LoopDeletion | ||
| LoopIdiom | ||
| LoopRotate | ||
| LoopSimplify | ||
| LoopStrengthReduce | ||
| LoopUnroll | ||
| LoopUnswitch | ||
| LoopVectorize | ||
| LowerAtomic | ||
| LowerExpectIntrinsic | ||
| LowerInvoke | ||
| LowerSwitch | ||
| Mem2Reg | ||
| MemCpyOpt | ||
| MergeFunc | ||
| MetaRenamer | ||
| ObjCARC | ||
| PhaseOrdering | ||
| PruneEH | ||
| Reassociate | ||
| Reg2Mem | ||
| ScalarRepl | ||
| SCCP | ||
| SimplifyCFG | ||
| SimplifyLibCalls | ||
| Sink | ||
| SLPVectorizer | ||
| SROA | ||
| StripSymbols | ||
| TailCallElim | ||
| TailDup | ||