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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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| .. | ||
| apelim.ll | ||
| arc-annotations.ll | ||
| basic.ll | ||
| cfg-hazards.ll | ||
| clang-arc-used-intrinsic-removed-if-isolated.ll | ||
| contract-marker.ll | ||
| contract-storestrong-ivar.ll | ||
| contract-storestrong.ll | ||
| contract-testcases.ll | ||
| contract.ll | ||
| empty-block.ll | ||
| ensure-that-exception-unwind-path-is-visited.ll | ||
| escape.ll | ||
| expand.ll | ||
| gvn.ll | ||
| intrinsic-use.ll | ||
| invoke.ll | ||
| lit.local.cfg | ||
| move-and-form-retain-autorelease.ll | ||
| move-and-merge-autorelease.ll | ||
| nested.ll | ||
| no-objc-arc-exceptions.ll | ||
| path-overflow.ll | ||
| pointer-types.ll | ||
| post-inlining.ll | ||
| pr12270.ll | ||
| retain-block-alloca.ll | ||
| retain-block-escape-analysis.ll | ||
| retain-block-load.ll | ||
| retain-block-side-effects.ll | ||
| retain-block.ll | ||
| retain-not-declared.ll | ||
| rle-s2l.ll | ||
| rv.ll | ||
| split-backedge.ll | ||
| tail-call-invariant-enforcement.ll | ||
| weak-contract.ll | ||
| weak-copies.ll | ||
| weak-dce.ll | ||
| weak.ll | ||