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AOT-DebugX64 crash #35321

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aartbik opened this Issue Dec 4, 2018 · 4 comments

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aartbik commented Dec 4, 2018

Found by extra DartFuzz run to find out why nightly is crashing often:

Isolate (/b/s/w/ir/tmp/t/dart_fuzzLIQXOB) AOT-DebugX64 - JIT-DebugSIMARM: !DIVERGENCE! 1.2:3503681466 (output=false)

fail1:
../../runtime/vm/compiler/backend/constant_propagator.cc: 1472: error: expected: reachable_->Contains(if_false->preorder_number())
thread=26969, isolate=isolate(0x55d4bea02900)
[0x000055d4bd6e285c] Unknown symbol
[0x000055d4bd6e285c] Unknown symbol
[0x000055d4bd9c56b2] Unknown symbol
[0x000055d4bd803bdf] Unknown symbol
[0x000055d4bd802ce4] Unknown symbol
[0x000055d4bd8d2a3d] Unknown symbol
[0x000055d4bd8d233f] Unknown symbol
[0x000055d4bd8d2607] Unknown symbol
[0x000055d4bd7d68f9] Unknown symbol
[0x000055d4bd7d9388] Unknown symbol
[0x000055d4bd7d2e74] Unknown symbol
[0x000055d4bd7d16dd] Unknown symbol
[0x000055d4bd7cca20] Unknown symbol
[0x000055d4bd7ca218] Unknown symbol
[0x000055d4bd7c9daf] Unknown symbol
[0x000055d4bd9b8d46] Unknown symbol
[0x000055d4bd426bf4] Unknown symbol
-- End of DumpStackTrace
/b/s/w/ir/cache/builder/sdk/pkg/vm/tool/precompiler2: line 106:

@aartbik aartbik self-assigned this Dec 4, 2018

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mraleph commented Dec 4, 2018

I have seen this before - often this means that one of the constant propagation rules is written incorrectly.

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aartbik commented Dec 4, 2018

The issue happens on this branch:

    CheckNull:98(v736 T{_Double?})
    v1409 <- Redefinition(v736) T{_Double}
    v114 <- RelationalOp(>=, v105, v1409 T{_Double}) T{bool}
    Branch if StrictCompare:102(===, v114, v21) goto (11, 14)
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aartbik commented Dec 7, 2018

Slava notes:

I looked at the predicates for IsConstant and IsNonConstant and they seem to be null safe.
However I just realized that they are using marker values that have kNullCid as their CID.
Maybe something goes wrong because of that.

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aartbik commented Dec 7, 2018

Looks like the definition of v105 causes the problem:

v105 <- BinaryDoubleOp(-, v1407 T{_Double}, v104) T{_Double}

sees the definite values null and Infinity, but it never gets a definite outcome itself!

dart-bot pushed a commit that referenced this issue Dec 7, 2018

[vm/compiler] Add missing case for CP
Rationale:
Constant propagator was missing a case for a
double binary operator.

#35321
#35355



Change-Id: Ie88fe082e88b74651e798d516784737b36b4dcd1
Reviewed-on: https://dart-review.googlesource.com/c/86101
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Aart Bik <ajcbik@google.com>

@aartbik aartbik closed this Dec 7, 2018

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