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19-Nov-2015 |
David Brazdil <dbrazdil@google.com> |
ART: Fix wide stores in Optimizing
SsaBuilder::VisitStoreLocal did not take into account the following:
(a) when storing a wide value, the high vreg must be invalidated,
(b) when storing into the high vreg of a wide value, the low vreg
must be invalidated.
Both situations cause overestimation of liveness but only (b) has
implications on correctness. CodeGenerator::EmitEnvironment will skip
the high vreg, causing deoptimizing and try/catch to load a wrong
value for that vreg.
In order to fix this bug, several changes had to be made to the
SsaBuilder:
(1) phis need to be initialized with a type which matches its
inputs' size,
(2) eagerly created loop header phis may end up being undefined
because of their corresponding vregs being invalidated inside
the loop; these are marked dead during input setting,
(3) the entire SSA-building algorithm should never revive an
undefined loop header phi.
Bug: 25677992
Bug: https://code.google.com/p/android/issues/detail?id=194022
Change-Id: Id8a852e38c3f5ff1c2e608b1aafd6d5ac8311e32
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