tree 6482a9ce5a34c04fc14d5b5db77d5daec1ec5aad
parent dde8b8694954c0268eb12a7ccbddf07d9de262fd
author David Brazdil <dbrazdil@google.com> 1447928979 +0000
committer David Brazdil <dbrazdil@google.com> 1448286586 +0000

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