ART: Try to statically evaluate some conditions.

If a condition 'cond' is evaluated in an HIf instruction then in
the successors of the this HIF_BLOCK we statically know the value
of the condition (TRUE in TRUE_SUCC, FALSE in FALSE_SUCC). Using
that we could replace another evaluation (use) EVAL of the same
'cond' with TRUE value (FALSE value) if every path from the
ENTRY_BLOCK to EVAL_BLOCK contains the edge HIF_BLOCK->TRUE_SUCC
(HIF_BLOCK->FALSE_SUCC).

  if (cond) {
    ...
    if (cond) {
      ...
    }
    ...
    int a = cond ? 5 : 105;
    ...
  }

The patch is a prerequisite step for "Loop peeling to eliminate
invariant exits" however it brings some value on its own with
a tiny code size reduction in boot-framework.oat (-8Kb).

Test: 458-checker-instruct-simplification
Test: test-art-target, test-art-host.
Change-Id: Ifbe45097dc2b5f098176fa1a1d023ea90b76d396

0 files changed, 0 insertions, 0 deletions