The problem is that bitcode like this:

  %cond = cmp %var, [mem]
  store ..., mem
  br cond, target1, target2

would be bool-folded into this:

  //deleted cmp
  store ..., mem
  br (%var==[mem]), target1, target2

And if the memory operands point to the same location, results are incorrect.

In addition to stores, this is a problem for RMW instructions, and most call instructions which could perform stores before returning.

BUG= https://bugs.chromium.org/p/nativeclient/issues/detail?id=4370
R=eholk@chromium.org, jpp@chromium.org

Review URL: https://codereview.chromium.org/1904233002 .