tree d4ee5e1dc613be5aa5227dfc9e3e827ceacae2ba
parent b692a6d18329d8a6978e013c96238506a0a7c46d
author Aart Bik <ajcbik@google.com> 1547763752 +0000
committer commit-bot@chromium.org <commit-bot@chromium.org> 1547763752 +0000

[vm/compiler] handle non-nullable null situation better

Rationale:
Previously, we avoided introducing redefinitions that
introduced the empty non-nullable null type. This situation
arises when we do a null check on an actual null value
(making all subsequent uses effectively dead code). This
is too simple, however, since it still allows hoisting the
uses before the check. This CL gives a better solution
by introducing redefinitions without a constraining type
(which are not removed and avoid the type). In the long
run perhaps the best solution would be to simply remove
all subsequent uses as dead.

https://github.com/dart-lang/sdk/issues/32167
https://github.com/dart-lang/sdk/issues/34473
https://github.com/dart-lang/sdk/issues/35335

Change-Id: Ib5dd072a9e546f6b91faa52ea08e8c0f6350d7e0
Reviewed-on: https://dart-review.googlesource.com/c/89922
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Commit-Queue: Aart Bik <ajcbik@google.com>