tree 5163433b4cdbb1bf2a08c6bd2e35b452f9fcdbab
parent 0c8a5988fea8ebf09972e74f4358eebba08994e5
author John Stiles <johnstiles@google.com> 1630436288 -0400
committer SkCQ <skcq-be@skia-corp.google.com.iam.gserviceaccount.com> 1630439745 +0000

Fix array timeout discovered by the fuzzer.

The fuzzer discovered that, when we attempt to verify that an array
doesn't contain any literal values that are out-of-range for its base
type, we pay a linear-time cost based on the size of the array. This
happens even when the array value isn't known at compile time; we still
iterate over its slot count and diligently discover that every single
constant-subexpression slot in the expression is "null".

We now have a helper function on Expression,
`allowsConstantSubexpressions`, which only returns true for expression
kinds that can contain constant subexpressions. We use this helper to
skip over this linear-per-subexpression check when the expression
cannot possibly contain a constant subexpression. In particular,
`AnyConstructor::compareConstant` and `Type::checkForOutOfRangeLiteral`
will now early-out for expressions that can't possibly contain a
constant subexpression.

Change-Id: Ia34e422afa67b478a8616acb0a0e9cd211b29698
Bug: oss-fuzz:37900
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/444136
Commit-Queue: John Stiles <johnstiles@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>