spirv-fuzz features transformations that should be applicable by
construction. Assertions are used to detect when such transformations
turn out to be inapplicable. Failures of such assertions indicate bugs
in the fuzzer. However, when using the fuzzer at scale (e.g. in
ClusterFuzz) reports of these assertion failures create noise, and
cause the fuzzer to exit early. This change adds an option whereby
inapplicable transformations can be ignored. This reduces noise and
allows fuzzing to continue even when a transformation that should be
applicable but is not has been erroneously created.
The following changes are introduced:
1. Entry block might have more than one predecessor, even if it is not
a selection/loop merge block. However Apply method asserts that
there is only one predecessor. Now, IsApplicable method ensures
that there is only one predecessor.
2. In fuzzer pass we exclude both loop headers and selection headers
as potential exit blocks.
Fixes#3827.
Adds a transformation that inserts a conditional statement with a
boolean expression of arbitrary value and duplicates a given
single-entry, single-exit region, so that it is present in each
conditional branch and will be executed regardless of which branch will
be taken.
Fixes#3614.
