This PR introduces a new fuzzer pass, which:
- finds all integer vectors or constants
- finds or creates the corresponding constants with opposite
signedness
- records such constants as synonyms of the first ones
- replaces the usages of the original constants with the new ones
if allowed
Fixes#2677.
This fuzzer pass:
For each zero-like constant, either finds the existing definition of
the corresponding toggled one (OpConstantNull becomes zero-valued
scalar OpConstant or vice versa) or creates a new one if it doesn't
exist and records that the two are synonyms
For each use of these constants, probabilistically decides whether to
change it with the corresponding toggled constant id (as described in
#3486 )
Only uses inside blocks of instructions are considered and not, for
example, in instructions declaring other constants.
