Some incorrect solutions can pass the Parallac tests, for instance
Here, LDACs are handled in the middle and SVACs on the outside. To decide what to push in the LDAC, it follows a simple truth table:
if both instructions are LDAC or SVAC, take the second one's value
otherwise, take the first instruction's value
So, this supports LDAC-LDAC and LDAC-SVAC, but SVAC-LDAC results in passing -, which is wrong and completely ignores the LDAC (while this is a place where pipeline bypassing is needed).
The SVAC-LDAC sequence is only tested by test 3, but the LDAC here is expected to not change the value so it doesn't catch the failure.
Some incorrect solutions can pass the Parallac tests, for instance
Here, LDACs are handled in the middle and SVACs on the outside. To decide what to push in the LDAC, it follows a simple truth table:
So, this supports LDAC-LDAC and LDAC-SVAC, but SVAC-LDAC results in passing -, which is wrong and completely ignores the LDAC (while this is a place where pipeline bypassing is needed).
The SVAC-LDAC sequence is only tested by test 3, but the LDAC here is expected to not change the value so it doesn't catch the failure.