Simplify common conditional expression

[plafosse]

I'm seeing a lot of this type of condition repeated that should be easy to simplify

(!A || (A && B)) Which simplifies down to just !A || B Similarly (A || (!A && B)) => A || B

[plafosse]

BNDB Shared internally cascade blueprint lantern mosaic has the following conditional at: 100002f37

[D0ntPanic]

Added in 4.1.5232

[plafosse]

Looks like the demorgan's variant of this case is still not handled

180022bbc In the unicorn chess taco rainbow binary

[plafosse]

So to clarify: The original equation if ((((rax_69 == 0x8007007a || rax_69 == 0x80020013) && rax_55 s>= 0) || (rax_69 != 0x8007007a && rax_69 != 0x80020013)) && rdi s< 0) A = (rax_69 == 0x8007007a || rax_69 == 0x80020013) !A = (rax_69 != 0x8007007a && rax_69 != 0x80020013) B = rax_55 s>= 0 C = rdi s< 0 This boils down to: ((A && B) || !A) && C We dont' care about C so we can drop it and rewrite the equation ((A && B) || !A) which can convert to (B || !A)

The final equation can be simplified down to:

if ((rax_55 s>= 0 || (rax_69 != 0x8007007a && rax_69 != 0x80020013)) && rdi s< 0)

[plafosse]

Another variant from the unicorn chess taco rainbow binary:

18000c304 if ((*(this + 0x2940) == 0 && result_5 s>= 0 && i != 0) || (*(this + 0x2940) != 0 && (i_1 u>= r13_1 || result_4 s>= 0) && i_1 u>= r13_1))

Substitute the following:

A = *(this + 0x2940) == 0
B = result_5 s>= 0 && i != 0
C = (i_1 u>= r13_1 || result_4 s>= 0) && i_1 u>= r13_1)

We get the equation: (A & B) | (!A & C) Can be translated to (A & B) | C

[plafosse]

Simliarly from the same binary:

18000c304                      if ((i_1 u>= r13_1 || result_4 s>= 0) && i_1 u< r13_1)

Substitute the following

A = i_1 u>= r13_1
B = result_4 s>= 0
C = i_1 u< r13_1

We get (A || B) && !A Which simplifies down to B && !A

[uniquadev]

Any attempt to implement Quine-McCluskey algorithm?

[plafosse]

@uniquadev I wasn't familiar with that algorithm until you mentioned it. That looks very interesting, thanks for the tip! We do have some additional constraints that we need to deal such as keeping a mapping of addresses from the original bytes.

[D0ntPanic]

These types of conditions are far more rare with the new control flow algorithm in 4.1, so the optimization is much less essential now.