Incorrect simplification

[d-xo]

The following expression is simplified down into a non equivalent expression:

ReadByte (Lit 0x1b) (CopySlice (Lit 0x58) (Sub (Lit 0x2e) (Lit 0x40)) (Lit 0x42) (AbstractBuf "esc_drxeJBJlnuTyjoGzkYZ") (AbstractBuf "esc_LmFwbKsRDIMCCxoqkYdzYXFiEEMwrgrrrxayeUmDpVYFLJfWSEtyOFxWMcL"))

This was discovered by the fuzzer during a CI run.

[msooseth]

This is now correct:

ghci> Expr.simplify (ReadByte (Lit 0x1b) (CopySlice (Lit 0x58) (Sub (Lit 0x2e) (Lit 0x40)) (Lit 0x42) (AbstractBuf "esc_drxeJBJlnuTyjoGzkYZ") (AbstractBuf "esc_LmFwbKsRDIMCCxoqkYdzYXFiEEMwrgrrrxayeUmDpVYFLJfWSEtyOFxWMcL")))
ReadByte (Lit 0x85) (AbstractBuf "esc_drxeJBJlnuTyjoGzkYZ")
ghci> 0x85
133

And indeed:

ghci> W256 (0x0-0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffee)
0x12
ghci> 0x1b+0x12+0x58
133