Assembly language programmers must be aware of hidden side effects — instructions that modify parts of the processor state which are not mentioned in the instruction's mnemonic. A classic example of a hidden side effect is an arithmetic instruction that implicitly modifies condition codes (a hidden side effect) while it explicitly modifies a register (the overt effect). One potential drawback of an instruction set with hidden side effects is that, if many instructions have side effects on a single piece of state, like condition codes, then the logic required to update that state sequentially may become a performance bottleneck. The problem is particularly acute on some processors designed with pipelining (since 1990) or with out-of-order execution . Such a processor may require additional control circuitry to detect hidden side effects and stall the pipeline if the next instruction depends on the results of those effects.
In the UK, Peter Bradshaw of The Guardian awarded the film a maximum five stars, calling it "a gripping psychological thriller about big pharma and mental health that cruelly leaves you craving one last fix". He praised the lead performance from Rooney Mara as "compelling" who "lays down the law with her presence. She demonstrates a potent Hitchcockian combination: an ability to be scared and scary at the same time, and Soderbergh's film manages to introduce its effects in some insidious, almost intravenous way".  The . Club ' s Scott Tobias called Mara "superb as the glue that binds this fractured psychological puzzle," and commended Soderbergh's sophisticated direction: " Side Effects screws around in its own thriller architecture, toying with feints of structure and clever bits of misdirection, and otherwise playing the audience like a fiddle. At this point in his career, Soderbergh pulls it off with the unpracticed ease of a maestro."  Robbie Collin of The Daily Telegraph awarded Side Effects a maximum five stars and also acknowledged its debt to earlier psychological thrillers. He wrote: "There's a lot of Alfred Hitchcock in what follows, but even more Henri-Georges Clouzot , with whose classic spine-tingler Les Diaboliques (1954) Soderbergh's film shares a poisonous tang".  Peter Travers of Rolling Stone praised the film's performances, the script and direction, writing "Soderbergh delivers ticking-bomb suspense laced with psychological acuity about a world where mood-altering meds are as disturbingly prevalent as social media".