On 17.07.2023 14:16, Nicola Vetrini wrote: > On 16/07/23 18:50, Julien Grall wrote: >> On 16/07/2023 10:20, Luca Fancellu wrote: >>>> On 14 Jul 2023, at 14:05, Julien Grall <jul...@xen.org> wrote: >>>> On 14/07/2023 12:49, Nicola Vetrini wrote: >>>>> The macro 'testop' expands to a function that declares the local >>>>> variable 'oldbit', which is written before being set, but is such a >>>>> way that is not amenable to automatic checking. >>>> >>>> The code is pretty straightforward. So I am not entirely sure why >>>> Eclair is not happy. Is it because the value is set by assembly code? > > Exactly. The reason why I didn't just state that oldbit is always > written or never read before being written in that function is that I > was unsure about the meaning of the assembly.
So I'm pretty sure the tool wouldn't take apart the string literal passed first to the asm(). Instead I expect it goes from the operands specified, which for oldbit is "=&r". There's nothing conditional here, so if the tool didn't trust that outputs are written, it would need to flag such an issue on about any asm() having outputs. I hope the issue isn't that the tool doesn't properly deal with the do/while. In any event: I may misremember earlier discussions, but isn't this a pretty obvious false positive? In which case didn't we mean to flag those as such (because really an improved checking tool could avoid them)? Jan
