On 5/30/2024 12:32 PM, Tomas Härdin wrote:
tor 2024-05-30 klockan 17:28 +0300 skrev Rémi Denis-Courmont:
Le 30 mai 2024 17:07:21 GMT+03:00, "Tomas Härdin" <g...@haerdin.se> a
écrit :
We should depend on punning as long as it conforms to the
standard.
My mistake, I forgot type punning is allowed in C. It's UB in C++
The standard compliant way
is to use memcpy()
That's way worse than union in terms of how proactively the
compiler
needs to optimise, and both approaches are as confirming.
A good compiler will do the same thing
True, and I don't care very much about memcpy vs union, as they both
rely on matching representation. AFAIR, FFmpeg tends to use unions
though.
Maybe I can get the riscv version covered by Eva as well. That's
beyond
the scope of this patchset
IMHO, this specific patch (and the following one) are beating dead
horses. Sure there may be theoretical UB in the current code, but if
there is a *better* implementation, better switch to that than bike
shedding the fix for the UB.
Are you saying that UB is acceptable? You know the compiler is free to
assume signed arithmetic doesn't overflow, right? If so then what other
UB might we accept?
He did not say that... He said we should switch to a better
implementation rather than trying to fix the existing potentially buggy one.
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