Jan Waclawek schrieb:
Moreover, in 4.7 it also stores the variable to stack frame even
without naked, so that could be called a missed
optimisation/regression.
Thanks for pointing this out. I was lost in all that optimization
conversation and thought it was an optimization issue from the first post.
There is nothing written like "program crashes because non-existent
frame used".
So the very problem is that there is a frame needed and there is none
because of "naked".
Well, that's a bug in the user code, not in the application:
You must not assume that the C code need no frame, even if it is a
reasonable assumption like here.
However, the frame is really strange and my first suspect is the
evildoer: -fcaller-saves.
That option causes evil in some places, or let me put things the other
way round: In some cases -fno-caller-saves can avoid harm like spill
fails in presence of high register pressure, see PR50925.
Johann
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