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Re: [tree-ssa] Lowering of VLA's
Hello,
> >>>If so, can't we simply
> >>>expose the calls to malloc/free at the begin/end of the BIND_EXPR and
> >>>not have to worry about any magic or new tree codes?
> >>
> >>These new magic codes require about the same amount of handling as
> >>these
> >>functions need. In fact I have considered making them just specially
> >>handled function calls; but it seemed to be cleaner this way to me.
> >>
> >But arent there subtle side effects optimizations might need to
> >consider
> >that a function call would expose, or that they need to be taught about
> >the new opcode?
>
> Yes.
> I can already see the pain new opcodes would cause me in SSAPRE load
> optimization (it's not that hard to handle it in PTA)
no more than calls. Just handle them the same way.
> Please don't add opcodes for things builtin calls handle adequately.
> These really should be __builtin_stack_alloc (size_t) __attribute__
> (malloc) or whatever.
> Repeat after me: Calls do not make code motion harder to program.
> Special side-effecting opcodes do.
Calls that do not behave exactly as calls would just make troubles on
other places.
Repeat after me :-) : thing that manipulates stack is special, and trying to
pretend that it is not will cause only problems.
Zdenek