On 8 March 2017 at 23:38, Dibyendu Majumdar <mobile@xxxxxxxxxxxxxxx> wrote:
> On 8 March 2017 at 06:53, Luc Van Oostenryck
> <luc.vanoostenryck@xxxxxxxxx> wrote:
>> On Tue, Mar 07, 2017 at 07:31:34AM +0000, Dibyendu Majumdar wrote:
>>> >> Here 'values' has been defined above as external global, whereas it
>>> >> should be allocated on the stack.
>>> >
>>> > Mmmh, I'll need to look a bit further at this one.
>>> >
>>>
>>> It appears that sparse-llvm only creates a local stack object for each
>>> OP_PHI instruction. What should be the general approach for
>>> identifying local stack objects in sparse linearized output?
>>
>> I've looked a bit at this and there is several issues at hand.
>> It's also not something LLVM specific.
>> So I can't answer to this for now. Hopefully, I'll be able to tell
>> you more in a few days.
>>
>
> Thank you for looking into this. It would be good to know what issues
> you have discovered. I was wondering if a simple solution is to check
> whether the symbol is marked as toplevel / extern - and if not then
> define it as a local symbol in LLVM. However we would need to handle
> scope - i.e. if the same symbol occurs multiple times in a function in
> different scopes then these need to be defined accordingly. Example:
>
> extern void init(int *v);
> int main(const char *argv[]) {
> int n = 0;
> {
> int x[5];
> init(x);
> n += x[0];
> }
> {
> int x[6];
> init(x);
> n += x[0];
> }
> return n;
> }
>
I think by combining the symbol's identifier and address a unique
reference can be created - thus whenever we encounter a symbol that is
not extern or toplevel we should create a local object using the
symbol's name + address as the LLVM identifier.
Regards
Dibyendu
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