llvm dev - Aug 2014 - [LLVMdev] The problem of densemap and loop

Hello, everyone, 

I created a dense map like this: DenseMap<Loop *, int> ls; 
And I have a module which contains 3 functions: 
function F and it has a loop which is " Loop at depth 1 containing:
%1<header><exiting>,%3,%5<latch> "
function G and it has two loops which are " 

Loop at depth 1 containing: %8<header><exiting>,%10,%14<latch>

Loop at depth 1 containing: %1<header><exiting>,%3,%5<latch>
"
function main and it has 3 loops which are " 

Loop at depth 1 containing:
%17<header><exiting>,%19,%23<latch>

Loop at depth 1 containing: %8<header><exiting>,%10,%14<latch 

Loop at depth 1 containing: %1<header><exiting>,%3,%5<latch>
"
Then I tried to insert these loops into ls and the expected result is that there
are 6 items in ls after the insertion.
But I got only 3. 

So my question is why this happened? 
The dense map uses the name of the loop to check if the element is in it? 
Is there anything wrong during my code? 

Looking forward to your answer. 

Thank you 

Sincerely, 

Hanbing 
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Dear Hanbing,

You haven't provided enough information to help diagnose the problem.  
It would help if you specified which 3 loops actually end up in the 
DenseMap.

One thing to check for is if your code is in a FunctionPass.  A 
FunctionPass computes its results anew each time it is run on a 
function, and so it's possible that this is the cause of the problem.  
Similarly, the Loop objects for each function might be deleted and 
re-allocated for new Loop objects every time you run the LoopAnalysis on 
a new function.  That would make it look like you only have three 
elements when, in fact, you've added six elements but three were 
deallocated.

Alternatively, you might have some something silly like making ls a 
local variable, so it gets destroyed each time you enter the 
function/method in which it appears.

However, these are just guesses.  I'm not certain it can be diagnosed 
even if you do provide more information.

Regards,

John Criswell


On 8/28/14, 12:49 PM, Hanbing Li wrote:
> Hello, everyone,
>
> I created a dense map like this: DenseMap<Loop *, int> ls;
> And I have a module which contains 3 functions:
> function F and it has a loop which is "Loop at depth 1 containing: 
> %1<header><exiting>,%3,%5<latch>"
> function G and it has two loops which are "
>
> Loop at depth 1 containing:
%8<header><exiting>,%10,%14<latch>
>
> Loop at depth 1 containing:
%1<header><exiting>,%3,%5<latch>
>
> "
> function main and it has 3 loops which are "
>
> Loop at depth 1 containing:
%17<header><exiting>,%19,%23<latch>
>
> Loop at depth 1 containing:
%8<header><exiting>,%10,%14<latch
>
> Loop at depth 1 containing:
%1<header><exiting>,%3,%5<latch>
>
> "
> Then I tried to insert these loops into ls and the expected result is 
> that there are 6 items in ls after the insertion.
> But I got only 3.
>
> So my question is why this happened?
> The dense map uses the name of the loop to check if the element is in it?
> Is there anything wrong during my code?
>
> Looking forward to your answer.
>
> Thank you
>
> Sincerely,
>
> Hanbing
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
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Dear John, 

First thing, the 3 loops in Densemap are all " Loop at depth 1 containing:
%1<header><exiting>,%3,%5<latch> " in the 3 functions.

The dense map is in a ImmutablePass. I got it in FunctionPass and tried insert
the information in this FunctionPass. So to turn the FunctionPass to ModulePass
may be a better idea?

Another interesting thing: if just before the insertion, I used "L ->
print(errs());" to print the Loop, there were 6 items in ls. BUT when I
tried to read it in a ModulePass, I can't get the correct result.
" 

for (Module::iterator FI = M.begin(), E = M.end(); FI != E; ) { 
F = FI++; 

if (!F->hasName() && !F->isDeclaration()){} 
else{ 

LoopInfo *LI = &getAnalysis<LoopInfo>(*F); 
WCETInfo *WI = &getAnalysis<WCETInfo>(); //WI is the ImmutablePass
which contains the dense map

for(LoopInfo::iterator i=LI->begin(); i!=LI->end(); ++i) { 
Loop *L = *i; 

int lb=0; 
lb=WI->outls(L); // the method: return ls.find(L)->second; 

} 

} 

} " 

Thank you 

Sincerely, 

Hanbing 

----- Mail original -----
> De: "John Criswell" <jtcriswel at gmail.com>
> À: "Hanbing Li" <hanbing.li at inria.fr>, llvmdev at
cs.uiuc.edu
> Envoyé: Jeudi 28 Août 2014 18:59:52
> Objet: Re: [LLVMdev] The problem of densemap and loop
> Dear Hanbing,
> You haven't provided enough information to help diagnose the problem.
It
> would help if you specified which 3 loops actually end up in the DenseMap.
> One thing to check for is if your code is in a FunctionPass. A FunctionPass
> computes its results anew each time it is run on a function, and so
it's
> possible that this is the cause of the problem. Similarly, the Loop objects
> for each function might be deleted and re-allocated for new Loop objects
> every time you run the LoopAnalysis on a new function. That would make it
> look like you only have three elements when, in fact, you've added six
> elements but three were deallocated.
> Alternatively, you might have some something silly like making ls a local
> variable, so it gets destroyed each time you enter the function/method in
> which it appears.
> However, these are just guesses. I'm not certain it can be diagnosed
even if
> you do provide more information.
> Regards,
> John Criswell
> On 8/28/14, 12:49 PM, Hanbing Li wrote:
> > Hello, everyone,
> 
> > I created a dense map like this: DenseMap<Loop *, int> ls;
> 
> > And I have a module which contains 3 functions:
> 
> > function F and it has a loop which is " Loop at depth 1
containing:
> > %1<header><exiting>,%3,%5<latch> "
> 
> > function G and it has two loops which are "
> 
> > Loop at depth 1 containing:
%8<header><exiting>,%10,%14<latch>
> 
> > Loop at depth 1 containing:
%1<header><exiting>,%3,%5<latch> "
> 
> > function main and it has 3 loops which are "
> 
> > Loop at depth 1 containing:
%17<header><exiting>,%19,%23<latch>
> 
> > Loop at depth 1 containing:
%8<header><exiting>,%10,%14<latch
> 
> > Loop at depth 1 containing:
%1<header><exiting>,%3,%5<latch> "
> 
> > Then I tried to insert these loops into ls and the expected result is
that
> > there are 6 items in ls after the insertion.
> 
> > But I got only 3.
> 
> > So my question is why this happened?
> 
> > The dense map uses the name of the loop to check if the element is in
it?
> 
> > Is there anything wrong during my code?
> 
> > Looking forward to your answer.
> 
> > Thank you
> 
> > Sincerely,
> 
> > Hanbing
> 
> > _______________________________________________
> 
> > LLVM Developers mailing list LLVMdev at cs.uiuc.edu
http://llvm.cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> 
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