[Soot-list] I set correct the jump points for goto and targets for if-s but "Cannot compute SCCs for graph with number of heads = 2"

[Cristina Ilie]

Hi,

I generate a code for loops and when I deal with nested loops I have some problems - I receive the exception [1],
specific for situations when a goto has a bad jump or an if has a bad target. For sample loop like:
for (i=0;i<n;i++){
            a = b*b;
 }

my tool generates the following code [2] which is correct and all works fine. But for this code:
for (j=0;j<n;j++)
       for (i=0;i<n;i++){
            a =
 b*b;
        }
my tool generates the following code[3] and throws the exception [1]. I followed the jump points of goto-s and the targets 

of if-s and all seem to be ok. I added tags for goto-s and if-s and it can be observed that the first goto (for loop with "j" counter)
the jump point is the last if (if belonging to loop with j counter) and the same for the loop with "i" counter. I codified the loop 

with "j" counter with 1 (has the color 1) and the loop with "i" counter with 0 (has the color 0).

Do you have idea what happens?

Cristina



[1] Caused by: java.lang.RuntimeException: Cannot compute SCCs for graph with number of heads = 2 (etc)

[2] 
    29 : nop                             tag: [loopFirstPointOfLoop]
    30 : adLoop = intAdStack.<IntLinkedStack: int pop()>()                             tag: []
    31 : i = adLoop                   
          tag: []
    32 : goto [?= (branch)]                             tag: [loopGoto 0] target tag: []
    33 : nop                             tag: [loopIfJumpPoint0]
   
 34 : b.<DerivType: double grad> = b.<DerivType: double 
grad> + a.<DerivType: double grad> * b.<DerivType: double 
value>                             tag: []
    35 : 
b.<DerivType: double grad> = b.<DerivType: double grad> + 
a.<DerivType: double grad> * b.<DerivType: double value>   
                          tag: []
    36 : a.<DerivType: double grad> = 0.0                             tag: []
    37 : a.<DerivType: double value> = adStack.<Stack: double pop()>()                             tag: []
    38 : i = i + 1                             tag: []
    39 : if i < n goto nop                             tag: []
 target tag: [loopIfJumpPoint0]

[3] 


    35 : nop                             tag: [loopFirstPointOfLoop]
    36 : adLoop = intAdStack.<IntLinkedStack: int pop()>()                             tag: []
    37 : j = adLoop                             tag: []
    38 : goto [?= (branch)]           
                  tag: [loopGoto 1] target tag: []
    39 : nop                             tag: [loopIfJumpPoint1]
    40 : nop                             tag: [loopFirstPointOfLoop]
    41 : adLoop = intAdStack.<IntLinkedStack: int pop()>()                             tag: []
    42 : i = adLoop                             tag: []
    43 : goto [?=
 (branch)]                             tag: [loopGoto 0] target tag: []
    44 : nop                             tag: [loopIfJumpPoint0]
   
 45 : b.<DerivType: double grad> = b.<DerivType: double 
grad> + a.<DerivType: double grad> * b.<DerivType: double 
value>                             tag: []
    46 : 
b.<DerivType: double grad> = b.<DerivType: double grad> + 
a.<DerivType: double grad> * b.<DerivType: double value>    
                   
      tag: []
    47 : a.<DerivType: double grad> = 0.0                             tag: []
    48 : a.<DerivType: double value> = adStack.<Stack: double pop()>()                             tag: []
    49 : i = i + 1                             tag: []
    50 : if i < n goto nop                             tag: [] target tag: [loopIfJumpPoint0]
    51 : j = j + 1   
                          tag: []
    52 : if j < n goto nop                             tag: [] target tag: [loopIfJumpPoint1]
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