Hello All:
I am proposing the new approach to Loop transformation as given below in the
example For the loops with
conditional expression inside the Loops. The Loop body should be reducible
control flow graph. The iteration
space is partitioned into different spaces for which either the cond_expr is
true or cond_expr is false. The
evaluation of cond_expr for the partitioned iteration spaces can be determined
statically. For the partitioned
iterations and based on the analysis of cond_expr on the partitioned iterations
spaces the Loops in fig (a) will
be transformed to Loops in fig (b).
for the iteration spaces of the conditional inside the loop is live in at the
entry of the cond_expr and Live out
the Control flow graph is topological ordered with the basic blocks for the
conditional CFG and the partitioned
iteration spaces can be formed for which the spaces can be true for conditional
expr and false and unknown.
Based on the above info and analysis the Loop of Fig (a) will be transformed to
Loop Fig (b).
This is much more optimized code as compared to the performance. The cases will
be triggered for SPEC
Benchmarks. Loops is partitioned to different version with different iteration
spaces. Optimized in the presence
Of the transformed generation of the loops without conditional.
For ( x1= lb1; x1<= ub1; x1++)
..
For(xn= lbn; xn <= ubn; xn++)
{
V = cond_expr;
If ( V)
Code_FOR _THEN;
Else
Code_FOR_ELSE;
}
}
Fig(a)
/* Loop for cond_expr == true */
For( x1 = ................................)
For(xn = ............................)
CODE_FOR_THEN;
End
End
/* Loop for cond_expr == false */
For ( x1 = ......................)
For( xn = .......................)
CODE_FOR_ELSE;
End
End
/* Loop for cond_expr == unknown *//
For ( x1 = ...........................)
For( xn = ........................
{
V = cond_expr;
If( v)
CODE_FOR_THEN;
Else
CODE_FOR_ELSE;
}
}
Fig ( b).
Thoughts Please ?
Thanks & Regards
Ajit
