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Tree SSA If-combine optimization pass in GCC


Hello All:

I can see the IF-combining (If-merging) pass of optimization on tree-ssa form of intermediate representation. 
The IF-combine or merging takes of merging the IF-THEN-ELSE if the condition Expr found be congruent or 
Similar.

The IF-combine happens if the two IF-THEN-ELSE are contiguous to each other. 
If the IF-THEN-ELSE happens to be not contiguous but are wide apart with there is code in between.
Does the If-combine takes care of this. This requires to do the head-duplication and Tail-duplication for the
Code in between If-THEN-ELSE to bring the IF-THEN-ELSE contiguous to each other.

After the head and tail duplication of the code in between the IF-THEN-ElSE sequence becomes contiguous 
to each other. Apart from this, Does the tree-ssa-if-combine pass considers the control flow of the body
of the IF-THEN-ELSE. Is there any limitation on control flow of the body of the IF-THEN-ELSE.

Can I know the scope of tree-ssa-ifcombine optimizations pass with respect to the above points.

Thoughts Please?

Thanks & Regards
Ajit


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