Hi. I have a question on loop representation in CFGs (which I get when using the -fdump-tree-cfg option). On the page describing gcc internals (http://gcc.gnu.org/onlinedocs/gccint/Loop-representation.html), the text says: "In general, a natural loop has one entry block (header) and possibly several back edges (latches) leading to the header from the inside of the loop. Loops with several latches may appear if several loops share a single header, or if there is a branching in the middle of the loop. The representation of loops in GCC however allows only loops with a single latch. During loop analysis, headers of such loops are split and forwarder blocks are created in order to disambiguate their structures." Assuming a function sampleFunc() uses structured statements only[*], will the loops in the associated CFG always be already in the form as described above (i.e. natural loops with a single latch)? If not, which would be the right steps to get such one? The main problem I have is, that I actually don't know at which stage (while processing the input file) the CFG is created. Though the semantics should remain the same, as far as I understand, the CFG representation of a function might (or will?) be different e.g. before and after some optimizations. That's why it seems to me being important to know whether the CFG is created before or after the "loop analysis" mentioned in the text above. [*] According to a few other documents I read on that subject, for functions using structured statetements only, the resulting CFG should always be reducible, so that if loops exist, they should be "natural". Thanks, Elena.
