Dumping tree with no opt flag
Hi all, I try to develop a tool that get the final CFG of gcc by passing the -fdump-tree-final_cleanup-lineno option and parsing the file dumped by gcc. I noticed that this flag does create an output only if at least the '-O1' (or more) is in the command line. I just would like to know if it would be possible to get the final_cleanup target even though no optimization flag has been given in the command line (for now, I'm just forcing '-O1' to be present if no other optimization flag has been detected in the command line). A final remark, not really significant, I noticed that since gcc 4.2, the name of the dumped tree files have slightly changed. Indeed before, I was used to src_file_name.t#id.type where in 4.2 it is more like src_file_name.#idt.type. I agree that this change is nothing but is there a reason for changing the position of the 't' character ? Regards -- Emmanuel Fleury There are only 10 types of people in the world. Those who understand binary and those who don't -- Unknown
Re: Dumping tree with no opt flag
On 7/30/07 11:15 AM, Emmanuel Fleury wrote: I just would like to know if it would be possible to get the final_cleanup target even though no optimization flag has been given in the command line (for now, I'm just forcing '-O1' to be present if no other optimization flag has been detected in the command line). No, because the final_cleanup pass is only executed when optimizing. For -O0, you need to determine what's the last phase executed and request a dump to that phase. Also, future versions of GCC may not have this phase as the final phase, or the dump file name may change, or both. Dump files are merely debugging aids. We make no guarantees as to their content or naming convention. A final remark, not really significant, I noticed that since gcc 4.2, the name of the dumped tree files have slightly changed. Indeed before, I was used to src_file_name.t#id.type where in 4.2 it is more like src_file_name.#idt.type. We amalgamated the dumping mechanism for trees and RTL. The 't' denotes a 'tree' dump, 'r' an RTL dump and 'i' an IPA dump.
Re: Dumping tree with no opt flag
Wow, that was quick. :) Diego Novillo wrote: On 7/30/07 11:15 AM, Emmanuel Fleury wrote: I just would like to know if it would be possible to get the final_cleanup target even though no optimization flag has been given in the command line (for now, I'm just forcing '-O1' to be present if no other optimization flag has been detected in the command line). No, because the final_cleanup pass is only executed when optimizing. For -O0, you need to determine what's the last phase executed and request a dump to that phase. Ok, this is more or less what I though. I guess that nobody want unoptimized code in his final build, so I think I can go with my hack (adding -O1 when needed). Also, future versions of GCC may not have this phase as the final phase, or the dump file name may change, or both. Dump files are merely debugging aids. We make no guarantees as to their content or naming convention. Hum, I'm coding a tool for static and (symbolic) dynamic analysis of code, would you recommend me a way to get the most final CFG you get inside GCC (other than the -fdump-tree-flags) ??? It would be very helpful for me to get a GENERIC/GIMPLE CFG (with SSA and so on) of the source code so that I can analyze all the languages that go through a gimplifier. :-/ A final remark, not really significant, I noticed that since gcc 4.2, the name of the dumped tree files have slightly changed. Indeed before, I was used to src_file_name.t#id.type where in 4.2 it is more like src_file_name.#idt.type. We amalgamated the dumping mechanism for trees and RTL. The 't' denotes a 'tree' dump, 'r' an RTL dump and 'i' an IPA dump. Damn, you also have inter-procedural analysis dumps ! More I know about GCC, more I love it ! I'll dig this. :) Actually, I know that these dumps are here, as you said, just for debugging purpose but why not making them 'permanent' and kind-of 'standardized' (I mean, not changing it too frequently), so that code analysis tools could plug on GCC ? (I know I'm asking a lot... sorry) Regards -- Emmanuel Fleury The memory management on the PowerPC can be used to frighten small children. -- Linus Torvalds
Re: Dumping tree with no opt flag
On 7/30/07 11:34 AM, Emmanuel Fleury wrote: Actually, I know that these dumps are here, as you said, just for debugging purpose but why not making them 'permanent' and kind-of 'standardized' (I mean, not changing it too frequently), so that code analysis tools could plug on GCC ? (I know I'm asking a lot... sorry) Because that's not their goal. The suggested way of doing this kind of analyses is to implement them in GCC directly. This way, instead of parsing the text output, you can access the data structures directly. That will be faster and easier to maintain in the future. We also realize that dealing with GCC's code base is time consuming and even difficult at first. You may be interested in a couple of recent projects to add plug-in functionality to future versions of GCC. You can read about them in the proceedings for this year's GCC Summit (http://gcc.gnu.org/wiki/HomePage?action=AttachFiledo=gettarget=GCC2007-Proceedings.pdf)
