On 07/26/2017 10:00 AM, Pierre-Marie de Rodat wrote: > Hello, > > At the last GNU Cauldron, Richard Biener and I talked about DWARF output > testing. Except for guality tests, which are disabled on several > targets, the only way tests check the DWARF is scanning the annotated > assembly (-dA), making it hard to write reliable tests. > > For instance, checking the number of times DW_AT_location is present in > order to check that some specific variable is assigned one is fuzzy. > Depending on the target and on the evolution of the compiler, the number > of output variables, or which one is assigned a location can vary > legitimately but still make the test fail. > > On my side, I already had written an out-of-tree testsuite for the DWARF > features I added for Ada. This testsuite uses a DWARF parser in order to > perform checks on a tree: > <https://github.com/pmderodat/dwarf-ada-testsuite/>. I had to update it > a couple of times, for instance when a change created a > DW_TAG_const_type DIE or removed one somewhere in a type tree, but > that’s very rare. I would say that I’m satisfied with the checks I could > express, but I don’t remember I ever caught a regression with them, so I > have no representative experience to share in this area. Maybe DWARF > back-end developpers do a too good job. ;-) > > Anyway, Richard and I discussed about doing something similar in-tree, > and here is a candidate set of patches to achieve that: > > * The first patch installs DejaGNU scripts to run a Python interpreter > in testcases. > > * The second one installs other DejaGNU scripts to detect DWARF > dumping tools, plus a small Python library to parse and pattern > match DIEs and their attributes. It also adds several C and Ada > tests as examples; these are inspired by existing homonym tests > based on assembly scanning. > > For now, this supports only platforms where objdump is available for the > current target, but extending it to other tools, such as otool on Darwin > should be doable. > > I would appreciate feedback about the idea and the implementation I > propose. This is the first time I do more in the testsuite than just > adding new tests, so thank you in advance for you patience in reviewing > these. :-) > > I tested these patches on x86_64-linux. I hate to throw in a wrench at this point, but has anyone looked at dwgrep from Petr Machata? He's not doing much with it anymore, but it might provide enough of a dwarf scanning framework to be useful for testing purposes.
jeff
