>>> On 11.08.14 at 16:53, <h...@zytor.com> wrote: > On 08/11/2014 07:17 AM, Jan Beulich wrote: >>> >>> The existing comments explain what every byte means. >>> They are useful if CFI-literate reader wants to check correctness >>> of the encoding of this annotation. >>> >>> There is no overall comment what this CFI annotation >>> *achieves*. In human language, what do we say >>> to DWARF decoder here? >> >> Short answer: DW_CFA_def_cfa_expression. >> >> Longer response: Just like I said before, what you're asking for is >> identical to ask for each other CFI annotation to get a comment >> associated to tell you what it's doing, which I don't think you >> really mean to ask for. (Our main problem here is that we can't >> specify expressions with the .cfi_* gas directives, and hence have >> to resort to .cfi_escape.) >> > > No, in *human language*. What does the DW_CFA_def_cfa_expression > actually aim to accomplish? If you don't know the innards of the DWARF > spec, the whole thing might as well be Hungarian.
Just like the other DW_CFA_def_cfa_* ones it sets the current frame address (CFA), just not via one of the pre-canned shortcuts, but via an expression (in the case here de-referencing the stack pointer to read the top of stack, and then adding the necessary offset). So it indeed is similar enough to other .cfi_* annotations we use without further comments. And btw., Hungarian isn't _that_ bad. Jan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
