Hello, While browsing through the mailing list archives a bit, I noticed Alex's project to improve GCC's debug information. This seems like a really interesting and worthwhile project. Alex, maybe you could add a Wiki page about this project, in the style of http://gcc.gnu.org/wiki/SampleProjectTemplate ... ?
I am worried about some of the things going on in the var-tracking-assignments branch. The thing that worries me most, is the introduction of an insn that is not an instruction: /* An annotation for variable assignment tracking. */ DEF_RTL_EXPR(DEBUG_INSN, "debug_insn", "iuuBieie", RTX_INSN) DEBUG_INSN is more like a note, AFAIU. I couldn't find any discussions about this idea, so I don't know if there is "sufficient" concensus that this is the right thing to do. IMHO, anything that is not an instruction should not be true under INSN_P. Yet, INSN_P returns true for DEBUG_INSN. This is already leading to a lot of special-casing of DEBUG_INSN throughout the RTL bits of the compiler on the branch. Also, registers mentioned in DEBUG_INSNs are counted as real uses, which is bound to confuse some existing RTL analyses, and makes it harder to implement new ones safely. The same issues arise with DEBUG_STMT for tree-ssa. Is this really a design that has the necessary support to make the branch eligible for merging into the trunk? What are the reasons for using a fake insn instead of a note for DEBUG_INSN? Thanks, Gr. Steven
