On Jul 27, 2008, Mark Mitchell <[EMAIL PROTECTED]> wrote: > In that case, I'm not sure that *type* ought to be modified at all, > from the debug perspective. To the extent there's still an object of > type "struct X" around, it's type is still what it was. And other > things you might do in a debugger, like ask "What member functions > does class X have?", have the same answer no matter the layout chosen > by the compiler, including throwing out half the fields and leaving > the rest in random registers. For that matter, "print sizeof(X)" > should print the same value when debugging optimized code as when > debugging unoptimized code, even if the compiler has optimized X away > to an empty structure!
+1 > There are other things we could do, like mark the *variables* of type > X (rather than the type) as having no location, so that you can't > print/modify objects that have been optimized in this way. Or construct the location lists using DW_OP_piece et al to denote the location of each fragment of the object. > I'm curious what we do with SRA at the moment. This is the same > sort of problem; do we have any solutions at present? no, we don't do this with SRA, but I designed VTA so that it would be trivial to annotate the scalarization assignments, which would then be maintained all the way up to var-tracking, where it could be turned into debug info for the separate pieces. -- Alexandre Oliva http://www.lsd.ic.unicamp.br/~oliva/ Free Software Evangelist [EMAIL PROTECTED], gnu.org} FSFLA Board Member ¡Sé Libre! => http://www.fsfla.org/ Red Hat Compiler Engineer [EMAIL PROTECTED], gcc.gnu.org}
