There was a question on the dev list a while ago about to print out all the
valid ranges of a variable. That's a useful bit of info if you're trying to
figure out where you could break to actually see or change a variable's value
in an optimized function. I think that's the motivation for the change, so
just showing the range that encompasses the address wouldn't satisfy that
initial impetus for the change.
It is a little awkward to put it in "image lookup -va" however, and odder to
have it be part of the printing of an Address. It seems more like something
you should ask a function?
Jim
> On Feb 17, 2022, at 12:57 AM, Pavel Labath via Phabricator
> <revi...@reviews.llvm.org> wrote:
>
> labath added a comment.
>
> I suppose one could ask the question whether this should be printing the
> entire set range of ranges, or just the one
>
>
>
> ================
> Comment at: lldb/source/Commands/Options.td:960
> "target modules.">;
> + def target_modules_lookup_variables_ranges :
> Option<"show-variables-ranges",
> + "R">, GroupRange<1, 6>, Desc<"Dump valid ranges of variables (must be
> used "
> ----------------
>
>
>
> ================
> Comment at: lldb/source/Commands/Options.td:961
> + def target_modules_lookup_variables_ranges :
> Option<"show-variables-ranges",
> + "R">, GroupRange<1, 6>, Desc<"Dump valid ranges of variables (must be
> used "
> + "in conjunction with --verbose">;
> ----------------
> A not widely known fact: It is possible to produce an long option without a
> short version by using an non-printable character in place of the short
> option. You can see and example of that in `disassemble --force`, defined in
> this file.
>
> If we are considering this a niche option, then maybe we don't need to use a
> random character just to have a short version.
>
>
> ================
> Comment at: lldb/test/Shell/SymbolFile/DWARF/x86/debug_loc.s:16
> +# CHECK-LABEL: image lookup -v -a 0 -R
> +# CHECK: Variable: {{.*}}, name = "x0", type = "int", location = DW_OP_reg5
> RDI, decl = , valid ranges =
> +# CHECK: Variable: {{.*}}, name = "x1", type = "int", location = <empty>,
> decl = , valid ranges =
> ----------------
> I don't think that the information itself is out of place here, but I think
> it can get confusing when one sees it like this, next to the `location`
> field. So, if we had an output like `location = RDI, valid ranges = [0, 20)`,
> I think one would/could read it as "the variable is in RDI from PC=0 to
> PC=20", but what it _really_ is telling you is "the variable (or its value --
> I'm not sure) exists between PC=0 and PC=20, *and* for the exact PC that you
> are querying (0 in this case), it's value happens to be in RDI".
>
> We could try to come up with a way to make this less confusing, but maybe we
> could just sidestep this problem and just print this information in the
> `image dump symfile` output.
>
>
> ================
> Comment at: lldb/test/Shell/SymbolFile/DWARF/x86/debug_loc.s:27
> # CHECK: Function{
> # CHECK: Variable{{.*}}, name = "x0", {{.*}}, scope = parameter, location
> =
> # CHECK-NEXT: [0x0000000000000000, 0x0000000000000001): DW_OP_reg5 RDI
> ----------------
> If you printed the information here, then there would be no (or less)
> confusion as the location field contains explicit range information.
> Additionally, the `image dump symfile` output is so verbose, than an extra
> field does not make a difference.
>
> (I'm sorry, I know it was I who suggested using `image lookup`, but I did not
> realize you would be adding an extra argument because of that.)
>
>
> Repository:
> rG LLVM Github Monorepo
>
> CHANGES SINCE LAST ACTION
> https://reviews.llvm.org/D119963/new/
>
> https://reviews.llvm.org/D119963
>
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