Messages in this thread | | | From | Namhyung Kim <> | Date | Fri, 29 Mar 2024 12:57:35 -0700 | Subject | Re: [PATCH 0/4] perf annotate: Use libcapstone as a disasssembler |
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Hi Ian,
On Fri, Mar 29, 2024 at 9:33 AM Ian Rogers <irogers@google.com> wrote: > > On Thu, Mar 28, 2024 at 4:20 PM Namhyung Kim <namhyung@kernel.org> wrote: > > > > Hello, > > > > As we've added libcapstone support, it's natural to use it for perf annotate > > as well. This change added the capstone support on x86 first. Other archs > > can be added later (by someone who can verify it doesn't break things). > > > > For now it tries to use capstone (if available) before objdump. But it > > doesn't support source file and line number info. So users should use the > > objdump (by passing --objdump=PATH option) if they need them. For example, > > this command line will keep the existing behavior (i.e. using objdump). > > > > # not to use capstone for disassembly > > $ perf annotate --objdump=objdump > > > > The capstone uses LLVM objdump style output which is slightly different than > > the GNU objdump. But it should not have differences besides that. I've > > verified the result of data type profiling and it produced the same output > > but gave me ~3x speedups. > > > > Thanks, > > Namhyung > > I wanted to see what -fsanitize=address would think of libcaptstone > and no issues, so: > > Tested-by: Ian Rogers <irogers@google.com>
Thanks for checking it!
> > Some thoughts: > - it may be worth adding to the commit message in "perf annotate: > Split out util/disasm.c" that there's no functional change, > - we lack perf annotate testing, > - it seems capstone should be opt-out rather than opt-in as a library > dependency (given the performance delta and the objdump interactions > are at best messy), > - if libcapstone could solve our addr2line issues too this would be great :-).
I think addr2line should be handled using libdw. I'll take a look.
Thanks, Namhyung
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