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    SubjectRe: [RFC PATCH] perf report: add sort by file lines
    Em Tue, Mar 29, 2011 at 07:08:53PM +0200, Peter Zijlstra escreveu:
    > On Tue, 2011-03-29 at 19:06 +0200, Peter Zijlstra wrote:
    > > On Tue, 2011-03-29 at 19:03 +0200, Peter Zijlstra wrote:
    > > > > Is it an unwind of the call frame stack to find out what data member was
    > > > > accessed?

    > > > No need to unwind stacks, DWARF should have information on function
    > > > local stack. It should be able to tell you the type of things like -8(%
    > > > rbp).

    > > That is, we don't even have a life stack to unwind, so we simply cannot
    > > unwind at all, but the debug information should be able to tell you the
    > > type of whatever would live at a certain stack position if we were to
    > > have a stack.

    > Furthermore, I've now completely exhausted my knowledge of debuginfo and
    > hope Masami and Arnaldo will help with further details ;-)

    :-)

    I think the place to look is 'perf probe', look for the way one
    variable is translated to an expression passed to the kprobe_tracer, I
    think you'll need the reverse operation.

    Look at tools/perf/util/probe-finder.c, function find_variable() and
    convert_variable_location().

    Understanding how those functions use the dwarf_ prefixed routines from
    libdw should be a good start.

    - Arnaldo


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