[Bug breakpoints/11662] New: agent expressions can't represent all DWARF locations

[Bug breakpoints/11662] New: agent expressions can't represent all DWARF locations

[tromey at redhat dot com]

It is difficult to translate all DWARF location expressions into
agent expressions.  This is true even for expressions which GCC
actually generates.

I think the best fix would be to add a few more opcodes to agent
expressions.

The difficult DWARF opcodes are enumerated here:

http://sourceware.org/ml/gdb-patches/2010-05/msg00407.html

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           Summary: agent expressions can't represent all DWARF locations
           Product: gdb
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: breakpoints
        AssignedTo: unassigned at sourceware dot org
        ReportedBy: tromey at redhat dot com
                CC: gdb-prs at sourceware dot org


http://sourceware.org/bugzilla/show_bug.cgi?id=11662

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[Bug breakpoints/11662] agent expressions can't represent all DWARF locations

[tromey at redhat dot com]

------- Additional Comments From tromey at redhat dot com  2010-06-02 22:27 -------
Also, DWARF does not have many restrictions on how an expression
can manipulate the stack.  For example, a DWARF expression may
push any number of values, while only the last value is used.
Branching can mean that the number of values on the stack at
any given point is not constant.

One simple way to deal with this problem would be to add new agent
opcodes to mark the stack depth and then pop to the mark.

-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=11662

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[Bug breakpoints/11662] agent expressions can't represent all DWARF locations

[tromey at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=11662

--- Comment #2 from Tom Tromey <tromey at redhat dot com> 2011-05-17 14:48:12 UTC ---
The DWARF->AX compiler also does not handle the typed DWARF extension.
See Bug 12617 for links.  At least integral types of various sizes
could be supported.

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