From: "Ulrich Weigand" <uweigand@de.ibm.com>
To: derodat@adacore.com (Pierre-Marie de Rodat)
Cc: brobecker@adacore.com (Joel Brobecker),
Pitchumani.Sivanupandi@atmel.com (Sivanupandi Pitchumani),
gdb@sourceware.org (gdb@sourceware.org),
andrew.burgess@embecosm.com (Andrew Burgess),
tom@tromey.com (tom@tromey.com)
Subject: Re: dynamic array's upper bound evaluated as address for AVR target
Date: Fri, 23 Oct 2015 16:47:00 -0000 [thread overview]
Message-ID: <20151023164734.4798E6160@oc7340732750.ibm.com> (raw)
In-Reply-To: <562A41EA.6020304@adacore.com> from "Pierre-Marie de Rodat" at Oct 23, 2015 10:19:22 AM
Pierre-Marie de Rodat wrote:
> Quick update: I started to dig into this. I still have a hard time
> wrapping the current implementation in my mind[1] and thinking about
> what we should do exactly:
>
> * Have different types for expressions and location lists (hence
> potentially renaming existing code): looks like a big commit!
>
> * Introduce another entry point to evaluate dynamic properties as
> expressions. Looks like a small change but a weaker design: how to
> evaluate depends a property depends on the property, not the evaluation
> context, so it would be great to keep types distinct.
>
> I cannot make any commitment on a schedule to implement this, though.
It seems to me the easiest path to implement the change incrementally
might be:
a.) We currently have:
enum dynamic_prop_kind
{
PROP_UNDEFINED, /* Not defined. */
PROP_CONST, /* Constant. */
PROP_ADDR_OFFSET, /* Address offset. */
PROP_LOCEXPR, /* Location expression. */
PROP_LOCLIST /* Location list. */
};
As a first step, add a value
PROP_EXPR /* DWARF expression. */
to this list.
b.) Add code to dwarf2_evaluate_property / dwarf2_compile_property_to_c
to support PROP_EXPR.
This is a bit tricky since there is no real infrastructure to evaluate
DWARF expressions, as opposed to location expressions. Note that the
existing routine dwarf_entry_parameter_to_value uses the trick to append
DW_OP_stack_value to the expression to force evaluation as a DWARF
expression instead of location. The same could probably be done here.
c.) For the range-related dynamic properties, create PROP_EXPR property
nodes instead of PROP_LOC* property nodes. This probably means splitting
the routine attr_to_dynamic_prop into two variants, one for locations
and one for dynamic properties.
-- At this point, everything should be functionally correct, the rest
is simply cleanup ---
d.) Create some new common mechanism to handle DWARF locations
e.) Change the various places where DWARF locations are handled to use
this new common mechanism:
- DW_AT_location [ currently uses SYMBOL_COMPUTED_OPS ]
- DW_AT_frame_base [ currently uses SYMBOL_BLOCK_OPS ]
- DW_AT_data_location [ currently uses dynamic_prop ]
- DW_AT_static_link [ currently uses dynamic_prop ]
f.) Finally, remove (now unused) support for PROP_LOCEXPR/PROP_LOCLIST
from the dynamic property code.
Bye,
Ulrich
--
Dr. Ulrich Weigand
GNU/Linux compilers and toolchain
Ulrich.Weigand@de.ibm.com
next prev parent reply other threads:[~2015-10-23 16:47 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-13 9:08 Sivanupandi, Pitchumani
2015-10-13 14:44 ` Pierre-Marie de Rodat
2015-10-14 6:33 ` Sivanupandi, Pitchumani
2015-10-14 6:54 ` Pierre-Marie de Rodat
2015-10-14 7:54 ` Sivanupandi, Pitchumani
2015-10-14 8:26 ` Pierre-Marie de Rodat
2015-10-14 9:41 ` Ulrich Weigand
2015-10-14 12:26 ` Joel Brobecker
2015-10-14 13:37 ` Pierre-Marie de Rodat
2015-10-23 14:19 ` Pierre-Marie de Rodat
2015-10-23 16:47 ` Ulrich Weigand [this message]
2015-10-14 10:15 ` Sivanupandi, Pitchumani
2015-10-14 13:39 ` Pierre-Marie de Rodat
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