From: Tom Tromey <tom@tromey.com>
To: "Torbjörn SVENSSON via Gdb-patches" <gdb-patches@sourceware.org>
Cc: "Torbjörn SVENSSON" <torbjorn.svensson@foss.st.com>,
luis.machado@arm.com, vanekt@volny.cz,
"Yvan Roux" <yvan.roux@foss.st.com>
Subject: Re: [PATCH v2 3/4] gdb: dwarf2 generic implementation for caching function data
Date: Tue, 20 Dec 2022 14:02:57 -0700 [thread overview]
Message-ID: <87ili5kcu6.fsf@tromey.com> (raw)
In-Reply-To: <20221118155252.113476-4-torbjorn.svensson@foss.st.com> (=?utf-8?Q?=22Torbj=C3=B6rn?= SVENSSON via Gdb-patches"'s message of "Fri, 18 Nov 2022 16:52:52 +0100")
>>>>> Torbjörn SVENSSON via Gdb-patches <gdb-patches@sourceware.org> writes:
> When there is no dwarf2 data for a register, a function can be called
> to provide the value of this register. In some situations, it might
> not be trivial to determine the value to return and it would cause a
> performance bottleneck to do the computation each time.
Thanks for the patch.
> This patch allows the called function to have a "cache" object that it
> can use to store some metadata between calls to reduce the performance
> impact of the complex logic.
> The cache object is unique for each function and frame, so if there are
> more than one function pointer stored in the dwarf2_frame_cache->reg
> array, then the appropriate pointer will be supplied (the type is not
> known by the dwarf2 implementation).
Does this ever happen? If not perhaps a simpler approach would be
better.
> +struct dwarf2_frame_fn_data
> +{
New type should have a comment.
> + struct value *(*fn) (frame_info_ptr this_frame, void **this_cache,
> + int regnum);
Shouldn't this use the fn_prev_register typedef?
> + void *data;
> + struct dwarf2_frame_fn_data* next;
Wrong placement of the "*", but really a lot of the code isn't following
the GNU / gdb style.
> +void *dwarf2_frame_get_fn_data (frame_info_ptr this_frame, void **this_cache,
> + fn_prev_register fn)
Normally new functions get a comment referring to the header where they
are declared.
> +
> +/* Allocate a new instance of the function unique data. */
> +
> +extern void *dwarf2_frame_allocate_fn_data (frame_info_ptr this_frame,
> + void **this_cache,
> + fn_prev_register fn,
> + unsigned long size);
> +
> +/* Retrieve the function unique data for this frame. */
> +
> +extern void *dwarf2_frame_get_fn_data (frame_info_ptr this_frame,
I think these comments could perhaps be expanded a bit.
Tom
next prev parent reply other threads:[~2022-12-20 21:03 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-18 15:52 [PATCH 0/4] v2 gdb/arm: Fixes for Cortex-M stack unwinding Torbjörn SVENSSON
2022-11-18 15:52 ` [PATCH v2 1/4] gdb/arm: Update active msp/psp when switching stack Torbjörn SVENSSON
2022-11-21 14:04 ` Luis Machado
2022-11-18 15:52 ` [PATCH v2 2/4] gdb/arm: Ensure that stack pointers are in sync Torbjörn SVENSSON
2022-11-21 14:04 ` Luis Machado
2022-11-18 15:52 ` [PATCH v2 3/4] gdb: dwarf2 generic implementation for caching function data Torbjörn SVENSSON
2022-11-18 16:01 ` Torbjorn SVENSSON
2022-12-20 21:04 ` Tom Tromey
2022-11-21 21:16 ` Luis Machado
2022-11-29 15:19 ` Torbjorn SVENSSON
2022-11-29 16:24 ` Tomas Vanek
2022-11-30 10:16 ` Torbjorn SVENSSON
2022-11-30 10:19 ` Luis Machado
2022-12-08 1:11 ` Luis Machado
2022-12-19 19:28 ` [PING] " Torbjorn SVENSSON
2022-12-20 21:02 ` Tom Tromey [this message]
2022-12-28 16:16 ` Torbjorn SVENSSON
2023-01-05 20:53 ` Torbjorn SVENSSON
2023-01-14 6:54 ` Joel Brobecker
2023-01-18 18:47 ` Tom Tromey
2023-01-19 10:31 ` Torbjorn SVENSSON
2022-11-18 15:52 ` [PATCH v2 4/4] gdb/arm: Use new dwarf2 function cache Torbjörn SVENSSON
2022-11-21 21:04 ` Luis Machado
2022-11-29 15:19 ` Torbjorn SVENSSON
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