* [PATCH v2 2/3] gas: Handle --compress-debug-sections=subopt1,subopt2
2023-02-28 0:16 [PATCH v2 1/3] gas: Unify parsing of --compress-debug-sections Tom de Vries
@ 2023-02-28 0:16 ` Tom de Vries
2023-02-28 0:16 ` [PATCH v2 3/3] gas: Add --compress-debug-sections={heuristic-always,heuristic-sizewin} Tom de Vries
2023-03-09 15:33 ` [PING] [PATCH v2 1/3] gas: Unify parsing of --compress-debug-sections Tom de Vries
2 siblings, 0 replies; 4+ messages in thread
From: Tom de Vries @ 2023-02-28 0:16 UTC (permalink / raw)
To: binutils
Add the possibility to specify more than one --compress-debug-sections subopt
at a time, using a comma separator.
Using --compress-debug-sections=subopt1,subopt2 is equivalent to using
--compress-debug-sections=subopt1 --compress-debug-sections=subopt2.
---
gas/as.c | 46 ++++++++++++++++++++++++++++++++++++++++------
1 file changed, 40 insertions(+), 6 deletions(-)
diff --git a/gas/as.c b/gas/as.c
index 40742b13511..c159c5d0d0a 100644
--- a/gas/as.c
+++ b/gas/as.c
@@ -419,13 +419,8 @@ Options:\n\
}
static void
-parse_compress_debug_optarg (const char *optarg)
+parse_compress_debug_optarg_1 (const char *optarg)
{
-#if !defined OBJ_ELF && !defined OBJ_MAYBE_ELF
- as_fatal (_("--compress-debug-sections=%s is unsupported"),
- optarg);
-#endif
-
gas_assert (optarg != NULL);
enum compressed_debug_section_type tmp
@@ -444,6 +439,45 @@ parse_compress_debug_optarg (const char *optarg)
flag_compress_debug = tmp;
}
+static void
+parse_compress_debug_optarg (const char *optarg)
+{
+#if !defined OBJ_ELF && !defined OBJ_MAYBE_ELF
+ as_fatal (_("--compress-debug-sections=%s is unsupported"),
+ optarg);
+#endif
+
+ gas_assert (optarg != NULL);
+
+ /* Tokenize subopts pass to parse_compress_debug_optarg_1. */
+ char sep = ',';
+ while (true)
+ {
+ const char *idx = optarg;
+ while (*idx != '\0' && *idx != sep)
+ idx++;
+
+ size_t len = idx - optarg;
+ if (len == 0)
+ {
+ /* Generate error. */
+ parse_compress_debug_optarg_1 ("");
+ break;
+ }
+
+ char *tmp = xstrndup (optarg, len);
+ parse_compress_debug_optarg_1 (tmp);
+ free (tmp);
+
+ if (*idx == '\0')
+ break;
+
+ /* Step over separator and continue tokenizing. */
+ gas_assert (*idx == sep);
+ optarg = idx + 1;
+ }
+}
+
/* Since it is easy to do here we interpret the special arg "-"
to mean "use stdin" and we set that argv[] pointing to "".
After we have munged argv[], the only things left are source file
--
2.35.3
^ permalink raw reply [flat|nested] 4+ messages in thread* [PATCH v2 3/3] gas: Add --compress-debug-sections={heuristic-always,heuristic-sizewin}
2023-02-28 0:16 [PATCH v2 1/3] gas: Unify parsing of --compress-debug-sections Tom de Vries
2023-02-28 0:16 ` [PATCH v2 2/3] gas: Handle --compress-debug-sections=subopt1,subopt2 Tom de Vries
@ 2023-02-28 0:16 ` Tom de Vries
2023-03-09 15:33 ` [PING] [PATCH v2 1/3] gas: Unify parsing of --compress-debug-sections Tom de Vries
2 siblings, 0 replies; 4+ messages in thread
From: Tom de Vries @ 2023-02-28 0:16 UTC (permalink / raw)
To: binutils
Gas has an option --compress-debug-sections that allows it to generate
compressed debug sections.
That does not guarantee that the debug sections are in fact compressed:
...
$ gcc hello.c -Wa,-gdwarf-5 -c -Wa,--compress-debug-sections=zstd
$ readelf -S -W hello.o | grep " .debug"
[ 9] .debug_line PROGBITS 0000a8 000053 00 0 0 1
[11] .debug_line_str PROGBITS 0000fb 000025 01 MS 0 0 1
[12] .debug_info PROGBITS 000120 000039 00 0 0 1
[14] .debug_abbrev PROGBITS 000159 000028 00 0 0 1
[15] .debug_aranges PROGBITS 000190 000030 00 0 0 16
[17] .debug_str PROGBITS 0001c0 000039 01 MS 0 0 1
...
Sensibly so, they're only compressed if that provides a size benefit.
However, for the purpose of testing components consuming dwarf
we may want the sections to be compressed regardless.
Add a new suboption --compress-debug-sections=heuristic-always that ignores
the size heuristic, such that we have instead:
...
$ gcc hello.c -Wa,-gdwarf-5 -c -Xassembler \
--compress-debug-sections=zstd,heuristic-always
$ readelf -S -W hello.o | grep " .debug"
[ 9] .debug_line PROGBITS 0000a8 000064 00 C 0 0 8
[11] .debug_line_str PROGBITS 000110 000046 01 MSC 0 0 8
[12] .debug_info PROGBITS 000158 000046 00 C 0 0 8
[14] .debug_abbrev PROGBITS 0001a0 000049 00 C 0 0 8
[15] .debug_aranges PROGBITS 0001f0 000034 00 C 0 0 8
[17] .debug_str PROGBITS 000228 00005a 01 MSC 0 0 8
...
Also add an option --compress-debug-sections=heuristic-sizewin that represents
the current default.
Advertised as:
...
$ as --help
...
--compress-debug-sections[={none|zlib|zlib-gnu|zlib-gabi|zstd|heuristic-always|heuristic-sizewin}]
compress DWARF debug sections
Default: zlib
...
Tested on x86_64-linux.
---
gas/as.c | 16 +++++++++++++++-
gas/as.h | 8 ++++++++
gas/write.c | 7 +++++--
3 files changed, 28 insertions(+), 3 deletions(-)
diff --git a/gas/as.c b/gas/as.c
index c159c5d0d0a..a766f864707 100644
--- a/gas/as.c
+++ b/gas/as.c
@@ -230,6 +230,8 @@ enum compressed_debug_section_type flag_compress_debug
= DEFAULT_COMPRESSED_DEBUG_ALGORITHM;
#endif
+enum compress_debug_heuristic compress_debug_heuristic = cdh_sizewin;
+
static void
show_usage (FILE * stream)
{
@@ -252,7 +254,7 @@ Options:\n\
fprintf (stream, _("\
--alternate initially turn on alternate macro syntax\n"));
fprintf (stream, _("\
- --compress-debug-sections[={none|zlib|zlib-gnu|zlib-gabi|zstd}]\n\
+ --compress-debug-sections[={none|zlib|zlib-gnu|zlib-gabi|zstd|heuristic-sizewin|heuristic-always}]\n\
compress DWARF debug sections\n")),
fprintf (stream, _("\
Default: %s\n"),
@@ -423,6 +425,18 @@ parse_compress_debug_optarg_1 (const char *optarg)
{
gas_assert (optarg != NULL);
+ if (strcmp (optarg, "heuristic-sizewin") == 0)
+ {
+ compress_debug_heuristic = cdh_sizewin;
+ return;
+ }
+
+ if (strcmp (optarg, "heuristic-always") == 0)
+ {
+ compress_debug_heuristic = cdh_always;
+ return;
+ }
+
enum compressed_debug_section_type tmp
= bfd_get_compression_algorithm (optarg);
diff --git a/gas/as.h b/gas/as.h
index 4c5fa9ecf7d..cd852500197 100644
--- a/gas/as.h
+++ b/gas/as.h
@@ -331,6 +331,14 @@ COMMON int flag_traditional_format;
/* Type of compressed debug sections we should generate. */
COMMON enum compressed_debug_section_type flag_compress_debug;
+/* Debug sections compression heuristics. */
+enum compress_debug_heuristic
+{
+ cdh_sizewin,
+ cdh_always
+};
+COMMON enum compress_debug_heuristic compress_debug_heuristic;
+
/* TRUE if .note.GNU-stack section with SEC_CODE should be created */
COMMON int flag_execstack;
diff --git a/gas/write.c b/gas/write.c
index 8273b7a42f1..34ea5746284 100644
--- a/gas/write.c
+++ b/gas/write.c
@@ -1463,9 +1463,11 @@ compress_debug (bfd *abfd, asection *sec, void *xxx ATTRIBUTE_UNUSED)
segment_info_type *seginfo = seg_info (sec);
bfd_size_type uncompressed_size = sec->size;
flagword flags = bfd_section_flags (sec);
+ bool compress_debug_heuristic_sizewin
+ = compress_debug_heuristic == cdh_sizewin;
if (seginfo == NULL
- || uncompressed_size < 32
+ || (compress_debug_heuristic_sizewin && uncompressed_size < 32)
|| (flags & SEC_HAS_CONTENTS) == 0)
return;
@@ -1582,7 +1584,8 @@ compress_debug (bfd *abfd, asection *sec, void *xxx ATTRIBUTE_UNUSED)
/* PR binutils/18087: If compression didn't make the section smaller,
just keep it uncompressed. */
- if (compressed_size >= uncompressed_size)
+ if (compress_debug_heuristic_sizewin
+ && compressed_size >= uncompressed_size)
return;
/* Replace the uncompressed frag list with the compressed frag list. */
--
2.35.3
^ permalink raw reply [flat|nested] 4+ messages in thread* [PING] [PATCH v2 1/3] gas: Unify parsing of --compress-debug-sections
2023-02-28 0:16 [PATCH v2 1/3] gas: Unify parsing of --compress-debug-sections Tom de Vries
2023-02-28 0:16 ` [PATCH v2 2/3] gas: Handle --compress-debug-sections=subopt1,subopt2 Tom de Vries
2023-02-28 0:16 ` [PATCH v2 3/3] gas: Add --compress-debug-sections={heuristic-always,heuristic-sizewin} Tom de Vries
@ 2023-03-09 15:33 ` Tom de Vries
2 siblings, 0 replies; 4+ messages in thread
From: Tom de Vries @ 2023-03-09 15:33 UTC (permalink / raw)
To: binutils
On 2/28/23 01:16, Tom de Vries via Binutils wrote:
> There are three related option forms:
> * --compress-debug-sections=<none|zlib|zlib-gnu|zlib-gabi>
> * --compress-debug-sections
> * --nocompress-debug-sections
> where the last two are documented as being equivalent to:
> * --compress-debug-section=zlib-gabi
> * --compress-debug-section=none
>
> However, the three related option forms are handled independently in
> parse_args, and there are minor differences in handling.
>
> For instance, in case !defined OBJ_ELF && !defined OBJ_MAYBE_ELF, using
> --compress-debug-section=zlib-gabi or --compress-debug-section=none will
> trigger as_fatal ("--compress-debug-sections=%s is unsupported"), while that's
> not the case for --compress-debug-sections and --nocompress-debug-sections.
>
> Fix this by:
> - factoring out a new function parse_compress_debug_optarg, and
> - using it to handle all three options forms.
>
> Also make the code easier to read by not nesting preprocessor conditionals.
Ping for this series.
FWIW, forgot to mention: I've dropped the doc bit in this series because
it seems a better idea to update that bit once we've settled on the
naming issue.
Also, the v1 was a patch and the v2 is a series, my hope is that
splitting it up would make it easier to review.
Thanks,
- Tom
> ---
> gas/as.c | 47 +++++++++++++++++++++++++++++------------------
> 1 file changed, 29 insertions(+), 18 deletions(-)
>
> diff --git a/gas/as.c b/gas/as.c
> index 598bfd56cf5..40742b13511 100644
> --- a/gas/as.c
> +++ b/gas/as.c
> @@ -418,6 +418,32 @@ Options:\n\
> fprintf (stream, _("Report bugs to %s\n"), REPORT_BUGS_TO);
> }
>
> +static void
> +parse_compress_debug_optarg (const char *optarg)
> +{
> +#if !defined OBJ_ELF && !defined OBJ_MAYBE_ELF
> + as_fatal (_("--compress-debug-sections=%s is unsupported"),
> + optarg);
> +#endif
> +
> + gas_assert (optarg != NULL);
> +
> + enum compressed_debug_section_type tmp
> + = bfd_get_compression_algorithm (optarg);
> +
> +#ifndef HAVE_ZSTD
> + if (tmp == COMPRESS_DEBUG_ZSTD)
> + as_fatal (_ ("--compress-debug-sections=zstd: gas is not "
> + "built with zstd support"));
> +#endif
> +
> + if (tmp == COMPRESS_UNKNOWN)
> + as_fatal (_("Invalid --compress-debug-sections option: `%s'"),
> + optarg);
> +
> + flag_compress_debug = tmp;
> +}
> +
> /* Since it is easy to do here we interpret the special arg "-"
> to mean "use stdin" and we set that argv[] pointing to "".
> After we have munged argv[], the only things left are source file
> @@ -747,28 +773,13 @@ This program has absolutely no warranty.\n"));
>
> case OPTION_COMPRESS_DEBUG:
> if (optarg)
> - {
> -#if defined OBJ_ELF || defined OBJ_MAYBE_ELF
> - flag_compress_debug = bfd_get_compression_algorithm (optarg);
> -#ifndef HAVE_ZSTD
> - if (flag_compress_debug == COMPRESS_DEBUG_ZSTD)
> - as_fatal (_ ("--compress-debug-sections=zstd: gas is not "
> - "built with zstd support"));
> -#endif
> - if (flag_compress_debug == COMPRESS_UNKNOWN)
> - as_fatal (_("Invalid --compress-debug-sections option: `%s'"),
> - optarg);
> -#else
> - as_fatal (_("--compress-debug-sections=%s is unsupported"),
> - optarg);
> -#endif
> - }
> + parse_compress_debug_optarg (optarg);
> else
> - flag_compress_debug = COMPRESS_DEBUG_GABI_ZLIB;
> + parse_compress_debug_optarg ("zlib-gabi");
> break;
>
> case OPTION_NOCOMPRESS_DEBUG:
> - flag_compress_debug = COMPRESS_DEBUG_NONE;
> + parse_compress_debug_optarg ("none");
> break;
>
> case OPTION_DEBUG_PREFIX_MAP:
>
> base-commit: d273049e140ef324be2b018e235ae0ba8021a769
^ permalink raw reply [flat|nested] 4+ messages in thread