From: Tsukasa OI <research_trasio@irq.a4lg.com>
To: Hau Hsu <hau.hsu@sifive.com>, Binutils <binutils@sourceware.org>
Subject: Re: [PATCH v2] RISC-V: Add --march=help
Date: Tue, 30 Jan 2024 17:43:43 +0900 [thread overview]
Message-ID: <cd0fe966-c47e-45a6-9396-748cbdfc2e57@irq.a4lg.com> (raw)
In-Reply-To: <20240130063630.2931301-1-hau.hsu@sifive.com>
Hi Hau,
I'm not yet ready to come back to Binutils development (because I
haven't finished writing my research paper) but I'd like to comment.
While your idea seems great at first glance, I would never like to see
"help" handling in the riscv_parse_subset function because many other
functions call it (some calls this function with an argument retrieved
from an assembly / object file and your design seems vulnerable from
adversarial files e.g. when disassembling files with unknown origin).
Besides that, I think that's not a bad idea (quite rare to see in the
GNU toolchain, though).
IMHO, the right place to put "help" handling (at least, its entry point)
is the md_parse_option function in gas/config/tc-riscv.c. Exiting
successfully from here is rare but at least cris and kvx does so for
help-like options.
Thanks,
Tsukasa
On 2024/01/30 15:36, Hau Hsu wrote:
> Use --march=help to print all supported extensions and versions.
>
> This patch assumes that the supported extensions with the same versions
> are listed together.
>
> For example
> static struct riscv_supported_ext riscv_supported_std_ext[] =
> {
> ...
> {"i", ISA_SPEC_CLASS_20191213, 2, 1, 0 },
> {"i", ISA_SPEC_CLASS_20190608, 2, 1, 0 },
> {"i", ISA_SPEC_CLASS_2P2, 2, 0, 0 },
> ...
> };
>
> For "i" extension, 2.1.0 with different spec class are listed together.
> This patch records the previous printed extension and version. If the
> current extension and version are the same as the previous one, skip
> printing.
>
> Here is part of the output of `as -march=help`:
>
> All available -march extensions for RISC-V:
> e 1.9
> i 2.1, 2.0
> m 2.0
> a 2.1, 2.0
> f 2.2, 2.0
> d 2.2, 2.0
> q 2.2, 2.0
> c 2.0
> v 1.0
> h 1.0
> zicbom 1.0
> zicbop 1.0
>
> Signed-off-by: Hau Hsu <hau.hsu@sifive.com>
> ---
> bfd/ChangeLog | 9 ++++++
> bfd/elfxx-riscv.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 81 insertions(+)
>
> diff --git a/bfd/ChangeLog b/bfd/ChangeLog
> index 97d0c585a56..0807a2e0bcb 100644
> --- a/bfd/ChangeLog
> +++ b/bfd/ChangeLog
> @@ -1,3 +1,12 @@
> +2024-01-17 Hau Hsu <hau.hsu@sifive.com>
> +
> + * elfxx-riscv.c (riscv_parse_subset): Parse 'help' keyword to print
> + available extension and versions.
> + (riscv_print_extensions): New function.
> + (riscv_same_extension_version): New function.
> + (riscv_same_extension_diff_version): New function.
> + (riscv_valid_ext): New function.
> +
> 2024-01-15 Nick Clifton <nickc@redhat.com>
>
> * 2.42 branch point.
> diff --git a/bfd/elfxx-riscv.c b/bfd/elfxx-riscv.c
> index 9a121b47121..bb394a589b1 100644
> --- a/bfd/elfxx-riscv.c
> +++ b/bfd/elfxx-riscv.c
> @@ -2051,6 +2051,71 @@ riscv_set_default_arch (riscv_parse_subset_t *rps)
> }
> }
>
> +static
> +bool riscv_same_extension_version(
> + const struct riscv_supported_ext* ext1,
> + const struct riscv_supported_ext* ext2)
> +{
> + return (strcmp(ext1->name, ext2->name) == 0
> + && ext1->major_version == ext2->major_version
> + && ext1->minor_version == ext2->minor_version);
> +}
> +
> +static
> +bool riscv_same_extension_diff_version(
> + const struct riscv_supported_ext* ext1,
> + const struct riscv_supported_ext* ext2)
> +{
> + return (strcmp(ext1->name, ext2->name) == 0
> + && !(ext1->major_version == ext2->major_version
> + && ext1->minor_version == ext2->minor_version));
> +}
> +
> +static
> +bool riscv_valid_ext(const struct riscv_supported_ext *ext)
> +{
> + return (ext->isa_spec_class != ISA_SPEC_CLASS_NONE
> + && ext->major_version != RISCV_UNKNOWN_VERSION
> + && ext->minor_version != RISCV_UNKNOWN_VERSION);
> +}
> +
> +static
> +void riscv_print_extensions(void)
> +{
> + /* Record the previous pritned extension.
> + Print the current one if they are not the same. */
> + const struct riscv_supported_ext *cur = NULL, *prev = NULL;
> +
> + int i, j;
> + printf ("All available -march extensions for RISC-V:");
> + for (i = 0; riscv_all_supported_ext[i] != NULL; i++)
> + {
> + const struct riscv_supported_ext *exts = riscv_all_supported_ext[i];
> + prev = NULL;
> + for (j = 0; exts[j].name != NULL; j++)
> + {
> + cur = &exts[j];
> + if (!riscv_valid_ext (cur))
> + continue;
> +
> + if (prev && riscv_same_extension_version (prev, cur))
> + continue;
> +
> + if (!prev || !riscv_same_extension_diff_version (prev, cur))
> + {
> + printf("\n\t%-40s%d.%d", cur->name, cur->major_version, cur->minor_version);
> + prev = &exts[j];
> + }
> + else
> + {
> + printf(", %d.%d", cur->major_version, cur->minor_version);
> + prev = &exts[j];
> + }
> + }
> + }
> + printf ("\n");
> +}
> +
> /* Function for parsing ISA string.
>
> Return Value:
> @@ -2089,6 +2154,13 @@ riscv_parse_subset (riscv_parse_subset_t *rps,
> }
>
> p = arch;
> + /* List all avaiable archs. */
> + if (strcmp (p, "help") == 0)
> + {
> + riscv_print_extensions();
> + exit (EXIT_SUCCESS);
> + }
> +
> if (startswith (p, "rv32"))
> {
> *rps->xlen = 32;
next prev parent reply other threads:[~2024-01-30 8:43 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-30 6:36 Hau Hsu
2024-01-30 8:43 ` Tsukasa OI [this message]
2024-01-30 12:32 ` Hau Hsu
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