From: Richard Sandiford <richard.sandiford@arm.com>
To: HAO CHEN GUI <guihaoc@linux.ibm.com>
Cc: gcc-patches <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH] Put absolute address jump table in data.rel.ro.local if targets support relocations
Date: Fri, 13 Nov 2020 09:27:20 +0000 [thread overview]
Message-ID: <mpt8sb561zb.fsf@arm.com> (raw)
In-Reply-To: <c86c8036-f811-5440-6bd2-3d2e2a4e8baa@linux.ibm.com> (HAO CHEN GUI's message of "Thu, 22 Oct 2020 10:53:56 +0800")
Hi,
Sorry for the slow reply. Just one minor nit:
HAO CHEN GUI <guihaoc@linux.ibm.com> writes:
> diff --git a/gcc/varasm.c b/gcc/varasm.c
> index ea0b59cf44a..40502049b61 100644
> --- a/gcc/varasm.c
> +++ b/gcc/varasm.c
> @@ -727,12 +727,26 @@ switch_to_other_text_partition (void)
> switch_to_section (current_function_section ());
> }
>
> -/* Return the read-only data section associated with function DECL. */
> +/* Return the read-only or relocated read-only data section
> + associated with function DECL. */
>
> section *
> -default_function_rodata_section (tree decl)
> +default_function_rodata_section (tree decl, bool relocatable)
> {
> - if (decl != NULL_TREE && DECL_SECTION_NAME (decl))
> + const char* sname;
> + unsigned int flags;
> +
> + flags = 0;
> +
> + if (relocatable)
> + {
> + sname = ".data.rel.ro.local";
> + flags = (SECTION_WRITE | SECTION_RELRO);
> + }
> + else
> + sname = ".rodata";
> +
> + if (decl && DECL_SECTION_NAME (decl))
> {
> const char *name = DECL_SECTION_NAME (decl);
>
> @@ -745,38 +759,57 @@ default_function_rodata_section (tree decl)
> dot = strchr (name + 1, '.');
> if (!dot)
> dot = name;
> - len = strlen (dot) + 8;
> + len = strlen (dot) + strlen (sname) + 1;
> rname = (char *) alloca (len);
>
> - strcpy (rname, ".rodata");
> + strcpy (rname, sname);
> strcat (rname, dot);
> - return get_section (rname, SECTION_LINKONCE, decl);
> + return get_section (rname, (SECTION_LINKONCE | flags), decl);
> }
> - /* For .gnu.linkonce.t.foo we want to use .gnu.linkonce.r.foo. */
> + /* For .gnu.linkonce.t.foo we want to use .gnu.linkonce.r.foo or
> + .gnu.linkonce.d.rel.ro.local.foo if the jump table is relocatable. */
> else if (DECL_COMDAT_GROUP (decl)
> && strncmp (name, ".gnu.linkonce.t.", 16) == 0)
> {
> - size_t len = strlen (name) + 1;
> - char *rname = (char *) alloca (len);
> + size_t len;
> + char *rname;
>
> - memcpy (rname, name, len);
> - rname[14] = 'r';
> - return get_section (rname, SECTION_LINKONCE, decl);
> + if (relocatable)
> + {
> + len = strlen (name) + strlen (".rel.ro.local") + 1;
> + rname = (char *) alloca (len);
> +
> + strcpy (rname, ".gnu.linkonce.d");
> + strcat (rname, ".rel.ro.local");
> + strcat (rname, name + 15);
I realise you probably wrote it like this to make the correlation
between the length calculation and the string operations more
obvious, but IMO it would be less surprising to have:
strcpy (rname, ".gnu.linkonce.d.rel.ro.local");
OK with that change, thanks.
Richard
next prev parent reply other threads:[~2020-11-13 9:27 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-14 3:01 HAO CHEN GUI
2020-09-28 0:52 ` HAO CHEN GUI
2020-10-01 17:47 ` Richard Sandiford
2020-10-22 2:53 ` HAO CHEN GUI
2020-11-06 1:06 ` HAO CHEN GUI
2020-11-13 9:27 ` Richard Sandiford [this message]
2020-11-17 5:57 ` HAO CHEN GUI
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