On Wed, Feb 17, 2021 at 12:04:34PM -0800, H.J. Lu wrote:> >
> + /* For -fretain-used-symbol, a "used" attribute also implies "retain". */
s/-symbol/-symbols/
> + if (flag_retain_used_symbols
> + && attributes
> + && (TREE_CODE (*node) == FUNCTION_DECL
> + || (VAR_P (*node) && TREE_STATIC (*node))
> + || (TREE_CODE (*node) == TYPE_DECL))
What will "retain" do on TYPE_DECLs? It only makes sense to me
for FUNCTION_DECL or non-automatic VAR_DECLs, unless for types
it means the types with that result in vars with those types automatically
getting "retain", but there is no code for that and I don't see "used"
handled that way.
> + if (SUPPORTS_SHF_GNU_RETAIN
> + && (TREE_CODE (node) == FUNCTION_DECL
> + || (VAR_P (node) && TREE_STATIC (node))
> + || (TREE_CODE (node) == TYPE_DECL)))
Likewise.
> + ;
> + else
> + {
> + warning (OPT_Wattributes, "%qE attribute ignored", name);
> + *no_add_attrs = true;
> + }
> +
> + return NULL_TREE;
> +}
> +
> /* Handle a "externally_visible" attribute; arguments as in
> struct attribute_spec.handler. */
>
> diff --git a/gcc/common.opt b/gcc/common.opt
> index c75dd36843e..70842481d4d 100644
> --- a/gcc/common.opt
> +++ b/gcc/common.opt
> @@ -2404,6 +2404,10 @@ frerun-loop-opt
> Common Ignore
> Does nothing. Preserved for backward compatibility.
>
> +fretain-used-symbols
> +Common Var(flag_retain_used_symbols)
> +Make the used attribute to imply the retain attribute if supported.
English is not my native language, but I think the "to " doesn't belong
here.
> +@item -fretain-used-symbols
> +@opindex fretain-used-symbols
> +On systems with recent GNU assembler and linker, the compiler makes
I think we should avoid recent here, new/old/recent etc. are relative terms.
Either use exact version (is it 2.36 or later) or say GNU assembler and
linker that supports the @code{.retain} directive or something similar.
> flags |= SECTION_NAMED;
> - if (SUPPORTS_SHF_GNU_RETAIN
> - && decl != nullptr
> + if (decl != nullptr
> && DECL_P (decl)
> - && DECL_PRESERVE_P (decl))
> + && DECL_PRESERVE_P (decl)
> + && lookup_attribute ("retain", DECL_ATTRIBUTES (decl)))
> flags |= SECTION_RETAIN;
> if (*slot == NULL)
> {
I think none of the varasm.c code should use DECL_PRESERVE_P when it means
retain, just lookup_attribute.
> @@ -487,7 +487,8 @@ resolve_unique_section (tree decl, int reloc
> ATTRIBUTE_UNUSED,
> if (DECL_SECTION_NAME (decl) == NULL
> && targetm_common.have_named_sections
> && (flag_function_or_data_sections
> - || (SUPPORTS_SHF_GNU_RETAIN && DECL_PRESERVE_P (decl))
> + || (DECL_PRESERVE_P (decl)
> + && lookup_attribute ("retain", DECL_ATTRIBUTES (decl)))
> || DECL_COMDAT_GROUP (decl)))
> {
> targetm.asm_out.unique_section (decl, reloc);
> @@ -1227,7 +1228,8 @@ get_variable_section (tree decl, bool prefer_noswitch_p)
> vnode->get_constructor ();
>
> if (DECL_COMMON (decl)
> - && !(SUPPORTS_SHF_GNU_RETAIN && DECL_PRESERVE_P (decl)))
> + && !(DECL_PRESERVE_P (decl)
> + && lookup_attribute ("retain", DECL_ATTRIBUTES (decl))))
> {
> /* If the decl has been given an explicit section name, or it resides
> in a non-generic address space, then it isn't common, and shouldn't
> @@ -7761,12 +7763,14 @@ switch_to_section (section *new_section, tree decl)
> {
> if (in_section == new_section)
> {
> - if (SUPPORTS_SHF_GNU_RETAIN
> - && (new_section->common.flags & SECTION_NAMED)
> + if ((new_section->common.flags & SECTION_NAMED)
> && decl != nullptr
> && DECL_P (decl)
> && (!!DECL_PRESERVE_P (decl)
> - != !!(new_section->common.flags & SECTION_RETAIN)))
> + != !!(new_section->common.flags & SECTION_RETAIN))
> + && (lookup_attribute ("retain",
> + DECL_ATTRIBUTES (new_section->named.decl))
> + || lookup_attribute ("retain", DECL_ATTRIBUTES (decl))))
> {
> /* If the SECTION_RETAIN bit doesn't match, switch to a new
> section. */
> --
> 2.29.2
>
Jakub
