[v5] Add retain attribute to place symbols in SHF_GNU_RETAIN section

Message ID CAMe9rOoQ1M7kBmPT7ZB3OwoRQJH11_WRytFXVTYuAfrDtXs0Dg@mail.gmail.com
State Superseded
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Series
  • [v5] Add retain attribute to place symbols in SHF_GNU_RETAIN section
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Commit Message

Patrick Palka via Gcc-patches Feb. 17, 2021, 8:50 p.m.
On Wed, Feb 17, 2021 at 12:14 PM Jakub Jelinek <jakub@redhat.com> wrote:
>

> 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/


Fixed.

> > +  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.


Fixed.

> > +  if (SUPPORTS_SHF_GNU_RETAIN

> > +      && (TREE_CODE (node) == FUNCTION_DECL

> > +       || (VAR_P (node) && TREE_STATIC (node))

> > +       || (TREE_CODE (node) == TYPE_DECL)))

>

> Likewise.


Fixed.

> > +    ;

> > +  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.


Fixed.

> > +@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.


Fixed.

> >    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.


Fixed.

> > @@ -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

> >


Here is the updated patch.

-- 
H.J.

Patch

From 28017e20ba70140f812934c91673ba4e7b4493c4 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Mon, 15 Feb 2021 11:31:12 -0800
Subject: [PATCH v5] Add retain attribute to place symbols in SHF_GNU_RETAIN
 section

When building Linux kernel, ld in bninutils 2.36 with GCC 11 generates
thousands of

ld: warning: orphan section `.data.event_initcall_finish' from `init/main.o' being placed in section `.data.event_initcall_finish'
ld: warning: orphan section `.data.event_initcall_start' from `init/main.o' being placed in section `.data.event_initcall_start'
ld: warning: orphan section `.data.event_initcall_level' from `init/main.o' being placed in section `.data.event_initcall_level'

Since these sections are marked with SHF_GNU_RETAIN, they are placed in
separate sections.  They become orphan sections since they aren't expected
in the Linux kernel linker script. But orphan sections normally don't work
well with the Linux kernel linker script and the resulting kernel crashed.

1. Add the "retain" attribute to place symbols in separate SHF_GNU_RETAIN
sections.  Issue a warning if the configured assembler/linker doesn't
support SHF_GNU_RETAIN.
2. Add -fretain-used-symbols to treat symbols with the "used" attribute
the same as the @code{retain} attribute.

gcc/

	PR target/99113
	* attribs.c (decl_attributes): Imply "retain" attribute for
	"used" attribute when -fretain-used-symbols is used.
	* common.opt: Add -fretain-used-symbols.
	* toplev.c (process_options): Issue a warning for
	-fretain-used-symbols without SUPPORTS_SHF_GNU_RETAIN.
	* varasm.c (get_section): Replace SUPPORTS_SHF_GNU_RETAIN with
	looking up the retain attribute.
	(resolve_unique_section): Likewise.
	(get_variable_section): Likewise.
	(switch_to_section): Likewise.
	* doc/extend.texi: Document the "retain" attribute.
	* doc/invoke.texi: Document -fretain-used-symbols.

gcc/c-family/

	PR target/99113
	* c-attribs.c (c_common_attribute_table): Add the "retain"
	attribute.
	(handle_retain_attribute): New function.

gcc/testsuite/

	PR target/99113
	* c-c++-common/attr-retain-1.c: New test.
	* c-c++-common/attr-retain-2.c: Likewise.
	* c-c++-common/attr-retain-3.c: Likewise.
	* c-c++-common/attr-retain-4.c: Likewise.
	* c-c++-common/pr99113.c: Likewise.
	* gcc.c-torture/compile/attr-retain-1.c: Likewise.
	* gcc.c-torture/compile/attr-retain-2.c: Likewise.
	* c-c++-common/attr-used.c: Pass -fretain-used-symbols if supported.
	* c-c++-common/attr-used-2.c: Likewise.
	* c-c++-common/attr-used-3.c: Likewise.
	* c-c++-common/attr-used-4.c: Likewise.
	* c-c++-common/attr-used-5.c: Likewise.
	* c-c++-common/attr-used-6.c: Likewise.
	* c-c++-common/attr-used-7.c: Likewise.
	* c-c++-common/attr-used-8.c: Likewise.
	* c-c++-common/attr-used-9.c: Likewise.
	* gcc.c-torture/compile/attr-used-retain-1.c: Pass
	-fretain-used-symbols.
	* gcc.c-torture/compile/attr-used-retain-2.c: Likewise.
---
 gcc/attribs.c                                 | 13 +++++++
 gcc/c-family/c-attribs.c                      | 25 ++++++++++++++
 gcc/common.opt                                |  4 +++
 gcc/doc/extend.texi                           |  8 +++--
 gcc/doc/invoke.texi                           |  6 ++++
 gcc/testsuite/c-c++-common/attr-retain-1.c    | 16 +++++++++
 gcc/testsuite/c-c++-common/attr-retain-2.c    | 12 +++++++
 gcc/testsuite/c-c++-common/attr-retain-3.c    |  7 ++++
 gcc/testsuite/c-c++-common/attr-retain-4.c    |  7 ++++
 gcc/testsuite/c-c++-common/attr-used-2.c      |  1 +
 gcc/testsuite/c-c++-common/attr-used-3.c      |  1 +
 gcc/testsuite/c-c++-common/attr-used-4.c      |  1 +
 gcc/testsuite/c-c++-common/attr-used-5.c      |  1 +
 gcc/testsuite/c-c++-common/attr-used-6.c      |  1 +
 gcc/testsuite/c-c++-common/attr-used-7.c      |  1 +
 gcc/testsuite/c-c++-common/attr-used-8.c      |  1 +
 gcc/testsuite/c-c++-common/attr-used-9.c      |  1 +
 gcc/testsuite/c-c++-common/attr-used.c        |  1 +
 gcc/testsuite/c-c++-common/pr99113.c          |  7 ++++
 .../gcc.c-torture/compile/attr-retain-1.c     | 34 +++++++++++++++++++
 .../gcc.c-torture/compile/attr-retain-2.c     | 15 ++++++++
 .../compile/attr-used-retain-1.c              |  1 +
 .../compile/attr-used-retain-2.c              |  2 +-
 gcc/toplev.c                                  |  7 ++++
 gcc/varasm.c                                  | 17 +++++-----
 25 files changed, 178 insertions(+), 12 deletions(-)
 create mode 100644 gcc/testsuite/c-c++-common/attr-retain-1.c
 create mode 100644 gcc/testsuite/c-c++-common/attr-retain-2.c
 create mode 100644 gcc/testsuite/c-c++-common/attr-retain-3.c
 create mode 100644 gcc/testsuite/c-c++-common/attr-retain-4.c
 create mode 100644 gcc/testsuite/c-c++-common/pr99113.c
 create mode 100644 gcc/testsuite/gcc.c-torture/compile/attr-retain-1.c
 create mode 100644 gcc/testsuite/gcc.c-torture/compile/attr-retain-2.c

diff --git a/gcc/attribs.c b/gcc/attribs.c
index 81322d40f1d..a5c2a8bf3a8 100644
--- a/gcc/attribs.c
+++ b/gcc/attribs.c
@@ -546,6 +546,19 @@  decl_attributes (tree *node, tree attributes, int flags,
 	attributes = tree_cons (get_identifier ("no_icf"),  NULL, attributes);
     }
 
+  /* For -fretain-used-symbols, a "used" attribute also implies "retain".  */
+  if (flag_retain_used_symbols
+      && attributes
+      && (TREE_CODE (*node) == FUNCTION_DECL
+	  || (VAR_P (*node) && TREE_STATIC (*node)))
+      && lookup_attribute ("used", attributes) != NULL
+      && lookup_attribute_spec (get_identifier ("used")))
+    {
+      if (lookup_attribute ("retain", attributes) == NULL)
+	attributes = tree_cons (get_identifier ("retain"), NULL,
+				attributes);
+    }
+
   targetm.insert_attributes (*node, &attributes);
 
   /* Note that attributes on the same declaration are not necessarily
diff --git a/gcc/c-family/c-attribs.c b/gcc/c-family/c-attribs.c
index 0cb51fddfaa..ae31e4c1f6f 100644
--- a/gcc/c-family/c-attribs.c
+++ b/gcc/c-family/c-attribs.c
@@ -163,6 +163,7 @@  static tree handle_objc_root_class_attribute (tree *, tree, tree, int, bool *);
 static tree handle_objc_nullability_attribute (tree *, tree, tree, int, bool *);
 static tree handle_signed_bool_precision_attribute (tree *, tree, tree, int,
 						    bool *);
+static tree handle_retain_attribute (tree *, tree, tree, int, bool *);
 
 /* Helper to define attribute exclusions.  */
 #define ATTR_EXCL(name, function, type, variable)	\
@@ -328,6 +329,8 @@  const struct attribute_spec c_common_attribute_table[] =
 			      handle_used_attribute, NULL },
   { "unused",                 0, 0, false, false, false, false,
 			      handle_unused_attribute, NULL },
+  { "retain",                 0, 0, true,  false, false, false,
+			      handle_retain_attribute, NULL },
   { "externally_visible",     0, 0, true,  false, false, false,
 			      handle_externally_visible_attribute, NULL },
   { "no_reorder",	      0, 0, true, false, false, false,
@@ -1564,6 +1567,28 @@  handle_unused_attribute (tree *node, tree name, tree ARG_UNUSED (args),
   return NULL_TREE;
 }
 
+/* Handle a "retain" attribute; arguments as in
+   struct attribute_spec.handler.  */
+
+static tree
+handle_retain_attribute (tree *pnode, tree name, tree ARG_UNUSED (args),
+			 int ARG_UNUSED (flags), bool *no_add_attrs)
+{
+  tree node = *pnode;
+
+  if (SUPPORTS_SHF_GNU_RETAIN
+      && (TREE_CODE (node) == FUNCTION_DECL
+	  || (VAR_P (node) && TREE_STATIC (node))))
+    ;
+  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..3d7567fd0e7 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 imply the retain attribute if supported.
+
 frounding-math
 Common Var(flag_rounding_math) Optimization SetByCombined
 Disable optimizations that assume default FP rounding behavior.
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 6eb1d327e97..8bbb93724a9 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -3913,8 +3913,10 @@  When applied to a member function of a C++ class template, the
 attribute also means that the function is instantiated if the
 class itself is instantiated.
 
+@item retain
+@cindex @code{retain} function attribute
 For ELF targets that support the GNU or FreeBSD OSABIs, this attribute
-will also save the function from linker garbage collection.  To support
+will save the function from linker garbage collection.  To support
 this behavior, functions that have not been placed in specific sections
 (e.g. by the @code{section} attribute, or the @code{-ffunction-sections}
 option), will be placed in new, unique sections.
@@ -7504,8 +7506,10 @@  When applied to a static data member of a C++ class template, the
 attribute also means that the member is instantiated if the
 class itself is instantiated.
 
+@item retain
+@cindex @code{retain} variable attribute
 For ELF targets that support the GNU or FreeBSD OSABIs, this attribute
-will also save the variable from linker garbage collection.  To support
+will save the variable from linker garbage collection.  To support
 this behavior, variables that have not been placed in specific sections
 (e.g. by the @code{section} attribute, or the @code{-fdata-sections} option),
 will be placed in new, unique sections.
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index e8baa545eee..8e91ff84f5c 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -16168,6 +16168,12 @@  DSOs; if your program relies on reinitialization of a DSO via
 @code{dlclose} and @code{dlopen}, you can use
 @option{-fno-gnu-unique}.
 
+@item -fretain-used-symbols
+@opindex fretain-used-symbols
+On ELF systems that support the GNU or FreeBSD OSABIs, with GNU binutils
+2.36 or later, the compiler makes the @code{used} attribute imply the
+@code{retain} attribute.
+
 @item -fpcc-struct-return
 @opindex fpcc-struct-return
 Return ``short'' @code{struct} and @code{union} values in memory like
diff --git a/gcc/testsuite/c-c++-common/attr-retain-1.c b/gcc/testsuite/c-c++-common/attr-retain-1.c
new file mode 100644
index 00000000000..d060fbf22cd
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/attr-retain-1.c
@@ -0,0 +1,16 @@ 
+/* { dg-do compile { target R_flag_in_section } } */
+/* { dg-options "-O3" } */
+
+static void function_declaration_before(void)
+  __attribute__((__used__, __retain__));
+
+static void function_declaration_before(void) {}
+
+static void function_declaration_after(void) {}
+
+static void function_declaration_after(void)
+  __attribute__((__used__, __retain__));
+
+/* { dg-final { scan-assembler "function_declaration_before" } } */
+/* { dg-final { scan-assembler "function_declaration_after" } } */
+/* { dg-final { scan-assembler "\.text.*,\"axR\"" { target R_flag_in_section } } } */
diff --git a/gcc/testsuite/c-c++-common/attr-retain-2.c b/gcc/testsuite/c-c++-common/attr-retain-2.c
new file mode 100644
index 00000000000..6baba844adc
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/attr-retain-2.c
@@ -0,0 +1,12 @@ 
+/* { dg-do compile { target R_flag_in_section } } */
+/* { dg-options "-Wall -O2" } */
+
+static int xyzzy __attribute__((__used__, __retain__)) = 1; 
+
+void foo()
+{
+  int x __attribute__((__retain__)); /* { dg-warning "attribute ignored|unused variable" } */
+}
+
+/* { dg-final { scan-assembler "xyzzy" } } */
+/* { dg-final { scan-assembler "\.data.*,\"awR\"" { target R_flag_in_section } } } */
diff --git a/gcc/testsuite/c-c++-common/attr-retain-3.c b/gcc/testsuite/c-c++-common/attr-retain-3.c
new file mode 100644
index 00000000000..a4077a1644d
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/attr-retain-3.c
@@ -0,0 +1,7 @@ 
+/* { dg-do compile { target R_flag_in_section } } */
+/* { dg-options "-Wall -O2 -fcommon" } */
+
+static int xyzzy __attribute__((__used__, __retain__)); 
+
+/* { dg-final { scan-assembler "xyzzy" } } */
+/* { dg-final { scan-assembler ",\"awR\"" { target R_flag_in_section } } } */
diff --git a/gcc/testsuite/c-c++-common/attr-retain-4.c b/gcc/testsuite/c-c++-common/attr-retain-4.c
new file mode 100644
index 00000000000..590e47cec86
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/attr-retain-4.c
@@ -0,0 +1,7 @@ 
+/* { dg-do compile { target R_flag_in_section } } */
+/* { dg-options "-Wall -O2 -fcommon" } */
+
+int xyzzy __attribute__((__used__, __retain__)); 
+
+/* { dg-final { scan-assembler "xyzzy" } } */
+/* { dg-final { scan-assembler ",\"awR\"" { target R_flag_in_section } } } */
diff --git a/gcc/testsuite/c-c++-common/attr-used-2.c b/gcc/testsuite/c-c++-common/attr-used-2.c
index eef2519643f..2614e90bdfd 100644
--- a/gcc/testsuite/c-c++-common/attr-used-2.c
+++ b/gcc/testsuite/c-c++-common/attr-used-2.c
@@ -1,5 +1,6 @@ 
 /* { dg-do compile } */
 /* { dg-options "-Wall -O2" } */
+/* { dg-additional-options "-fretain-used-symbols" { target R_flag_in_section } } */
 
 static int xyzzy __attribute__((__used__)) = 1; 
 
diff --git a/gcc/testsuite/c-c++-common/attr-used-3.c b/gcc/testsuite/c-c++-common/attr-used-3.c
index ca64197929c..ea40d30ebb3 100644
--- a/gcc/testsuite/c-c++-common/attr-used-3.c
+++ b/gcc/testsuite/c-c++-common/attr-used-3.c
@@ -1,5 +1,6 @@ 
 /* { dg-do compile } */
 /* { dg-options "-Wall -O2 -fcommon" } */
+/* { dg-additional-options "-fretain-used-symbols" { target R_flag_in_section } } */
 
 static int xyzzy __attribute__((__used__)); 
 
diff --git a/gcc/testsuite/c-c++-common/attr-used-4.c b/gcc/testsuite/c-c++-common/attr-used-4.c
index 1cbc4c703e9..805d55e66b4 100644
--- a/gcc/testsuite/c-c++-common/attr-used-4.c
+++ b/gcc/testsuite/c-c++-common/attr-used-4.c
@@ -1,5 +1,6 @@ 
 /* { dg-do compile } */
 /* { dg-options "-Wall -O2 -fcommon" } */
+/* { dg-additional-options "-fretain-used-symbols" { target R_flag_in_section } } */
 
 int xyzzy __attribute__((__used__)); 
 
diff --git a/gcc/testsuite/c-c++-common/attr-used-5.c b/gcc/testsuite/c-c++-common/attr-used-5.c
index 5b4924160fd..0abdd527516 100644
--- a/gcc/testsuite/c-c++-common/attr-used-5.c
+++ b/gcc/testsuite/c-c++-common/attr-used-5.c
@@ -1,6 +1,7 @@ 
 /* { dg-do compile } */
 /* { dg-skip-if "non-ELF target" { *-*-darwin* } } */
 /* { dg-options "-Wall -O2" } */
+/* { dg-additional-options "-fretain-used-symbols" { target R_flag_in_section } } */
 
 struct dtv_slotinfo_list
 {
diff --git a/gcc/testsuite/c-c++-common/attr-used-6.c b/gcc/testsuite/c-c++-common/attr-used-6.c
index 3cf288dd28f..cf9b433dc24 100644
--- a/gcc/testsuite/c-c++-common/attr-used-6.c
+++ b/gcc/testsuite/c-c++-common/attr-used-6.c
@@ -1,6 +1,7 @@ 
 /* { dg-do compile } */
 /* { dg-skip-if "non-ELF target" { *-*-darwin* } } */
 /* { dg-options "-Wall -O2" } */
+/* { dg-additional-options "-fretain-used-symbols" { target R_flag_in_section } } */
 
 struct dtv_slotinfo_list
 {
diff --git a/gcc/testsuite/c-c++-common/attr-used-7.c b/gcc/testsuite/c-c++-common/attr-used-7.c
index 1721a8afc4e..2be2ecdb5da 100644
--- a/gcc/testsuite/c-c++-common/attr-used-7.c
+++ b/gcc/testsuite/c-c++-common/attr-used-7.c
@@ -1,6 +1,7 @@ 
 /* { dg-do compile } */
 /* { dg-skip-if "non-ELF target" { *-*-darwin* } } */
 /* { dg-options "-Wall -O2" } */
+/* { dg-additional-options "-fretain-used-symbols" { target R_flag_in_section } } */
 
 int __attribute__((used,section(".data.foo"))) foo2 = 2;
 int __attribute__((section(".data.foo"))) foo1 = 1;
diff --git a/gcc/testsuite/c-c++-common/attr-used-8.c b/gcc/testsuite/c-c++-common/attr-used-8.c
index 20662cadf70..9ebd9462880 100644
--- a/gcc/testsuite/c-c++-common/attr-used-8.c
+++ b/gcc/testsuite/c-c++-common/attr-used-8.c
@@ -1,6 +1,7 @@ 
 /* { dg-do compile } */
 /* { dg-skip-if "non-ELF target" { *-*-darwin* } } */
 /* { dg-options "-Wall -O2" } */
+/* { dg-additional-options "-fretain-used-symbols" { target R_flag_in_section } } */
 
 int __attribute__((section(".data.foo"))) foo1 = 1;
 /* { dg-warning "'.*' without 'used' attribute and '.*' with 'used' attribute are placed in a section with the same name" "" { target R_flag_in_section } .-1 } */
diff --git a/gcc/testsuite/c-c++-common/attr-used-9.c b/gcc/testsuite/c-c++-common/attr-used-9.c
index 5847b0550ce..29d71512085 100644
--- a/gcc/testsuite/c-c++-common/attr-used-9.c
+++ b/gcc/testsuite/c-c++-common/attr-used-9.c
@@ -1,6 +1,7 @@ 
 /* { dg-do compile } */
 /* { dg-skip-if "non-ELF target" { *-*-darwin* } } */
 /* { dg-options "-Wall -O2" } */
+/* { dg-additional-options "-fretain-used-symbols" { target R_flag_in_section } } */
 
 struct dtv_slotinfo_list
 {
diff --git a/gcc/testsuite/c-c++-common/attr-used.c b/gcc/testsuite/c-c++-common/attr-used.c
index 2036533c959..38480df3afa 100644
--- a/gcc/testsuite/c-c++-common/attr-used.c
+++ b/gcc/testsuite/c-c++-common/attr-used.c
@@ -1,5 +1,6 @@ 
 /* { dg-do compile } */
 /* { dg-options "-O3" } */
+/* { dg-additional-options "-fretain-used-symbols" { target R_flag_in_section } } */
 
 static void function_declaration_before(void) __attribute__((__used__));
 
diff --git a/gcc/testsuite/c-c++-common/pr99113.c b/gcc/testsuite/c-c++-common/pr99113.c
new file mode 100644
index 00000000000..01814014ac8
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/pr99113.c
@@ -0,0 +1,7 @@ 
+/* { dg-do compile } */
+/* { dg-options "-Wall -O2" } */
+
+static int xyzzy __attribute__((__used__)) = 1; 
+
+/* { dg-final { scan-assembler "xyzzy" } } */
+/* { dg-final { scan-assembler-not "\.data.*,\"awR\"" { target R_flag_in_section } } } */
diff --git a/gcc/testsuite/gcc.c-torture/compile/attr-retain-1.c b/gcc/testsuite/gcc.c-torture/compile/attr-retain-1.c
new file mode 100644
index 00000000000..6cab15547cc
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/attr-retain-1.c
@@ -0,0 +1,34 @@ 
+/* { dg-do compile { target R_flag_in_section } } */
+/* { dg-final { scan-assembler ".text.*,\"axR\"" } } */
+/* { dg-final { scan-assembler ".bss.*,\"awR\"" } } */
+/* { dg-final { scan-assembler ".data.*,\"awR\"" } } */
+/* { dg-final { scan-assembler ".rodata.*,\"aR\"" } } */
+/* { dg-final { scan-assembler ".data.used_foo_sec,\"awR\"" } } */
+
+void __attribute__((used,retain)) used_fn (void) { }
+void unused_fn (void) { }
+void __attribute__((hot,used,retain)) used_hot_fn (void) { }
+void __attribute__((hot)) unused_hot_fn (void) { }
+void __attribute__((cold,used,retain)) used_cold_fn (void) { }
+void __attribute__((cold)) unused_cold_fn (void) { }
+int __attribute__((used,retain)) used_bss = 0;
+int __attribute__((used,retain)) used_data = 1;
+const int __attribute__((used,retain)) used_rodata = 2;
+int __attribute__((used,retain)) used_comm;
+static int __attribute__((used,retain)) used_lcomm;
+
+int unused_bss = 0;
+int unused_data = 1;
+const int unused_rodata = 2;
+int unused_comm;
+static int unused_lcomm;
+
+/* Test switching back to the used,retained sections.  */
+void __attribute__((used,retain)) used_fn2 (void) { }
+int __attribute__((used,retain)) used_bss2 = 0;
+int __attribute__((used,retain)) used_data2 = 1;
+const int __attribute__((used,retain)) used_rodata2 = 2;
+int __attribute__((used,retain)) used_comm2;
+static int __attribute__((used,retain)) used_lcomm2;
+
+int __attribute__((used,retain,section(".data.used_foo_sec"))) used_foo = 2;
diff --git a/gcc/testsuite/gcc.c-torture/compile/attr-retain-2.c b/gcc/testsuite/gcc.c-torture/compile/attr-retain-2.c
new file mode 100644
index 00000000000..0208ffe37ab
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/attr-retain-2.c
@@ -0,0 +1,15 @@ 
+/* { dg-do compile { target R_flag_in_section } } */
+/* { dg-final { scan-assembler ".text.used_fn,\"axR\"" } } */
+/* { dg-final { scan-assembler ".text.used_fn2,\"axR\"" } } */
+/* { dg-final { scan-assembler ".bss.used_bss,\"awR\"" } } */
+/* { dg-final { scan-assembler ".bss.used_bss2,\"awR\"" } } */
+/* { dg-final { scan-assembler ".data.used_data,\"awR\"" } } */
+/* { dg-final { scan-assembler ".data.used_data2,\"awR\"" } } */
+/* { dg-final { scan-assembler ".rodata.used_rodata,\"aR\"" } } */
+/* { dg-final { scan-assembler ".rodata.used_rodata2,\"aR\"" } } */
+/* { dg-final { scan-assembler ".bss.used_lcomm,\"awR\"" { target arm-*-* } } } */
+/* { dg-final { scan-assembler ".bss.used_lcomm2,\"awR\"" { target arm-*-* } } } */
+/* { dg-final { scan-assembler ".data.used_foo_sec,\"awR\"" } } */
+/* { dg-options "-ffunction-sections -fdata-sections" } */
+
+#include "attr-retain-1.c"
diff --git a/gcc/testsuite/gcc.c-torture/compile/attr-used-retain-1.c b/gcc/testsuite/gcc.c-torture/compile/attr-used-retain-1.c
index 5f6cbca6e33..a1eea089ccd 100644
--- a/gcc/testsuite/gcc.c-torture/compile/attr-used-retain-1.c
+++ b/gcc/testsuite/gcc.c-torture/compile/attr-used-retain-1.c
@@ -5,6 +5,7 @@ 
 /* { dg-final { scan-assembler ".data.*,\"awR\"" } } */
 /* { dg-final { scan-assembler ".rodata.*,\"aR\"" } } */
 /* { dg-final { scan-assembler ".data.used_foo_sec,\"awR\"" } } */
+/* { dg-options "-fretain-used-symbols" } */
 
 void __attribute__((used)) used_fn (void) { }
 void unused_fn (void) { }
diff --git a/gcc/testsuite/gcc.c-torture/compile/attr-used-retain-2.c b/gcc/testsuite/gcc.c-torture/compile/attr-used-retain-2.c
index be5f3917ac8..a8c3a891b05 100644
--- a/gcc/testsuite/gcc.c-torture/compile/attr-used-retain-2.c
+++ b/gcc/testsuite/gcc.c-torture/compile/attr-used-retain-2.c
@@ -11,6 +11,6 @@ 
 /* { dg-final { scan-assembler ".bss.used_lcomm,\"awR\"" { target arm-*-* } } } */
 /* { dg-final { scan-assembler ".bss.used_lcomm2,\"awR\"" { target arm-*-* } } } */
 /* { dg-final { scan-assembler ".data.used_foo_sec,\"awR\"" } } */
-/* { dg-options "-ffunction-sections -fdata-sections" } */
+/* { dg-options "-ffunction-sections -fdata-sections -fretain-used-symbols" } */
 
 #include "attr-used-retain-1.c"
diff --git a/gcc/toplev.c b/gcc/toplev.c
index d8cc254adef..d84e89085a5 100644
--- a/gcc/toplev.c
+++ b/gcc/toplev.c
@@ -1761,6 +1761,13 @@  process_options (void)
   if (flag_large_source_files)
     line_table->default_range_bits = 0;
 
+  if (flag_retain_used_symbols && !SUPPORTS_SHF_GNU_RETAIN)
+    {
+      warning_at (UNKNOWN_LOCATION, 0, "%qs is not supported for this target",
+		  "-fretain-used-symbols");
+      flag_retain_used_symbols = 0;
+    }
+
   /* Please don't change global_options after this point, those changes won't
      be reflected in optimization_{default,current}_node.  */
 }
diff --git a/gcc/varasm.c b/gcc/varasm.c
index 29478ab0d8d..b3e9241e180 100644
--- a/gcc/varasm.c
+++ b/gcc/varasm.c
@@ -297,10 +297,9 @@  get_section (const char *name, unsigned int flags, tree decl,
   slot = section_htab->find_slot_with_hash (name, htab_hash_string (name),
 					    INSERT);
   flags |= SECTION_NAMED;
-  if (SUPPORTS_SHF_GNU_RETAIN
-      && decl != nullptr
+  if (decl != nullptr
       && DECL_P (decl)
-      && DECL_PRESERVE_P (decl))
+      && lookup_attribute ("retain", DECL_ATTRIBUTES (decl)))
     flags |= SECTION_RETAIN;
   if (*slot == NULL)
     {
@@ -487,7 +486,7 @@  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))
+	  || lookup_attribute ("retain", DECL_ATTRIBUTES (decl))
 	  || DECL_COMDAT_GROUP (decl)))
     {
       targetm.asm_out.unique_section (decl, reloc);
@@ -1227,7 +1226,7 @@  get_variable_section (tree decl, bool prefer_noswitch_p)
     vnode->get_constructor ();
 
   if (DECL_COMMON (decl)
-      && !(SUPPORTS_SHF_GNU_RETAIN && 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 +7760,12 @@  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)))
+	  && (!!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