V4 [PATCH 1/3] Switch to a new section if the SECTION_RETAIN bit doesn't match
H.J. Lu
hjl.tools@gmail.com
Tue Dec 15 17:30:29 GMT 2020
When definitions marked with used attribute and unmarked definitions are
placed in the section with the same name, switch to a new section if the
SECTION_RETAIN bit doesn't match.
gcc/
PR target/98146
* output.h (switch_to_section): Add a tree argument, default to
nullptr.
* varasm.c (get_section): If the SECTION_RETAIN bit doesn't match,
return and switch to a new section later.
(assemble_start_function): Pass decl to switch_to_section.
(assemble_variable): Likewise.
(switch_to_section): If the SECTION_RETAIN bit doesn't match,
switch to a new section.
gcc/testsuite/
PR target/98146
* c-c++-common/attr-used-5.c: New test.
* 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/output.h | 2 +-
gcc/testsuite/c-c++-common/attr-used-5.c | 26 ++++++++++++++++++
gcc/testsuite/c-c++-common/attr-used-6.c | 26 ++++++++++++++++++
gcc/testsuite/c-c++-common/attr-used-7.c | 8 ++++++
gcc/testsuite/c-c++-common/attr-used-8.c | 8 ++++++
gcc/testsuite/c-c++-common/attr-used-9.c | 28 +++++++++++++++++++
gcc/varasm.c | 34 ++++++++++++++++++++----
7 files changed, 126 insertions(+), 6 deletions(-)
create mode 100644 gcc/testsuite/c-c++-common/attr-used-5.c
create mode 100644 gcc/testsuite/c-c++-common/attr-used-6.c
create mode 100644 gcc/testsuite/c-c++-common/attr-used-7.c
create mode 100644 gcc/testsuite/c-c++-common/attr-used-8.c
create mode 100644 gcc/testsuite/c-c++-common/attr-used-9.c
diff --git a/gcc/output.h b/gcc/output.h
index fa8ace1f394..1f9af46da1d 100644
--- a/gcc/output.h
+++ b/gcc/output.h
@@ -548,7 +548,7 @@ extern void switch_to_other_text_partition (void);
extern section *get_cdtor_priority_section (int, bool);
extern bool unlikely_text_section_p (section *);
-extern void switch_to_section (section *);
+extern void switch_to_section (section *, tree = nullptr);
extern void output_section_asm_op (const void *);
extern void record_tm_clone_pair (tree, tree);
diff --git a/gcc/testsuite/c-c++-common/attr-used-5.c b/gcc/testsuite/c-c++-common/attr-used-5.c
new file mode 100644
index 00000000000..9fc0d3834e9
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/attr-used-5.c
@@ -0,0 +1,26 @@
+/* { dg-do compile } */
+/* { dg-options "-Wall -O2" } */
+
+struct dtv_slotinfo_list
+{
+ struct dtv_slotinfo_list *next;
+};
+
+extern struct dtv_slotinfo_list *list;
+
+static int __attribute__ ((section ("__libc_freeres_fn")))
+free_slotinfo (struct dtv_slotinfo_list **elemp)
+{
+ if (!free_slotinfo (&(*elemp)->next))
+ return 0;
+ return 1;
+}
+
+__attribute__ ((used, section ("__libc_freeres_fn")))
+static void free_mem (void)
+{
+ free_slotinfo (&list);
+}
+
+/* { dg-final { scan-assembler "__libc_freeres_fn,\"ax\"" { target R_flag_in_section } } } */
+/* { dg-final { scan-assembler "__libc_freeres_fn,\"axR\"" { target R_flag_in_section } } } */
diff --git a/gcc/testsuite/c-c++-common/attr-used-6.c b/gcc/testsuite/c-c++-common/attr-used-6.c
new file mode 100644
index 00000000000..0cb82ade5a9
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/attr-used-6.c
@@ -0,0 +1,26 @@
+/* { dg-do compile } */
+/* { dg-options "-Wall -O2" } */
+
+struct dtv_slotinfo_list
+{
+ struct dtv_slotinfo_list *next;
+};
+
+extern struct dtv_slotinfo_list *list;
+
+static int __attribute__ ((used, section ("__libc_freeres_fn")))
+free_slotinfo (struct dtv_slotinfo_list **elemp)
+{
+ if (!free_slotinfo (&(*elemp)->next))
+ return 0;
+ return 1;
+}
+
+__attribute__ ((section ("__libc_freeres_fn")))
+void free_mem (void)
+{
+ free_slotinfo (&list);
+}
+
+/* { dg-final { scan-assembler "__libc_freeres_fn,\"ax\"" { target R_flag_in_section } } } */
+/* { dg-final { scan-assembler "__libc_freeres_fn,\"axR\"" { target R_flag_in_section } } } */
diff --git a/gcc/testsuite/c-c++-common/attr-used-7.c b/gcc/testsuite/c-c++-common/attr-used-7.c
new file mode 100644
index 00000000000..fba2706ffc1
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/attr-used-7.c
@@ -0,0 +1,8 @@
+/* { dg-do compile } */
+/* { dg-options "-Wall -O2" } */
+
+int __attribute__((used,section(".data.foo"))) foo2 = 2;
+int __attribute__((section(".data.foo"))) foo1 = 1;
+
+/* { dg-final { scan-assembler ".data.foo,\"aw\"" { target R_flag_in_section } } } */
+/* { dg-final { scan-assembler ".data.foo,\"awR\"" { target R_flag_in_section } } } */
diff --git a/gcc/testsuite/c-c++-common/attr-used-8.c b/gcc/testsuite/c-c++-common/attr-used-8.c
new file mode 100644
index 00000000000..4da4aabe573
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/attr-used-8.c
@@ -0,0 +1,8 @@
+/* { dg-do compile } */
+/* { dg-options "-Wall -O2" } */
+
+int __attribute__((section(".data.foo"))) foo1 = 1;
+int __attribute__((used,section(".data.foo"))) foo2 = 2;
+
+/* { dg-final { scan-assembler ".data.foo,\"aw\"" { target R_flag_in_section } } } */
+/* { dg-final { scan-assembler ".data.foo,\"awR\"" { target R_flag_in_section } } } */
diff --git a/gcc/testsuite/c-c++-common/attr-used-9.c b/gcc/testsuite/c-c++-common/attr-used-9.c
new file mode 100644
index 00000000000..cf3bde67622
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/attr-used-9.c
@@ -0,0 +1,28 @@
+/* { dg-do compile } */
+/* { dg-options "-Wall -O2" } */
+
+struct dtv_slotinfo_list
+{
+ struct dtv_slotinfo_list *next;
+};
+
+extern struct dtv_slotinfo_list *list;
+
+static int __attribute__ ((used, section ("__libc_freeres_fn")))
+free_slotinfo (struct dtv_slotinfo_list **elemp)
+{
+ if (!free_slotinfo (&(*elemp)->next))
+ return 0;
+ return 1;
+}
+
+__attribute__ ((section ("__libc_freeres_fn")))
+static void free_mem (void)
+/* { dg-warning "defined but not used" "" { target *-*-* } .-1 } */
+{
+ free_slotinfo (&list);
+}
+
+/* { dg-final { scan-assembler-not "__libc_freeres_fn\n" } } */
+/* { dg-final { scan-assembler-not "__libc_freeres_fn,\"ax\"" { target R_flag_in_section } } } */
+/* { dg-final { scan-assembler "__libc_freeres_fn,\"axR\"" { target R_flag_in_section } } } */
diff --git a/gcc/varasm.c b/gcc/varasm.c
index c5487a78b13..e3e49d53e5d 100644
--- a/gcc/varasm.c
+++ b/gcc/varasm.c
@@ -281,7 +281,8 @@ get_noswitch_section (unsigned int flags, noswitch_section_callback callback)
/* Return the named section structure associated with NAME. Create
a new section with the given fields if no such structure exists.
- When NOT_EXISTING, then fail if the section already exists. */
+ When NOT_EXISTING, then fail if the section already exists. Return
+ the existing section if the SECTION_RETAIN bit doesn't match. */
section *
get_section (const char *name, unsigned int flags, tree decl,
@@ -343,6 +344,11 @@ get_section (const char *name, unsigned int flags, tree decl,
sect->common.flags |= (SECTION_WRITE | SECTION_RELRO);
return sect;
}
+ /* If the SECTION_RETAIN bit doesn't match, return and switch
+ to a new section later. */
+ if ((sect->common.flags & SECTION_RETAIN)
+ != (flags & SECTION_RETAIN))
+ return sect;
/* Sanity check user variables for flag changes. */
if (sect->named.decl != NULL
&& DECL_P (sect->named.decl)
@@ -1879,7 +1885,7 @@ assemble_start_function (tree decl, const char *fnname)
/* Switch to the correct text section for the start of the function. */
- switch_to_section (function_section (decl));
+ switch_to_section (function_section (decl), decl);
if (crtl->has_bb_partition && !hot_label_written)
ASM_OUTPUT_LABEL (asm_out_file, crtl->subsections.hot_section_label);
@@ -2375,7 +2381,7 @@ assemble_variable (tree decl, int top_level ATTRIBUTE_UNUSED,
&& (strcmp (sect->named.name, ".vtable_map_vars") == 0))
handle_vtv_comdat_section (sect, decl);
else
- switch_to_section (sect);
+ switch_to_section (sect, decl);
if (align > BITS_PER_UNIT)
ASM_OUTPUT_ALIGN (asm_out_file, floor_log2 (align / BITS_PER_UNIT));
assemble_variable_contents (decl, name, dont_output_data,
@@ -7742,10 +7748,28 @@ output_section_asm_op (const void *directive)
the current section is NEW_SECTION. */
void
-switch_to_section (section *new_section)
+switch_to_section (section *new_section, tree decl)
{
if (in_section == new_section)
- return;
+ {
+ if (HAVE_GAS_SHF_GNU_RETAIN
+ && (new_section->common.flags & SECTION_NAMED)
+ && decl != nullptr
+ && DECL_P (decl)
+ && (!!DECL_PRESERVE_P (decl)
+ != !!(new_section->common.flags & SECTION_RETAIN)))
+ {
+ /* If the SECTION_RETAIN bit doesn't match, switch to a new
+ section. */
+ if (DECL_PRESERVE_P (decl))
+ new_section->common.flags |= SECTION_RETAIN;
+ else
+ new_section->common.flags &= ~(SECTION_RETAIN
+ | SECTION_DECLARED);
+ }
+ else
+ return;
+ }
if (new_section->common.flags & SECTION_FORGET)
in_section = NULL;
--
2.29.2
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