* V2 [PATCH 0/2] Switch to a new section if the SECTION_RETAIN bit doesn't match
@ 2020-12-04 16:17 H.J. Lu
2020-12-04 16:17 ` V2 [PATCH 1/2] " H.J. Lu
2020-12-04 16:17 ` V2 [PATCH 2/2] Warn used and not used symbols in section with the same name H.J. Lu
0 siblings, 2 replies; 3+ messages in thread
From: H.J. Lu @ 2020-12-04 16:17 UTC (permalink / raw)
To: gcc-patches
When SECTION_RETAIN is used, definitions marked with used attribute and
unmarked definitions are placed in a section with the same name. Instead
of issue an error:
[hjl@gnu-cfl-2 gcc]$ /usr/gcc-11.0.0-x32/bin/gcc -S c.c -fdiagnostics-plain-output
c.c:2:49: error: ‘foo1’ causes a section type conflict with ‘foo2’
c.c:1:54: note: ‘foo2’ was declared here
[hjl@gnu-cfl-2 gcc]$
the first patch switches to a new section if the SECTION_RETAIN bit
doesn't match. The second optional patch issues a warning:
[hjl@gnu-cfl-2 gcc]$ ./xgcc -B./ -S c.c
c.c:2:49: warning: ‘foo1’ without ‘used’ attribute and ‘foo2’ with ‘used’ attribute are placed in a section with the same name [-Wattributes]
2 | const int __attribute__((section(".data.foo"))) foo1 = 1;
| ^~~~
c.c:1:54: note: ‘foo2’ was declared here
1 | const int __attribute__((used,section(".data.foo"))) foo2 = 2;
|
[hjl@gnu-cfl-2 gcc]$
H.J. Lu (2):
Switch to a new section if the SECTION_RETAIN bit doesn't match
Warn used and not used symbols in section with the same name
gcc/output.h | 2 +-
gcc/testsuite/c-c++-common/attr-used-5.c | 27 ++++++++++++++
gcc/testsuite/c-c++-common/attr-used-6.c | 27 ++++++++++++++
gcc/testsuite/c-c++-common/attr-used-7.c | 9 +++++
gcc/testsuite/c-c++-common/attr-used-8.c | 9 +++++
gcc/testsuite/c-c++-common/attr-used-9.c | 28 +++++++++++++++
gcc/varasm.c | 45 +++++++++++++++++++++---
7 files changed, 142 insertions(+), 5 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
--
2.28.0
^ permalink raw reply [flat|nested] 3+ messages in thread
* V2 [PATCH 1/2] Switch to a new section if the SECTION_RETAIN bit doesn't match
2020-12-04 16:17 V2 [PATCH 0/2] Switch to a new section if the SECTION_RETAIN bit doesn't match H.J. Lu
@ 2020-12-04 16:17 ` H.J. Lu
2020-12-04 16:17 ` V2 [PATCH 2/2] Warn used and not used symbols in section with the same name H.J. Lu
1 sibling, 0 replies; 3+ messages in thread
From: H.J. Lu @ 2020-12-04 16:17 UTC (permalink / raw)
To: gcc-patches
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.
---
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/varasm.c | 29 ++++++++++++++++++++----
6 files changed, 94 insertions(+), 5 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
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/varasm.c b/gcc/varasm.c
index 0fac3688828..c85d39813ec 100644
--- a/gcc/varasm.c
+++ b/gcc/varasm.c
@@ -342,6 +342,11 @@ 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)
@@ -1852,7 +1857,7 @@ 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);
@@ -2348,7 +2353,7 @@ 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,
@@ -7715,10 +7720,26 @@ 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
+ && decl != nullptr
+ && (!!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;
--
2.28.0
^ permalink raw reply [flat|nested] 3+ messages in thread
* V2 [PATCH 2/2] Warn used and not used symbols in section with the same name
2020-12-04 16:17 V2 [PATCH 0/2] Switch to a new section if the SECTION_RETAIN bit doesn't match H.J. Lu
2020-12-04 16:17 ` V2 [PATCH 1/2] " H.J. Lu
@ 2020-12-04 16:17 ` H.J. Lu
1 sibling, 0 replies; 3+ messages in thread
From: H.J. Lu @ 2020-12-04 16:17 UTC (permalink / raw)
To: gcc-patches
When SECTION_RETAIN is used, issue a warning when a symbol without used
attribute and a symbol with used attribute are placed in the section with
the same name, like
int __attribute__((used,section(".data.foo"))) foo2 = 2;
int __attribute__((section(".data.foo"))) foo1 = 1;
since assembler will put them in different sections with the same section
name.
gcc/
PR target/98146
* varasm.c (switch_to_section): Warn when a symbol without used
attribute and a symbol with used attribute are placed in the
section with the same name.
gcc/testsuite/
PR target/98146
* c-c++-common/attr-used-5.c: Updated.
* 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/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 | 28 ++++++++++++++++++++++++
gcc/varasm.c | 22 ++++++++++++++++---
6 files changed, 51 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/c-c++-common/attr-used-9.c
diff --git a/gcc/testsuite/c-c++-common/attr-used-5.c b/gcc/testsuite/c-c++-common/attr-used-5.c
index 9fc0d3834e9..38ca8ef83f3 100644
--- a/gcc/testsuite/c-c++-common/attr-used-5.c
+++ b/gcc/testsuite/c-c++-common/attr-used-5.c
@@ -10,6 +10,7 @@ extern struct dtv_slotinfo_list *list;
static int __attribute__ ((section ("__libc_freeres_fn")))
free_slotinfo (struct dtv_slotinfo_list **elemp)
+/* { dg-warning "'.*' without 'used' attribute and '.*' with 'used' attribute are placed in a section with the same name" "" { target *-*-* } .-1 } */
{
if (!free_slotinfo (&(*elemp)->next))
return 0;
diff --git a/gcc/testsuite/c-c++-common/attr-used-6.c b/gcc/testsuite/c-c++-common/attr-used-6.c
index 0cb82ade5a9..a4800f6d0f1 100644
--- a/gcc/testsuite/c-c++-common/attr-used-6.c
+++ b/gcc/testsuite/c-c++-common/attr-used-6.c
@@ -18,6 +18,7 @@ free_slotinfo (struct dtv_slotinfo_list **elemp)
__attribute__ ((section ("__libc_freeres_fn")))
void free_mem (void)
+/* { dg-warning "'.*' without 'used' attribute and '.*' with 'used' attribute are placed in a section with the same name" "" { target *-*-* } .-1 } */
{
free_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 fba2706ffc1..39923cdde33 100644
--- a/gcc/testsuite/c-c++-common/attr-used-7.c
+++ b/gcc/testsuite/c-c++-common/attr-used-7.c
@@ -3,6 +3,7 @@
int __attribute__((used,section(".data.foo"))) foo2 = 2;
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 *-*-* } .-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
index 4da4aabe573..032cdd20901 100644
--- a/gcc/testsuite/c-c++-common/attr-used-8.c
+++ b/gcc/testsuite/c-c++-common/attr-used-8.c
@@ -2,6 +2,7 @@
/* { dg-options "-Wall -O2" } */
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 *-*-* } .-1 } */
int __attribute__((used,section(".data.foo"))) foo2 = 2;
/* { dg-final { scan-assembler ".data.foo,\"aw\"" { 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..502c768c813
--- /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,\"ax\"" } }*/
+/* { dg-final { scan-assembler-not "__libc_freeres_fn\n" } } */
+/* { dg-final { scan-assembler "__libc_freeres_fn,\"axR\"" { target R_flag_in_section } } } */
diff --git a/gcc/varasm.c b/gcc/varasm.c
index c85d39813ec..025e0fb32fe 100644
--- a/gcc/varasm.c
+++ b/gcc/varasm.c
@@ -7731,11 +7731,27 @@ switch_to_section (section *new_section, tree decl)
{
/* If the SECTION_RETAIN bit doesn't match, switch to a new
section. */
+ tree used_decl, no_used_decl;
+
if (DECL_PRESERVE_P (decl))
- new_section->common.flags |= SECTION_RETAIN;
+ {
+ new_section->common.flags |= SECTION_RETAIN;
+ used_decl = decl;
+ no_used_decl = new_section->named.decl;
+ }
else
- new_section->common.flags &= ~(SECTION_RETAIN
- | SECTION_DECLARED);
+ {
+ new_section->common.flags &= ~(SECTION_RETAIN
+ | SECTION_DECLARED);
+ used_decl = new_section->named.decl;
+ no_used_decl = decl;
+ }
+ warning (OPT_Wattributes,
+ "%+qD without %<used%> attribute and %qD with "
+ "%<used%> attribute are placed in a section with "
+ "the same name", no_used_decl, used_decl);
+ inform (DECL_SOURCE_LOCATION (used_decl),
+ "%qD was declared here", used_decl);
}
else
return;
--
2.28.0
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-12-04 16:17 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-12-04 16:17 V2 [PATCH 0/2] Switch to a new section if the SECTION_RETAIN bit doesn't match H.J. Lu
2020-12-04 16:17 ` V2 [PATCH 1/2] " H.J. Lu
2020-12-04 16:17 ` V2 [PATCH 2/2] Warn used and not used symbols in section with the same name H.J. Lu
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).