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| author | H.J. Lu <hjl.tools@gmail.com> | 2020-02-03 11:55:43 -0800 |
|---|---|---|
| committer | H.J. Lu <hjl.tools@gmail.com> | 2020-12-01 16:42:50 -0800 |
| commit | 6fbec038f7a7ddf29f074943611b53210d17c40c (patch) | |
| tree | 17b1d7fb7010085b8d79deab1e4a07edf51ddf9b /gcc/output.h | |
| parent | 670f5095e4aacc30099f6b73c1e67c06df76f36b (diff) | |
| download | gcc-6fbec038f7a7ddf29f074943611b53210d17c40c.zip gcc-6fbec038f7a7ddf29f074943611b53210d17c40c.tar.gz gcc-6fbec038f7a7ddf29f074943611b53210d17c40c.tar.bz2 | |
Use SHF_GNU_RETAIN to preserve symbol definitions
In assemly code, the section flag 'R' sets the SHF_GNU_RETAIN flag to
indicate that the section must be preserved by the linker.
Add SECTION_RETAIN to indicate a section should be retained by the linker
and set SECTION_RETAIN on section for the preserved symbol if assembler
supports SHF_GNU_RETAIN. All retained symbols are placed in separate
sections with
.section .data.rel.local.preserved_symbol,"awR"
preserved_symbol:
...
.section .data.rel.local,"aw"
not_preserved_symbol:
...
to avoid
.section .data.rel.local,"awR"
preserved_symbol:
...
not_preserved_symbol:
...
which places not_preserved_symbol definition in the SHF_GNU_RETAIN
section.
gcc/
2020-12-01 H.J. Lu <hjl.tools@gmail.com>
* configure.ac (HAVE_GAS_SHF_GNU_RETAIN): New. Define 1 if
the assembler supports marking sections with SHF_GNU_RETAIN flag.
* output.h (SECTION_RETAIN): New. Defined as 0x4000000.
(SECTION_MACH_DEP): Changed from 0x4000000 to 0x8000000.
(default_unique_section): Add a bool argument.
* varasm.c (get_section): Set SECTION_RETAIN for the preserved
symbol with HAVE_GAS_SHF_GNU_RETAIN.
(resolve_unique_section): Used named section for the preserved
symbol if assembler supports SHF_GNU_RETAIN.
(get_variable_section): Handle the preserved common symbol with
HAVE_GAS_SHF_GNU_RETAIN.
(default_elf_asm_named_section): Require the full declaration and
use the 'R' flag for SECTION_RETAIN.
* config.in: Regenerated.
* configure: Likewise.
* doc/sourcebuild.texi: Document R_flag_in_section.
gcc/testsuite/
2020-12-01 H.J. Lu <hjl.tools@gmail.com>
Jozef Lawrynowicz <jozef.l@mittosystems.com>
* c-c++-common/attr-used.c: Check the 'R' flag.
* c-c++-common/attr-used-2.c: Likewise.
* c-c++-common/attr-used-3.c: New test.
* c-c++-common/attr-used-4.c: Likewise.
* gcc.c-torture/compile/attr-used-retain-1.c: Likewise.
* gcc.c-torture/compile/attr-used-retain-2.c: Likewise.
* lib/target-supports.exp
(check_effective_target_R_flag_in_section): New proc.
Diffstat (limited to 'gcc/output.h')
| -rw-r--r-- | gcc/output.h | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/gcc/output.h b/gcc/output.h index b44c1bd..729c520 100644 --- a/gcc/output.h +++ b/gcc/output.h @@ -381,7 +381,11 @@ extern void no_asm_to_stream (FILE *); #define SECTION_COMMON 0x800000 /* contains common data */ #define SECTION_RELRO 0x1000000 /* data is readonly after relocation processing */ #define SECTION_EXCLUDE 0x2000000 /* discarded by the linker */ -#define SECTION_MACH_DEP 0x4000000 /* subsequent bits reserved for target */ +#define SECTION_RETAIN 0x4000000 /* retained by the linker. */ + +/* NB: The maximum SECTION_MACH_DEP is 0x10000000 since AVR needs 4 bits + in SECTION_MACH_DEP. */ +#define SECTION_MACH_DEP 0x8000000 /* subsequent bits reserved for target */ /* This SECTION_STYLE is used for unnamed sections that we can switch to using a special assembler directive. */ |