[binutils-gdb] gas: add --enable-default-sframe configure option
Sam James
sjames@sourceware.org
Sat Aug 23 02:06:22 GMT 2025
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=b0653e3db9c6d0d4f1f547e19aaad621aad58920
commit b0653e3db9c6d0d4f1f547e19aaad621aad58920
Author: Sam James <sam@gentoo.org>
Date: Thu Jul 3 11:08:59 2025 +0100
gas: add --enable-default-sframe configure option
SFrames make the most sense when userland as a whole is built with them,
so add a --enable-default-sframe configure flag to facilitate distributors
and vendors doing that.
The primary motivation for a configure-time flag is that we don't support
SFrame for 32-bit x86 but some packaging uses the same flags (with some
added on top) for multilib builds (to support old binaries like games),
and simply adding `-Wa,--gsframe` to the standard build flags isn't an
option (*).
That aside, I believe it'll be helpful for testing and eventual adoption
in any case.
In summary, combined with the recent --gsframe=[yes|no] support (**):
* Configured with --enable-default-sframe and nothing is passed
=> SFrames (previously no SFrames)
* Configured with --enable-default-sframe and --gsframe=yes is passed
=> SFrames (no change from before)
* Configured with --enable-default-sframe and --gsframe=no is passed
=> No SFrames (no change from before)
* Configured with --enable-default-sframe and --gsframe is passed
=> SFrames (no change from before)
* Configured with --disable-default-sframe and nothing is passed
=> No SFrames (no change from before)
* Configured with --disable-default-sframe and --gsframe=yes is passed
=> SFrames (no change from before)
* Configured with --disable-default-sframe and --gsframe=no is passed
=> No SFrames (no change from before)
* Configured with --disable-default-sframe and --gsframe is passed
=> SFrames (no change from before)
I've introduced a sframe_as_bad macro on Indu's suggestion. A following
patch uses its sibling sframe_as_warn heavily and having symmetry plus
the macro as a form of documentation of intent seems useful.
(*) It gets added to multilib builds too and then we hit the
`.sframe not supported for target` error in gas/dw2gencfi.c.
(**) I've verbosely listed --gsframe=yes but it's the same as --gsframe.
gas/
PR gas/33126
* as.c (enum gen_sframe_option): Initialize if DEFAULT_SFRAME.
* config.in (DEFAULT_SFRAME): New.
* configure: Regenerate.
* configure.ac: Add --enable-default-sframe.
* doc/as.texi: Document --enable-default-sframe.
* dw2gencfi.c (cfi_finish): Don't warn if SFrames are enabled
by default but unavailable for this target.
* gen-sframe.h (sframe_as_bad): New macro.
Diff:
---
gas/as.c | 8 +++++++-
gas/config.in | 3 +++
gas/configure | 24 ++++++++++++++++++++++--
gas/configure.ac | 16 ++++++++++++++++
gas/doc/as.texi | 3 ++-
gas/dw2gencfi.c | 6 +++++-
gas/gen-sframe.h | 10 ++++++++++
7 files changed, 65 insertions(+), 5 deletions(-)
diff --git a/gas/as.c b/gas/as.c
index 58ed0a59e21..efcc80deef1 100644
--- a/gas/as.c
+++ b/gas/as.c
@@ -113,6 +113,12 @@ int flag_use_elf_stt_common = DEFAULT_GENERATE_ELF_STT_COMMON;
bool flag_generate_build_notes = DEFAULT_GENERATE_BUILD_NOTES;
#endif
+/* If DEFAULT_SFRAME is 0 instead, flag_gen_sframe gets the default
+ enum value GEN_SFRAME_DEFAULT_NONE. */
+#if DEFAULT_SFRAME
+enum gen_sframe_option flag_gen_sframe = GEN_SFRAME_CONFIG_ENABLED;
+#endif
+
segT reg_section;
segT expr_section;
segT text_section;
@@ -312,7 +318,7 @@ Options:\n\
generate GNU Build notes if none are present in the input\n"));
fprintf (stream, _("\
--gsframe[={no|yes}] whether to generate SFrame stack trace information\n\
- (default: no)\n"));
+ (default: %s)\n"), DEFAULT_SFRAME ? "yes" : "no");
# if defined (TARGET_USE_SCFI) && defined (TARGET_USE_GINSN)
fprintf (stream, _("\
--scfi=experimental Synthesize DWARF CFI for hand-written asm\n\
diff --git a/gas/config.in b/gas/config.in
index bb896244640..ba042ca44eb 100644
--- a/gas/config.in
+++ b/gas/config.in
@@ -60,6 +60,9 @@
/* Define default value for RISC-V -mpriv-spec */
#undef DEFAULT_RISCV_PRIV_SPEC
+/* Define to 1 if you want to emit SFrames by default. */
+#undef DEFAULT_SFRAME
+
/* Define to 1 if you want to check x86 TLS relocation by default. */
#undef DEFAULT_X86_TLS_CHECK
diff --git a/gas/configure b/gas/configure
index 97340444b72..12d96a5acd2 100755
--- a/gas/configure
+++ b/gas/configure
@@ -820,6 +820,7 @@ enable_default_compressed_debug_sections_algorithm
enable_x86_relax_relocations
enable_x86_tls_check
enable_elf_stt_common
+enable_default_sframe
enable_generate_build_notes
enable_mips_fix_loongson3_llsc
enable_x86_used_note
@@ -1497,6 +1498,7 @@ Optional Features:
--enable-x86-tls-check check x86 TLS relocation by default
--enable-elf-stt-common generate ELF common symbols with STT_COMMON type by
default
+ --enable-default-sframe generate SFrame by default
--enable-generate-build-notes
generate GNU Build notes if none are provided by the
input
@@ -10777,7 +10779,7 @@ else
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
-#line 10780 "configure"
+#line 10782 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
@@ -10883,7 +10885,7 @@ else
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
-#line 10886 "configure"
+#line 10888 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
@@ -11599,6 +11601,15 @@ if test "${enable_elf_stt_common+set}" = set; then :
esac
fi
+ac_default_sframe=unset
+# Provide a configure time option to override our default.
+# Check whether --enable-default-sframe was given.
+if test "${enable_default_sframe+set}" = set; then :
+ enableval=$enable_default_sframe; case "${enableval}" in
+ yes) ac_default_sframe=1 ;;
+ no) ac_default_sframe=0 ;;
+esac
+fi
# Decide if the ELF assembler should default to generating
# GNU Build notes if none are provided by the input.
@@ -12723,6 +12734,15 @@ cat >>confdefs.h <<_ACEOF
_ACEOF
+if test ${ac_default_sframe} = unset; then
+ ac_default_sframe=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define DEFAULT_SFRAME $ac_default_sframe
+_ACEOF
+
+
cat >>confdefs.h <<_ACEOF
#define DEFAULT_GENERATE_BUILD_NOTES $ac_default_generate_build_notes
diff --git a/gas/configure.ac b/gas/configure.ac
index c65797fdf0a..78fe021bafd 100644
--- a/gas/configure.ac
+++ b/gas/configure.ac
@@ -117,6 +117,15 @@ AC_ARG_ENABLE(elf_stt_common,
yes) ac_default_elf_stt_common=1 ;;
esac])dnl
+ac_default_sframe=unset
+# Provide a configure time option to override our default.
+AC_ARG_ENABLE(default-sframe,
+ AS_HELP_STRING([--enable-default-sframe],
+ [generate SFrame by default]),
+[case "${enableval}" in
+ yes) ac_default_sframe=1 ;;
+ no) ac_default_sframe=0 ;;
+esac])dnl
# Decide if the ELF assembler should default to generating
# GNU Build notes if none are provided by the input.
@@ -757,6 +766,13 @@ AC_DEFINE_UNQUOTED(DEFAULT_GENERATE_ELF_STT_COMMON,
[Define to 1 if you want to generate ELF common symbols with the
STT_COMMON type by default.])
+if test ${ac_default_sframe} = unset; then
+ ac_default_sframe=0
+fi
+AC_DEFINE_UNQUOTED(DEFAULT_SFRAME,
+ $ac_default_sframe,
+ [Define to 1 if you want to emit SFrames by default.])
+
AC_DEFINE_UNQUOTED(DEFAULT_GENERATE_BUILD_NOTES,
$ac_default_generate_build_notes,
[Define to 1 if you want to generate GNU Build attribute notes
diff --git a/gas/doc/as.texi b/gas/doc/as.texi
index 2db5f4896ee..28fb6a6a97b 100644
--- a/gas/doc/as.texi
+++ b/gas/doc/as.texi
@@ -864,7 +864,8 @@ configure option.
@itemx --gsframe=yes
Create @var{.sframe} section from CFI directives. The explicit
@option{--gsframe=yes} option behaves the same as @option{--gsframe}.
-Generation can be suppressed with @option{--gsframe=no}.
+Generation can be suppressed with @option{--gsframe=no}. The default can be
+controlled by a configure option @option{--enable-default-sframe}.
@end ifset
diff --git a/gas/dw2gencfi.c b/gas/dw2gencfi.c
index c28856cdf24..186dfa667c8 100644
--- a/gas/dw2gencfi.c
+++ b/gas/dw2gencfi.c
@@ -2598,9 +2598,11 @@ cfi_finish (void)
/* Generate SFrame section if the user:
- enables via the command line option, or
+ - default-enabled at configure-time via --enable-default-sframe, or
- specifies .sframe in the .cfi_sections directive and does not disable
via the command line. */
if (flag_gen_sframe == GEN_SFRAME_ENABLED
+ || flag_gen_sframe == GEN_SFRAME_CONFIG_ENABLED
|| ((all_cfi_sections & CFI_EMIT_sframe) != 0
&& flag_gen_sframe != GEN_SFRAME_DISABLED))
{
@@ -2619,7 +2621,9 @@ cfi_finish (void)
}
else
#endif
- as_bad (_(".sframe not supported for target"));
+ /* Avoid erroring with DEFAULT_SFRAME for non-default options, like
+ -32 on x86_64. */
+ sframe_as_bad (_(".sframe not supported for target"));
}
if ((all_cfi_sections & CFI_EMIT_debug_frame) != 0)
diff --git a/gas/gen-sframe.h b/gas/gen-sframe.h
index e4a4c6ea0ce..8ad521b5cbe 100644
--- a/gas/gen-sframe.h
+++ b/gas/gen-sframe.h
@@ -21,6 +21,16 @@
#ifndef GENSFRAME_H
#define GENSFRAME_H
+/* Errors shouldn't be emitted either if SFrames are default-enabled, as
+ we interpret default-enabled as "opportunistic SFrames". Users don't
+ want to be bothered by something preventing emission of SFrames in
+ such a case. */
+#define sframe_as_bad(format, ...) \
+ do { \
+ if (flag_gen_sframe == GEN_SFRAME_ENABLED) \
+ as_bad (format, ##__VA_ARGS__); \
+ } while (0)
+
#define SFRAME_FRE_ELEM_LOC_REG 0
#define SFRAME_FRE_ELEM_LOC_STACK 1
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