gcc/libstdc++-v3/crossconfig.m4
Jonathan Wakely 637e3668fd libstdc++: Allow emergency EH alloc pool size to be tuned [PR68606]
Implement a long-standing request to support tuning the size of the
emergency buffer for allocating exceptions after malloc fails, or to
disable that buffer entirely.

It's now possible to disable the dynamic allocation of the buffer and
use a fixed-size static buffer, via --enable-libstdcxx-static-eh-pool.
This is a built-time choice that is baked into libstdc++ and so affects
all code linked against that build of libstdc++.

The size of the pool can be set by --with-libstdcxx-eh-pool-obj-count=N
which is measured in units of sizeof(void*) not bytes. A given exception
type such as std::system_error depends on the target, so giving a size
in bytes wouldn't be portable across 16/32/64-bit targets.

When libstdc++ is configured to use a dynamic buffer, the size of that
buffer can now be tuned at runtime by setting the GLIBCXX_TUNABLES
environment variable (c.f. PR libstdc++/88264). The number of exceptions
to reserve space for is controlled by the "glibcxx.eh_pool.obj_count"
and "glibcxx.eh_pool.obj_size" tunables. The pool will be sized to be
able to allocate obj_count exceptions of size obj_size*sizeof(void*) and
obj_count "dependent" exceptions rethrown by std::rethrow_exception.

With the ability to tune the buffer size, we can reduce the default pool
size on 32-bit and 16-bit targets. Most users never need to throw 1kB
exceptions in parallel from hundreds of threads after malloc is OOM. The
users who do need that can use the tunables to select larger sizes.

The old defaults can be chosen at runtime by setting GLIBCXX_TUNABLES
to:
64-bit: glibcxx.eh_pool.obj_count=64:glibcxx.eh_pool.obj_size=112
32-bit: glibcxx.eh_pool.obj_count=32:glibcxx.eh_pool.obj_size=104

Or approximated by configuring with:
64-bit: --with-libstdcxx-eh-pool-obj-count=252
32-bit: --with-libstdcxx-eh-pool-obj-count=94

libstdc++-v3/ChangeLog:

	PR libstdc++/68606
	* Makefile.in: Regenerate.
	* acinclude.m4 (GLIBCXX_EMERGENCY_EH_ALLOC): New macro.
	* configure: Regenerate.
	* configure.ac: Use GLIBCXX_EMERGENCY_EH_ALLOC.
	* crossconfig.m4: Check for secure_getenv.
	* doc/Makefile.in: Regenerate.
	* doc/xml/manual/configure.xml: Document new configure options.
	* doc/xml/manual/evolution.xml: Document addition of tunables.
	* doc/xml/manual/using_exceptions.xml: Document emergency
	buffer and tunables.
	* doc/html/*: Regenerate.
	* include/Makefile.in: Regenerate.
	* libsupc++/Makefile.am: Use EH_POOL_FLAGS.
	* libsupc++/Makefile.in: Regenerate.
	* libsupc++/eh_alloc.cc (EMERGENCY_OBJ_SIZE): Define in units
	of sizeof(void*) not including the ABI's exception header.
	(EMERGENCY_OBJ_COUNT): Define as target-independent calculation
	based on word size.
	(MAX_OBJ_COUNT): Define macro for upper limit on pool size.
	(pool) [_GLIBCXX_EH_POOL_STATIC]: Use fixed-size buffer.
	(pool::buffer_size_in_bytes): New static member function.
	(pool::pool): Parse GLIBCXX_TUNABLES environment variable to set
	pool size at runtime.
	(pool::in_pool): Use std::less<void*> for total order.
	(__freeres) [_GLIBCXX_EH_POOL_STATIC]: Do nothing.
	(__cxa_free_exception, __cxa_free_dependent_exception): Add
	[[unlikely]] attributes.
	* po/Makefile.in: Regenerate.
	* python/Makefile.in: Regenerate.
	* src/Makefile.in: Regenerate.
	* src/c++11/Makefile.in: Regenerate.
	* src/c++17/Makefile.in: Regenerate.
	* src/c++20/Makefile.in: Regenerate.
	* src/c++98/Makefile.in: Regenerate.
	* src/filesystem/Makefile.in: Regenerate.
	* src/libbacktrace/Makefile.in: Regenerate.
	* testsuite/Makefile.in: Regenerate.
2022-10-11 16:21:48 +01:00

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dnl
dnl This file contains details for non-native builds.
dnl
AC_DEFUN([GLIBCXX_CROSSCONFIG],[
# Base decisions on target environment.
case "${host}" in
arm*-*-symbianelf*)
# This is a freestanding configuration; there is nothing to do here.
;;
avr*-*-*)
AC_DEFINE(HAVE_ACOSF)
AC_DEFINE(HAVE_ASINF)
AC_DEFINE(HAVE_ATAN2F)
AC_DEFINE(HAVE_ATANF)
AC_DEFINE(HAVE_CEILF)
AC_DEFINE(HAVE_COSF)
AC_DEFINE(HAVE_COSHF)
AC_DEFINE(HAVE_EXPF)
AC_DEFINE(HAVE_FABSF)
AC_DEFINE(HAVE_FLOORF)
AC_DEFINE(HAVE_FMODF)
AC_DEFINE(HAVE_FREXPF)
AC_DEFINE(HAVE_SQRTF)
AC_DEFINE(HAVE_HYPOTF)
AC_DEFINE(HAVE_LDEXPF)
AC_DEFINE(HAVE_LOG10F)
AC_DEFINE(HAVE_LOGF)
AC_DEFINE(HAVE_MODFF)
AC_DEFINE(HAVE_POWF)
AC_DEFINE(HAVE_SINF)
AC_DEFINE(HAVE_SINHF)
AC_DEFINE(HAVE_TANF)
AC_DEFINE(HAVE_TANHF)
;;
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AC_SUBST(SECTION_FLAGS)
GLIBCXX_CHECK_COMPILER_FEATURES
GLIBCXX_CHECK_LINKER_FEATURES
GLIBCXX_CHECK_MATH_SUPPORT
GLIBCXX_CHECK_STDLIB_SUPPORT
AC_DEFINE(HAVE_FINITE)
AC_DEFINE(HAVE_HYPOT)
AC_DEFINE(HAVE_ISNAN)
AC_DEFINE(HAVE_ISINF)
AC_DEFINE(HAVE_LDEXPF)
AC_DEFINE(HAVE_MODF)
AC_DEFINE(HAVE_SQRTF)
;;
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GLIBCXX_CHECK_LINKER_FEATURES
GLIBCXX_CHECK_MATH_SUPPORT
GLIBCXX_CHECK_STDLIB_SUPPORT
AC_DEFINE(_GLIBCXX_USE_DEV_RANDOM)
AC_DEFINE(_GLIBCXX_USE_RANDOM_TR1)
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#GCC_CHECK_TLS
AM_ICONV
AC_DEFINE(HAVE_USELOCALE)
;;
*-darwin*)
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GLIBCXX_CHECK_MATH_SUPPORT
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AC_CHECK_FUNCS(uselocale)
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AC_DEFINE(HAVE_ISINF)
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AC_DEFINE(HAVE_FINITE)
AC_DEFINE(HAVE_SINCOS)
AC_DEFINE(HAVE_HYPOT)
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GLIBCXX_CHECK_LINKER_FEATURES
AC_DEFINE(HAVE_SETENV)
AC_DEFINE(HAVE_FINITEF)
AC_DEFINE(HAVE_FINITE)
AC_DEFINE(HAVE_FREXPF)
AC_DEFINE(HAVE_HYPOT)
AC_DEFINE(HAVE_HYPOTF)
AC_DEFINE(HAVE_ISINF)
AC_DEFINE(HAVE_ISNAN)
AC_DEFINE(HAVE_ISNANF)
AC_DEFINE(HAVE_ACOSF)
AC_DEFINE(HAVE_ASINF)
AC_DEFINE(HAVE_ATAN2F)
AC_DEFINE(HAVE_ATANF)
AC_DEFINE(HAVE_CEILF)
AC_DEFINE(HAVE_COSF)
AC_DEFINE(HAVE_COSHF)
AC_DEFINE(HAVE_EXPF)
AC_DEFINE(HAVE_FABSF)
AC_DEFINE(HAVE_FLOORF)
AC_DEFINE(HAVE_FMODF)
AC_DEFINE(HAVE_FREXPF)
AC_DEFINE(HAVE_LDEXPF)
AC_DEFINE(HAVE_LOG10F)
AC_DEFINE(HAVE_LOGF)
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AC_DEFINE(HAVE_POWF)
AC_DEFINE(HAVE_SINF)
AC_DEFINE(HAVE_SINHF)
AC_DEFINE(HAVE_SQRTF)
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AC_CHECK_FUNCS(__cxa_thread_atexit)
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AC_CHECK_FUNCS(timespec_get)
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*-fuchsia*)
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;;
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AC_DEFINE(HAVE_SINF)
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AC_DEFINE(HAVE_SQRTF)
# GLIBCXX_CHECK_STDLIB_SUPPORT
AC_DEFINE(HAVE_STRTOLD)
GCC_CHECK_TLS
;;
*-linux* | *-uclinux* | *-gnu* | *-kfreebsd*-gnu | *-cygwin* | *-solaris*)
GLIBCXX_CHECK_COMPILER_FEATURES
GLIBCXX_CHECK_LINKER_FEATURES
GLIBCXX_CHECK_MATH_SUPPORT
GLIBCXX_CHECK_STDLIB_SUPPORT
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AC_DEFINE(_GLIBCXX_USE_RANDOM_TR1)
GCC_CHECK_TLS
AC_CHECK_FUNCS(__cxa_thread_atexit_impl)
AC_CHECK_FUNCS(aligned_alloc posix_memalign memalign _aligned_malloc)
AC_CHECK_FUNCS(timespec_get)
AC_CHECK_FUNCS(sockatmark)
AC_CHECK_FUNCS(uselocale)
AC_CHECK_FUNCS(secure_getenv)
AM_ICONV
;;
*-mingw32*)
GLIBCXX_CHECK_LINKER_FEATURES
GLIBCXX_CHECK_MATH_SUPPORT
GLIBCXX_CHECK_STDLIB_SUPPORT
AC_CHECK_FUNCS(aligned_alloc posix_memalign memalign _aligned_malloc)
AC_CHECK_FUNCS(_wfopen)
GCC_CHECK_TLS
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AC_CHECK_FUNCS(aligned_alloc posix_memalign memalign _aligned_malloc)
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GLIBCXX_CHECK_LINKER_FEATURES
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AC_DEFINE(HAVE_LOGF)
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AC_DEFINE(HAVE_LOG10F)
AC_DEFINE(HAVE_LOG10L)
AC_DEFINE(HAVE_SINF)
AC_DEFINE(HAVE_SINL)
AC_DEFINE(HAVE_SINHF)
AC_DEFINE(HAVE_SINHL)
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AC_DEFINE(HAVE_FREXPF)
AC_DEFINE(HAVE_HYPOTF)
AC_DEFINE(HAVE_ISINF)
AC_DEFINE(HAVE_ISINFF)
AC_DEFINE(HAVE_ISNAN)
AC_DEFINE(HAVE_ISNANF)
AC_DEFINE(HAVE_SINCOS)
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AC_DEFINE(HAVE_HYPOTL)
AC_DEFINE(HAVE_ISINFL)
AC_DEFINE(HAVE_ISNANL)
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;;
*-*vms*)
# Check for available headers.
# Don't call GLIBCXX_CHECK_LINKER_FEATURES, VMS doesn't have a GNU ld
GLIBCXX_CHECK_MATH_SUPPORT
GLIBCXX_CHECK_STDLIB_SUPPORT
;;
*-vxworks*)
AC_DEFINE(HAVE_ACOSF)
AC_DEFINE(HAVE_ASINF)
AC_DEFINE(HAVE_ATAN2F)
AC_DEFINE(HAVE_ATANF)
AC_DEFINE(HAVE_CEILF)
AC_DEFINE(HAVE_COSF)
AC_DEFINE(HAVE_COSHF)
AC_DEFINE(HAVE_EXPF)
AC_DEFINE(HAVE_FABSF)
AC_DEFINE(HAVE_FLOORF)
AC_DEFINE(HAVE_FMODF)
AC_DEFINE(HAVE_HYPOT)
AC_DEFINE(HAVE_LOG10F)
AC_DEFINE(HAVE_LOGF)
AC_DEFINE(HAVE_POWF)
AC_DEFINE(HAVE_SINF)
AC_DEFINE(HAVE_SINHF)
AC_DEFINE(HAVE_SQRTF)
AC_DEFINE(HAVE_TANF)
AC_DEFINE(HAVE_TANHF)
dnl # Different versions and execution modes implement different
dnl # subsets of these functions. Instead of hard-coding, test for C
dnl # declarations in headers. The C primitives could be defined as
dnl # macros, in which case the tests might fail, and we might have to
dnl # switch to more elaborate tests.
GLIBCXX_CHECK_MATH_DECLS([
acosl asinl atan2l atanl ceill cosl coshl expl fabsl floorl fmodl
frexpl ldexpl log10l logl modfl powl sinl sinhl sqrtl tanl tanhl hypotl
ldexpf modff hypotf frexpf])
dnl # sincosl is the only one missing here, compared with the *l
dnl # functions in the list guarded by
dnl # long_double_math_on_this_cpu in configure.ac, right after
dnl # the expansion of the present macro.
;;
*)
AC_MSG_ERROR([No support for this host/target combination.])
;;
esac
])
dnl
dnl Check to see if the (math function) argument passed is
dnl declared when using the c compiler
dnl
dnl Define HAVE_CARGF etc if "cargf" is declared
dnl
dnl argument 1 is name of function to check
dnl
dnl ASSUMES argument is a math function
dnl
dnl GLIBCXX_CHECK_MATH_DECL
AC_DEFUN([GLIBCXX_CHECK_MATH_DECL], [
AC_CACHE_CHECK([for $1 declaration],
[glibcxx_cv_func_$1_use], [
AC_LANG_SAVE
AC_LANG_C
AC_TRY_COMPILE([
#include <math.h>
#ifdef HAVE_IEEEFP_H
# include <ieeefp.h>
#endif
#undef $1
], [
void (*f)(void) = (void (*)(void))$1;
], [glibcxx_cv_func_$1_use=yes
], [glibcxx_cv_func_$1_use=no])])
if test "x$glibcxx_cv_func_$1_use" = xyes; then
AC_DEFINE_UNQUOTED(AS_TR_CPP([HAVE_$1]))
fi
])
dnl
dnl Check to see whether multiple math functions are
dnl declared when using the c compiler
dnl
dnl Define HAVE_CARGF HAVE_POWL etc if "cargf" and "powl"
dnl are declared
dnl
dnl argument 1 is a word list naming function to check
dnl
dnl ASSUMES arguments are math functions
dnl
dnl GLIBCXX_CHECK_MATH_DECLS
AC_DEFUN([GLIBCXX_CHECK_MATH_DECLS], [
m4_foreach_w([glibcxx_func], [$1], [
GLIBCXX_CHECK_MATH_DECL(glibcxx_func)
])
])