Sorry about the mangled content... So I add a new add-options for libatomic_16b:
--- libstdc++-v3/ChangeLog: * include/bits/atomic_base.h: add __builtin_clear_padding in __atomic_float constructor. * testsuite/lib/dg-options.exp: add new add-options for libatomic_16b. * testsuite/29_atomics/atomic_float/compare_exchange_padding.cc: New test. --- libstdc++-v3/include/bits/atomic_base.h | 7 ++- .../atomic_float/compare_exchange_padding.cc | 50 +++++++++++++++++++ libstdc++-v3/testsuite/lib/dg-options.exp | 22 ++++++++ 3 files changed, 78 insertions(+), 1 deletion(-) create mode 100644 libstdc++-v3/testsuite/29_atomics/atomic_float/compare_exchange_padding.cc diff --git a/libstdc++-v3/include/bits/atomic_base.h b/libstdc++-v3/include/bits/atomic_base.h index f4ce0fa53..104ddfdbe 100644 --- a/libstdc++-v3/include/bits/atomic_base.h +++ b/libstdc++-v3/include/bits/atomic_base.h @@ -1283,7 +1283,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION constexpr __atomic_float(_Fp __t) : _M_fp(__t) - { } + { +#if __cplusplus >= 201402L && __has_builtin(__builtin_clear_padding) + if _GLIBCXX17_CONSTEXPR (__atomic_impl::__maybe_has_padding<_Fp>()) + __builtin_clear_padding(std::__addressof(_M_fp)); +#endif + } __atomic_float(const __atomic_float&) = delete; __atomic_float& operator=(const __atomic_float&) = delete; diff --git a/libstdc++-v3/testsuite/29_atomics/atomic_float/compare_exchange_padding.cc b/libstdc++-v3/testsuite/29_atomics/atomic_float/compare_exchange_padding.cc new file mode 100644 index 000000000..d538b3d55 --- /dev/null +++ b/libstdc++-v3/testsuite/29_atomics/atomic_float/compare_exchange_padding.cc @@ -0,0 +1,50 @@ +// { dg-do run { target c++20 } } +// { dg-options "-O0" } +// { dg-timeout 10 } +// { dg-additional-options "-mlong-double-80" { target x86_64-*-* } } +// { dg-do run { target { ia32 || x86_64-*-* } } } +// { dg-add-options libatomic_16b } + +#include <atomic> +#include <testsuite_hooks.h> + +template<typename T> +void __attribute__((noinline,noipa)) +fill_padding(T& f) +{ + T mask; + __builtin_memset(&mask, 0xff, sizeof(T)); + __builtin_clear_padding(&mask); + unsigned char* ptr_f = (unsigned char*)&f; + unsigned char* ptr_mask = (unsigned char*)&mask; + for (int i = 0; i < sizeof(T); i++) + { + if (ptr_mask[i] == 0x00) + { + ptr_f[i] = 0xff; + } + } +} + +void +test01() +{ + long double f = 0.5f; // long double may contains padding on X86 + fill_padding(f); + std::atomic<long double> as{ f }; // padding cleared on constructor + long double t = 1.5; + + as.fetch_add(t); + long double s = f + t; + t = as.load(); + VERIFY(s == t); // padding ignored on float comparing + fill_padding(s); + VERIFY(as.compare_exchange_weak(s, f)); // padding cleared on cmpexchg + fill_padding(f); + VERIFY(as.compare_exchange_strong(f, t)); // padding cleared on cmpexchg +} + +int main() +{ + test01(); +} diff --git a/libstdc++-v3/testsuite/lib/dg-options.exp b/libstdc++-v3/testsuite/lib/dg-options.exp index 850442b6b..25da20d58 100644 --- a/libstdc++-v3/testsuite/lib/dg-options.exp +++ b/libstdc++-v3/testsuite/lib/dg-options.exp @@ -356,6 +356,28 @@ proc add_options_for_libatomic { flags } { return $flags } +# Add option to link to libatomic, if required for atomics on 16-byte (128-bit) +proc add_options_for_libatomic_16b { flags } { + if { ([istarget i?86-*-*] || [istarget x86_64-*-*]) + } { + global TOOL_OPTIONS + + set link_flags "" + if ![is_remote host] { + if [info exists TOOL_OPTIONS] { + set link_flags "[atomic_link_flags [get_multilibs ${TOOL_OPTIONS}]]" + } else { + set link_flags "[atomic_link_flags [get_multilibs]]" + } + } + + append link_flags " -latomic " + + return "$flags $link_flags" + } + return $flags +} + # Add options to enable use of deprecated features. proc add_options_for_using-deprecated { flags } { return "$flags -U_GLIBCXX_USE_DEPRECATED -D_GLIBCXX_USE_DEPRECATED=1" -- 2.25.1 Xi Ruoyao <xry...@xry111.site> 于2024年1月16日周二 18:12写道: > > On Tue, 2024-01-16 at 17:53 +0800, xndcn wrote: > > Thanks, so I add a test: atomic_float/compare_exchange_padding.cc, > > which will fail due to timeout without the patch. > > Please resend in plain text instead of HTML. Sending in HTML causes the > patch mangled. > > And libstdc++ patches should CC libstd...@gcc.gnu.org, in addition to > gcc-patches@gcc.gnu.org. > > > --- > > libstdc++-v3/ChangeLog: > > > > * include/bits/atomic_base.h: add __builtin_clear_padding in > > __atomic_float constructor. > > * testsuite/lib/dg-options.exp: enable libatomic for IA32 and X86-64. > > * testsuite/29_atomics/atomic_float/compare_exchange_padding.cc: New test. > > --- > > libstdc++-v3/include/bits/atomic_base.h | 7 ++- > > .../atomic_float/compare_exchange_padding.cc | 50 +++++++++++++++++++ > > libstdc++-v3/testsuite/lib/dg-options.exp | 1 + > > 3 files changed, 57 insertions(+), 1 deletion(-) > > create mode 100644 > > libstdc++-v3/testsuite/29_atomics/atomic_float/compare_exchange_padding.cc > > > > diff --git a/libstdc++-v3/include/bits/atomic_base.h > > b/libstdc++-v3/include/bits/atomic_base.h > > index d3a2c4f3805..cbe3749e17f 100644 > > --- a/libstdc++-v3/include/bits/atomic_base.h > > +++ b/libstdc++-v3/include/bits/atomic_base.h > > @@ -1283,7 +1283,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > > > > constexpr > > __atomic_float(_Fp __t) : _M_fp(__t) > > - { } > > + { > > +#if __cplusplus >= 201402L && __has_builtin(__builtin_clear_padding) > > + if _GLIBCXX17_CONSTEXPR (__atomic_impl::__maybe_has_padding<_Fp>()) > > + __builtin_clear_padding(std::__addressof(_M_fp)); > > +#endif > > + } > > > > __atomic_float(const __atomic_float&) = delete; > > __atomic_float& operator=(const __atomic_float&) = delete; > > diff --git > > a/libstdc++-v3/testsuite/29_atomics/atomic_float/compare_exchange_padding.cc > > > > b/libstdc++-v3/testsuite/29_atomics/atomic_float/compare_exchange_padding.cc > > new file mode 100644 > > index 00000000000..9376ab22850 > > --- /dev/null > > +++ > > b/libstdc++-v3/testsuite/29_atomics/atomic_float/compare_exchange_padding.cc > > @@ -0,0 +1,50 @@ > > +// { dg-do run { target c++20 } } > > +// { dg-options "-O0" } > > +// { dg-timeout 10 } > > +// { dg-additional-options "-mlong-double-80" { target x86_64-*-* } } > > +// { dg-do run { target { ia32 || x86_64-*-* } } } > > +// { dg-add-options libatomic } > > + > > +#include <atomic> > > +#include <testsuite_hooks.h> > > + > > +template<typename T> > > +void __attribute__((noinline,noipa)) > > +fill_padding(T& f) > > +{ > > + T mask; > > + __builtin_memset(&mask, 0xff, sizeof(T)); > > + __builtin_clear_padding(&mask); > > + unsigned char* ptr_f = (unsigned char*)&f; > > + unsigned char* ptr_mask = (unsigned char*)&mask; > > + for (int i = 0; i < sizeof(T); i++) > > + { > > + if (ptr_mask[i] == 0x00) > > + { > > + ptr_f[i] = 0xff; > > + } > > + } > > +} > > + > > +void > > +test01() > > +{ > > + long double f = 0.5f; // long double may contains padding on X86 > > + fill_padding(f); > > + std::atomic<long double> as{ f }; // padding cleared on constructor > > + long double t = 1.5; > > + > > + as.fetch_add(t); > > + long double s = f + t; > > + t = as.load(); > > + VERIFY(s == t); // padding ignored on float comparing > > + fill_padding(s); > > + VERIFY(as.compare_exchange_weak(s, f)); // padding cleared on cmpexchg > > + fill_padding(f); > > + VERIFY(as.compare_exchange_strong(f, t)); // padding cleared on cmpexchg > > +} > > + > > +int main() > > +{ > > + test01(); > > +} > > diff --git a/libstdc++-v3/testsuite/lib/dg-options.exp > > b/libstdc++-v3/testsuite/lib/dg-options.exp > > index bc387d17ed7..d9a19dadd7f 100644 > > --- a/libstdc++-v3/testsuite/lib/dg-options.exp > > +++ b/libstdc++-v3/testsuite/lib/dg-options.exp > > @@ -337,6 +337,7 @@ proc add_options_for_libatomic { flags } { > > || ([istarget powerpc*-*-*] && [check_effective_target_ilp32]) > > || [istarget riscv*-*-*] > > || ([istarget sparc*-*-linux-gnu] && [check_effective_target_ilp32]) > > + || ([istarget i?86-*-*] || [istarget x86_64-*-*]) > > This seems too overkill as "dg-add-options libatomic" is not intended to > handle 16-byte atomics. Maybe we can fork this to a new dg-add-options > like "add_options_for_libatomic_16b"? > > > } { > > global TOOL_OPTIONS > > > > -- > > 2.25.1 > > -- > Xi Ruoyao <xry...@xry111.site> > School of Aerospace Science and Technology, Xidian University