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      1 // Control various target specific ABI tweaks.  ARM version.
      2 
      3 // Copyright (C) 2004-2024 Free Software Foundation, Inc.
      4 //
      5 // This file is part of the GNU ISO C++ Library.  This library is free
      6 // software; you can redistribute it and/or modify it under the
      7 // terms of the GNU General Public License as published by the
      8 // Free Software Foundation; either version 3, or (at your option)
      9 // any later version.
     10 
     11 // This library is distributed in the hope that it will be useful,
     12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
     13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     14 // GNU General Public License for more details.
     15 
     16 // Under Section 7 of GPL version 3, you are granted additional
     17 // permissions described in the GCC Runtime Library Exception, version
     18 // 3.1, as published by the Free Software Foundation.
     19 
     20 // You should have received a copy of the GNU General Public License and
     21 // a copy of the GCC Runtime Library Exception along with this program;
     22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
     23 // <http://www.gnu.org/licenses/>.
     24 
     25 /** @file bits/cxxabi_tweaks.h
     26  *  This is an internal header file, included by other library headers.
     27  *  Do not attempt to use it directly. @headername{cxxabi.h}
     28  */
     29 
     30 #ifndef _CXXABI_TWEAKS_H
     31 #define _CXXABI_TWEAKS_H 1
     32 
     33 #ifdef __cplusplus
     34 namespace __cxxabiv1
     35 {
     36   extern "C"
     37   {
     38 #endif
     39 
     40 #ifdef __ARM_EABI__
     41   // The ARM EABI uses the least significant bit of a 32-bit
     42   // guard variable.
     43 #define _GLIBCXX_GUARD_TEST(x) ((*(x) & 1) != 0)
     44 #define _GLIBCXX_GUARD_SET(x) *(x) = 1
     45 #define _GLIBCXX_GUARD_BIT 1
     46 #define _GLIBCXX_GUARD_PENDING_BIT __guard_test_bit (1, 1)
     47 #define _GLIBCXX_GUARD_WAITING_BIT __guard_test_bit (2, 1)
     48   typedef int __guard;
     49 
     50 #define _GLIBCXX_GUARD_TEST_AND_ACQUIRE(x) \
     51   ((__atomic_load_n(x, __ATOMIC_ACQUIRE) & 1) != 0)
     52 #define _GLIBCXX_GUARD_SET_AND_RELEASE(x) \
     53   __atomic_store_n(x, 1, __ATOMIC_RELEASE)
     54 
     55   // We also want the element size in array cookies.
     56 #define _GLIBCXX_ELTSIZE_IN_COOKIE 1
     57 
     58   // __cxa_vec_ctor should return a pointer to the array.
     59   typedef void * __cxa_vec_ctor_return_type;
     60 #define _GLIBCXX_CXA_VEC_CTOR_RETURN(x) return x
     61   // Constructors and destructors return the "this" pointer.
     62   typedef void * __cxa_cdtor_return_type;
     63 
     64 #else // __ARM_EABI__
     65 
     66   // The generic ABI uses the first byte of a 64-bit guard variable.
     67 #define _GLIBCXX_GUARD_TEST(x) (*(char *) (x) != 0)
     68 #define _GLIBCXX_GUARD_SET(x) *(char *) (x) = 1
     69 #define _GLIBCXX_GUARD_BIT __guard_test_bit (0, 1)
     70 #define _GLIBCXX_GUARD_PENDING_BIT __guard_test_bit (1, 1)
     71 #define _GLIBCXX_GUARD_WAITING_BIT __guard_test_bit (2, 1)
     72   __extension__ typedef int __guard __attribute__((mode (__DI__)));
     73 
     74   // __cxa_vec_ctor has void return type.
     75   typedef void __cxa_vec_ctor_return_type;
     76 #define _GLIBCXX_CXA_VEC_CTOR_RETURN(x) return
     77   // Constructors and destructors do not return a value.
     78   typedef void __cxa_cdtor_return_type;
     79 
     80 #endif //!__ARM_EABI__
     81 
     82 #ifdef __cplusplus
     83   }
     84 } // namespace __cxxabiv1
     85 #endif
     86 
     87 #endif
     88