text: /*
   * Copyright (C) 2008 The Android Open Source Project
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *  * Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   *  * Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
   * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
   * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  
  /* This file contains dummy references to libgcc.a functions to force the
   * dynamic linker to copy their definition into the final libc.so binary.
   *
   * They are required to ensure backwards binary compatibility with
   * Android 1.5, 1.6 and even 3.0  system images. Some applications built
   * using the NDK require them to be here.
   *
   * Now, for a more elaborate description of the issue:
   *
   * libgcc.a is a compiler-specific library containing various helper
   * functions used to implement certain operations that are not necessarily
   * supported by the target CPU. For example, integer division doesn't have a
   * corresponding CPU instruction on ARMv5, and is instead implemented in the
   * compiler-generated machine code as a call to an __idiv helper function.
   *
   * Normally, one has to place libgcc.a in the link command used to generate
   * target binaries (shared libraries and executables) after all objects and
   * static libraries, but before dependent shared libraries, i.e. something
   * like:
   *         gcc <options> -o libfoo.so  foo.a libgcc.a -lc -lm
   *
   * This ensures that any helper function needed by the code in foo.a is copied
   * into the final libfoo.so. Unfortunately, the Android build system has been
   * using this instead:
   *
   *         gcc <options> -o libfoo.so foo.a -lc -lm libgcc.a
   *
   * The problem with this is that if one helper function needed by foo.a has
   * already been copied into libc.so or libm.so, then nothing will be copied
   * into libfoo.so. Instead, a symbol import definition will be added to it
   * so libfoo.so can directly call the one in libc.so at runtime.
   *
   * When changing toolchains for 2.0, the set of helper functions copied to
   * libc.so changed, which resulted in some native shared libraries generated
   * with the NDK to fail to load properly.
   *
   * The NDK has been fixed after 1.6_r1 to use the correct link command, so
   * any native shared library generated with it should now be safe from that
   * problem. On the other hand, existing shared libraries distributed with
   * applications that were generated with a previous version of the NDK
   * still need all 1.5/1.6 helper functions in libc.so and libn.so
   *
   * After 3.2, the toolchain was updated again, adding __aeabi_f2uiz to the
   * list of requirements. Technically, this is due to mis-linked NDK libraries
   * but it is easier to add a single function here than asking several app
   * developers to fix their build.
   *
   * Final note: some of the functions below should really be in libm.so to
   *             completely reflect the state of 1.5/1.6 system images. However,
   *             since libm.so depends on libc.so, it's easier to put all of
   *             these in libc.so instead, since the dynamic linker will always
   *             search in libc.so before libm.so for dependencies.
   */
  
  #define   COMPAT_FUNCTIONS_LIST \
      XX(__adddf3)             \
      XX(__addsf3)             \
      XX(__aeabi_cdcmpeq)      \
      XX(__aeabi_cdcmple)      \
      XX(__aeabi_cdrcmple)     \
      XX(__aeabi_d2f)          \
      XX(__aeabi_d2iz)         \
      XX(__aeabi_dadd)         \
      XX(__aeabi_dcmpeq)       \
      XX(__aeabi_dcmpge)       \
      XX(__aeabi_dcmpgt)       \
      XX(__aeabi_dcmple)       \
      XX(__aeabi_dcmplt)       \
      XX(__aeabi_dcmpun)       \
      XX(__aeabi_ddiv)         \
      XX(__aeabi_dmul)         \
      XX(__aeabi_drsub)        \
      XX(__aeabi_dsub)         \
      XX(__aeabi_f2d)          \
      XX(__aeabi_f2iz)         \
      XX(__aeabi_f2uiz)        \
      XX(__aeabi_fadd)         \
      XX(__aeabi_fcmpun)       \
      XX(__aeabi_fdiv)         \
      XX(__aeabi_fmul)         \
      XX(__aeabi_frsub)        \
      XX(__aeabi_fsub)         \
      XX(__aeabi_i2d)          \
      XX(__aeabi_i2f)          \
      XX(__aeabi_l2d)          \
      XX(__aeabi_l2f)          \
      XX(__aeabi_lmul)         \
      XX(__aeabi_ui2d)         \
      XX(__aeabi_ui2f)         \
      XX(__aeabi_ul2d)         \
      XX(__aeabi_ul2f)         \
      XX(__cmpdf2)             \
      XX(__divdf3)             \
      XX(__divsf3)             \
      XX(__eqdf2)             \
      XX(__extendsfdf2)        \
      XX(__fixdfsi)            \
      XX(__fixsfsi)            \
      XX(__floatdidf)          \
      XX(__floatdisf)          \
      XX(__floatsidf)          \
      XX(__floatsisf)          \
      XX(__floatundidf)        \
      XX(__floatundisf)        \
      XX(__floatunsidf)        \
      XX(__floatunsisf)        \
      XX(__gedf2)              \
      XX(__gtdf2)              \
      XX(__ledf2)              \
      XX(__ltdf2)              \
      XX(__muldf3)             \
      XX(__muldi3)             \
      XX(__mulsf3)             \
      XX(__nedf2)              \
      XX(__subdf3)             \
      XX(__subsf3)             \
      XX(__truncdfsf2)         \
      XX(__unorddf2)           \
      XX(__unordsf2)           \
  
  #define  XX(f)    extern void f(void);
  COMPAT_FUNCTIONS_LIST
  #undef XX
  
  void  __bionic_libgcc_compat_hooks(void)
  {
  #define XX(f)    f();
  COMPAT_FUNCTIONS_LIST
  #undef XX
  }
  