gcc/doc/gcc/c-implementation-defined-behavior/architecture.rst

   1 ..
   2   Copyright 1988-2022 Free Software Foundation, Inc.
   3   This is part of the GCC manual.
   4   For copying conditions, see the copyright.rst file.
   5
   6 .. _architecture-implementation:
   7
   8 Architecture
   9 ************
  10
  11 * The values or expressions assigned to the macros specified in the
  12   headers ``<float.h>``, ``<limits.h>``, and ``<stdint.h>``
  13   (C90, C99 and C11 5.2.4.2, C99 7.18.2, C99 7.18.3, C11 7.20.2, C11 7.20.3).
  14
  15   Determined by ABI.
  16
  17 * The result of attempting to indirectly access an object with
  18   automatic or thread storage duration from a thread other than the one
  19   with which it is associated (C11 6.2.4).
  20
  21   Such accesses are supported, subject to the same requirements for
  22   synchronization for concurrent accesses as for concurrent accesses to
  23   any object.
  24
  25 * The number, order, and encoding of bytes in any object
  26   (when not explicitly specified in this International Standard) (C99
  27   and C11 6.2.6.1).
  28
  29   Determined by ABI.
  30
  31 * Whether any extended alignments are supported and the contexts
  32   in which they are supported (C11 6.2.8).
  33
  34   Extended alignments up to 2^{28} (bytes) are supported for
  35   objects of automatic storage duration.  Alignments supported for
  36   objects of static and thread storage duration are determined by the
  37   ABI.
  38
  39 * Valid alignment values other than those returned by an _Alignof
  40   expression for fundamental types, if any (C11 6.2.8).
  41
  42   Valid alignments are powers of 2 up to and including 2^{28}.
  43
  44 * The value of the result of the ``sizeof`` and ``_Alignof``
  45   operators (C90 6.3.3.4, C99 and C11 6.5.3.4).
  46
  47   Determined by ABI.