gnu/packages/patches/smalltalk-multiplication-overflow.patch

   1 Extracted from this commit without the ChangeLog to avoid conflicts:
   2 http://git.savannah.gnu.org/cgit/smalltalk.git/commit/?id=72ada189aba0283c551ead16635c1983968080b8
   3
   4 The upstream commit message is
   5 From 72ada189aba0283c551ead16635c1983968080b8 Mon Sep 17 00:00:00 2001
   6 From: Holger Hans Peter Freyther <holger@moiji-mobile.com>
   7 Date: Sat, 7 Nov 2015 18:09:31 +0100
   8 Subject: libgst: Add alternative multiplication overflow check
   9
  10 Apple clang on OSX and the version on FreeBSD optimize the
  11 multiplication check away. Clang introduced a family of
  12 builtins to do the multiplication and check for the overflow
  13 and GCC made the API usable. For clang we would need to know
  14 if intptr_t is of type int, long int, long long int and
  15 then use the smul, smull smulll.
  16 Luckily clang is adopting the better interface and this is
  17 what we are starting to use now. This means the new code
  18 will be used on GCC5 (and later) and some future versions of
  19 clang.
  20
  21 2015-11-07  Holger Hans Peter Freyther  <holger@freyther.de>
  22
  23         * build-aux/overflow-builtins.m4: Add new macro.
  24         * configure.ac: Use GST_C_OVERFLOW_BUILTINS macro.
  25
  26 2015-11-07  Holger Hans Peter Freyther  <holger@freyther.de>
  27
  28         * interp.inl: Add alternative mul_with_check implementation.
  29 ---
  30  ChangeLog                      |  5 +++++
  31  build-aux/overflow-builtins.m4 | 23 +++++++++++++++++++++++
  32  configure.ac                   |  1 +
  33  libgst/ChangeLog               |  4 ++++
  34  libgst/interp.inl              | 22 ++++++++++++++++++++++
  35  5 files changed, 55 insertions(+)
  36  create mode 100644 build-aux/overflow-builtins.m4
  37
  38 diff --git a/build-aux/overflow-builtins.m4 b/build-aux/overflow-builtins.m4
  39 new file mode 100644
  40 index 00000000..9d050196
  41 --- /dev/null
  42 +++ b/build-aux/overflow-builtins.m4
  43 @@ -0,0 +1,23 @@
  44 +dnl Check whether the host supports synchronization builtins.
  45 +
  46 +AC_DEFUN([GST_C_OVERFLOW_BUILTINS], [
  47 +  AC_REQUIRE([AC_CANONICAL_HOST])
  48 +  AC_CACHE_CHECK([whether the host supports __builtin_mul_overflow],
  49 +                 gst_cv_have_builtin_mul_overflow, [
  50 +    save_CFLAGS="$CFLAGS"
  51 +    case $host in
  52 +      i?86-apple-darwin*) ;;
  53 +      i?86-*-*) CFLAGS="$CFLAGS -march=i486" ;;
  54 +    esac
  55 +    AC_LINK_IFELSE([AC_LANG_PROGRAM([[int foovar = 0;]], [[
  56 +if (__builtin_mul_overflow(44444, 55555, &foovar))
  57 +       return 23;]])],
  58 +                  [gst_cv_have_builtin_mul_overflow=yes],
  59 +                  [gst_cv_have_builtin_mul_overflow=no])
  60 +    CFLAGS="$save_CFLAGS"
  61 +  ])
  62 +  if test $gst_cv_have_builtin_mul_overflow = yes; then
  63 +    AC_DEFINE(HAVE_OVERFLOW_BUILTINS, 1,
  64 +              [Define to 1 if the host supports __builtin_*_overflow builtins])
  65 +  fi
  66 +])
  67 diff --git a/configure.ac b/configure.ac
  68 index e789be45..0bac23ef 100644
  69 --- a/configure.ac
  70 +++ b/configure.ac
  71 @@ -243,6 +243,7 @@ GST_C_SYNC_BUILTINS
  72  if test $gst_cv_have_sync_fetch_and_add = no; then
  73    AC_MSG_ERROR([Synchronization primitives not found, please use a newer compiler.])
  74  fi
  75 +GST_C_OVERFLOW_BUILTINS
  76
  77  GST_LOCK
  78  AC_SYS_LARGEFILE
  79 diff --git a/libgst/interp.inl b/libgst/interp.inl
  80 index e18e27c7..dbc631bc 100644
  81 --- a/libgst/interp.inl
  82 +++ b/libgst/interp.inl
  83 @@ -159,6 +159,27 @@ sub_with_check (OOP op1, OOP op2, mst_Boolean *overflow)
  84  OOP
  85  mul_with_check (OOP op1, OOP op2, mst_Boolean *overflow)
  86  {
  87 +#ifdef HAVE_OVERFLOW_BUILTINS
  88 +  intptr_t a = TO_INT (op1);
  89 +  intptr_t b = TO_INT (op2);
  90 +  intptr_t result;
  91 +
  92 +  if (__builtin_mul_overflow(a, b, &result))
  93 +    {
  94 +       *overflow = true;
  95 +       return FROM_INT(0);
  96 +    }
  97 +
  98 +
  99 +  if (result < MIN_ST_INT || result > MAX_ST_INT)
 100 +    {
 101 +       *overflow = true;
 102 +       return FROM_INT(0);
 103 +    }
 104 +
 105 +  *overflow = false;
 106 +  return FROM_INT(result);
 107 +#else
 108    intptr_t a = TO_INT (op1);
 109    intptr_t b = TO_INT (op2);
 110    intmax_t result = (intmax_t)a * b;
 111 @@ -188,6 +209,7 @@ mul_with_check (OOP op1, OOP op2, mst_Boolean *overflow)
 112      }
 113
 114    return FROM_INT (0);
 115 +#endif
 116  }
 117
 118  /* State of the random generator.
 119 --
 120 2.29.2
 121