122 lines
3.8 KiB
Diff
122 lines
3.8 KiB
Diff
Extracted from this commit without the ChangeLog to avoid conflicts:
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http://git.savannah.gnu.org/cgit/smalltalk.git/commit/?id=72ada189aba0283c551ead16635c1983968080b8
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The upstream commit message is
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From 72ada189aba0283c551ead16635c1983968080b8 Mon Sep 17 00:00:00 2001
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From: Holger Hans Peter Freyther <holger@moiji-mobile.com>
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Date: Sat, 7 Nov 2015 18:09:31 +0100
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Subject: libgst: Add alternative multiplication overflow check
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Apple clang on OSX and the version on FreeBSD optimize the
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multiplication check away. Clang introduced a family of
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builtins to do the multiplication and check for the overflow
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and GCC made the API usable. For clang we would need to know
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if intptr_t is of type int, long int, long long int and
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then use the smul, smull smulll.
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Luckily clang is adopting the better interface and this is
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what we are starting to use now. This means the new code
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will be used on GCC5 (and later) and some future versions of
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clang.
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2015-11-07 Holger Hans Peter Freyther <holger@freyther.de>
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* build-aux/overflow-builtins.m4: Add new macro.
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* configure.ac: Use GST_C_OVERFLOW_BUILTINS macro.
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2015-11-07 Holger Hans Peter Freyther <holger@freyther.de>
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* interp.inl: Add alternative mul_with_check implementation.
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---
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ChangeLog | 5 +++++
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build-aux/overflow-builtins.m4 | 23 +++++++++++++++++++++++
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configure.ac | 1 +
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libgst/ChangeLog | 4 ++++
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libgst/interp.inl | 22 ++++++++++++++++++++++
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5 files changed, 55 insertions(+)
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create mode 100644 build-aux/overflow-builtins.m4
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diff --git a/build-aux/overflow-builtins.m4 b/build-aux/overflow-builtins.m4
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new file mode 100644
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index 00000000..9d050196
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--- /dev/null
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+++ b/build-aux/overflow-builtins.m4
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@@ -0,0 +1,23 @@
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+dnl Check whether the host supports synchronization builtins.
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+
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+AC_DEFUN([GST_C_OVERFLOW_BUILTINS], [
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+ AC_REQUIRE([AC_CANONICAL_HOST])
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+ AC_CACHE_CHECK([whether the host supports __builtin_mul_overflow],
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+ gst_cv_have_builtin_mul_overflow, [
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+ save_CFLAGS="$CFLAGS"
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+ case $host in
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+ i?86-apple-darwin*) ;;
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+ i?86-*-*) CFLAGS="$CFLAGS -march=i486" ;;
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+ esac
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+ AC_LINK_IFELSE([AC_LANG_PROGRAM([[int foovar = 0;]], [[
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+if (__builtin_mul_overflow(44444, 55555, &foovar))
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+ return 23;]])],
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+ [gst_cv_have_builtin_mul_overflow=yes],
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+ [gst_cv_have_builtin_mul_overflow=no])
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+ CFLAGS="$save_CFLAGS"
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+ ])
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+ if test $gst_cv_have_builtin_mul_overflow = yes; then
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+ AC_DEFINE(HAVE_OVERFLOW_BUILTINS, 1,
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+ [Define to 1 if the host supports __builtin_*_overflow builtins])
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+ fi
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+])
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diff --git a/configure.ac b/configure.ac
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index e789be45..0bac23ef 100644
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--- a/configure.ac
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+++ b/configure.ac
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@@ -243,6 +243,7 @@ GST_C_SYNC_BUILTINS
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if test $gst_cv_have_sync_fetch_and_add = no; then
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AC_MSG_ERROR([Synchronization primitives not found, please use a newer compiler.])
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fi
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+GST_C_OVERFLOW_BUILTINS
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GST_LOCK
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AC_SYS_LARGEFILE
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diff --git a/libgst/interp.inl b/libgst/interp.inl
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index e18e27c7..dbc631bc 100644
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--- a/libgst/interp.inl
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+++ b/libgst/interp.inl
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@@ -159,6 +159,27 @@ sub_with_check (OOP op1, OOP op2, mst_Boolean *overflow)
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OOP
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mul_with_check (OOP op1, OOP op2, mst_Boolean *overflow)
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{
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+#ifdef HAVE_OVERFLOW_BUILTINS
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+ intptr_t a = TO_INT (op1);
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+ intptr_t b = TO_INT (op2);
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+ intptr_t result;
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+
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+ if (__builtin_mul_overflow(a, b, &result))
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+ {
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+ *overflow = true;
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+ return FROM_INT(0);
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+ }
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+
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+
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+ if (result < MIN_ST_INT || result > MAX_ST_INT)
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+ {
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+ *overflow = true;
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+ return FROM_INT(0);
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+ }
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+
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+ *overflow = false;
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+ return FROM_INT(result);
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+#else
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intptr_t a = TO_INT (op1);
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intptr_t b = TO_INT (op2);
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intmax_t result = (intmax_t)a * b;
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@@ -188,6 +209,7 @@ mul_with_check (OOP op1, OOP op2, mst_Boolean *overflow)
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}
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return FROM_INT (0);
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+#endif
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}
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/* State of the random generator.
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--
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2.29.2
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