[Pixman] [PATCH 2/7] Add enable_fp_exceptions() function in utils.[ch]

[Søren Sandmann]

From: Søren Sandmann Pedersen <ssp at redhat.com>

This function enables floating point traps if possible.
---
 configure.ac |    8 ++++++++
 test/utils.c |   26 ++++++++++++++++++++++++++
 test/utils.h |    3 +++
 3 files changed, 37 insertions(+), 0 deletions(-)

diff --git a/configure.ac b/configure.ac
index 147e1bf..2570c84 100644
--- a/configure.ac
+++ b/configure.ac
@@ -639,6 +639,14 @@ if test x$have_getpagesize = xyes; then
    AC_DEFINE(HAVE_GETPAGESIZE, 1, [Whether we have getpagesize()])
 fi
 
+AC_CHECK_HEADER([fenv.h],
+   [AC_DEFINE(HAVE_FENV_H, [1], [Define to 1 if we have <fenv.h>])])
+
+AC_CHECK_LIB(m, feenableexcept, have_feenableexcept=yes, have_feenableexcept=no)
+if test x$have_feenableexcept = xyes; then
+   AC_DEFINE(HAVE_FEENABLEEXCEPT, 1, [Whether we have feenableexcept()])
+fi
+
 AC_CHECK_FUNC(gettimeofday, have_gettimeofday=yes, have_gettimeofday=no)
 AC_CHECK_HEADER(sys/time.h, have_sys_time_h=yes, have_sys_time_h=no)
 if test x$have_gettimeofday = xyes && test x$have_sys_time_h = xyes; then
diff --git a/test/utils.c b/test/utils.c
index f6278fe..a7c55f6 100644
--- a/test/utils.c
+++ b/test/utils.c
@@ -1,3 +1,5 @@
+#define _GNU_SOURCE
+
 #include "utils.h"
 #include <signal.h>
 
@@ -15,6 +17,10 @@
 #include <sys/mman.h>
 #endif
 
+#ifdef HAVE_FENV_H
+#include <fenv.h>
+#endif
+
 /* Random number seed
  */
 
@@ -469,6 +475,26 @@ fail_after (int seconds, const char *msg)
 #endif
 }
 
+void
+enable_fp_exceptions (void)
+{
+#ifdef HAVE_FENV_H
+#ifdef HAVE_FEENABLEEXCEPT
+    /* Note: we don't enable the FE_INEXACT trap because
+     * that happens quite commonly. It is possible that
+     * over- and underflow should similarly be considered
+     * okay, but for now the test suite passes with them
+     * enabled, and it's useful to know if they start
+     * occuring.
+     */
+    feenableexcept (FE_DIVBYZERO	|
+		    FE_INVALID		|
+		    FE_OVERFLOW		|
+		    FE_UNDERFLOW);
+#endif
+#endif
+}
+
 void *
 aligned_malloc (size_t align, size_t size)
 {
diff --git a/test/utils.h b/test/utils.h
index 2ea4170..bac2916 100644
--- a/test/utils.h
+++ b/test/utils.h
@@ -82,6 +82,9 @@ fuzzer_test_main (const char *test_name,
 void
 fail_after (int seconds, const char *msg);
 
+/* If possible, enable traps for floating point exceptions */
+void enable_fp_exceptions(void);
+
 /* A pair of macros which can help to detect corruption of
  * floating point registers after a function call. This may
  * happen if _mm_empty() call is forgotten in MMX/SSE2 fast
-- 
1.6.0.6