c-family:

	* c-opts.c (c_common_post_options): Set -ffp-contract=off in C
	standards modes.
	* c-cppbuiltin.c (cpp_iec_559_value): Consider -ffp-contract=fast
	to mean lack of IEEE 754 support.

testsuite:
	* gcc.dg/torture/c99-contract-1.c: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@204460 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 8 insertions, 5 deletions

diff --git a/gcc/c-family/c-cppbuiltin.c b/gcc/c-family/c-cppbuiltin.c
index 61a124c509c..b9a0f18cd7e 100644
--- a/gcc/c-family/c-cppbuiltin.c
+++ b/gcc/c-family/c-cppbuiltin.c
@@ -726,16 +726,19 @@ cpp_iec_559_value (void)
     ret = 0;
 
   /* In strict C standards conformance mode, consider unpredictable
-     excess precision to mean lack of IEEE 754 support.  ??? The same
-     should apply to unpredictable contraction, but at present
-     standards conformance options do not enable conforming
-     contraction.  For C++, and outside strict conformance mode, do
-     not consider these options to mean lack of IEEE 754 support.  */
+     excess precision to mean lack of IEEE 754 support.  The same
+     applies to unpredictable contraction.  For C++, and outside
+     strict conformance mode, do not consider these options to mean
+     lack of IEEE 754 support.  */
   if (flag_iso
       && !c_dialect_cxx ()
       && TARGET_FLT_EVAL_METHOD != 0
       && flag_excess_precision_cmdline != EXCESS_PRECISION_STANDARD)
     ret = 0;
+  if (flag_iso
+      && !c_dialect_cxx ()
+      && flag_fp_contract_mode == FP_CONTRACT_FAST)
+    ret = 0;
 
   /* Various options are contrary to IEEE 754 semantics.  */
   if (flag_unsafe_math_optimizations