PR middle-end/36578

	* convert.c (convert_to_real): Do not optimize conversions of
	binary arithmetic operations between binary and decimal
	floating-point types.  Consider mode of target type in determining
	decimal type for arithmetic.  Unless
	flag_unsafe_math_optimizations, do not optimize binary conversions
	where this may change rounding behavior.
	* real.c (real_can_shorten_arithmetic): New.
	* real.h (real_can_shorten_arithmetic): Declare.

testsuite:
	* gcc.dg/dfp/convert-bfp-13.c, gcc.dg/dfp/convert-bfp-14.c,
	gcc.dg/dfp/convert-dfp-fold-2.c, gcc.target/i386/pr36578-1.c,
	gcc.target/i386/pr36578-2.c: New tests.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@141432 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 22 insertions, 0 deletions

diff --git a/gcc/testsuite/gcc.target/i386/pr36578-1.c b/gcc/testsuite/gcc.target/i386/pr36578-1.c
new file mode 100644
index 00000000000..cae0d708837
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr36578-1.c
@@ -0,0 +1,22 @@
+/* Test for unsafe floating-point conversions.  PR 36578.  */
+/* { dg-do run } */
+/* { dg-options "-msse2 -mfpmath=sse" } */
+
+#include "sse2-check.h"
+
+extern void abort (void);
+extern void exit (int);
+extern int printf(const char *, ...);
+
+volatile double d1 = 1.0;
+volatile double d2 = 0x1.00001p-53;
+volatile double d3;
+
+static void
+sse2_test (void)
+{
+  d3 = (double)((long double)d1 + (long double)d2);
+  if (d3 != d1)
+    abort ();
+  exit (0);
+}