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, 5 insertions, 0 deletions

diff --git a/gcc/real.h b/gcc/real.h
index 44e79c36e17..5a686536608 100644
--- a/gcc/real.h
+++ b/gcc/real.h
@@ -438,6 +438,11 @@ extern rtx const_double_from_real_value (REAL_VALUE_TYPE, enum machine_mode);
 /* Replace R by 1/R in the given machine mode, if the result is exact.  */
 extern bool exact_real_inverse (enum machine_mode, REAL_VALUE_TYPE *);
 
+/* Return true if arithmetic on values in IMODE that were promoted
+   from values in TMODE is equivalent to direct arithmetic on values
+   in TMODE.  */
+bool real_can_shorten_arithmetic (enum machine_mode, enum machine_mode);
+
 /* In tree.c: wrap up a REAL_VALUE_TYPE in a tree node.  */
 extern tree build_real (tree, REAL_VALUE_TYPE);