On Thu, Dec 19, 2013 at 10:00:18PM +0000, Peter Maydell wrote:
> We implement a number of float-to-integer conversions using conversion
> to an integer type with a wider range and then a check against the
> narrower range we are actually converting to. If we find the result to
> be out of range we correctly raise the Invalid exception, but we must
> also suppress other exceptions which might have been raised by the
> conversion function we called.
>
> This won't throw away exceptions we should have preserved, because for
> the 'core' exception flags the IEEE spec mandates that the only valid
> combinations of exception that can be raised by a single operation are
> Inexact + Overflow and Inexact + Underflow. For the non-IEEE softfloat
> flag for input denormals, we can guarantee that that flag won't have
> been set for out of range float-to-int conversions because a squashed
> denormal by definition goes to plus or minus zero, which is always in
> range after conversion to integer zero.
>
> This bug has been fixed for some of the float-to-int conversion routines
> by previous patches; fix it for the remaining functions as well, so
> that they all restore the pre-conversion status flags prior to raising
> Invalid.
>
> Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
> ---
> NB that I've worded the commit message on the assumption that the
> patches Tom Musta has written for PPC bugs go in first; as it happens
> the patches don't actually conflict, though.
>
> Some of these fix wrong-exception-flags bugs in 32 bit ARM VCVT.
>
> fpu/softfloat.c | 28 ++++++++++++++++------------
> 1 file changed, 16 insertions(+), 12 deletions(-)
>
> diff --git a/fpu/softfloat.c b/fpu/softfloat.c
> index dbda61b..253e6b3 100644
> --- a/fpu/softfloat.c
> +++ b/fpu/softfloat.c
> @@ -6432,17 +6432,18 @@ uint32 float32_to_uint32( float32 a STATUS_PARAM )
> {
> int64_t v;
> uint32 res;
> + int old_exc_flags = get_float_exception_flags(status);
>
> v = float32_to_int64(a STATUS_VAR);
> if (v < 0) {
> res = 0;
> - float_raise( float_flag_invalid STATUS_VAR);
> } else if (v > 0xffffffff) {
> res = 0xffffffff;
> - float_raise( float_flag_invalid STATUS_VAR);
> } else {
> - res = v;
> + return v;
> }
> + set_float_exception_flags(old_exc_flags, status);
> + float_raise(float_flag_invalid STATUS_VAR);
> return res;
> }
>
> @@ -6450,17 +6451,18 @@ uint32 float32_to_uint32_round_to_zero( float32 a
> STATUS_PARAM )
> {
> int64_t v;
> uint32 res;
> + int old_exc_flags = get_float_exception_flags(status);
>
> v = float32_to_int64_round_to_zero(a STATUS_VAR);
> if (v < 0) {
> res = 0;
> - float_raise( float_flag_invalid STATUS_VAR);
> } else if (v > 0xffffffff) {
> res = 0xffffffff;
> - float_raise( float_flag_invalid STATUS_VAR);
> } else {
> - res = v;
> + return v;
> }
> + set_float_exception_flags(old_exc_flags, status);
> + float_raise(float_flag_invalid STATUS_VAR);
> return res;
> }
>
> @@ -6468,17 +6470,18 @@ uint_fast16_t float32_to_uint16_round_to_zero(float32
> a STATUS_PARAM)
> {
> int64_t v;
> uint_fast16_t res;
> + int old_exc_flags = get_float_exception_flags(status);
>
> v = float32_to_int64_round_to_zero(a STATUS_VAR);
> if (v < 0) {
> res = 0;
> - float_raise( float_flag_invalid STATUS_VAR);
> } else if (v > 0xffff) {
> res = 0xffff;
> - float_raise( float_flag_invalid STATUS_VAR);
> } else {
> - res = v;
> + return v;
> }
> + set_float_exception_flags(old_exc_flags, status);
> + float_raise(float_flag_invalid STATUS_VAR);
> return res;
> }
>
> @@ -6522,17 +6525,18 @@ uint_fast16_t float64_to_uint16_round_to_zero(float64
> a STATUS_PARAM)
> {
> int64_t v;
> uint_fast16_t res;
> + int old_exc_flags = get_float_exception_flags(status);
>
> v = float64_to_int64_round_to_zero(a STATUS_VAR);
> if (v < 0) {
> res = 0;
> - float_raise( float_flag_invalid STATUS_VAR);
> } else if (v > 0xffff) {
> res = 0xffff;
> - float_raise( float_flag_invalid STATUS_VAR);
> } else {
> - res = v;
> + return v;
> }
> + set_float_exception_flags(old_exc_flags, status);
> + float_raise(float_flag_invalid STATUS_VAR);
> return res;
> }
>
Reviewed-by: Aurelien Jarno <aurel...@aurel32.net>
--
Aurelien Jarno GPG: 1024D/F1BCDB73
aurel...@aurel32.net http://www.aurel32.net
