diff options
| -rw-r--r-- | target/s390x/fpu_helper.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/target/s390x/fpu_helper.c b/target/s390x/fpu_helper.c index dcad9c367a..64efab72a4 100644 --- a/target/s390x/fpu_helper.c +++ b/target/s390x/fpu_helper.c @@ -64,6 +64,19 @@ static void handle_exceptions(CPUS390XState *env, uintptr_t retaddr) s390_exc = s390_softfloat_exc_to_ieee(qemu_exc); /* + * IEEE-Underflow exception recognition exists if a tininess condition + * (underflow) exists and + * - The mask bit in the FPC is zero and the result is inexact + * - The mask bit in the FPC is one + * So tininess conditions that are not inexact don't trigger any + * underflow action in case the mask bit is not one. + */ + if (!(s390_exc & S390_IEEE_MASK_INEXACT) && + !((env->fpc >> 24) & S390_IEEE_MASK_UNDERFLOW)) { + s390_exc &= ~S390_IEEE_MASK_UNDERFLOW; + } + + /* * FIXME: * 1. Right now, all inexact conditions are inidicated as * "truncated" (0) and never as "incremented" (1) in the DXC. |