diff options
| author | Paolo Bonzini <pbonzini@redhat.com> | 2020-02-21 17:20:17 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-02-25 09:18:01 +0100 |
| commit | 93c3593ad04f2610fd0a176dfa89a7e40b6afe1f (patch) | |
| tree | ec2a66d9b003ce146f45e20bdccdd5d8985d8d0e | |
| parent | cce8944cc9efab47d4bf29cfffb3470371c3541b (diff) | |
target/i386: check for empty register in FXAM
The fxam instruction returns the wrong result after fdecstp or after
an underflow. Check fptags to handle this.
Reported-by: <chengang@emindsoft.com.cn>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | target/i386/fpu_helper.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/target/i386/fpu_helper.c b/target/i386/fpu_helper.c index 99f28f267f..792a128a6d 100644 --- a/target/i386/fpu_helper.c +++ b/target/i386/fpu_helper.c @@ -991,7 +991,11 @@ void helper_fxam_ST0(CPUX86State *env) env->fpus |= 0x200; /* C1 <-- 1 */ } - /* XXX: test fptags too */ + if (env->fptags[env->fpstt]) { + env->fpus |= 0x4100; /* Empty */ + return; + } + expdif = EXPD(temp); if (expdif == MAXEXPD) { if (MANTD(temp) == 0x8000000000000000ULL) { |