| Message ID | 1422459650-12490-1-git-send-email-libhu.so@gmail.com |
|---|---|
| State | New |
| Headers | show |
On 28 January 2015 at 15:40, Xiangyu Hu <libhu.so@gmail.com> wrote: > While FMULX returns a 2.0f float when two operators are infinity and > zero, those operators should be unpacked from raw inputs first. Inconsistent > cases would occur when operators are denormalized floats in flush-to-zero > mode. A wrong codepath will be entered and 2.0f will not be returned > without this patch. > Fix by checking whether inputs need to be flushed before running into > different codepaths. > > Signed-off-by: Xiangyu Hu <libhu.so@gmail.com> Applied to target-arm.next, thanks. It looks like we have equivalent bugs in the FRECPS and FRSQRTS instructions... -- PMM
diff --git a/target-arm/helper-a64.c b/target-arm/helper-a64.c index 81066ca..ebd9247 100644 --- a/target-arm/helper-a64.c +++ b/target-arm/helper-a64.c @@ -135,6 +135,9 @@ float32 HELPER(vfp_mulxs)(float32 a, float32 b, void *fpstp) { float_status *fpst = fpstp; + a = float32_squash_input_denormal(a, fpst); + b = float32_squash_input_denormal(b, fpst); + if ((float32_is_zero(a) && float32_is_infinity(b)) || (float32_is_infinity(a) && float32_is_zero(b))) { /* 2.0 with the sign bit set to sign(A) XOR sign(B) */ @@ -148,6 +151,9 @@ float64 HELPER(vfp_mulxd)(float64 a, float64 b, void *fpstp) { float_status *fpst = fpstp; + a = float64_squash_input_denormal(a, fpst); + b = float64_squash_input_denormal(b, fpst); + if ((float64_is_zero(a) && float64_is_infinity(b)) || (float64_is_infinity(a) && float64_is_zero(b))) { /* 2.0 with the sign bit set to sign(A) XOR sign(B) */
While FMULX returns a 2.0f float when two operators are infinity and zero, those operators should be unpacked from raw inputs first. Inconsistent cases would occur when operators are denormalized floats in flush-to-zero mode. A wrong codepath will be entered and 2.0f will not be returned without this patch. Fix by checking whether inputs need to be flushed before running into different codepaths. Signed-off-by: Xiangyu Hu <libhu.so@gmail.com> --- target-arm/helper-a64.c | 6 ++++++ 1 file changed, 6 insertions(+)