Fix FMULX not squashing denormalized inputs when FZ is set.

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 <[email protected]>
Message-id: 1422459650[email protected]
Signed-off-by: Peter Maydell <[email protected]>

diff --git a/target-arm/helper-a64.c b/target-arm/helper-a64.c
index 81066ca936e85e9cd87340edb740151ba666bf4d..ebd9247f6ce023b1e38e043a9d96ce22fad0771f 100644 (file)
--- 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) */