target-arm: Squash input denormals in FRECPS and FRSQRTS

The helper functions for FRECPS and FRSQRTS have special case
handling that includes checks for zero inputs, so squash input
denormals if necessary before those checks. This fixes incorrect
output when the FPCR DZ bit is set to enable squashing of input
denormals.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Tested-by: Laurent Desnogues <laurent.desnogues@gmail.com>

diff --git a/target-arm/helper-a64.c b/target-arm/helper-a64.c
index ebd9247f6ce023b1e38e043a9d96ce22fad0771f..8aa40e9763ca03b1c5db2e15612f013db54d336a 100644 (file)
--- a/target-arm/helper-a64.c
+++ b/target-arm/helper-a64.c
@@ -229,6 +229,9 @@ float32 HELPER(recpsf_f32)(float32 a, float32 b, void *fpstp)
 {
     float_status *fpst = fpstp;
 
+    a = float32_squash_input_denormal(a, fpst);
+    b = float32_squash_input_denormal(b, fpst);
+
     a = float32_chs(a);
     if ((float32_is_infinity(a) && float32_is_zero(b)) ||
         (float32_is_infinity(b) && float32_is_zero(a))) {
@@ -241,6 +244,9 @@ float64 HELPER(recpsf_f64)(float64 a, float64 b, void *fpstp)
 {
     float_status *fpst = fpstp;
 
+    a = float64_squash_input_denormal(a, fpst);
+    b = float64_squash_input_denormal(b, fpst);
+
     a = float64_chs(a);
     if ((float64_is_infinity(a) && float64_is_zero(b)) ||
         (float64_is_infinity(b) && float64_is_zero(a))) {
@@ -253,6 +259,9 @@ float32 HELPER(rsqrtsf_f32)(float32 a, float32 b, void *fpstp)
 {
     float_status *fpst = fpstp;
 
+    a = float32_squash_input_denormal(a, fpst);
+    b = float32_squash_input_denormal(b, fpst);
+
     a = float32_chs(a);
     if ((float32_is_infinity(a) && float32_is_zero(b)) ||
         (float32_is_infinity(b) && float32_is_zero(a))) {
@@ -265,6 +274,9 @@ float64 HELPER(rsqrtsf_f64)(float64 a, float64 b, void *fpstp)
 {
     float_status *fpst = fpstp;
 
+    a = float64_squash_input_denormal(a, fpst);
+    b = float64_squash_input_denormal(b, fpst);
+
     a = float64_chs(a);
     if ((float64_is_infinity(a) && float64_is_zero(b)) ||
         (float64_is_infinity(b) && float64_is_zero(a))) {