softfloat: silence sNaN for conversions to/from floatx80

Conversions between IEEE floating-point formats should convert
signaling NaNs to quiet NaNs.  Most of those in QEMU's softfloat code
do so, but those for floatx80 fail to.  Fix those conversions to
silence signaling NaNs as well.

Signed-off-by: Joseph Myers <joseph@codesourcery.com>
Message-Id: <alpine.DEB.2.21.2005042336170.22972@digraph.polyomino.org.uk>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

1 files changed, 63 insertions, 0 deletions

diff --git a/tests/tcg/i386/test-i386-snan-convert.c b/tests/tcg/i386/test-i386-snan-convert.c
new file mode 100644
index 0000000..ed6d535
--- /dev/null
+++ b/tests/tcg/i386/test-i386-snan-convert.c
@@ -0,0 +1,63 @@
+/* Test conversions of signaling NaNs to and from long double.  */
+
+#include <stdint.h>
+#include <stdio.h>
+
+volatile float f_res;
+volatile double d_res;
+volatile long double ld_res;
+
+volatile float f_snan = __builtin_nansf("");
+volatile double d_snan = __builtin_nans("");
+volatile long double ld_snan = __builtin_nansl("");
+
+int issignaling_f(float x)
+{
+    union { float f; uint32_t u; } u = { .f = x };
+    return (u.u & 0x7fffffff) > 0x7f800000 && (u.u & 0x400000) == 0;
+}
+
+int issignaling_d(double x)
+{
+    union { double d; uint64_t u; } u = { .d = x };
+    return (((u.u & UINT64_C(0x7fffffffffffffff)) >
+            UINT64_C(0x7ff0000000000000)) &&
+            (u.u & UINT64_C(0x8000000000000)) == 0);
+}
+
+int issignaling_ld(long double x)
+{
+    union {
+        long double ld;
+        struct { uint64_t sig; uint16_t sign_exp; } s;
+    } u = { .ld = x };
+    return ((u.s.sign_exp & 0x7fff) == 0x7fff &&
+            (u.s.sig >> 63) != 0 &&
+            (u.s.sig & UINT64_C(0x4000000000000000)) == 0);
+}
+
+int main(void)
+{
+    int ret = 0;
+    ld_res = f_snan;
+    if (issignaling_ld(ld_res)) {
+        printf("FAIL: float -> long double\n");
+        ret = 1;
+    }
+    ld_res = d_snan;
+    if (issignaling_ld(ld_res)) {
+        printf("FAIL: double -> long double\n");
+        ret = 1;
+    }
+    f_res = ld_snan;
+    if (issignaling_d(f_res)) {
+        printf("FAIL: long double -> float\n");
+        ret = 1;
+    }
+    d_res = ld_snan;
+    if (issignaling_d(d_res)) {
+        printf("FAIL: long double -> double\n");
+        ret = 1;
+    }
+    return ret;
+}