math: Set fenv exceptions for several Neon routines

In most cases, we mask lanes which should not trigger exceptions with
a neutral value, then let the existing special-case handler fix them
up later. For exp and exp2 we replace the more complex special-case
handler with a simple scalar fallback. All new behaviour is tested in
runulp.sh, with a new option to pass -f to the run line. We also
extend the fenv testing to Neon log and logf, which already triggered
exceptions correctly. New behaviour is mostly hidden behind a new
config setting, WANT_SIMD_EXCEPT.

1 files changed, 16 insertions, 3 deletions

diff --git a/math/v_sinf.c b/math/v_sinf.c
index d2e18b5..ee6ed9a 100644
--- a/math/v_sinf.c
+++ b/math/v_sinf.c
@@ -24,6 +24,7 @@ static const float Poly[] = {
 #define A7 v_f32 (Poly[1])
 #define A9 v_f32 (Poly[0])
 #define RangeVal v_f32 (0x1p20f)
+#define TinyBound v_f32 (0x1p-61f)
 #define InvPi v_f32 (0x1.45f306p-2f)
 #define Shift v_f32 (0x1.8p+23f)
 #define AbsMask v_u32 (0x7fffffff)
@@ -41,11 +42,23 @@ v_f32_t
 V_NAME(sinf) (v_f32_t x)
 {
   v_f32_t n, r, r2, y;
-  v_u32_t sign, odd, cmp;
+  v_u32_t sign, odd, cmp, ir;
 
-  r = v_as_f32_u32 (v_as_u32_f32 (x) & AbsMask);
+  ir = v_as_u32_f32 (x) & AbsMask;
+  r = v_as_f32_u32 (ir);
   sign = v_as_u32_f32 (x) & ~AbsMask;
-  cmp = v_cond_u32 (v_as_u32_f32 (r) >= v_as_u32_f32 (RangeVal));
+
+#if WANT_SIMD_EXCEPT
+  cmp = v_cond_u32 ((ir - v_as_u32_f32 (TinyBound)
+		     >= v_as_u32_f32 (RangeVal) - v_as_u32_f32 (TinyBound)));
+  if (unlikely (v_any_u32 (cmp)))
+    /* If fenv exceptions are to be triggered correctly, set any special lanes
+       to 1 (which is neutral w.r.t. fenv). These lanes will be fixed by
+       specialcase later.  */
+    r = v_sel_f32 (cmp, v_f32 (1), r);
+#else
+  cmp = v_cond_u32 (ir >= v_as_u32_f32 (RangeVal));
+#endif
 
   /* n = rint(|x|/pi) */
   n = v_fma_f32 (InvPi, r, Shift);