Fix packetmath_1 float tests for arm/aarch64.

Added missing `pmadd<Packet2f>` for NEON. This leads to significant
improvement in precision than previous `pmul+padd`, which was causing
the `pcos` tests to fail. Also added an approx test with
`std::sin`/`std::cos` since otherwise returning any `a^2+b^2=1` would
pass.

Modified `log(denorm)` tests.  Denorms are not always supported by all
systems (returns `::min`), are always flushed to zero on 32-bit arm,
and configurably flush to zero on sse/avx/aarch64. This leads to
inconsistent results across different systems (i.e. `-inf` vs `nan`).
Added a check for existence and exclude ARM.

Removed logistic exactness test, since scalar and vectorized versions
follow different code-paths due to differences in `pexp` and `pmadd`,
which result in slightly different values. For example, exactness always
fails on arm, aarch64, and altivec.

1 files changed, 16 insertions, 8 deletions

diff --git a/test/packetmath.cpp b/test/packetmath.cpp
index a57a3b6a5..72a9c8d51 100644
--- a/test/packetmath.cpp
+++ b/test/packetmath.cpp
@@ -8,6 +8,7 @@
 // Public License v. 2.0. If a copy of the MPL was not distributed
 // with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+#include <limits>
 #include "packetmath_test_shared.h"
 
 template <typename T>
@@ -666,9 +667,6 @@ void packetmath_real() {
     h.store(data2, logistic.packetOp(h.load(data1)));
     for (int i = 0; i < PacketSize; ++i) {
       VERIFY_IS_APPROX(data2[i], logistic(data1[i]));
-#ifdef EIGEN_VECTORIZE  // don't check for exactness when using the i387 FPU
-      VERIFY_IS_EQUAL(data2[i], logistic(data1[i]));
-#endif
     }
   }
 
@@ -702,11 +700,16 @@ void packetmath_real() {
       VERIFY_IS_EQUAL(std::log((std::numeric_limits<Scalar>::min)()), data2[0]);
       VERIFY((numext::isnan)(data2[1]));
 
-      data1[0] = std::numeric_limits<Scalar>::denorm_min();
-      data1[1] = -std::numeric_limits<Scalar>::denorm_min();
-      h.store(data2, internal::plog(h.load(data1)));
-      // VERIFY_IS_EQUAL(std::log(std::numeric_limits<Scalar>::denorm_min()), data2[0]);
-      VERIFY((numext::isnan)(data2[1]));
+      // Note: 32-bit arm always flushes denorms to zero.
+#if !EIGEN_ARCH_ARM
+      if (std::numeric_limits<Scalar>::has_denorm == std::float_denorm_style::denorm_present) {
+        data1[0] = std::numeric_limits<Scalar>::denorm_min();
+        data1[1] = -std::numeric_limits<Scalar>::denorm_min();
+        h.store(data2, internal::plog(h.load(data1)));
+        // VERIFY_IS_EQUAL(std::log(std::numeric_limits<Scalar>::denorm_min()), data2[0]);
+        VERIFY((numext::isnan)(data2[1]));
+      }
+#endif
 
       data1[0] = Scalar(-1.0f);
       h.store(data2, internal::plog(h.load(data1)));
@@ -745,6 +748,11 @@ void packetmath_real() {
           VERIFY(data2[PacketSize + 0] <= Scalar(1.) && data2[PacketSize + 0] >= Scalar(-1.));
           VERIFY(data2[PacketSize + 1] <= Scalar(1.) && data2[PacketSize + 1] >= Scalar(-1.));
 
+          VERIFY_IS_APPROX(data2[0], std::cos(data1[0]));
+          VERIFY_IS_APPROX(data2[1], std::cos(data1[1]));
+          VERIFY_IS_APPROX(data2[PacketSize + 0], std::sin(data1[0]));
+          VERIFY_IS_APPROX(data2[PacketSize + 1], std::sin(data1[1]));
+
           VERIFY_IS_APPROX(numext::abs2(data2[0]) + numext::abs2(data2[PacketSize + 0]), Scalar(1));
           VERIFY_IS_APPROX(numext::abs2(data2[1]) + numext::abs2(data2[PacketSize + 1]), Scalar(1));
         }